Optimization of juice extraction from custard apple and fermentation to ethanol

Abstract

Custard apple is a most popular tropical fruit known for its sweet taste, rich flavour and pleasant aroma with creamy juicy flesh. The fresh fruit is enriched with precious nutrients which have great potential for nutraceutical. Though the fruit is nutritionally balanced, it is highly perishable in nature due to high respiration rate and therefore there is a great need to explore alternate methods for its utilization. Preparation of beverages could be an alternative to value addition and its economic utilization. In this study, an attempt was made to optimize the process juice juice extraction from custard apple and its further processing to ethanol production. Different concentrations of enzyme pectinase and time of incubation were explored to achieve the desired yield of ethanol. The juice thus obtained was evaluated for total soluble solids, titratable acidity, ascorbic acid, pH and sugars and used as raw for ethanol production using Saccharomyces cerevisiae var. ellipsoideus. The inoculum of yeast was also optimized during the value addition. The maximum production of ethanol (10.05 %,v/v) was achieved at 10 % (v/v) inoculum level with low reducing sugar (2.01 % w/v), total sugars 5.96 % (w/v), titratable acidity (0.61%, w/v) and pH (3.6), respectively. The ethanol so produced was without amelioration as the juice contained total soluble solids of 24º B.