Optimization of pretreatment of potato waste for release of fermentable sugars for vodka production: response surface methodology approach

Vodka is a transparent distilled alcoholic beverage, obtained by fermenting various substrates such as cereal grains, potatoes, and molasses, offering economic viability and widespread availability. A bioprocess for vodka production was optimized using potato waste collected from Iscon Balaji Foods Pvt. Ltd. Ladhowal, comprising of potato peel, mash, and industrial water. The proximate and physicochemical analysis showed high starch content (59%) and rich organic constituents in potato peel and mash mixture. The response surface methodology was used to optimize liquefaction with α-amylase (5000 IU/mL/min) dose of 0.72% (v/v) for 62.15 min at 59.8 °C and saccharification with glucoamylase (1000 IU/mL/min) dose of 1.7% (v/v) for 28.5 h at 52 °C. The concentration of fermentable sugars in the wort before fermentation was 13.03 mg/mL of total sugars and 10.69 mg/mL of reducing sugars. The ethanol fermentation was carried out by inoculating Saccharomyces cerevisiae (MK680910) at the pitching rate of 6% and after 3 days of fermentation the alcohol content of 7.6% (v/v) was recorded in potato waste mixture. Subsequent fractional distillation at 80 °C resulted in ethanol concentration of 38.4% with 76.8° proof. Hence, this study presents an efficient method for fermentative processing of potato waste into vodka.