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Aroma is one of the most important quality criteria of fruit and wine products. It is known, that aroma compounds are present in fruit in a free state and in the form of glycosides. In this review, the effect of glycosidases on flavour recovery from glycosides in fruit juice production and in winemaking was discussed.

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Industrial wine yeasts Saccharomyces bayanus and two interspecies hybrids (S. cerevisiae × S. bayanus) were checked for their suitability for fermentation of apple musts with different l-malic acid content (4, 7 and 11 g/l). The fermentation profiles including main organic acids, acetaldehyde, diacetyl, glycerol, esters and polyphenols were presented. The results were obtained by HPLC method (organic acids, acetaldehyde, glycerol, diacetyl), GC (esters), colorimetrically (polyphenols) and enzymatically (l-malic acid, ethanol). Although the fermentation profiles of wines were characteristic for specific yeast strains, similarities in organic acid profiles of wines fermented by S. bayanus and its hybrid S-779/25 were noted. In all the tested wines l-malic, pyruvic and citric acids were dominant. Statistical analysis of all wine parameters indicates that yeast strains respond individually to different acidities of the fermentation environment. In order to choose the right yeast strain for the fermentation of acidic musts, information about fermentation profiles should be included in the collection certificate of yeast strains.

Distribution of cyanogenic glucosides contained in elderberry fruit was investigated in the course of technological operations usually utilised for obtaining musts. The degree of glucoside hydrolysis was estimated by the amount of liberated hydrogen cyanide. After fermentation on skins the must contained 2.08 mg litre-l of hydrogen cyanide. Hydrogen cyanide in the must from depectinised fruit pulp was at a level of 2.31 mg litre-l. After heat treatment the must contained 1.07 mg litre-l of hydrogen cyanide.

Abstract:In wines from elderberry fruit harvested in four successive years, 36-12.36 mg litre-' of histamine were detected. Histamine content in the wines depended on the pulp treatment prior to processing and the yeast strain used for the fermentation. The investigation of factors affecting the formation of histamine has shown that it is formed as a result of the action of histidine decarboxylase (EC 4.1.1.22) of elderberry fruit, enzymes contained in Polish pectolytic preparation 'Pectopol PT', and during fermentation under the effect of histidine decarboxylase produced by yeasts. The highest activity of this enzyme has been found in Bordeaux yeast, with decreasing activities in Burgundy, Malaga, Tokay and Syrena yeasts.

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