| Bran is a by-product of wheat flour production,which is the best source of dietary fiber.The taste ofthe bran is rough and it is difficult to digest directly,so it is often used as animal feed and an auxiliary material for fermented food,and the product utilization rate is very low.Jujube is a high-quality food with the same origin of medicine and food and the "tonic king" in the fruit,which is rich in sugar,so it is an excellent substrate for lactic acid bacteria fermentation.The bran powder was gelatinized,enzymatically hydrolyzed and saccharified,then it was mixed with jujube pulp to prepare an bran and jujube mash.After adding lactic acid bacteria,lactic acid fermentation was used to produce bran and jujube tablets fermented by lactic acid bacteria,which provided theoretical basis and technological parameters for the development and utilization of bran and the production of bran and jujube tablets fermented by lactic acid bacteria.The test results were summarized as follows:1.Through the screening of the acidity production ability and functionality of six lactic acid bacterium commonly used in the food fermentation industries,it was determined that the Lactobacillus plantarum(LP)and Lactobacillus fermentum(LF)with good growth and high yield of organic acids were chose as the fermented bacteria for bran and jujube mash.2.A medium optimization experiment was carried out for high-density culture which was suitable for the growth of LP strain and LF strain.Nutrients such as glucose,tomato juice and barium chloride were added to the basic medium to promote the growth of LP strain and LF strain.After the two strains were cultured for 24 h in the optimized growth medium,the OD600 value of LP strain was 1.24,whose the increase rate of bacterial concentration up to 38%;the OD600 value of LF strain was 0.93,and the increase rate up to 30%.3.Total acid of reducing sugar conversion in bran and jujube mash was used as evaluation index and the compounding ratio of raw bran and jujube,the moisture content of fermented mash,the optimum temperature of lactic acid fermentation,the inoculating amount of fermentation strain and the fermentation time were analyzed.The results showed that the suitable compounding ratio of bran and jujube was 32(dry weight),the suitable moisture content of fermented mash was 60%,and the mixed bacteria suspension of LP and LF strains with a concentration of 1×10~9 cfu/mL was added at 10%inoculation amount,after fermenting at 36.5 ? for 48 h,the acid content of the fermented mash was 2.59 g/100g.The mash was sweet and sour taste,flavor coordination and no off-flavors.4.After lactic acid fermentation,the total acid content in the bran and jujube mash was 2.59 g/100g,the reducing sugar content was 5.03 g/100g;the protein contentwas 5.14 g/100g.The viable bacteria counts in the fermented mash reached up to 1.93x10~9 cfu/g.The total acid content of lyophilized powder was 6.28 g/100g,the reducing sugar was 12.12 g/100g,the protein content was 12.89 g/100g,and the lactic acid bacteria count was 1.9×10~8 cfu/g.5.The composition and changes of organic acids in bran and jujube mash before and after fermentation and lyophilized powder were analyzed.The results showed that,after lactic acid fermentation,the content of malic acid and citric acid in the mash decreased;the content of lactic acid,acetic acid and succinic acid increased significantly and the lactic acid produced in the fermented mash was 2.01 g/100g;the fumaric acid content increased,while the content of tartaric acid did not change significantly,meantime the adipic acid was not detected.The main organic acids and their contents of lyophilized powder were 4.91 g/100g of lactic acid,1.14 g/100g of acetic acid,0.55 g/100g of succinic acid,0.26 g/100g of tartaric acid and 0.12 g/100g ofcitric acid.6.The composition and changes of amino acids in bran and jujube mash before and after fermentation and lyophilized powder were determined by automatic amino acid analyzer.The results showed that,after lactic acid fermentation,the total amino acid content in the mash was 24.16 g/kg.The flavor amino acid composition was significantly changed,whose the content of umami amino acid and sweet amino acid increased by 32.55%and 14.17%,respectively;the bitter amino acid content decreased by 21.39%and the aromatic amino acid content increased slightly.The content of the total amino acids in lyophilized powder was 53.79 g/kg,the contents of umami amino acid and the sweet amino acid were 16.92 g/kg and 20.30 g/kg,respectively.7.The bran and jujube mash after lactic acid fermentation was vacuum-dried,and the tablet was prepared withmicrocrystalline cellulose,xanthan gum,magnesium stearate,and glucose.The optimum raw and auxiliary ingredients ratios were as follows:the lyophilized powder content of bran and jujube mash was 65%,glucose 15%,microcrystalline cellulose 20%,xanthan gum 0.5%and magnesium stearate 1%.The contents of moisture,total acid,total sugar,dietary fiber,and lactic acid bacteria content in the bran and jujube tablets fermented by lactic acid bacteria were 4.59 g/100g,3.99 g/100g,38.10 g/100g,35.23 g/100 and 1.1 x10~8 cfu/g,respectively.The appearance was complete and smooth,the color was pale brown and uniform,The texture was fine and smooth,firm and not loose.Sweet and sour taste,and the fermented tablets had the jujube flavor and lactic acid fermentation flavor. |
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