【作者】 李芳；

【导师】 阚建全； 杜木英；

【作者基本信息】 西南大学 ， 食品科学， 2009， 硕士

【摘要】 桑椹俗名桑树枣、桑果,为桑科落叶桑树（Morusalbal）的成熟果实。桑椹果形细长,由无数颗粒的肉质构成,大如指头,成长圆形,初熟时呈红色,老熟变成紫黑色,果肉多汁,味微酸而甜。桑椹果醋以桑椹果汁为原料添加适量蔗糖经酒精发酵和醋酸发酵而成,既可作为调味品又可以作为饮料直接饮用。本试验主要对优良醋酸菌种的筛选、果胶酶对桑椹取汁的影响、醋酸发酵工艺参数的确定、发酵过程中主要化学成分的变化进行了系统地研究。主要研究结果如下:1、通过静置发酵试验对醋酸菌种AS1.41、SICC1.41、SICC1.42、B₁、B₂进行了筛选,其中醋酸菌AS1.41产酸迅速,培养基酸度最高,本试验选择AS1.41为桑椹果醋发酵菌种。2、通过单因素试验和正交试验,桑椹最佳取汁条件为果胶酶用量为70 U/g,作用时间为120 min,作用温度为40℃,在此条件下桑椹出汁率为76.8%,是未经果胶酶处理42.1%的1.8倍。3、通过对不同发酵方式、装液量、发酵温度、接种量、初始pH值、初始酒度、初始糖度的单因素试验及对初始pH值、初始酒度、接种量和初始糖度的L₉（3⁴）正交试验得出:影响醋酸发酵的主次因素为初始pH值＞初始糖度＞初始酒度＞接种量。醋酸发酵最佳工艺参数为接种量11%,装液量20%,初始酒度7%,初始糖度2%,初始pH 3.5,发酵温度31℃,发酵方式为摇床发酵,在此条件下酿制的桑椹果醋酸度为6.39g/100mL。4、研究了桑椹果醋在酒精发酵过程中酒度、还原糖和色度的变化以及醋酸发酵过程中酒度、酸度和色度的变化。结果表明:（1）酒精发酵过程中,糖度呈下降趋势,酒度呈上升趋势,即发酵前2d,糖度迅速下降,但酒度上升趋势缓慢;2d后糖度迅速下降,酒度迅速上升;6d后酒度和糖度变化趋于平缓;7d后酒度不再上升,糖度不再下降,酒精发酵结束。（2）在醋酸发酵过程中,酒度呈下降趋势,酸度呈上升趋势,即发酵前2d酒度和酸度变化缓慢;从第3天开始酒度迅速下降,酸度迅速上升;6d后酒度和酸度变化趋于平缓,醋酸含量累积到最大。（3）在整个发酵过程中,色度呈下降趋势,而在陈酿过程中又显著上升并超过发酵前期色度。6、采用GC-MS方法对桑椹果汁在发酵过程中挥发性风味物质的变化进行了分析鉴定。研究表明,从桑椹汁中共鉴定了41种组分,从桑椹果酒中鉴定了47种组分,从桑椹果醋中鉴定了44种组分,共同的组分有8种,主要为醇、酯、酸。在整个发酵过程中,醇的相对含量先上升后下降,酸的相对含量一直上升,酯的相对含量一直下降。7、桑椹果醋色泽紫红,有光泽,果香及醋香浓郁,无异味;总酸度为6.0～6.4g/100mL,挥发酸的含量为5.1～5.6g/100mL,可溶性固形物的含量为7.0%,还原糖的含量为1.0～1.2g/100mL,总酯的含量为1.2～1.4g/100mL;细菌总数≤100cfu/mL,大肠菌群≤3MPN/100mL,致病菌未检出。更多还原

【Abstract】 Mulberry,fruit of Morusalbal,sizes as finger.When it ripes,it turns to black purple.It tastes sweet and sour.MUlberry vinegar is maken by mulberry juice,which deal with alcoholic fermentation and acetic acid fermentation.Mulberry vinegar can be used as spice and drink.This paper mainly deals with the selection of higher quality acetic acid bacteria, the influence of pectinase on juice extraction of mulberry pulp,making certain of the acetic acid fermentation technical parameters,the characteristic variations of fermentation,the changes of main chemical ingredients.The results as follow:1.From stationary fermentation of acetic acid bacteria of AS1.41,SICC1.41, SICC1.42,B₁ and B₂,it is found that the AS1.41 acidity raised fast.The acidity of culture medium of AS1.41 is highest,so the AS1.41 is the best choice.2.The optimal condition of juice extracting is:the dosage of pectinase is 70U/g; the acting time is 120 min;the acting temperature is 40℃.Under this condition the mulberry pulp extraction is 76.8%,which is 1.8 times to CK.3.From the single factor experiment of different fermentation methods,the volume-loading,the fermentation temperature,the inoculation volume,pH,the initial alcohol content,initial sugar degree and the orthogonal experiments L₉（3⁴） of the initial alcohol content,the fermentation temperature,pH,initial sugar degree,it is found that the primary and secondary factors affecting vinegar fermentation are pH,the initial sugar degree,the initial alcohol content,the inoculation volume.The optimal condition of vinegar fermentation is the volume-loading:20%,the fermentation temperature:31 ℃,pH:3.5,initial sugar degree:2%,initial alcohol content:7%,inoculation volume: 11%,ferment in shaker:.Hereunder,the acid content is 6.39g/100mL.4.The change of alcohol content,sugar degree during alcoholic fermentation and the change of alcohol content,acidity during acetic fermentation were determined.The reducing sugar decreased and the alcohol content in alcoholic fermentation rose all the time.In the first two days,sugar degree decreased gradually.The sugar degree fell quickly and the alcohol content presented obvious rise from the second to sixth days. The change of alcohol content and sugar degree was slowly on the sixth day.The alcohol content and sugar degree was almost unchanged after 7 days and the alcoholic fermentation was over.The alcohol content decreased gradually and the acidity rose all the time in acetic fermentation.In the first two days,alcohol content and acidity changed slowly.The alcohol content fell quickly and the acidity presented obvious rise from the third to sixth days.The alcohol content and acidity changed slowly after the sixth and the acidity came up to highest on the seventh days.The variation of chromaticity is analyzed by spectrophotometer throughout the fermentation process. The chromaticity decreased at the fermentation process and rose by aging.6.Analysis the flavor components variation of fruit vinegar made from mulberry by GC-MS elementary,and 41 flavor components of mulberry juice,47 flavor components of mulberry wine,44 flavor components of mulberry vinegar are identified, which are almost ester,alcohol and acid.There are 8 same flavor components.The alcohol rose first then decreased;the acid rose all the time;the ester decreased all the time.7.The fruit vinegar beverages possess claret-colored,gratifying fruit and honey savory,harmonious sourness,clarity.The total acid was content 6.0～6.4g/100mL.The volatilization acid content is 5.1～5.6g/100mL.The dissolubility solid thing is 7.0%. The deoxidize sugar is 1.0～1.2g/100mL.The total ester is 1.2～1.4g/100mL.The gross bacteria are＜100cfu/mL.The coliform is＜3MPN/100mL.There are no dangerous bacterias.更多还原