Ethanol production from cashew apple juice using statistical designs

Abstract

Statistical experimental designs were carried out for enhancing the ethanol production from cashew apple juice after obtaining the biochemical analysis of cashew apple juice. The biochemical analysis of the cashew apple juice was as follows: 79.2 % moisture, 12.5 % total sugars, 4.9 % reducing sugars, 0.16 % protein, 0.2 % fat, 1.91 % tannin and 1.13 % ascorbic acid. Cashew apple juice can be preserved at -18oC for several months. The Plackett - Burman design was used initially to screen seven nutritional parameters which are critical and important for growth of Saccharomyces cerevisiae as well as enhancing ethanol production. Among them three parameters were found to have a significant effect on ethanol production and these three elements were further optimized using central composite design (CCD) by response surface methodology. The optimal values of three variables obtained for maximum production of ethanol was (g/l): ammonium chloride 0.45, magnesium sulfate 0.08 and dipotassium phosphate 0.21 and the predicted ethanol production was 61.34 g/l. With the predicted optimal values, experiments conducted in the laboratory yielded an ethanol production of 59.80 g/l equal to 93.62% of its theoretical yield. Statistical experimental designs such as Plackett-Burman design and CCD are critical and important for rapid screening and determining significant nutritional parameters and then optimizing them for enhancing the ethanol production.