| The purple sweet potato is agricultural product which have high nutritional value and development prospect, purple sweet potato has being widely extended in Japan and other developed countries, because in addition to containing ordinary sweet potato nutrients outside, it still contain functional ingredients,such as selenium, anthocyanidins (anthocyanidin), yellow ketone, glycoprotein, pectin, chlorogenic acid, and have a variety of medicinal function, such as scavenging free radicals, antioxidation, preventing and curing angiocardiopathy, and so on. This experiment with enzymatic hydrolysis of purple sweet potato starch, studied the best wine fermentation technology; with chitosan for clarifying agent, studied the technology of clarification of purple sweet potato wine; at last, through determine the scavenging free radicals, reducing power, etc, studied the antioxidation ability of purple sweet potato wine.1. The fermentation techniques of purple sweet potato wine by liquefaction processing were studied and the results suggested as follows:The optimal liquefaction process is,using purple sweet potato powder as raw material, and then after adjusting material liquid ratio to 1:2.5, with moderate pectinase hydrolysis, and 2.5h liquefaction at 90-100℃with 2u/g amylase, the liquefied mash with good fluidity was produced. Addition of 0.03% lactic acid to adjust mash PH value to 4.5 as liquefied mash temperature dropped at 60℃, then addition of 340u/g saccharifying enzyme in the mash, and the state maintained for 2h at 60℃. When the mash cooled, adding 5% of the k-yeast, keeping fermentation for 7days between 25℃and 28℃, and then, after centrifuge, clarification with chitosan, filling and sterilizing,keep the wine in quite and keep the temperature between 10℃and 15℃for ageing.2. Adopt chitosan as clarify agent, studied the technology of clarification of purple sweet potato wine, and obtained the best clarified conditions:the additive amount of chitosan is 0.6g/L, the clarify time is 2 hour, the temperature of clarify is 20℃.The clarifying of chitosan raise the clarity, decrease the contents of soluble protein and polyphenol, decrease the bitter taste, and increase the stability of sweet potato wine, to make the sweet potato wine taste soft, clean and transparent, full aroma, color and luster very attractive,and meet the national standard of quality. Use GC-MS method to analyze the aroma compositions of purple sweet potato wine, the result analysis shows that aroma compositions containing purple sweet potato wine is riches with 37 kinds of variety, and they can be divided into alcohols, ether alcohol, esters, aldehydes, ketone, acids, phenols and alkanes. The major flavour substances are isoamylol (47..26%), propylene glycol monomethyl ether (35.28%), phenethyl alcohol (8.33%), benzaldehyde (3.21%),2,3-butanediol (1.46%), isoamyl acetate (1.11%),2-Amino-5-methylbenzoic acid (0.49%), ethyl hexanoate (0.46%),1-Methyl-4-cyclohexyl acetate (0.45%), guaiacol (0.40%). 3. With the market dry red wine and the purple sweet potato wine which was homemade by the laboratory as compared. The oxidation resistance test was did by determining dry red wine and purple sweet potato alcoholic strength, anthocyanin content, total polyphenols content and NO2+ removal capacity, and determination the reducing power and clear the DPPH radicals of dry red wine and purple sweet wine. By the results of comparison and analysis of the data obtained, purple sweet potato wine contains a lot of anthocyanins pigment, the clearance rate of NO2+ was 99.96%, the free radical clearance rate of DPPH was 79.7%,and the reducing power increased with the concentration of growth rate higher than the red wine. With good antioxidant capacity, the purple sweet potato wine have a good health care function on the human body. |
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