Evaluating The Effects of Sweet Potato Varieties On Flour Quality

Volume 8, Issue 4, April – 2023 International Journal of Innovative Science and Research Technology
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Evaluating the Effects of Sweet Potato

Varieties on Flour Quality
Mazviita Kimberly Bure
Department of Biotechnology, Chinhoyi University of Technology, Chinhoyi
Abstract:- Sweet potatoes are a highly nutritious food produce favorable samples for all treatments. Sensory
group, they continue to gain interest on account of the evaluation established that fermentation was a favored
diversity of the tuber and the number of products that pretreatment option whilst Victoria, Tsumaya and
can be developed from the tuber itself. This is true on the Chingovha were amongst the popular varieties and as
global scale, however; locally the amount of such such should be formulated into sweet potato based
products on market is minimal. Such should be available instant porridge.
to cater to gluten intolerant and celiac disease niches and
also exhaust the favorable SP production cycle. The Keywords:- Water and Oil Holding Capacity, Emulsification
overall purpose of this study is to determine the best Stability, Acceptability.
variety and treatment for flour production, for use in the
formulation of a sweet potato based instant porridge. I. INTRODUCTION
Seven varieties of sweet potato tubers: Chingovha (white
flesh), Delvia (orange flesh), Irene (yellow flesh), Victoria  Background to Study
(orange flesh), Namanga (orange flesh), Alicia (yellow The Great Famine of Ireland of 1845 to 1849 (Kianely,
flesh) and Tsumaya (pale yellow flesh) were harvested at 1997); the drastic and tumultuous crumbling of the Irish
physiological maturity and processed to flour on a lab- economy and government is termed throughout history as a
based pilot via thermal processing. The fresh tubers result of natural events. Potato blight infected all potato
were washed, sliced and treated with Ascorbic acid to crops to the point of significantly slashing the nation’s
prevent browning. Following ascorbic acid population, stirring uprisings and causing widespread unrest
pretreatment; for treatment 1 fresh tubers were dried throughout Europe (Kelly & Fotheringham, 2011). Although
immediately, slices for treatment 2 were parboiled for 10 drastic; the ‘Hard Times’ emphasized the significance of
minutes before drying whilst slices for treatment 3 were tubers and even related them to the well-standing of the
fermented prior to drying for 1-3 days in 5% brine and European economies. As the time lapsed with growing
1% sucrose solution. Post-drying: the slices were ground populations and increased food demand, this prompted
to fine powder and the flour product assessed on both further classification of crops and their relevance. A study
functional and physiochemical properties with particular was carried out (Bhattachary, 2011) in which sweet potato
emphasis for use in instant porridge formulation. A was ranked position 5 for crops that feed the world. The
Randomized Block Design was used for the experiment study concludes that Ipomoea batatas although highly under-
while sensory evaluation wase used to determine product utilized had vast potential in that it maintained agricultural
acceptability. The product was assessed according to relevance in withstanding adverse abiotic and biotic stresses,
flour quality (color, emulsification stability, oil and nutritional composition, ease of propagation, source of
water holding capacity, foreign matter and moisture subsistence, ‘famine relief’ and immense industrial value
content), treatment effect (before and after processing such as in the extraction of starch for the production of
based on protein content, starch content, phenolic animal feed. The study further emphasized the significance
content, gluten content, Beta carotene content). Together of the tuber especially relative to the nutritional composition
these parameters determined that the ideal mode of with respect to derivatives that could be attained from the
treatment for flour production was fermentation in that tuber and an outline of the ease of processing.
it exhibited the least nutritive reductive effect across all
varieties. There were significant differences (p-value) With that in mind; it is unfortunate that the vast of
between varieties with respect to flour quality amongst Africa, which contains the most developing countries
oil and water holding capacities, moisture content but (Rampa. F., 2011) , regard the crop as ‘poor person’ food,
not for emulsification stability. The most ideal treatment which as a result has caused the lag in exhausting tuber
was fermentation in that amongst the analyzed properties by means of sweet potato processing. In fact, in
parameters; the greatest nutrient retention was observed Africa from the period before 2010 the crop was mostly
for fermented samples. Tsumaya was observed to grown for subsistence through backyard farming.
IJISRT23APR1526 www.ijisrt.com 1576

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Fig 1 Sweet potato production quantity curve in Zimbabwe for the period 1998 to 2019
(Zimbabwe: Sweet potatoes production quantity (tons), 2020)
To support this, it was highlighted that during the least gelation concentration, gelatinization temperature and
period between 2005-2011 Zimbabwe’s sweet potato bulk density and moisture content. The study highlighted
production was an estimated 2% whilst China was well that some functional properties such as those that can be
above 75% (Stathers, 2018). The great gap in production found in potato and green gram flour can enhance the
yield could be attributed to the public perception of the bulk nutritional quality of value-added products, such as fat,
tuber in Africa and the large scope availability of post- vitamins and minerals. Functional characteristics are
harvest technologies in China. China attributes its large fundamental physicochemical properties which in turn
sweet potato production to the presence and means for post- provide an indication of purpose. Such include foreign
harvest processing technologies. The development of such matter, nutritional value, quality and product acceptability.
technologies has led to various processing products in
China, for example, sweet potato noodles, vermicelli and Foreign matter is used as a highlight of product purity
sheet jelly, wedges, chips, starch, flour and organic products and assessor of effect of processing. It is often identified as
including ethanol (Zhang, 2009). Contrarily the local any kind of outside contaminant introduced to a food
perception is centered largely on the bulk alone; the tuber is product at any point in its production or distribution.
mostly harvested, transacted and consumed as is and no (Dogan. H., 2010). As such foreign matter provides an
processing technologies have been publicized to date. indication of how safe the food may be for consumption by
identifying the consequence of processing. In processing
Flour is one of the products that can be harnessed from glass is common under foreign matter. For example; under
the tubers processed via thermal processing. The qualities cereal processing, foreign matter is accounted for under
that make up ‘good’ or ‘acceptable’ flour vary immensely. It refractions, of which these are to include filth and any
has been alluded that certain characteristic may be used as particles separated from product during processing: sieved
quality indicators. (Zhygunov. D., 2019) sums up and filth- particles of specific size ranges separated
estimates the quality indicators as follows: whiteness 1-71 quantitatively from product by use of sieves. (FSSAI.,
units, gluten deformation index 40-100 units, gluten content 2016).
2-36%, protein content 9.8-18.2%, ash content 0.31-2.23%
and water absorbing capacity from 53.5 – 69.7. Such  Problem Statement
information is key in using weighted average quality The onset of the year 2020 was met with wheat
indicators to comply to specific standards for and when shortages in Zimbabwe; nationwide. This in turn resulted in
grading. However, the chief indicator used in grade bread shortages and the unprecedented halts in
determination is whiteness or color acceptability. On the confectionery-based businesses, bakeries and businesses
other hand, some indicators such as ash content are alike (Demaree-Saddler. H., 2020). In response to the
significant in cereals since they control separation of brans imminent starvation; the government called for wheat
from the endosperm in assessing flour quality. substitutes from which sweet potato ranked top of the list
(FEWS NET., 2020). This however was met with reluctance
In another study (Samsher, 2013) where the functional from the public on account of how the tuber is perceived
properties of different flours were assessed between wheat locally. The bulk of Africa consume the tuber traditionally,
flour, rice flour, green gram flour and potato flour. The that is, it is harvested and consumed as is; ‘from the ground
identified functional properties evaluated included swelling to the pot’ (Mmasa. J.J., 2012). The amount of sweet potato
capacity, water absorption capacity, oil absorption capacity, derived products should be well exhausted within the
emulsion activity and stability, foam capacity and stability, national market. Such should be able to cater to many

