【作者】 沈昌；

【导师】 顾振新；

【作者基本信息】 南京农业大学 ， 食品工程， 2007， 硕士

【摘要】 紫甘薯（Ipomoea batatas（L.）Lam）块根肉色紫红，富含花色苷，具有营养保健多重作用。近年来，紫甘薯在国际、国内市场走俏，发展前景极为广阔。本论文对果酒酵母分离、筛选、生理特性、紫甘薯醪制备、紫甘薯酒发酵条件进行了研究，旨在为紫甘薯应用提供理论依据。研究结果如下：从果园土壤和水果表皮中分离得到84株酵母菌，经过三级筛选发现有32株菌均能产CO₂和酒精，其中10株菌的发酵液香气浓郁、口味纯正，经SO₂抗性试验，最终确定两株菌N-1，N-2为试验菌株，进行生理特性研究。二者发酵7天酒精度分别达到7.5％和9.2％；在酒精度分别为16％和19％时且SO₂浓度在160 mg／L时，均能产气发酵。经感官评定，二者典型性最好，香气最为浓郁，可作为下一步试验菌株。筛选得到的酵母菌N-1和N-2菌株的最适生长温度分别为28℃和32℃，最适生长pH值均为6.0，生长21h后均达到最大生物量，但N-2显著高于N-1；最适发酵温度为28℃和32℃，最适初始pH值均为6.0，筛选菌株可满足一般果酒的酿造要求，且产香能力比较强。用果胶酶、淀粉酶和糖化酶连续酶解紫甘薯醪，最终紫甘薯醪黏度仅为0.6 PaS，淀粉含量仅为5 mg／mL，还原糖含量高达155 mg／mL，完全适用于酵母菌发酵。紫甘薯酒中紫甘薯醪的最适添加量为40～50％，最适发酵温度28℃，最适初始pH值为4.0，接种量为2.0×10⁷个／mL。在此条件下发酵得到的紫甘薯酒花色苷含量保存的最多，发酵液中还原糖含量最低，酒精度最高。紫甘薯醪发酵的成品酒既保留糯米酒的风格又降低了糯米酒的苦味，色泽鲜红、酒液清亮。更多还原

【Abstract】 Purple sweet potato has been paid increasing attention at home and abroad due to its richness inanthocyanins and potential benefits for human health. In this dissertation, isolation and screening ofyeast strains suitable for fruit wine production was carried out and the physiological properties ofselected yeast strains were investigated. The purple sweet potato wine was produced with the selectedyeast strain. The results and findings were summarized as follows:Eighty-four yeast strains were isolated from the soil in fruit orchard and some fruits surface. Of which,thirty-two Strains which had the capacities of carbon oxide and alcohol production were screened out.And ten of thirty-two strains could ferment to make the fermented, mash strong aroma and good mouthfeeling. Through SO₂ tolerance test, two strains of N-1 and N-2 were obtained. It was found that withinseven fermentation inoculated with N-1 and N-2, 7.5 % and 9.2 % of the alcoholic concentration （v/v）were obtained, respectively and in the malt worts with the alcoholic concentrations of 16% and 19 %（v/v） and 160 mg/L of SO₂, both could ferment, producing CO₂ and strong aroma. Their physiologicalproperties were observed. The results showed that the optimum temperatures for the growth of N-1 andN-2 were 28℃and 32℃, respectively, and the optimum initial pH Value were all 6.0. Under thoseoptimum conditions, the maximum biomass was reached in 21 hour fermentation and the biomass of N-1was obviously higher than that of N-2. Those properties suggested N-1 and N-2 were all adapted to wineproduction.The viscosity of 0.6 PaS, 5 mg/mL of starch and 55 mg/mL of reducing sugars in purple sweet potatomash were reached through consequent treatment with pectinase, amylase and saccharifying enzyme, itwas suitable for yeast fermentation. The optimum fermentation process parameters for purple sweetpotato wine were 40% purple sweet potato mash, inoculation population of N-1 2.0×10⁷, temperature28℃, initial pH value 4.0. Based on the optimum conditions, the highest retention of anthocyanins,lowest content of reducing sugars and maximum alcoholic concentration in purple sweet potato winewere observed. This wine had bright red color, clearness, lower bitter with some characteristics of stickrice wine.更多还原