| In this experiment,Lactobacillus plantarum and Bacillus subtilis were combined 1:1and inoculated into defective pear at different levels for fermentation.By analyzing sensory quality,fermentation quality,p H and microbial quantity changes under aerobic exposure,to determine the appropriate level of inoculation.The quality of mixed defective pear fermentation and corn stalks,defective pear,microbial combination and corn stalks were determined,and the suitable fermentation process was selected out.The diversity of bacteria in the mixed fermentation of defective pear fermentation and corn stalks,the degradation characteristics of in vitro fermentation after 90 days were determined,and the suitable fermentation ratio was selected out,which laid a foundation for the utilization of defective pear and corn stalks resources.TestⅠ:Effects of different levels of lactic acid bacteria combination on fermentation quality of defective pear.In this experiment,the 1:1 combination of Lactobacillus plantarum and Bacillus subtilis was inoculated into defective pear at different levels to study its effect on fermentation quality of defective pear,aiming to determine the inoculation level of microbial combination.It was inoculated to the crushed defective pear at five levels(1.14×10~4CFU/g,1.29×10~5CFU/g,1.38×10~6CFU/g,1.45×10~7CFU/g and 1.58×10~8CFU/g)for fermentation,the blank was not added with microbial combination.The sensory quality,fermentation quality,p H under aerobic exposure and the number of microorganisms were determined.The results showed that with the increase of the level of microbial combination,the sensory score of defective fermentation increased,and when the supplemental level reached 1.38×10~6CFU/g or above,the sensory score was 20,all grades are excellent.p H and butyric acid(BA)showed a decreasing trend,while lactic acid(LA)and acetic acid(AA)increased with the increase of microbial combination.With the extension of aerobic exposure time,p H,the number of yeast and mold in each treatment gradually increased,and the number of LAB gradually decreased.The number of LAB in CK was significantly lower than that in other treatments(P<0.05),and the number of mold was significantly higher than that in other treatments(P<0.05).When the inoculation level reached 1.38×10~6CFU/g and above,the difference in mold quantity was not significant(P>0.05).Therefore,the addition of microbial combinations can improve the quality of defective pear fermentation,the higher the level of microbial combination inoculation,the better.And the inoculation level of the microbial combination set to 1.38×10~6CFU/g.TestⅡ:Effects of different fermentation technology on mixed fermentation quality of defective pear and corn stalks.In this study,defective pear fermentation obtained by testⅠ,the optimal level of microbial combination,defective pear with corn stalks.Selecting the suitable fermentation process.Process(Ⅰ)defective pear fermentation with corn stalks:JG(0:100),L20(20:80),L30(30:70),L40(40:60),L50(50:50),L60(60:40),L70(70:30).Process(Ⅱ)defective pear was added into microbial combination(1.38×10~6CFU/g)and mixed with corn stalks for fermentation:JG(0:100),CL20(20:80),CL30(30:70),CL40(40:60),CL50(50:50),CL60(60:40)and CL70(70:30)were treated with a total of 14 treatments,and each treatment had 3 replicates.After 90 days of fermentation,the nutrient composition,fermentation quality,p H and microbial quantity of the two process were analyzed respectively.It was found that defective pear fermentation and defective pear could improve the content of water soluble carbohydrate(WSC),reduce the content of neutral detergent fiber(NDF)and acid detergent fiber(ADF)of corn stalks.Sensory scores of JG were inferior,and sensory scores of L30～L50,CL30～CL50 were superior.The contents of LA and AA inⅠandⅡwere increased with the increase of defective pear fermentation and defective pear.During aerobic exposure,the number of LAB in JG was significantly lower than that in other treatments(P<0.05),the number of yeast and mold was significantly higher than that in other treatments.Therefore,adding a certain amount of defective pear fermentation or defective pear improve the quality of corn stalks,but the microbial combination inoculation into the defective pear to make a defective pear fermentation can better preserve the nutritional value,and at the same time solve the contradiction between defective pear and corn stalks harvested at different periods.TestⅢ:Analysis of bacterial diversity in mixed fermentation of defective pear and corn stalk.In this experiment,the bacterial diversity was studied by mixing defective pear fermentation with corn stalks,the aim of selecting a suitable fermentation ratio.The bacterial diversity was determined at 1 d,7 d,14 d,30 d and 90 d by mixing the defective pear fermentation with corn stalks.The results showed that the dominant bacteria at the phylum level evolved from Proteobacteria to Firmicutes in JG,L60 and L70,while the dominant bacteria at the phylum level remained in the thick-walled phylum in the other treatments.The relative abundance of Lactobacillus was consistently higher in the treatment with defective pear fermentation than in the treatment without it,with the relative abundance of Lactobacillus consistently higher in treatments L20,L30,L40 and L50.TestⅣ:In vitro degradation characteristics of mixed fermentation feed of defective pear and corn stalks.In this experiment,the mixed fermentation feed of defective pear fermentation and corn stalks were used as the test material,the digestion process in the rumen was simulated by in vitro method,so as to select out the appropriate fermentation ratio.The fermented feed from processⅠin experiment 2 was incubated in vitro and the gas production was recorded for 2 h,4 h,8 h,12 h,24 h,36 h,48 h and 72 h of incubation to determine the fermentation parameters and degradation rate.The results showed that the in vitro fermentation and degradation rate of corn stalks fermentation with defective pear fermentation were improved.Except the difference of gas production rate(c)was not significant(P>0.05),the gas production(GP),rapid gas production(a),slow gas production(b)and potential gas production(a+b)at 72 h increased with the increase of the proportion of defective pear fermentation,and the gas production(59.47 m L)of corn stalks silage(JG)was always the lowest within 72 h.The p H of fermentation broth of each treatment were 6.43～6.86,which were all within the normal p H range of rumen(6～7).Ammonia nitrogen concentration decreased first and then increased with the increase of the proportion of defective pear fermentation,and the ammonia nitrogen concentration of L40 was significantly lower than that of other treatments(P<0.05).Total volatile fatty acids tended to increase and then decrease with the addition of defective pear fermentation,with L50 reaching the highest level.The dry matter degradation rate,neutral detergent fibre degradation rate and acid detergent fibre degradation rate gradually increased with the addition of defective pear fermentation,and JG without the addition of defective pear fermentation had the lowest dry matter degradation rate,neutral detergent fibre degradation rate and acid detergent fibre degradation rate,which were significantly lower than the treatment with the addition of defective pear fermentation(P<0.05).In conclusion,the inoculation level of microbial combination was determined to be1.38×10~6CFU/g.The process of mixing fermentation with defective pear fermentation and corn stalks I is better.The bacterial diversity and degradation characteristics of defective pear fermentation with corn stalks were determined after 90 days of fermentation.The results showed that the ratio of defective pear fermentation with corn stalks was 30:70～50:50. |
