Study Of The Step By Step Fermentation Process Of Rapeseed Meal

Rapeseed meal, as the most potential applications plant protein resources, is imminent for large-scale rational development and utilization. In this study, based on a large number of previous studies, rapeseed meal was fermented by a step-by-step fermentation process, which was firstly to use a solid-state aerobic fermentation method to promote a large number of micro-organisms multiplication and the degradation of anti-nutrients and macromolecules, by control of the fermentation time, to prevent substantial loss of nutrients; then transferred to use the anaerobic fermentation method to enrich the species of product, and increase their nutritional value. The setting of the evaluation, including the increasing rate of polypeptide, the degradation rate of total glucosinolates and the increasing rate of total acid, indicated that it’s closer to the actual production. Then, in order to balance the amino acids constitution in the product, an appropriate amount of cottonseed meal was added. Finally, the study of polypeptide in the fermentation rapeseed meal product not only further evaluated the nutritional value of fermentation product, but also verified the feasibility of utilizing this fermentation method to obtain bioactive rapeseed peptides.(1) By the rapeseed meal aerobic fermentation strains screening and process optimization experiments, the following conclusions were got:24h was appropriate for expanding training by each single-strain growth curve, the count results showed that, they had reached the vaccination requirements;3#-910,5#,7#three predominant strains were screened by single strain screening experiment; the mixed strains screening experiments showed that the best ratio of three strains was3#-910:5#:7#2:1:1. The single factor process optimization experiment results showed that:when the inoculation amount was2.0%, the fermentation time was3d and longer, the fermentation temperature was36℃, the ratio of material to water was1:0.75and more, the effect of each single factor was best on the aerobic fermentation experiment result. Combination of multi-factor process optimization experiments result, following-up arrangements and the actual production,it was determined that the best combination of aerobic fermentation process was1.5%of the inoculation amount, fermentation time3D, fermentation temperature36℃, the ratio of material to water1:1.(2) By the anaerobic fermentation strains screening experiment,5#this dominant strain was selected. By anaerobic fermentation process optimization experiment, combined with the research results of aerobic fermentation stage, the rapeseed meal step-by-step fermentation total process was determined:firstly mix3#-910,5#,7#the three single strain which was cultured for24h in the logarithmic phase by the ratio of2:1:1, then access the rapeseed meal solid-state fermentation medium by the inoculation amount of1.5%, the material to water ratio of1:1, the aerobic fermentation time3d at36℃; followed by accessing5#facultative anaerobe by the inoculation amount of0.5%, the anaerobic fermentation3d at33℃, to obtain the final product.(3) By the rapeseed meal solid-state fermentation medium optimization experiment, the adding amount of cottonseed meal was determined that15%was appropriate, other growth factors can not be added considering of the economic cost.(4) The measuring of various substances content in the rapeseed meal raw materials and fermentation products indicated that the effect of the fermentation was very satisfactory. The results showed:After fermentation, the polypeptide content of rapeseed meal increased from15.44mg/g to69.19mg/g, the increasing rate was348.2%; total acid content increased from1.227%to4.368%, the increasing rate was256.0%; total glucosinolates degraded from2.755mg/g to1.427mg/g, by48.20%; the ITC content degraded from0.5199mg/g to0.3774mg/g, by27.40%, the OZT content degraded from the0.2799mg/g to0.02362mg/g, the degradation rate was91.56%; crude protein content increased by7.458%; crude fiber degraded by1.184%; phytic acid degraded by14.81%; tannin content slightly increased. On organic acids, the content of various organic acids which have the value of increasing flavor and palatability of product, partial replacement of the role of antibiotics had significantly improved.By adding cottonseed meal to optimize the fermentation medium, polypeptide content in the mixed medium fermentation products increased from15.44mg/g to69.45mg/g, by349.8%; total acid content increased from1.227%to4.424%, by260.6%; total glucosinolates content degraded from2.755mg/g to1.613mg/g, by41.44%; the ITC content degraded from0.5199mg/g to0.3976mg/g, the degradation rate was23.50%, the OZT content degraded from0.2799mg/g to0.05926mg/g, the degradation rate was78.83%; crude protein content increased by14.47%; crude fiber degraded by6.550%; phytic acid degraded by6.209%; tannin content slightly increased. On hydrolysis amino acid, the content of Lysine, leucine and other limiting amino acids increased than the single fermentation rapeseed meal, and by adding cottonseed meal, the amount of total amino acids also increased, amino acids were more balanced.(5)And the study about the composition、molecular weight and functional activity of polypeptide in the fermentation rapeseed meal products indicated:the molecular weight of most polypeptide in the fermentation rapeseed meal products were less than1600Da, most of them were around500Da, this molecular weight range was suitable. Primary and secondary mass spectrometry assisted us to further define the amino acid composition and the amino acid sequence of peptide chain, dipeptide such as Thr-Met and tetrapeptide, as (N)-Ser-leu (Ile)-Phe-Met-(C) and (N)-Ser-leu (Ile)-Ala-Tyr-(C), had been detected. They all further enriched the nutritional value of fermentation rapeseed products. In addition, the study of fermentation rapeseed polypeptide sample ACE inhibitory activity showed that:their ACE inhibitory activity IC50reached to0.0565mg/ml,after checked the extensive literature we found that the ACE inhibitory activity was very high, it indicated that these fermentation rapeseed meal polypeptides had high added value, also illustrated us that this fermentation process was feasible to obtain biological active peptides.