Development of apple wine from Golden Delicious cultivar using a local yeast isolate

Abstract

The present study was conducted to optimize fermentation parameters for apple wine production using Golden Delicious apples. Physicochemical analysis of the cultivar revealed a °Brix-acid ratio of 24.61 with ample amount of total and reducing sugars (9.6 and 6.03% w/v); making it a suitable substrate to produce ethanol. Microbiological analysis lead to isolation of a yeast strain (namely A2) which was molecularly identified and accessed at GenBank as S. cerevisiae KY069279. Ethanol fermentation optimization using response surface methodology revealed that a temperature of 20°C, an inoculum size of 7.08 (%v/v) and diammonium hydrogen phosphate supplementation @ 154.4mg/100mL as optimum for apple wine production which lead to 10.73% (v/v) ethanol production with a desirability of 86.9%. Fresh wine having malic acid content of 1.87 (mg/100mL) was subjected to malolactic fermentation (MLF) for 8days using Leuconostoc oenos NCIM 2219 resulting in apple wine having 0.4 (mg/100mL) malic acid. Sensory analysis of MLF and non-MLF apple wines categorised them as superior quality with average scores of 69.5 and 74.5, respectively. Gas chromatography-mass spectrometric analysis of apple wine revealed the presence of 38 volatile compounds including higher alcohols, acids, esters etc. The study thus revealed a process for apple wine preparation using an indigenous yeast and also optimized and compared malolactic and non-malolactic fermented ciders.