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niches; for example, as table condiments, infant feed, animal II. MATERIAL AND METHODOLOGY
feed, vitamin supplements, beverages and so on, so much
that it substitutes and reduces the significantly high national The plant material used throughout this study:
demand on wheat and maize and their derived products. As Chingovha, Delvia, Irene, Victoria, Namanga, Alicia and
it stands there are no local product variations to the sweet Tsumaya. were grown at Chinhoyi University of
potato tuber, which highly contribute to its under-utilization Technology Farm and harvested at physiological maturity.
in developing countries, particularly in Zimbabwe. The Mature tubers were randomly picked for each cultivar.
sweet potato is harnessed, transacted and consumed as is; in
its raw unprocessed form. Granted such variations become A. Experiment 1: Flour Production
readily available, this would eventually mean; for every
wheat or maize derived product there is a sweet potato  Experiment 1: Effect of Sweet Potato Variety on Flour
equivalent; such would reduce the constraints on the current Production Quality and Yield:
mainline crops which have become subject to high demand The sweet potato tubers were washed under running
and shortages. This would mean any predicted or sudden water to remove all dirt and soil debris, care was taken not
shortages will not impact and affect the nation immensely to immerse the tubers in water for prolonged periods. The
on the account that a sweet potato product will be readily tubers were sliced transversely into slices of about 1 cm in
available in place of any maize or wheat derived product. As width. (9x) 200g of each sweet potato variety were weighed
a result, the range of consumer options will be enhanced and 3 samples assigned to treatments either 1, 2 or 3. The
which in turn will fast-track the production of more sweet initial mass was recorded and used as the wet mass for
potato products, create an all-new market and introduce a analysis. The slices were immediately transferred and
new processing avenue for sweet potatoes in Zimbabwe. pretreated in a solution of 7% Ascorbic acid for a period of
10 minutes to prevent browning (Ojeda. G. A., 2014).
Table 1 Set up of Experiment

1 2 3
Treatment Fresh Fermentation Parboiling
Number of varieties to undergo treatment 7 7 7
Replicates for each variety 3 3 3
Number of samples for each treatment 3 3 3
Total number of samples for each treatment 21 21 21
Total number of samples for each variety 9 9 9
For treatment 1 after pretreatment the slices were  Preparation of Raw Sample
transferred to an oven for thermal treatment, for treatment 2, A mass of 50g from each sample was weighed and
after pretreatment, the slices were transferred to boiling labelled accordingly. They were washed in clean water to
water for 5-10 minutes, then transferred to ice cold water to remove all soil and debris and sliced transversely into 1cm
stop the cooking process. Once cooled the slices were then width slices. The slices were pretreated in a 7% solution of
transferred to the oven for thermal treatment (Fetuga. G. O., Ascorbic acid for a period of 10 minutes after which they
2013). Lastly for treatment 3, after pretreatment the slices were chopped further finely and ground by mortar and pestle
were chopped roughly into flakes and transferred to into a fine paste. These samples were used for pre-process
anaerobic vessels for natural fermentation in 5% salt and 1% analyses.
sucrose concentration at rtp (28-30℃) for 1-3 days
(Yuliana. N., 2020) after which they were rinsed under  Preparation of Fermentation Broth Samples
running water and transferred to the oven for thermal For each fermenting sample, the fermentation broth
treatment. For all treatments the slices were dried at 60℃ was extracted at 24hr intervals and stored at 4℃ for use
(Farinu. A., 2007) until a constant mass was achieved and during analysis of fermentation kinetics.
the final mass recorded and the slices ground to fine powder.
Table 2 Sample Identification

SAMPLE ID DESCRIPTION
A Chingovha
B Delvia
C Irene
D Victoria
E Namanga
F Alicia
G Tsumaya

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 Baseline Survey for Sensory Evaluation. centrifuged at 1000g for 15 minutes. Excess oil was
The baseline survey was conducted using a decanted by inverting the tubes over tissue paper to drain for
questionnaire (Appendix 2: questionnaire). The aim of the 10 minutes, final mass measured and expressed as a
questionnaire was to collect information on the consumption percentage increase from the initial mass as used by Ladjal
of SP and assess familiarity of SP processing technology in et al (Ladjal. E. Y., 2015)
New Strathaven, Avondale in Harare. The questionnaire was
given to volunteers who upon further agreement were The OHC was Determined as follows:
provided with sensory evaluation form and flour samples
from experiment 1 for sensory analysis. This information
was used to determine the most preferred SP product that
could be formulated into an instant porridge. The
questionnaire was administered to 30 residents of New  Determination of Moisture Content
Strathaven, Avondale, Harare. Due to the COVID 19 (AOAC, 2000); 200g of each variety was weighed,
restrictions and appointed lockdowns, the panelists were treated and dried to a constant mass and the final mass
selected by means of proximity and guidelines observed and recorded. The moisture content was calculated as follows:
practiced.
III. STATISTICAL ANALYSES AND METHODS
 Determination of Flour Quality

 Determination of Foreign Matter
 Determination of the Effect of Treatment on Product (FSSAI, 2016) A mass of 50g of the flour was
Color. weighed and sieved through sieves of aperture; 600µm and
For each variety, the samples were analyzed according 710µm for each sample product.
to skin and flesh color and the overall color of the tuber for
characterization. Color software was used to determine the  Determination of Gluten content
initial color of the raw tubers using Color Picker online/ Hex Gluten content was determined using the method
Color Picker/HTML Color Picker outlined in cereal and cereal products method for analysis
(https://imagecolorpicker.com/en). (FSSAI., 2016). 10g of each sample was weighed into a dish
and a volume of water added to make a dough. The formed
 Determination of Emulsification Stability. dough was gently kept in a beaker filled with water and
Emulsification stability was observed using the visual allowed to stand for 1 hour. The dough was removed and
method as outlined by Yin Hu et al (Hu. Y. T., 2016) using placed in a piece of bolting silk cloth/ cheese cloth (with an
water and sunflower oil. 2g of each flour sample were aperture of 0.16 mm) and washed with a gentle stream of
transferred to a tube where 5ml of distilled water and 5ml of water until water passing through the silk did not give a blue
sunflower oil were added the tubes were mixed well by color with a drop of iodine solution. The silk cloth was
vortex and left to stand at rtp. Immediately after mixing, the spread tight on a porcelain plate to facilitate scraping and
timer was set to start to measure the time taken for creaming the residue collected using a blade to form a ball. Excess
or sedimentation. water was removed by forming a ball and squeezing in the
palms to remove excess water, then transferring to a petri
 Determination of WHC dish and kept in the oven at 105±1°C for drying. When
WHC was determined by transferring a 0.5g of each partially dried, the mold was removed and cut into several
flour sample into a pre-weighed centrifuge and 5ml of pieces with scissors and kept in the oven to dry then cooled
distilled water added. The samples were vortexed for 1 in a desiccator and weighed. The pieces were returned to the
minute and allowed to stand at rtp, after which they were oven for half an hour, cooled and weighed and process
centrifuged at 1000g for 15 minutes. The excess water was repeated until a constant weight was achieved. The data was
decanted by inverting the tubes over tissue paper to drain for analyzed as follows:
10 minutes, final mass measured and expressed as a
percentage increase from the initial mass (Giami. S. Y.,
1994) (Ladjal. E. Y., 2015) .
The WHC was determined as follows:  Evaluation of the Effect of Treatment on Selected
Chemical Properties
 Evaluation of Protein Content (LOWRY Method)
 Extraction of Protein from sample

 Determination of Oil Holding Capacity The protein content in raw SP was measured and
OHC was determined by transferring a 0.5g of each compared to that in the raw, fresh, parboiled and fermented
flour sample into a pre-weighed centrifuge and 5ml of
flour products using the Lowry Method (Waterbog. J H.,
distilled water added. The samples were vortexed for 1 1996). 5g of each sample were weighed and placed in
minute and allowed to stand at rtp, after which they were

