Glycerol and other fermentation products of apiculate wine yeasts.

Ninety-six strains of apiculate wine yeasts were studied for their ability to produce glycerol, acetaldehyde, ethyl acetate, sulphur dioxide and hydrogen sulphide in synthetic medium. Hanseniaspora guilliermondii produced smaller quantities of glycerol, acetaldehyde and hydrogen sulphide than Kloeckera apiculata, whereas the production of ethyl acetate and sulphur dioxide was found to be similar. Strains characterized by different capacities and properties were found for both species. The existence of apiculate strains differing in secondary compound production is of technological interest, as these yeasts constitute potential flavour producers. Selected strains of apiculate yeasts might favour an enhanced flavour formation and yield desirable characteristics to the final product.

Biometric Study of Acetoin Production in Hanseniaspora guilliermondii and Kloeckera apiculata.

Gas chromatographic analysis by direct injection of samples yielded quantitative data on acetoin content. Ninety-six strains of Hanseniaspora guilliermondii and Kloeckera apiculata were investigated for the ability to produce acetoin in synthetic medium and in must. High-level production of acetoin was found to be a characteristic of both species. In synthetic medium, the two species were not significantly different with respect to sugar utilization and ethanol or acetoin production. In grape must, the two species were significantly different (P = 0.001) in acetoin production and K. apiculata exhibited a significantly negative correlation between acetoin production and either sugar consumption or ethanol production. Use of selected apiculate yeasts in mixed cultures with Saccharomyces cerevisiae seems promising for optimization of wine bouquet.