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

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 @ 154.4 mg/100 mL 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/100 mL) was subjected to malolactic fermentation (MLF) for 8 days using Leuconostoc oenos NCIM 2219 resulting in apple wine having 0.4 (mg/100 mL) 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.