Experimental Study On Lactic Acid Fermentation By Mixed Bacteria Of Food Waste

At present,advanced technology is needed for promoting the disposal of kitchen waste in China.Lactic acid production by food waste fermentation is a new way to realize the recycling of food waste.The process takes food waste as raw material,and obtains abundant of lactic acid which has broad market demand.Food waste has complex component,the saccharification need high consumption.Furthermore,high grease and chloridion in food waste could cause the inhibition on lactic acid production.For these problems,firstly,the study selects Bacillus amyloliquefaciens and Deshi Lactobacillus as the mixed fermentation system and optimized the technological conditions.Then the study investigates the effects of grease and chloridion on lactic acid production in mixed fermentation system,respectively.Finally,the study explores the enhance of lactic acid production by pH control and nitrogen source addition.The main results are as follows:1)Under the open condition,the saccharification rate of Bacillus amyloliquefaciens is 44.1%,which is higher than that of yeast.It is determined that Bacillus amyloliquefaciens and Lactobacillus delbruckii are the best mixed fermentation strains.The yield of lactic acid could reach 0.242 g·gTS^-1.The comparison of the total sugar conversion rate among the three processes:“glucoamylase+Bacillus amyloliquefaciens>glucoamylase>Bacillus amyloliquefaciens”.2)The optimizational parameters of mixed fermentation process:The fermentation temperature is 45?,the inoculation interval is 1.5 h,and the initial pH is 6.5.The output of lactic acid can be reached at 0.351 g·gTS^-1.3)Great and chloridion in food waste could inhibit the fermentation of mixed bacteria in lacitic acid production,and chloridion has a little influence on saccharification process.The addition of lipase could improve lacitic acid production with mixed fermentation system.4)The results of enhancement test with external nitrogen source addition in food waste fermentation with mixed culture system shows that urea could increase the yield of lactic acid.The productivity of lactic acid could reach 0.468 g·gTS^-1 under the optimal condition.