Study On Effect Of Organic Acid On The Quality Of Fermenting Vegetable

The fermented vegetable has a long history,and it is popular with its rich nutrition and special flavor.Our country is one of the world's largest vegetable producer,which has more than half of the world production,but the production of fermented vegetable is rarely.At present,the majority of kimchi manufacturing enterprises of our country are sporadic,scattered and small-scale.Only a few enterprises have industrial production capacity.At the same time,its production,chiefly by natural fermentation,is processed in manual workshops,which is limited by season and needs a long processing cycle,with poor safety and unstable quality.Therefore,substantial resources are wasted and industrial production is limited.The study is under this background.At present,there are many researches on improving the quality of fermented vegetable products,but many of them are from the spice,fermentation time and temperature.To add organic acids to lower the pH value of fermentation and improve the quality of fermented vegetable products are rarely.The study focuses on adding citric acid,lactic acid,acetic acid,malic acid and compound organic acids in natural fermentation and inoculated fermentation respectively,and studied by measuring the total number of bacteria and lactic acid bacteria,pH value,total acid content and sensory evaluation of products to analyze the affect on product quality.On this basis,we can determine the optimal fermentation time and the best acid add volume.The conclusion of the study is:1.The natural fermentations which add single organic acids of different concentrations need five days to finish.They reduce the time of the fermentation and improve the efficiency of the production.The products are better than the products with no acid fermentation.The product which adds 0.5%lactic acid is the best for its transparent color,better crispness,moderate acidity and strong fermentation fragrance.2.The natural fermentations which add compound organic acids of different concentrations need five days to finish.The products are better than the products with no acid fermentation.The product which adds 0.4%:0.2%(lactic acid to acetic acid) compound acid is the best for its transparent color,better crispness,moderate acidity and strong fermentation fragrance.3.Adding different organic acids can suppress the corrupt microorganism in the natural fermentation process.The product which adds 0.5%lactic acid is the best.The bacteria number decreases with the lactic acid increasing in the first day,and the bacteria number of 0.1%,0.3%and 0.5%concentration decrease to 4.02 logCFU/ml,3.25 logCFU/ml and 2.49logCFU/ml in the fifth day,and the lactic acid number of them are 3.68 logCFU/ml,3.17 logCFU/ml and 2.46 logCFU/ml,respectively.But the bacteria number of 0.7%and 0.9%concentration change small.It proves that too much of lactic acid can suppress the fermentation,and so acid must be not excessive.Adding different compound organic acids have the similar situation.The fermentation product which adds 0.4%to 0.2%of lactic acid and acetic acid is the best,and its bacteria number is 3.66 logCFU/ml in the first day.The bacteria number and lactic acid number are 2.08 logCFU/ml and 2.04 logCFU/ml in the fifth day.But the bacteria number is small in the first day at the concentration of 0.6%to 0.1%.4.The inoculated fermentations which add single organic acids of different concentrations need five days to finish.They reduce the time of the fermentation and improve the efficiency of the production.The products are better than the products with no acid fermentation.The product which adds 0.5%lactic acid is the best for its transparent color,better crispness,more acidity and strong fermentation fragrance.5.The inoculated fermentations which add compound organic acids of different concentrations need five days to finish.The products are better than the products with no acid fermentation.The product which adds 0.5%:0.1%(lactic acid and citric acid) compound acid is the best for its transparent color, better crispness,more acidity and strong fermentation fragrance.6.Adding different organic acids can suppress the corrupt microorganism in the inoculated fermentation process.The bacteria number decreases with the acid increasing.The product which adds 0.5%lactic acid is the best,and in the first day the bacteria number is 4.66 logCFU/ml,and in the fifth day it is 3.5 logCFU/ml.But the concentrations of 0.7%and 0.9%have strong suppress,and the bacteria number of them are 3.47 logCFU/ml and 2.99 logCFU/ml spectively.It proves that too much of lactic acid can suppress the fermentation,and so acid must be not excessive.Adding different compound organic acids have the similar situation.The fermentation product which adds 0.5%to 0.1%of lactic acid and citric acid is the best,and its bacteria number is 4.62 logCFU/ml in the first day.The bacteria number and lactic acid number are 3.19 logCFU/ml and 3.13 logCFU/ml in the fifth day.But the bacteria number decreases small at the concentration of 0.5%to 0.2%.7.In conclusion,adding organic acids can effectively reduce the fermentation time,suppresses a part of corrupt microorganisms growthing,and it makes lactic acid bacteria become superiority.So it is advantageous in controlling vegetables quality,saving cost and improving quality.The product of natural fermentation which adds 0.5%lactic acid is the best for its flavor.