Screening And Application Of Probiotics In Pepper

Zuolajiao,a traditional Chinese fermented hot pepper product in Sichuan,Hubei,Hunan and Guizhou with a long history.It would have a profitable market prospect for which fulfill unique taste and can be eaten directly or used in food processing,and popular in the local area and has a wide range of flavors.However,many of them are produced in the form of small family factory production and lack of standardized production processes.The fermentation mainly depends on the role of lactic acid bacteria in the raw materials,so uncertainty of fermentation microorganisms and indefinite and the fermentation process,and cause products are susceptible to bacterial contamination easily.And the fermentation conditions are susceptible to seasonal,temperature and so on,and there were problems of unstable and uncontrolled product quality.These problems have seriously hampered the development and promotion of fermented peppers as functional foods,and are not conducive to industrialized utilization of the fermented pepper resources.In this paper,6 new strains of fast acid-producing were isolated from the traditional product of Zuolajiao.Lactobacillus fermentum 17-1,Lactobacillus brevis L3-5 and Lactobacillus fermentum 18-2 were selected as probiotics-producing strains through the study of probiotic properties.then the fresh millet pepper was used as the raw material for pure fermentation,and finally Lactobacillus fermentum 17-1 was determined as ferment strain which suitable for the fermentation of pepper.Furthermore,process optimization,the optimum conditions for fermenting peppers were determined,and the differences in physical and chemical indicators,microbial indicators,and sensory indexes between pure and natural fermentations were studied,which provided a certain theoretical basis for a new type of functional food.Followed are the main research contents and results:1.Determination of microbial composition in Zuolajiao samplesIn this experiment,the sample was obtained from Jianhe County farmers' market in Guizhou Province,the microbial composition were studied.The results showed that the content of lactic acid bacteria was 10.23±0.14 Log(CFU/mL),the yeast content was 5.37±0.04 Log(CFU/mL),and Escherichia coli was not detected.2.Isolation and identification of bacteria16 strains of gram-positive and enzyme-negative strains of lactic acid bacteria were isolated from the Zuolajiao.The initial screening was based on the rate of acid producing ability.Six strains were obtained with fast growth and fast acid production.All of the 6 strains were able to reach a stable growth period after 14 h of culture,with final pH of 4.0 to 4.4 and total titrate acid range of 1.28%to 1.71%.The morphology observation,physiological and biochemical tests and molecular identification indicated that strains 7-2,6-1 and L3-4 were lactobacillus plantarum,L3-5 was Lactobacillus brevis,18-2 and 17-1 were Lactobacillus fermentum.3.Screening of probioticsArtificial gastrointestinal environment resistance,cell adhension colonization and protection of intestinal capacity,functional properties and safety evaluation were evaluated for selected probiotic strains.The results showed that strains L3-5,L3-4,18-2 and 17-1 were able to tolerate extremely adverse environments and reach the small intestine with a certain degree of have bile salt hydrolase(BSH)activity,have stronger intestinal adhesion ability and can produce bacteriocins with having a broad-spectrum bacteriostatic effect to inhibit the growth of pathogenic bacteria.All of the three strains of lactic acid bacteria have antioxidant capacity,among which the fermentation supernatant played a major antioxidant role,while the bacterial suspension and cell-free extracts had a much weaker antioxidant capacity.All strains have y-aminobutyric acid(GABA)-producing ability and higher ability to degrade sodium nitrite.and are all safe strains.None of the 3 strains of bacteria are hemolytic bacteria.They are not DNase producers and they are safe for food fermentation.Therefore,Lactobacillus fermentum 18-2,Lactobacillus brevis L3-5 and Lactobacillus fermentum 17-1 were selected for the next experimental study.4.Determination of the best fermentation conditions for the fermentation of probiotics and peppersThe screening of growth in different concentrations of NaCl medium and re-screening of fermenting with actually raw peppers were tested,Lactobacillus fermentum 17-1 was selected as the most suitable ferment strain with the tolerance to salt and produces more acid and has higher acid production and amino acid nitrogen content in raw materials.Using Lactobacillus fermentum 17-1 to prepared peppers and taking sensory evaluation scores,total acidity and amino acid nitrogen content as the standard.Through the single factor and orthogonal design,the optimum technological parameters for the pure fermentation of pepper were determined as follows:fermentation time 4 days,fermentation temperature 32?,inoculation amount 7%.Under the optimal conditions,the total acid content of the pepper products was 1.22%,the amino acid nitrogen was 0.27%,and the sensory evaluation score was 91.5.Comparison of quality of peppers with different fermentation methodsThe pepper was fermented according to the optimized conditions,and the quality of the pure-seed and natural-fermented products was compared and analyzed.The physicochemical differences of peppers with different fermentation methods was tested.The pH value,total acid content,amino acid nitrogen content,protein content,reducing sugar,nitrite content and solid content of the fermented product were determined.The results showed that the content of total acid and amino acid nitrogen in inoculated and fermented pepper was higher than that of natural fermentation,and the pH value,soluble solids and protein content were lower.Moreover,the nitrite content in fermentation process was always lower than natural fermentation,and all sensory scores were higher than natural fermentation.Therefore,inoculation fermentation can shorten the fermentation cycle,save production costs,effectively improve food safety,and increase the nutritional value of pepper.