| Sweet corn has high low-molecular-weight sugar content because of its genetic characteristics that inhibit the conversion of low-molecular-weight sugar to starch.Sweet corn is both a fruit and a vegetable.Besides it's high sugar,sweet corn also rich in nutrients such as multivitamins and minerals,and has high nutritional and health benefits.In recent years,with the recognition of the nutritional value of sweet corn,the demand for sweet corn had been increasing,and the planting area of sweet corn had been expanding.At present,sweet corn products were mostly canned sweet kernel corn,pure fermented wine was less.In this study,the yeast screened by sweet corn epidermis was induced into a mutant strain with good fermentation performance for the first time.The mutant strain was inoculated to sweet corn slurry for fermentation and the fermentation process was optimized.The sweet corn fermentation wine we obtained had high alcohol content and the unique aroma and taste.The specific conclusions were as follows:(1)Preliminary Screening of Fermented Yeast Strains.Five yeast strains were isolated from the epidermis of sweet corn.A strain HBF-2 with best fermentation indexes as high alcohol content,low reducing sugar and low total acid was selected from 5 yeast strains which were obtained from the epidermis of sweet corn.The results showed that the alcohol content of sweet corn wine was 8.6%(v/v)when using HBF-2 for preliminary fermentation.By plotting the growth curve of strain HBF-2,combined with its growth stability and higher bacteria number requirements,culture time before mutation was determined to be 14 h.(2)UV Mutagenesis and NTG Mutagenesis of HBF-2.The mutant strain UV-6 was obtained by UV mutagenesis,and its wine-producing ability was increased by 22.1% compared with the original strain HBF-2.The mutant NTG-7 was obtained by NTG mutagenesis,and its wine-producing ability was increased by 10.5% compared with the original strain HBF-2.The fermentation stability of mutant strain UV-6 was confirmed by 5 subcultures.Therefore,the mutant strain UV-6 was identified as S.cerevisiae for sweet corn fermentation.(3)Determination and optimization of sweet corn syrup process conditions.Optimization of saccharification process conditions by single factor test and orthogonal test.Finally,the optimal process conditions for sweet corn syrup saccharification were obtained: The added amount of saccharifying enzyme was 200 U/g,the saccharification temperature was 65°C,the saccharification solution p H was 4.6,and the saccharification time was 3.5 hours.The reducing sugar content obtained by saccharifying sweet corn pulp was 21.2%.(4)Determination and optimization of sweet corn wine main fermentation process conditions.Optimization of the main fermentation process of sweet corn wine by single factor test and orthogonal test.The optimal scheme of the process conditions was: yeast UV-6 inoculation amount 3%,fermentation broth p H value 5.0,fermentation temperature 28°C.The alcohol content of sweet corn fermented wine which produced under this fermentation conditions was 12.5%(v/v).(5)Analysis of aroma composition of new wine and three months old sweet corn wine.The results of GC-MS analysis of the two sweet corn wines were as follows: 42 components were detected in the new sweet corn wine,including alcohols,esters,and acids;a total of 34 components were detected in the sweet corn wine aged for 3 months,including alcohols,esters and ketones.The main aroma component of new wine was dominated by isoamyl alcohol,which makes the sweet corn wine with spicy spicy taste and rough wine quality;the main aroma component of 3-month sweet corn wine was dominated by 2,3-butanediol,which has the special sweet aroma of light and pleasant.In summary,the taste and aroma of sweet corn wine aged for 3 months has more advantages than the new sweet corn wine. |
PDF Full Text Request