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centrifuge tubes and a volume of 5ml Phosphate buffer  Evaluation of Β Carotene Content
added and the tubes vortexed for 1 minute to ensure Total Beta carotene content was extracted using
adequate mixing. The tubes were then centrifuged at x15000 ethanol at rtp (Calvo. M.M., 2006) and the concentration
rpm for 15 minutes after which the samples partitioned into determined by spectrophotometry and Beer Lambert’s Law
pellet and supernatant (used for the analysis) in which the molar extinction was used as 125.3 based on
studies (Nubel. U., 2000) (Oren. A., 1995).
 Standard Solution Preparation
50mg of BSA was dissolved in 50ml of sterile distilled  Extraction of Carotene
water to make a 1mg/ml BSA Stock Solution from which 5g of each sample were weighed and placed in a small
serial dilutions were made. glass beaker and a volume of 30ml of absolute ethanol
added (1:6 ratio). The solution was then left to stand for an
2ml of each sample (supernatant) were transferred; hour at rtp, covered in Aluminum foil and left in the dark.
each to a clean tube. To each tube, a volume of 4ml of Stirring and shaking was done at 10 minutes intervals to
Biuret solution was added and gently swirled. The tubes facilitate extraction. The solution was then filtered into a
were allowed to stand at rtp for a period of 10 minutes. A clean beaker using Whatman filter paper and carried over
volume of 500µl of Folin Ciocalteu Reagent was then added for analysis. The absorbance was read at 486nm and a 5ml
to each tube, swirled immediately for mixing and allowed to volume of chloroform used as the blank and the and the
stand for 30 minutes in the dark. Contents from each tube results read and recorded Carotene extraction was carried
were transferred to a clean cuvette and absorbance read at a out on the day of analysis for minimum degradation of
wavelength of 660nm and sterile distilled water used as a sample.
blank.
 Evaluation of Sugar Content
 Evaluation of Total Phenolic Content
The TPC was determined according to the Folin  Sample Preparation and Sugar Extraction
Ciocalteu Spectrophotometric method (Singleton. V. L., Sugar was extracted from flour; (Marangoni. A. C.,
1965) as applied in determination of phenolic compounds 1997) and fermentation broth and the results determined by
(Ngamsuk. S., 2019) on raw sample, fresh, parboiled and UV/VIS Spectrophotometry at 340nm.
fermented flour products.
 1g of the sample was weighed and transferred to clean
 Extraction of Phenolics from Sample. reaction tubes. Mixing and homogenization of sample
5g of the sample was weighed and placed in a was conducted in methanol (8 ml) for 2 mins by
centrifuge tube and a volume of 5ml of Methanol was added vortexing and the homogenate treated with 0.5g of
into each tube. The tubes were vortexed for 1 minute and the carbon (activated charcoal) and shaken for 18-20 min at
tubes centrifuged at x15000 rpm for 15 minutes. The rtp by bench top orbital shaker and filtered through
samples partitioned into pellet and supernatant and the Whatmann filter paper. (Javed. M.S., 2020)
supernatant used for the analysis.
 For each fermented sample; a small volume of the
 Preparation of Standard Solution. media was retained and stored at the end of each 24hr
0.5g of dry gallic acid was weighed and placed into a interval (24hrs, 48hrs and 72 hrs.). 1ml of each volume
clean beaker and a volume of 10ml of Ethanol added to the was added to a clean beaker and 8ml of Methanol was
beaker to dissolve the powder. A volume of distilled water added and the mixing carried out for 2 minutes by
was added to the beaker to the 100ml mark to prepare a 5g/L vortexing, 0.5g of activated charcoal was added and the
solution and used for serial dilutions. contents shaken for 18-20 minutes in a bench top orbital
shaker and then filtered through Whatmann filter paper.
 Preparation of Sodium Carbonate Solution
7.5g of Sodium Carbonate was dissolved in 100ml  Preparation of Standard Stock
distilled water. 1g of glucose was dissolved into 100ml distilled water
to prepare a 1% stock solution used for serial dilutions.
20µl of the extracted sample was pipetted into a clean
test tube, 1 580µl of sterile distilled water was used to dilute  Evaluation of Product Acceptability
each sample, mixture was swirled gently for adequate
mixing and allowed to stand for at least 30 seconds at rtp.  Pilot Study
100µl of FC Reagent was added to each tube, mixed gently The target population was determined by proximity on
by swirling and allowed to stand at rtp for 8 minutes. A account of the lockdown restrictions. A pilot study was
volume of 300µl of Sodium Carbonate Solution was then carried out in which 8 individuals representative of each age
added to each tube, followed by gentle shaking and the tubes group (under 21, 22-31, 32-40 and over 40) were selected
allowed to stand for 30 minutes at 40℃. The absorbance of and provided with the questionnaire. The goal of the pilot
each solution was read at 765nm. Determination of phenolic was to detect and allow revisions of questions deemed
concentration was based on gallic acid standard linear graph unclear and allow for revisions. (Van Teijingen. E. D., June
plotted absorbance versus concentration. 2002).

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 Data Gathering system with highest count 5 representing ‘great’ and the
An introduction section indicating that the research lowest count of 1 representing ‘awful’. The parameters
would be specifically for academic purposes was attached to evaluated by the panelists included; color, texture and smell
the questionnaires. Before answering the questionnaires, the with the option of commenting.
respondents were told the main objectives of the study as
indicated under section 1.3.1 and how their input would  Data Analysis
assist in realizing the research objectives. Questionnaires Ordinal data was summarized using descriptive
were administered at the completion of experiment 1 and statistics from which the maximum and minimum number of
prior to sensory evaluation from which ordinal data is to be responses per sample was used in Multiple Samples Sensory
gathered. The panel comprised of 30 untrained voluntary Ranking categorize samples according to respondent’s
respondents. Evaluation was based on a 5-point hedonic preference. (Carabante. K. M., 2018)
IV. RESULTS AND DISCUSSION
A. Determination of Flour Quality
 Determination of the Effect of Treatment on Product Color

The pretreatment with ascorbic acid prevented enzymatic browning in that all treated products were comparable to their
initial color. This was mostly shown from the sample products in treatment 1 and 3. The color profiles of the parboiled varieties
presented a deepened off-color profile as compared to treatment 1 samples which could be due to the additional heat treatment;
This is illustrated in the table below;
Table 3 Effect of Treatment on the Final Product Color

INITIAL TREAT 1 TREAT 2 TREAT 3
A

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C

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G
KEY procedure was carried out under rtp. A study (Yuliana. N.,
A CHINGOVHA TREAT1 Fresh 2019) was carried out in which natural fermentation in 5%
B DELVIA TREAT 2 Parboiled brine showed potential; both as a preservation technique and
C IRENE TREAT 3 Fermentation in the induction of lactic acid fermentation. Fermentation
D VICTORIA has been rendered ideal in SP with regard to the starch
E NEMANGA content whereas Lactic acid production capabilities have
F ALICIA been identified as well (Pagana. I., 2013). Additionally,
G TSUMAYA saline solutions as that used in fermentation treatment have
been observed to have properties that prevent browning in
Generally ascorbic acid has been identified as an agent selected foods and additional antimicrobial properties.
for retention of carotenoids (Minuye. M., 2021) being heat (Baiano. A., 2003). The best color profiles were observed
sensitive. Studies suggest that the heat sensitive nature of for the fermented products which in turn indicates positive
ascorbic acid in treatment generally makes it non-ideal as a interactions between ascorbic acid pretreatment and saline
pretreatment to be followed by boiling (Mercali. G. D., conditions in fermentation treatment in preventing browning
2014). For this reason, the parboiled dried flakes had an (Baiano. A., 2003). Contrastingly, the color profiles of the
unappealing discoloring outwardly which could be parboiled products could indicate negative interaction
attributed as browning, whilst the interior retained some of between the ascorbic acid pretreatment and the heat
its natural coloring. For this reason; some studies that have treatment.
coupled ascorbic acid as pretreatment to thermal drying
have favored the use of sulfur dioxide and sodium  Determination of Emulsification Stability
metabisulfite solutions instead (Shawky. A. S., 2020). The The analysis determined that the flour product had low
fermented products maintained a color profile comparable to emulsification stability. The determined mean was 11.41s
the treatment 1 products due to the fermentation conditions. (to 2d.p) and a median of 11s with the minimum value of
The fermentation procedure used throughout the scope of 6.4s and the maximum value; 17.4s. For all samples,
this study was predetermined to mimic natural spontaneous regardless of treatment and variety phase partitioning was
fermentation, to achieve this, there was no heat input and the observed and the results illustrated as follows:
Fig 2 Effect of Sweet Potato Variety and Post-Harvest Tuber Treatment on Emulsification Stability of Flour Products

