The Effect of Biofungicides on Grape Composition, Fermentation, and Sensory Characteristics of Wines from California

Synthetic fungicides have demonstrated adverse environmental impacts and effects on finished wine attributes. Alternatives such as biofungicides employ organisms for the control of pathogens. The purpose of this study is to assess the effects of biofungicides on grape and wine chemistry, fermentation, and wine sensory characteristics. Four separate grape crops treated with biofungicides were vinified, consisting of Pinot noir and Chardonnay from the Central Coast, and Carignan and Chardonnay from the San Joaquin Valley. Treatments consisted of three different biofungicides utilizing two different bacterial strains: Bacillus subtilis strain QST 713 and Streptomyces lydicus strain WYEC 108, and an extract of Reynoutria sachalinensis. Two controls consisted of synthetic fungicide applications, and no fungicide, and all treatments were carried out in quadruplicate. Data has been collected on fermentation and basic grape and wine chemical parameters such as Brix, pH, tiratable acidity (TA), and ethanol. Preliminary results for the Central Coast indicate significant differences in Brix compared to untreated controls, while no significant differences were found in grape and wine chemical parameters for the San Joaquin trials. Preliminary sensory trials show differences in color and aromatic intensity between treatments. Further analyses will be conducted on the wine color, phenolic content utilizing high performance liquid chromatography (HPLC), and sensory characteristics using descriptive sensory analysis.