Two apple juices were fermented at 8°C and 18°C using thirteen strains of Saccharomyces uvarum. Glucose, fructose, malic, lactic, isobutanol, 2-3 butanediol, isoamyl alcohol, ethyl acetate and titratable acidity were determined in the two resulting experimental ciders. This data was correlated by means of multiple regression equations derived from earlier work with the following organoleptic characteristics: sweetness, sourness, fruity, scented, sharp and irritating flavours and a "global hedonlc score" for overall acceptability. A significant effect of yeast strain could be detected on all component concentrations except ethanol, ethyl acetate, amyl alcohols and titratable acidity. The amounts of malic acid and titratable acidity found in cider depends mainly on the source of the juice. The anticipated effect of the source of the juice on sourness and on sharpness and fruity flavours is therefore significant Yeast strain is also expected to have a significant effect on fruity and sharp flavours as well as on overall acceptability.
An apple juice was fermented at 8°C using twelve strains of Saccharomyces uvarum. Glucose, fructose, malic and L-lactic adds, isobutanol, 2,3 butanediol, isoamyl alcohol, ethyl acetate and titratable acidity were determined and monitored in the course of fermentation. It was observed that yeast strains differed from one another mainly In fermentation rates. When components were determined in ciders of the same remaining fructose concentration, rather than after the same fermentation time, the only significant effect of the yeast strain was on the amounts of glucose and ethanol in sweeter cider (fructose 34 g/IHre), or on the amounts of glucose, acetic add, isobutanol and amyl alcohols in dryer ciders (fructose 17 g/litre).A sensory analysis showed that standard deviations of concentrations of remaining or formed components in dders fermented by different yeast strains, was sufficient to be detected by the taste panel. Added glucose in this range of concentration (1.5 g/litre) in dder reduced the perception of sourness while the addition of acetic add (0.3 g/litre) reduced the perception of the scanted flavour. Added Isobutnol (6 mg/litre) reduced the perception of sweetness. No significant effect of added isoamyl alcohol (30 mg/litre) could be detected.Chemical determinations were correlated by means of regression equations derived from earlier work with some organoleptic characteristics. No anticipated effect of the yeast strain could be detected on any studied flavour characteristic. It is concluded that in ciders of the same attenuation, the effect if ft does exist, of the S.uvarum strain isolated from ciders, must be low.
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