Alcohol production from potato industry starchy waste

ABSTRACT

Potato starchy waste from potato chips industry amounted about 18% of company production could be utilized in alcohol production. The starchy waste was hydrolyzed using 0.5 N sulfuric acid at 121C for one hour using solid liquid ratio 45 resulting in glucose syrup of about 70% glucose. Saccharomyces cerevisiae AFZ-998 with high power to produce alcohol by fermentation from cane-molasses was employed using batch fermentation. Physiological studies to optimize the culture conditions for efficient ethanol production were conducted. Slow shaking resulted a decrease in the fermentation period from 60 to 48 hr. Similarly, increasing the inoculum size to 8% [v/v] resulted in shortening of the fermentation time from 48 to 36 hr. The highest alcohol level [13.2% v/v] was achieved after 24 hr at 34C in a medium contained 25% w/v glucose with initial pH 5.0 using urea as the sole nitrogen source at a level of 0.075%, orthophosphoric acid 0.05% [v/v], inoculum size 8% [v/v] and shaking rate 100 rpm. Under the above conditions, the culture gave 12.5 g dry yeast/l contained 36% crude protein and can be used in feeding purposes: