Microwine Predictor

Growth predictor of spoilage yeasts in wine and concentrated grapes juice

This application is based on predictive microbiology and allows estimating the wine susceptibility to develop a sensorial defect associated with Brettanomyces bruxellensis and to estimate the microbial stability of concentrated grape juice in two temperature conditions (standard storage and overseas shipping).

Wine: Interaction between the three major wine-relevant “barriers”: pH, ethanol and free sulphite determine the growth rate of the yeast and consequently the speed at which the defect will become perceptible. There is a direct relationship between the level of Brettanomyces population and the concentrations of ethyl phenols produced. The application allows the calculation of the free sulphite concentration required to achieve a desired probability of “no- growth” based upon pH and ethanol concentration in the wine.

Concentrated grape juice: The combination of pH and sugar concentration determines the

growth rate at which the main spoilage yeast Zygosaccharomyces rouxii will be able to grow, and also the time to reach a population greater than 10 6 cells/g where the spoilage becomes evident. The application allows to predict what is the pH value that

should be reached in the concentrated grape juice to get a microbiological shelf-life long enough to allow the product to arrive at its destination in safe conditions.

This application was developed by the INTA, from its Mendoza Experimental Agricultural Station, dependent on the Mendoza- San Juan Regional Center.