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Generally, the emulsification stability of the parboiled Furthermore, Analysis of Variance indicated that
varieties demonstrated the most values below or along the generally there was no statistically significant difference in
mean value of 11. This could be attributed to the product varieties with respect to emulsion stability (p>0.05).
size. It was observed that particle size of flour products from
fresh and fermentation treatments were smaller and finer  Determination of WHC
compared to the parboiled flour products. Studies have WHC also known as water absorption capacity refers
alluded that the smaller the particle size the more emulsions to the is the ability of food to hold its own or added water
as compared to the larger counterparts (Iyer. V., 2015). On during the application of force, pressure, centrifugation, or
the other hand, none of the flour samples demonstrated heat (Mu. T., 2017). The WHC of the different samples was
ability in the prevention of phase partitioning. determined as a percentage of the initial mass of the dry
Emulsification stability is a measure on the delay or product at rtp. It was determined experimentally that on
prevention in immiscibility between water and oil (Sjoblom. average flour samples across all treatments had a WHC of
J., 2013). This in turn is determined experimentally as the 312. 517%; flour could retain more than 300% of its initial
rate of phase separation, for this reason the presence of mass worth of water. However, it was observed that the
phase separation indicated low emulsification stability attained percentages for the parboiled samples all fell below
(Tekin. Z. H., 2020). Since the samples exhibited low the identified mean value. The minimum value of 102% was
emulsification stability throughout assessment, this in turn observed in parboiled samples whilst the maximum value of
highlights their limitations as emulsifiers. 557% was observed for treatment 1. The attained results are
outlined in the table as follows:
Fig 3 Effect of Sweet Potato Variety and Post-Harvest Tuber Treatment on Water Holding Capacity
In any case WHC demonstrates the relationship and sweet potato in turn holds a comparable WHC (Doporto. M.
interaction between protein and water in food systems. The C., 2012). For this; reason, sweet potato holds potential in
protein within the sampled product achieves this by being a chief ingredient in formulating instant porridge.
absorbing, retaining and entrapping water against gravity
and by so doing prevents water from being expelled The p value< 0.05 (Appendix 4: table 11) highlights
(Rakszegi. M., 2014). Towards the development of cereal the significant differences between varieties with respect to
and instant porridge, wetting and hydration as that water holding capacity.
demonstrated through determination of WHC is significant
in demonstrating interactions. For example; rice and maize  Determination of OHC.
are the most popular ingredients for gluten free foods, but The OHC of the different flour samples as shown
they tend to exhibit limited technological properties below are expressed in grams per 100g fresh sample. It was
especially with regard to cohesive interactions (Boucheham. determined that the statistical mean was 169.36% (correct to
N., 2019). This in turn highlights that any product intended 2 d.p). The analysis also highlighted that all values attained
to substitute wheat in any cereal-based product should under treatment 2 of parboiling fell below the estimated
exhibit functional properties somewhat comparable or mean value, the same for fermentation treatment except for
consistent with that of wheat. There is a correlation between Tsumaya. In that same light, the minimum value 57.50%
the WHC of a flour and the solvent retention capacity, these was found for parboiled Chingovha variety. Generally, there
combined properties establish the functional profile of the was a significant difference between the OHC for the
flour product (Kweon. M., 2011). Generally, it has been different samples as suggested by the p value (α<0.05):
determined that gluten can absorb liquid water more than 2 Appendix 4; table 12. The attained results are presented as
times its initial weight, the results attained indicate that follows:

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Fig 4 Effect of Sweet Potato Variety and Post-Harvest Tuber Treatment on the Oil Holding Capacity
OHC is a measure of the interactive properties the intricate differences and consequences of the treatment
between the samples in question and oil. This has been options).
described as to the amount of oil that a sample can absorb
per unit of weight (Ladjal. E Y., 2015). As such OHC is a  Determination of Moisture Content (According to
relevant measure on how well the texture of a product will AOAC Method 1995)
be. The analysis is crucial in that it provides an indication of Generally, SP have a predetermined moisture content
application. Generally, it is expected that boiled flours ought of 62.58 – 64.34 ±0.42% (Vimala. B., 2011). In this
to portray greater oil entrapment capacity compared to the experiment the minimum value for treatment 1, treatment 2
other treatments (Ma. Z., 2011). However, in this and treatment 3 were 62.8% (Alicia: treatment 1), 59.57%
experiment it is exhibited below the statistical mean. This is (Namanga; treatment 2) and 31.98% (Victoria treatment 3),
because OHC is a direct measure on the surface availability whilst the maximum values were 74.7% (Tsumaya;
of hydrophobic amino acids and non-polar chains (Benitez. treatment 1), 88.76% (Tsumaya; treatment 2) and 72.284%
V., 2013). Since the consequence of gelatinization was (Alicia; treatment 3) respectively. The acquired mean value
exhibited for parboiled samples, this affected particle size; for each treatment was 68.99%, 75.94% and 56.69%
flour particles from parboiled treatments were larger after respectively. From these values it is determined that
grinding. On the other hand, OHC for treatment 1 for Namanga and Tsumaya had the moisture content that fell
Chingovha, Delvia, Irene, Victoria and Namanga were above the treatment 1 mean, Delvia and Namanga had the
significantly higher across all treatments. This illustrates the moisture content that fell below the treatment 2 mean and
availability of non-polar chains and hydrophobic amino Victoria and Namanga had the moisture content values that
acids within the raw dried tubers. The differences in OHC fell below the treatment 3 mean. This is shown in Fig 7:
across the different treatments for the same varieties indicate
Fig 5 Effect of SP Variety on Moisture Content

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Moisture content is an analysis based on the water (Senkumba. J., 2017). Generally fibrous varieties tend to
content of a product in question. The primary treatment of have lower water content as compared to the fleshy
drying which is applied to the tubers generally is aimed at varieties, the bulkier and more compact varieties have less
the expulsion of water to produce a dehydrated form of the water content as compared to the softer and juicier varieties.
product (Mermelstein. N. H., 2009). Moisture content The results also indicated that varietal differences tend to
maintains an inverse relationship with product feasibility; have an implication on the choice of drying temperature.
the higher the moisture content the less feasible product 60℃ was used throughout the experiment, although
development becomes as production becomes uneconomical adequate for fresh and fermented samples, the same was not
(Kuka. M. G. K., 2018). The Moisture Content of observed for the parboiled varieties. Amongst all the
Chingovha, Alicia, Delvia, Irene, Alicia and Tsumaya samples; parboiled Tsumaya dried to the point of hard and
maintained a close relation across all three treatments. brittle, other varieties although achieving constant mass
Although slight differences were observed, the results of the remained soft. This means for samples A to F; starch
aforementioned remained close within a specific range. gelatinization was a consequence of the pretreatment option.
However, the results suggest that the fermentation treatment Gelatinization has been defined as the loss of molecular
for Victoria and Namanga significantly reduced the mass order of starch granules, the point at which starch granules
loss during drying treatment. This supports the claim from swell and absorb water (BeMiller. J. N., 2019). The
the study of natural fermentation carried out on soy that gelatinization temperature of sweet potatoes has been
natural fermentation decreases moisture, carbohydrate and considered to fall within the range of 60 ℃to 65℃
fat contents (Obadina. A. O., 2013) (BeMiller. J. N. a. W., 2009). This means the allocated
timeframe of 10 minutes parboiling treatment was not an
The results attained indicate significant differences ideal as a uniform treatment option. The determination of
(p≤0.05; Appendix 4; table 13) and that generally Tsumaya drying temperatures post parboiling should have put into
(G) regardless of treatment option has a higher moisture consideration factors such as gelatinization and pasting
content. Studies have shown that moisture content typically temperatures as well as sample texture.
varies according to the physical properties of the tubers
Table 4 Texture Profiles of the Different SP Varieties

Sample Texture
A Smooth and Compact
B Smooth and Soft
C Smooth and Soft
D Smooth and Soft
E Smooth and Compact
F Rough and Compact
G Fibrous
Oven drying proved an ideal means of thermal  Determination of Foreign Matter

processing and preservation in that it introduced When products were ground into fine powder and
containment and restricted the introduction of foreign sieved through sieves with aperture of 600µm and 710µm
matter. Other thermal options such as sun-drying tend to no foreign material was detected. From the experiment it
introduce contaminants to the final product that can be was demonstrated that the option of thermal treatment and
detrimental to consumer health, and introduces a variable process of flour production did not introduce foreign matter.
that cannot be controlled in research (Eswara. A. R., 2013). This was conclusive for all samples regardless of the
In fact, it has been alluded that; although sun drying is an treatment option. For the purposes of this experiment
economic choice, its challenges can be addressed by foreign matter was defined as physical contaminants such as
integration into controlled and automated systems to make hair, filth, bark or wood, insects, and any food particles that
for a more plausible treatment option (Feili. H.R., 2012) are not part of the sample (Goodwin. D., 2014). The analysis
especially in agriculture and food processing. fulfils a requirement as an indication of food safety as that
governed by FDA authorities in food production (Lupo. L.,
Moisture content is primarily important in that there is 2020). Typically, the choice for thermal treatment using
correlation in diminished or reduced water content and oven instead of sun drying is favored on account that it
product preservation (Guine. R. P. F., 2018) and allows for reduces the likelihood of environmental contamination
product development. The initial step in numerous product (Famurewa. J. A. V., 2011).
development protocols is drying. This is because it reduces
product bulkiness; water loss is associated with mass  Determination of Gluten Content.
transfer and facilitates storage and transportation by The results attained indicate absence of gluten in the
eliminating the need for cooling systems and halts chemical SP samples processed down to flour. When dough placed in
and enzymatic changes (Guine. F., 2008). silk cloth was washed under running stream, residue was
broken down slowly until no excess was left, and no residue
was available for drying. The results suggest that within the
full mass of each sample, no gluten was present. This in turn

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is supported by studies that have identified sweet potatoes as B. Evaluation of the Effect of Treatment on Selected
gluten free; (Alfani. N. N. A., 2019), studies that incorporate Chemical Properties
sweet potato into wheat-based products as a means of gluten
reduction (Ayo-Omogie. H., 2020), and studies that  Evaluation of Protein Content (Lowry Method)
completely substitute gluten flours with sweet potato It was determined that there was a significant
derived flour; (Giri. N. A., 2019). For this reason, sweet difference in the effect of treatment on protein content (p
potato proves ideal for the growing gluten intolerant value≤ 0.05; Appendix 4; table 14). From this it was
population and patients of celiac disease (Degeorge. K., determined that the statistical mean was 0.432 (to 3d.p), the
2017). highest protein concentration was observed for fermented
flour products, with the overall highest being in Namanga
and the lowest protein concentration observed for parboiled
Alicia. The results were recorded as follows:
Fig 6 Effect of Pre-Thermal Treatment on Sweet Potato Flour Protein Content
The protein content in raw SP samples was first based methods exploit extraction procedures prior to
determined. It has been determined that protein in SP is measurement as a means for selective detection. This means
dominantly sporamin A and B, which are subject to increase the spectrophotometry values are only based on the amount
and decrease during sprouting, maturation and storage of substance that has been successfully extracted from the
(Maeshima. M., 1985). However; SP are generally not given sample. The low values observed for parboiled flour
regarded as a rich protein source, (Shireen. K. F., 2001). For may have been a consequence of ineffective protein
this reason, the objective of introducing processing extraction. Studies have shown that particle size has a
techniques should be focused on methods that retain the significant impact on the rate of extraction (Russin. T. A.,
most nutritional composition of the starting product (Lyimo. 2007) (Yuliani. S. H., 2019).
M. E., 2010).
Fermentation on the other hand is typically held in
Generally parboiled flour samples exhibited a regard as a nutritional enhancer (Samtiya. M., 2021). For
significant decline in protein content when compared to the this reason; the protein content in fermented samples was
raw values (with an exception for Victoria and Tsumaya). both expected and observed to be higher than that from the
Throughout the analysis they uniformly maintained a raw samples. This is synonymous in a study carried out in
decline with respect to the analysis. This detail suggests Indonesia that explored improving flour properties by
damage and destruction to the protein constituents as a fermentation (Yuliana. N., 2016). Similarly, fermentation is
consequence of the heat treatment. Generally boiling has favored on SP with respect to the high starch content of the
been identified to have a detrimental impact on protein tubers; (Bach. D., 2021) and introduction of flavors.
(Shehu. D. M., 2018). On that same note; the raw values are
comparable to that for fresh (treatment 1), this suggests that  Evaluation of TPC (Folin Ciocalteu Spectrophotometric
the heat input used to dry the raw tubers (treatment 1) was Method)
not extensively aggressive to the point of denaturing The results indicated there was a significant difference
proteins. The rises and declines observed between raw and in the effect of treatment on TPC (p≤0.05; Appendix 4;
treatment 1 can be attributed to the conclusions drawn by table 15). The statistical mean was found to be 0.789 (to 3
Maeshima (Maeshima. M., 1985). On the other hand, the d.p), the maximum value; 1.689 (to 3 dp) was observed for
effect of gelatinization on particle size as observed for the raw Victoria (before processing) whilst the minimum
parboiled samples may have contributed to the low phenolic value was observed for Alicia having undergone
availability of protein for measurement. Spectrophotometry treatment 1. The results are shown as follows:

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Fig 7 Effect of Pre-Thermal Treatment on Sweet Potato Flour Phenolic Content
Generally phenolic content in tubers is subject to impact flavor (Rodriguez. H., 2009). Parboiled flour
factors such as: cultivar, environmental conditions, cultural samples exhibited lower values as compared to the raw
practices, postharvest practices, processing conditions, and samples. The subjection of thermal processing in water
storage (Chandrasekara. A., 2016). For this reason, the results in changes in phenolic composition in that certain
initial TPC in the raw samples vary. Chingovha had the degrees of boiling are associated with phenolic retention
lowest values across all treatments, whilst the orange which can be attributed to higher extractability, rupture of
varieties had amongst the highest values, this supports the polyphenolic complexes and inactivation of polyphenol
evidence that highlight that flesh color as an indicator of oxidase (POD) (Minatel. I. O., 2017). The choice of drying
TPC (Musilova. J., 2017) The decrease of these values method generally induces reduction of phenolic compounds,
across all treatments was typical as expected on account of and brings into account factors such as drying temperature,
their unstable structures and hence easily prone to drying time and air velocity (Miranda. M., 2010). The rate
degradation (Minatel. I. O., 2017). As such the TPC in raw of degradation brings into account other factors such as
samples had the highest values across all treatment and were handling and quality of tubers and type of phenolic acid in
comparable to the values obtained post fermentation question.
(treatment 3). The increase demonstrated under treatment 3
is as a result of the choice of treatment. Fermentation has  Evaluation of Β Carotene Content
been identified to demonstrate a marked increase in the TPC It was determined that the mean concentration across
for the product in question (Adetuyi. F. O., 2014). all treatments was 0.017 (to 3 dp) and the maximum and
Fermentation is the favored option with respect to food minimum values; 0.031 and 0.000144 respectively. The
processing in that it increases the bioavailability of phenolic attained results are shown below:
compounds in food and generation of compounds that
Fig 8 Showing Effect of Pre-Thermal Treatment on Sweet Potato Flour Beta Carotene Quantity

