Autophagy in wine making.

Aging that involves contact with dying yeast cells is one of the differential processes between sparkling and still wine production. The release of the products of autolysis during this aging step is fundamental for the quality of sparkling wines made by the traditional method. These cells undergo an autolysis process characterized by self-digestion of yeast intracellular and cell-wall macromolecules, and the release of the degradation products to the wine. Autolysis is the source of several molecules responsible for the quality of sparkling wines, as well as still wines aged on lees (yeast cells). Autolysis is a slow process under sparkling wine production conditions, and there is interest, from the industrial side, in the design of strategies for rapid development of autolysis. Some years ago our research group hypothesized that, during the process of sparkling wine production, autophagy would take place. This had important implications for the design of genetic engineering strategies aimed to accelerate autolysis. The relationships between autolysis and autophagy are not completely elucidated, but in case autophagy preceded autolysis during the aging step of sparkling wine production, there were at least two possibilities for accelerating autolysis by targeting genes involved in autophagy. This chapter discusses methods to demonstrate the development of autophagy under enological conditions. This is accomplished by using either laboratory strains defective in autophagy and/or the Cvt pathway, in conditions that mimic sparkling wine production or industrial wine yeast strains under real sparkling wine production conditions.