Study On The Solid-state Fermentation Of Rapeseed Meal And Its Protein Quality

Rapeseed meal is one of the high quality plant protein resources, and the crude protein content of it is around28%-44%. Rapeseed meal protein contains most of the essential amino acids thus it has the protential used in food and feed industry. But the glucosinolate, phytic acid, 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 This paper mainly investigated the fermentation rapeseed protein extraction technology, and determined its molecular weight distribution and amino acid composition. The antioxidant activities of rapeseed protein was also studied. The main conclusions of the experiments were as follows:(1) Effects of multi-microbial solid-state fermentation on the anti-nutritional factors content of rapeseed meal. Solid-state fermentation of ordinary rapeseed meal with single strain and multi-strains are carried out to study the effect of fermentation on the contents of glucosinolates, phytic acid, tannic, crude protein and small peptides in rapeseed meal. Results show that the ratio of inoculation quantity of Lactobacillus plantarum:Bacillus subtilis:Aspergillus oryzae is9%:9%:9%, the temperature of fermentation is33℃and the fermentation time is96h, pH6.5, water/dry mass1.2:1. Under these conditions the glucosinolates content of the rapeseed meal decreases from32.33μmol/g (dry base) to2.97μmol/g (dry base), degraded by90.79%, phytic acid was degraded by79.03%, tannic was degraded by85.71%, the content of crude protein rises6.56percentage, and the content of small peptides was6.28%.(2) Research on the extraction of rapeseed meal protein by the response surface method. The theoretic guidance for the development and utilization of rapeseed meal and its protein was provided through the research on the extracting technology of protein from solid-state fermentation of rapeseed meal. The solid-state fermentation of rapeseed meal detoxified being taken as raw material, the ef of the different factors on the extracting rate of protein was experimented and the affecting factor optimized with response surface method. Based on the result, the level of the pH, the extraction temperature and the ratio of material to liquid was further optimized with response surface method and while the argument was the pH of12.4, the temperature of55.7℃and the ratio of material to liquid of1:16.2, the optimum prediction yield of the protein from rapeseed meal was64.79%.(3) Studies on antioxidant activities of rapeseed meal. Results show that the fermentation rapeseed meal protein was significantly better than the usual rapeseed protein on removing superoxide anion, DPPH, hydroxyl radical and total antioxidant activity. Results show that rapeseed protein has better antioxidant activity after fermentation. The fermentation rapeseed protein can be used as natural antioxidants or functional food additives in the food industry.