Study on Separation of Purple Pigment from α-Amylase Enzymatic Hydrolyzate of Purple Sweet Potato and Production of Ethanol with the Sugar Liquid by Fermentation

In this paper,purple sweet potato resources were comprehensively utilized,purple pigment and sugar liquid were extracted at the same time,and sugar liquid was further fermented to prepare ethanol. The purple pigment and sugar liquid from purple sweet potato α-amylase hydrolysate separated by macroporous resin,the effects of kinds and amounts of nitrogen source,yeast dosage and fermentation time on producing ethanol by fermentation of sugar liquid were investigated and optimized the process of ethanol production by sugar fermentation through orthogonal experiment. The results showed that the purple sweet potato enzymatic hydrolysate was separated by HPD400 macroporous resin. The color value of purple pigment was E_{1 cm}^1%=86.3(at 530 nm)and the content of total sugar in solution was 55.5 mg/L. (NH₄)₂SO₄ as nitrogen source with a dosage of 3.0 g in 100 mL sugar solution,the yeast of 1.5 mL and the fermentation time of 7 day. Under the conditions,an ethanol solution with 13.0%vol concentration was obtained. In the process,purple sweet potato pigment was obtained and ethanol was also got by fermentation of the by-product sugar solution,which provides a reference for comprehensive utilization of purple sweet potato.