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Chingovha (white flesh) had the lowest beta carotene samples, but higher than values for fresh (Wu. X., 2008).
values across all treatments, all of which fell under the The effect of boiling at short intervals on SP has been shown
experimental mean and the overall minimum value being to increase beta carotene concentration (Buratti. S., 2020).
observed from treatment 1 sample (fresh) (Hussein. S. M., This can be explained in terms of enhancement of
2014). For this reason, it may prove as a candidate for extractability as a result of boiling (Dincer. C., 2011). The
biofortification in processing particularly for augmenting concentration in raw samples and fermented samples were
beta carotene content. In contrast the orange fleshed comparable in that for each variety the range in difference
varieties Delvia (B) Victoria (D), and Namanga (E) and was smaller as compared to the other treatments. This
yellow fleshed varieties (Irene (C), and Alicia (F) Tsumaya suggests that the enhancement of nutritional composition as
(G) exhibited a significantly higher beta carotene level with that offered by fermentation technology has an
the maximum value being in Victoria. This is supported by advantageous effect on the product beta carotene levels in
characterization studies which conclude that the order of terms of both retention and bioavailability (Mapelli-Brahm.
carotenoid concentration is least in white fleshed varieties, P., 2020). The p-value indicated that there were significant
increases in yellow fleshed varieties and is highest in the differences on the carotene quantity with respect to the
orange fleshed varieties (Kammona. S., 2014). Generally, all pretreatment choice Appendix 4; table 16.
treatments demonstrated a reductive effect in beta carotene
content across all varieties, however with varied extents  Evaluation of Sugar Content
(Bechoff. A., 209). In this study the choice of processing;
thermal drying resulted in a decline in concentration as  Evaluation of Sugar Content in Flour
compared the initial raw concentration; demonstrated by The mean of sugar was determined as 0.017 (to 3 d.p),
treatment 1-fresh. This is because carotenoid degradation is and the median 0.017 (to 3 d.p) and the maximum and
a consequence of heat treatment in addition polymerization minimum values 0.031 and 0.00014 respectively and p-
of sidechains (Qui. D., 2009). Similar findings have been value demonstrated to be less than the α- value (Appendix 4;
produced in cherry tomatoes (D'Evoli. L., 2013), fruit and table 17). The results attained are provided in the graph as
vegetables (Penicaud. C., 2011) (Marx. M., 2003). follows:
Similarly, parboiled sample concentrations were also
significantly lower than the initial concentration in raw
Fig 9 Showing Effect of Pre-Thermal Treatment on Sweet Potato Flour Sugar Content
The above results show differences in varieties as such sugars is as a result of maturation and storage. As such
exhibited by initial sugar concentration differences in raw the variability on sugar content has been alluded to be due to
samples. For this reason; F and G (Alicia and Tsumaya had type of cultivar and the effects of harvest time and storage
the highest initial sugar concentrations). This has also been (Adu-Kwarteng. E., 2014). Sweet potato is generally
alluded in other studies that observe the implication of superior as compared to other starches on account of
varietal differences on nutritional composition of different richness in vitamins, minerals and dietary fibre, bioactive
sweet potato varieties (Ingabire. M. R., 2011). Such compounds, whilst possessing a low glycemic index.
differences are key in the determination of product Sweetness in sweet potato is due to presence of endogenous
formulation, development and design (Elmadfa. I., 2010). In sugars present during harvest and the effect of processing
this analysis; total soluble sugar content comprises of treatment (Kays. S. J., 2005). Generally drying
glucose, fructose and sucrose. Naturally accumulation of independently and boiling prior to drying are expected to

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increase the total sugar content in flour (Haruna. S. A., with works reported that suggest that although coupled with
2018). However, in this study the contrary may be true in nutritional composition and enhanced bioavailability; sugar
that the maximum values for each treatment were observed decrease is accounted for as an expense in fermentation
for the raw tuber. In this study Ascorbic acid treatment was processing (Dos Reis. B. A., 2013), (Samtiya. M., 2021).
applied as a means for browning prevention, this illustrates a
loss in sugar content during and prior to treatment.  Evaluation of Sugar Content in Fermentation Broth
Parboiling (treatment 2) exposes sweet potato slices to high Changes in sugar content, biomass build up and end
temperatures and exposure to water which creates an product accumulation are amongst the dynamic changes
atmosphere for sugar to leach out (Olatunde. G. O., 2015). expected characteristic of the fermentation process by both
On the other hand, fermentation values across all treatments bacteria and yeast (Yuliana. N., 2018). The sugar content in
were the lowest for each variety. This suggests the fermentation broth was assessed at 24hourly intervals and
occurrence of natural fermentation. The utilization of sugars the O D Readings recorded as follows:
as an energy source is observed as a decrease in the overall
sugar content after treatment. This in turn is in agreement
Fig 10 Showing Changes in Total Soluble Sugar Content During Fermentation at 24hr Intervals
Generally, sugar is gradually consumed during fermentation which during spectrophotometry can be observed as decrease in
the OD reading. A decline in absorbance value was observed for each variety at 24-hour intervals. For varieties A, B, C and G
there is a peak in the values followed by gradual decline at t=48hrs and t=72hours. Whilst A, C, D, E and G exhibit peaks at the
t=72hour intervals. Similar peaks have been observed in fermentation studies involving both yeast and bacteria. In bacteria the
peak or plateau in concentrations are suggested to be as a result of the utilization and replacement of sugar via microbial
metabolism, whilst a continuous decline would have been observed upon sugar depletion with no replacement (Horvath. B. O.,
2020). The sugar reduction rates are not synonymous on account of the differences in varieties and their independent reaction
kinetics, initial sugar content, concentration of fermenting agents, fermentation conditions and the microbe in question (Sharma.
R., 2020). This was implied with the p-value≤0.05 (Appendix 4; table 18). The color changes were also observed and noted down
as follows:
Table 5 Color Changes in Media Broth During Fermentation at 24hr Intervals

SAMPLE @24hrs @ 48hrs @ 72hrs
A colorless cloudy colorless cloudy colorless cloudy
B pale yellow cloudy pale yellow cloudy dark brown cloudy
C colorless cloudy yellow cloudy light brown cloudy
D brown cloudy brown cloudy brown cloudy
E light brown cloudy brown cloudy brown cloudy
F brown cloudy brown cloudy light brown cloudy
G light brown cloudy brown cloudy light brown cloudy
O colorless colorless colorless
C. Determination of Product Acceptability

From the pilot it was determined that all the questions and responses were clear and concise, no revisions were made.
 Results of Survey Work.

The survey data revealed that all participants were familiar with at least one variety of SP and that the majority of
respondents were unaware of SP processing and derived products. The results are provided:

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Table 6 Information Collected on SP During Baseline Survey and Percentage Respondents
Information collected Percentage respondents
Age Under 21 30
22-31 27
32-40 20
Over 40 23
Sex Male 50
Female 50
Education O Level 10
A Level 23
Degree 53
Masters 10
PhD 3
Enjoy eating SP Yes 63
No 3
Indifferent 33
Familiar SP cultivars White flesh 100
Yellow Flesh 20
Orange Flesh 47
Purple Flesh 3
SP processing in household No processing; strictly consumption 100
Boiling then drying 0
Boiling the freezing 7
None of the above 0
Familiarity with SP derived products Yes 7
on market No 93
Have you tried or would you be open Yes 97
to trying SP derived products No 3
Probability of purchasing SP derived Extremely likely 23
products in place of competing maize Very likely 30
and wheat products Somewhat likely 43
Not so likely 0
Not at all likely 3
Sensory evaluation panelist Yes 100
No 0
The data highlights the popularity of the raw tubers within households and limited availability and information of SP
processing or their derived products.100% of the respondents were familiar with the white fleshed SP variety, however the same
could not attributed to the other varieties, especially the purple-fleshed variety; where 1 in the 30 respondents was familiar with
the variety. SP was largely prepared within the respective households at a need-to-eat basis; strictly for consumption in which no
freezing or drying followed after. Although the number of respondents who had come across SP derived products within the
market was low, the number of respondents open to purchasing and potentially replacing wheat and maize competing products
was well into the 90th percentile. This could be alluded as the respondents being open to new products, or the respondents being
exhausted from the current selection on the maize and wheat competing products.
Generally, all respondents exhibited a keen interest in the potential product as all respondents proceeded to be panelists for
the sensory evaluation.
 Results of Sensory Evaluation

Descriptive statistics (Appendix 4; table 19) was used to define the maximum and minimum values with respect to each
point within the hedonic scale and a sensory parameter and the results are outlined as follows:
Table 7 Ranking of Most Popular Samples from Sensory Evaluation

AWFUL BAD MODERATE GOOD GREAT
Color Par Alicia Ferm Irene Par Victoria Fresh Chingovha Ferm Victoria
Fresh Tsumaya Ferm Tsumaya
Texture Par Delvia Par Alicia Par Tsumaya Ferm Victoria Ferm Delvia
Smell Fresh Victoria Par Namanga Par Delvia Fresh Chingovha Ferm Tsumaya
Ferm Victoria
(Based on Maximum Values)

