Study On Detoxification Of Rapeseed Meal And Improvement Of Its Protein Quality By Fermentation

Rapeseed meal is one of the high quality plant protein resources,and the crude protein content of it is around 28%-44%.Rapeseed meal protein contains most of the essential amino acids thus it has the protential of taking the place of soybean meal as a feedsruff component.But the glucosinolate,tannin and other anti-nutritional factors in rapeseed meal have badly influenced its feed value.This subject employed fermentation method to reduce glucosinolate and other toxic substances.Relaying on the enzymes that producted during the activity of microbe,the protein in rapeseed meal are degraded into peptides and proteins with small molecular weight which could be absorbed easily by animals.All of this with no doubt can improved the nutritional quality of the rapeseed meal,as well as increased the dosage added to the feedstuff.Based on the 79 stains after preliminary screening which were obtained from laboratory and enriching palces,total 8 stains with high detoxification ability named ndt, Br,Zfl et al were found.A strain named Z4 could significantly reduce the content of cellulose was found among 45 stains which has similar ability.The 9 stains were after mixed fermentation research.Then,the optimum combination for fermentation was ndt+Br+Zfl,ndt was identified as Bacillus subtilis,Br was reserved in lab as Bacillus cereus,Zfl was identified as Lactobacillus casei.The best process parameters were confirmed:Fermentation duration was 48 h,feed to water ratio was 1 to 0.8,inoculums dose was 3%,temperature was 30℃and initial pH was just in nature state.This work also found some extraneous source(s) such as 0.2%FeSO₄ and 10%cottonseed meal had positive effects in solid-state fermentation.Based on the monofactorial and orthogonal experiments,Response surface design was built.After 5 straight repeats,the detoxification ratio can reach to 70.28%,total phenylic acid droped to 31.16%,and the content of crude protein reached to 40.91%, which exceeded 13.5 percent than before.Judging from the pattern of SDS-PAGE,most of the rapeseed meal protein was decomposed and its molecular weight below 20 kD; most of which were around 7 kD in use of the gel filtration mothad.All this depicted that most of the rapeseed meal protein was decomposed to peptides.The viable count raised up to about 6.80×10⁸ CFU/g during the fermentation period.In conclution,rapeseed meal can obviously improve its feeding quality after solid-state fermentation by microbes.