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The behaviour of Kloeckera apiculata, Candida pulcherrima and Saccharomyces cerevisiae was studied with pure and mixed cultures in grape juice. The non-Saccharomyces species showed significant growth and survival in mixed cultures, although S. cerevisiae dominated the fermentation. Ethanol production was higher with S. cerevisiae in both cultures. K. apiculata and C. pulcherrima formed the lowest amounts of ethanol with high residual sugars and the highest contents of ethyl acetate in pure cultures. The concentrations of ethyl acetate produced in mixed cultures were higher than those produced using only S. cerevisiae. Moreover, other volatile compounds were not formed in undesirable levels in mixed cultures. © 2002 Elsevier Science Ltd. All rights reserved. FBE.2000 This study was supported by Cukurova University Research Fund (FBE.2000.YL.110). H. Erten thanks G. McKernan of International Centre for Brewing and Distilling, Heriot-Watt University, UK for his advice and assistance with GC. Thanks are also due to Professor A. Canbas of Cukurova University, Turkey and H. Saglicak of Bogazici University, Turkey for their critical reading.

The stereoselectivity of the reduction of rac-3-methyl-1-(phenylsulfonyl)hexan-2-one (1) to 3-methyl-1-(phenylsulfonyl)hexan-2-ol (2) diastereomers by more than 20 yeasts was studied. Reduction of carbonyl group in 1 proceeds with a high Re-face enantioselectivity: Candida guillermondii (989% e.e.), C. zeylanoides (>99.9%) and Kloeckera apiculata (99.6%), respectively and the (R)- 1 enantiomer usually reacted faster. The enantioselectivity was determined by GC on chiral cyclodextrine phases and absolute configurations of products were assigned by NMR spectroscopy and a chemical correlation.

Volatile substances of wines obtained by fermentation of musts from ‘Monastrell’ grapes (Alicante, Spain) was studied for yeast isolated from such musts. The results of the statistical treatment performed show the importance of yeasts of low fermentative power, particulary Kloeckera apiculata , in the production of volatile substances. Saccharomyces cerevisiae var. chevalieri was found to be the most important yeast of high fermentative power.

The effect of commercial processing (blanching and/or roasting) on total vitamin B6 retention in processed almonds (Prunus amygdalus, Batsch) was investigated. The yeasts Saccharomyces uvarum and Kloeckera apiculata were used as comparative test organisms for the assay. Different values for vitamin B6 content were obtained from the same samples by using different test organisms. The use of K. apiculata resulted in significantly higher values for total vitamin B6 content than those obtained using S. uvarum. These differences in vitamin B6 values could be attributed to the inherent differences in the nutritional requirements of the two yeasts to vitamin B6 and to the differences in the natural responses of the two organisms towards the different forms of vitamin B6. The overall results obtained indicate that both blanching and roasting processes resulted in some loss of vitamin B6 content. Roasted almonds retained approximately 76% (with S. uvarum) and 74% (with K. apiculata) of their initial vitamin B6 content. Similarly, blanched almonds retained 88% (with S. uvarum) and 87% (with K. apiculata) of their initial vitamin B6 content. Almonds that were blanched and then roasted retained approximately 78% (with S. uvarum) and 73% (with K. apiculata) of their initial vitamin B6 content. The total vitamin B6 content of the natural unprocessed (raw) almonds was 0.83 μg/g (with S. uvarum) and 1.74 μg/g (with K. apiculata) on a dry-weight basis. These values were used as the basis for calculating the percent retention in the processed almond samples.