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The most preferred samples were identified as those that had undergone either treatment 1 or treatment 3 (good and great)
whilst the parboiled samples ranked most in the lower scales (awful to moderate) and Victoria, Tsumaya and Chingovha being the
most favored varieties. The information was relevant in that it indicated potential consumer decision with respect to perception
and preference (Yang. X., 2016). This in turn highlighted the choice varieties and pre-treatment option for SP flour product for
chief ingredient in instant porridge. This is because flour quality and nutrient retention post processing can be favorable and most
ideal, however these factors have the potential to remain unnoticed in a given product should the product not meet consumer
acceptability (Garces. G. A., 2016).
Table 8 Ranking of Least Popular Samples from Sensory Evaluation

AWFUL BAD MODERATE GOOD GREAT
Color Par Tsumaya Ferm Delvia Fresh Tsumaya Par Tsumaya Par Chingovha
Ferm Victoria Ferm Victoria Ferm Tsumaya Par Delvia
Ferm Tsumaya Fresh Tsumaya Par Namanga
Fresh Victoria Ferm Tsumaya Par Alicia
Fresh Chingovha
Texture Ferm Delvia Fresh Chingovha Par Victoria Par Irene Fresh Chingovha
Par Victoria Fresh Delvia Par Chingovha Par Namanga
Ferm Victoria Ferm Delvia Fresh Alicia Par Alicia
Fresh Victoria Par Alicia
Ferm Tsumaya
Smell Par Chingovha Fresh Chingovha Par Tsumaya Par Chingovha Par Chingovha
Fresh Irene Par Tsumaya Par Irene
Ferm Irene Par Victoria
Fresh Alicia Ferm Namanga
Ferm Alicia Par Alicia
Fresh Tsumaya Ferm Alicia
Par Tsumaya
Ferm Tsumaya
Fresh Namanga
Par Namanga
Ferm Namanga
(Based on Minimum Values)
KEY
Par Parboiled
Ferm Fermented
The lowest preferences were observed mostly for the parboiled flour samples with the exception of parboiled Tsumaya
which ranked least awful with respect to both color and smell. Interestingly Tsumaya variety across all treatments had the least
awful ranking. This highlights a fundamental distinction of the raw tuber in that choice of pretreatment option did not have a
severely detrimental effect on the sensory attributes of the flour product.
V. CONCLUSION AND RECOMMENDATIONS fleshed was significantly low. This highlighted the need for
targeted efforts and strategies in raising awareness on the
SP tubers are an essential diet component, the different SP varieties and their health benefits. The study
nutritional diversity and constitution of the tuber makes it has demonstrated strategies towards production of SP flour
ideal for product development in the form of SP derived and in so doing has highlighted areas for optimization.
products. Such products would maintain the health benefits Although fermentation was demonstrated to be the most
of the tuber whilst introducing variety in the form of ideal pretreatment relative to flour quality, effect of
exciting and ready to eat products with the potential to treatment on chemical properties and product acceptability,
compete with mainline crop-based derivatives specifically there is need for standardization of the processing procedure
instant porridge. The questionnaire revealed a lag in the to achieve quality SP flour product prior to formulation into
availability and knowledge of such products while the instant porridge for example in defining fermentative
sensory evaluation demonstrated a keen interest on such pathways. This is expected to result in increased demand for
products. The study showed that thermal processing in SP SP tubers and development of a protocol for post-harvest
flour production could be coupled with pretreatments such tuber handling and storage prior to processing. It is also
as parboiling and fermentation. However, each pretreatment recommended that the parboiling pretreatment be further
choice had varying implications on nutrition loss or improved and optimized to suit variations in SP tuber
retention and general sensory appeal. The number of texture so as to avoid the consequence of gelatinization as
respondents familiar with SP varieties other than the white- opposed to ruling it out completely as a pretreatment option.

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LIST OF APPENDICES
A. Appendix 1
 Manual for Analysis of Cereal and Cereal Products

Standards for cereals, pulses and their products are laid down in Section 2.4 of Food Safety and Standards (Food Product
Standards and Food Additives) Regulations, 2011. These include standards for food grains, their milled products and processed
cereal products. In addition, standards for malted foods and solvent extracted edible oilseed flours are also included under this
item. (Welfare., 2016). https://old.fssai.gov.in/Portals/0/Pdf/15Manuals/CEREALS%20AND%20CEREAL%20PRODUCTS.pdf
B. Appendix 2
 Baseline Survey Questionnaire

Description: Below is a questionnaire on sweet potato. This is an academic study intended to provide information on the
individual’s general perception of the tuber. Should you decide to proceed; sensory evaluation will follow, whereby the
respondent will be provided with flour samples derived from different SP varieties from which the respondent is to rank each
sample with respect to color, texture and smell according to how well they like the sample with the least being 1 for awful and
highest being 5 for great.
Thank you for Agreeing to Answer this Short Questionnaire. Please Answer all Questions by Ticking the Most Appropriate
Response. Tick in the Boxes Provided. all Responses are Strictly Confidential and Anonymous
 How Old are you
□ Under 21
□ 22-31 years
□ 32-40 years
□ Over 40
 What is your Sex?
□ Male
□ Female
□ Non binary
 What is your Highest Level of Education?
□ Ordinary level
□ Advanced level
□ Degree
□ Masters
□ PhD
 Do you Enjoy Eating Sweet Potato Tubers?
□ Yes
□ No
□ Indifferent
 Which Sweet Potato Cultivars are you Mostly Familiar with?
□ White flesh
□ Yellow flesh
□ Orange flesh
□ Purple flesh
 How do you Process Sweet Potatoes within your Household?
□ No processing; strictly consumption

□ Boiling then drying
□ Boiling then freezing

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□ None of the above
 Have you come Across any Sweet Potato Derived Products Currently within your Local Markets, Such Products Include;
Flour, Paste, Beverages, Alcohol, Dried Flakes Etc.
□ Yes
□ No
 Have you Tried or Would you be Open to Trying Such Sweet Potato Derived Products?
□ Yes
□ No
 If Sweet Potato Derived Products were Available Today, how Likely would you be to Purchase them Instead of Competing
Products Currently Available from Maize and wheat?
□ Extremely likely
□ Very likely
□ Somewhat likely
□ Not so likely
□ Not at all likely
 Would you be Interested in being Part of a Sensory Evaluation Panel on the Best Sweet Potato Variety for Flour to be
Incorporated Into an Instant Porridge Formulation?
□ Yes
□ No
C. Appendix 3
 Sensory Evaluation Form
Table 9 Sensory Evaluation Form

Sample Code Color Texture Smell
1A 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
2A 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
3A 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
1B 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
2B 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
2B 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
1C 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
2C 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
3C 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
1D 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
2D 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
3D 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
1E 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
2E 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
3E 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
1F 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
2F 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
3F 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
1G 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
2G 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
3G 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
KEY 1 2 3 4 5
Awful Bad Moderate Good Great
Comment:………………………………………………………………………………………………………………………………
……………………………………

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D. Appendix 4:
 Tables and Figures
Table 10 One Way ANOVA for the effect of SP variety on Emulsification Stability
ANOVA: Single Factor
SUMMARY
Groups Count Sum Average Variance
Column 1 7 86.9 12.41429 15.33476
Column 2 7 68.2 9.742857 6.682857
Column 3 7 84.5 12.07143 7.949048
ANOVA
Source of Variation SS df MS F P-value F crit
Between Groups 29.5781 2 14.78905 1.48055 0.253937 3.554557
Within Groups 179.8 18 9.988889
Total 209.3781 20
Table 1 One Way ANOVA for the effect of SP variety on WHC

SUMMARY
Column 1 7 25.72286 3.674695 1.332299
Column 2 7 12.50277 1.786109 0.368832
Column 3 7 27.40608 3.915154 0.550449
ANOVA
Between Groups 19.03395 2 9.516975 12.6804 0.000366 3.554557
Within Groups 13.50948 18 0.750527
Total 32.54343 20
Table 2 One Way ANOVA for the effect of SP variety on OHC

