Abstract:

The tuber of purple sweet potato (Ipomoea batatas cultivar Jizishu No.1) was processed through combination
of starch enzymatic hydrolysis and alcoholic yeast fermentation into a red wine similar in color to grape wine. The starch
liquefaction and saccharification as well as fermentation conditions were optimized using an orthogonal array design. The
aroma components of the sweet potato wine were determined by gas chromatography-mass spectrometry (GC-MS) and the
contents of amino acids and organic acids were detected by high performance liquid chromatography (HPLC). The maximum
hydrolysis efficiency of starch of 92% was obtained when the starch liquefaction was carried out at 92 ℃ for 60 min with
3 U/g of amylase at a material to water ratio of 1:3, followed by 60 min saccharification at 50 ℃ and pH 4.5 with 300 U/g
of glucomylase. The subsequent fermentation was performed for 7 days at 23 ℃ and pH 4.0 after inoculation with 2 × 106
active dry yeast cells/mL, yielding an alcohol content of 12.4% (V/V). A total of 46 aroma components, 17 amino acids and
9 organic acids were identified in the wine and it contained 145 mg/L anthocyanins. The purple potato red wine possesses a
unique flavor and various nutritional components and thus it has the potential for further development.

Key words: purple sweet potato red wine, process optimization, chemical analysis