SUMMARY
Column 1 7 17.46041 2.494344 0.94248
Column 2 7 7.910666 1.130095 0.162749
Column 3 7 10.19417 1.45631 1.445375
ANOVA
Between Groups 7.105245 2 3.552623 4.178566 0.032312 3.554557
Within Groups 15.30362 18 0.850201
Total 22.40887 20
Table 3 One Way ANOVA for effect of SP variety on Moisture Content

SUMMARY
65.62089 6 417.2919 69.54865 16.61968
78.42386 6 453.169 75.52816 97.58671
67.10305 6 329.7093 54.95155 259.9594
ANOVA
Between Groups 1344.454 2 672.2272 5.389807 0.017223 3.68232
Within Groups 1870.829 15 124.7219
Total 3215.284 17

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Table 4 One Way ANOVA for Determination of effect of treatment on protein content.
SUMMARY
Column 1 7 3.428046 0.489721 0.0312
Column 2 7 2.912987 0.416141 0.009728
Column 3 7 1.909186 0.272741 0.017769
Column 4 7 3.857889 0.551127 0.022377
ANOVA
Between Groups 0.30196 3 0.100653 4.966037 0.008037 3.008787
Within Groups 0.486441 24 0.020268
Total 0.788401 27
Fig 11 Standards calibration curve for the determination of protein concentration
Table 5 One Way ANOVA for Determination of effect of treatment on TPC

SUMMARY
Column 1 7 6.922265 0.988895 0.126542
Column 2 7 3.633667 0.519095 0.081481
Column 3 7 5.20398 0.743426 0.059808
Column 4 7 6.318747 0.902678 0.12984
ANOVA
Between Groups 0.894638 3 0.298213 2.999593 0.05046 3.008787
Within Groups 2.386024 24 0.099418
Total 3.280662 27

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Fig 12 Standards calibration curve for the determination of phenolic concentration
Table 6 One Way ANOVA For Determination Of Effect Of Treatment On Beta Carotene Content
SUMMARY
Column 1 7 0.163891 0.023413 0.000115
Column 2 7 0.071191 0.01017 3.28E-05
Column 3 7 0.104099 0.014871 5.22E-05
Column 4 7 0.143358 0.02048 0.000101
ANOVA
Between Groups 0.000729 3 0.000243 3.233935 0.040021 3.008787
Within Groups 0.001804 24 7.52E-05
Total 0.002534 27
Table 7 One Way ANOVA for Determination of effect of treatment on sugar content in flour
SUMMARY
Column 1 7 1.6653 0.2379 0.013702
Column 2 7 1.238 0.176857 0.011678
Column 3 7 1.465 0.209286 0.011419
Column 4 7 0.5223 0.074614 0.000692
ANOVA
Between Groups 0.106485 3 0.035495 3.787134 0.023482 3.008787
Within Groups 0.224942 24 0.009373
Total 0.331427 27
Table 8 One Way ANOVA for Determination of sugar content in fermentation broth at 24-hour intervals
SUMMARY
Column 1 7 4.393 0.627571 0.000504
Column 2 7 4.521 0.645857 0.031729
Column 3 7 2.761 0.394429 0.002752
Column 4 7 3.305 0.472143 0.006256
ANOVA

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Between Groups 0.311991 3 0.103997 10.08695 0.000174 3.008787
Within Groups 0.247441 24 0.01031
Total 0.559432 27
Fig 13 Standards calibration curve for the determination of sugar concentration
Table 9 showing summary of descriptive statistics for sensory evaluation panelist’s responses
A1 A2 A3 A4 A5 B1 B2 B3 B4 B5 C1 C2 C3 C4 C5
Mean 5.809524 5.714286 7.571429 6.428571 4.47619 4.952381 7.285714 5.190476 8.333333 4.238095 0.571429 3.904762 14.09524 6.904762 4.52381
Standard Error
1.382921 1.102255 0.919553 1.520607 1.269831 1.136989 1.625896 0.97497 1.906547 1.5336 0.147542 0.572816 1.453902 1.09741 0.855289
Median 3 6 7 2 1 4 6 4 6 1 0 4 15 6 3
Mode 0 0 6 2 1 1 0 1 0 1 0 6 10 6 1
Standard Deviation
6.337342 5.051167 4.213923 6.968296 5.819098 5.210338 7.450791 4.467875 8.736895 7.027836 0.676123 2.624972 6.662618 5.028964 3.919427
Sample Variance
40.1619 25.51429 17.75714 48.55714 33.8619 27.14762 55.51429 19.9619 76.33333 49.39048 0.457143 6.890476 44.39048 25.29048 15.3619
Kurtosis 0.200723 0.140175 0.022741 -0.2315 -0.61076 0.821084 0.279163 0.146419 -0.40052 3.002594 -0.35019 -0.96083 -0.81555 0.872945 1.830545
Skewness 0.993821 0.751215 0.690734 1.074153 1.124148 1.265293 0.975842 1.006106 0.911132 2.09698 0.788162 0.132579 -0.18044 0.901407 1.431081
Range 21 17 16 20 15 18 25 15 28 23 2 9 23 20 14
Minimum 0 0 1 0 0 0 0 0 0 0 0 0 2 0 1
Maximum 21 17 17 20 15 18 25 15 28 23 2 9 25 20 15
Sum 122 120 159 135 94 104 153 109 175 89 12 82 296 145 95
Count 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21
Largest(1) 21 17 17 20 15 18 25 15 28 23 2 9 25 20 15
Smallest(1) 0 0 1 0 0 0 0 0 0 0 0 0 2 0 1
Confidence Level(95.0%)
2.884724 2.299264 1.918155 3.17193 2.648822 2.371717 3.391559 2.033752 3.976987 3.199033 0.307768 1.194873 3.032787 2.289157 1.784102
 Key
A Awful
B Bad
C Moderate
D Good
E Great
1 Color
2 Texture
3 Smell
All statical analysis used throughout this study were carried out and exported from Microsoft excel.

Evaluating The Effects of Sweet Potato Varieties On Flour Quality

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Evaluating The Effects of Sweet Potato Varieties On Flour Quality

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Volume 8, Issue 4, April – 2023 International Journal of Innovative Science and Research Technology

Evaluating the Effects of Sweet Potato

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Table 1 Set up of Experiment

Table 2 Sample Identification

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III. STATISTICAL ANALYSES AND METHODS

 Determination of Flour Quality

 Evaluation of Protein Content (LOWRY Method)

 Extraction of Protein from sample

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IV. RESULTS AND DISCUSSION

A. Determination of Flour Quality

 Determination of the Effect of Treatment on Product Color

Table 3 Effect of Treatment on the Final Product Color

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Fig 5 Effect of SP Variety on Moisture Content

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Table 4 Texture Profiles of the Different SP Varieties

Oven drying proved an ideal means of thermal  Determination of Foreign Matter

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Fig 6 Effect of Pre-Thermal Treatment on Sweet Potato Flour Protein Content

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Fig 7 Effect of Pre-Thermal Treatment on Sweet Potato Flour Phenolic Content

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Table 5 Color Changes in Media Broth During Fermentation at 24hr Intervals

C. Determination of Product Acceptability

 Results of Survey Work.

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 Results of Sensory Evaluation

Table 7 Ranking of Most Popular Samples from Sensory Evaluation

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Table 8 Ranking of Least Popular Samples from Sensory Evaluation

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 Manual for Analysis of Cereal and Cereal Products

 Baseline Survey Questionnaire

 How Old are you

 What is your Sex?

 What is your Highest Level of Education?

 Do you Enjoy Eating Sweet Potato Tubers?

 Which Sweet Potato Cultivars are you Mostly Familiar with?

 How do you Process Sweet Potatoes within your Household?

□ No processing; strictly consumption

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 Sensory Evaluation Form

Table 9 Sensory Evaluation Form

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 Tables and Figures

Table 1 One Way ANOVA for the effect of SP variety on WHC

Table 2 One Way ANOVA for the effect of SP variety on OHC

Table 3 One Way ANOVA for effect of SP variety on Moisture Content

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