Activities And Mechanisms Of Low-temperature Soybean Meal Solid-fermented By Bacillus Natto

Low-temperature soybean meal is a by-product of the oil extraction of soybean, which is obtained from the wet soybean meal by removing solvent at the condition of low temperature. It is a kind of high-quality protein plant resource and highly produced in China as a source of readily available and inexpensive agricultural resources, but it is mainly used for feed, which results in a waste of resources. It is necessary to develop a kind of healthy food resources in order to make full use of soybean meal.Natto has many functions including thrombolyitc activity, antitumor, antioxidation, prevention of osteoporosis, antibiosis and regulation of intestinal function. Bacillus natto has been recognized as one of strains can be fed directly to animals by Ministry of Agriculture of China and FDA.In the present work, Bacillus natto was employed to ferment low-temperature soymean meal and antioxidant activity of fermented soybean meal extract from fermented low-temperature soybean meal was investigated. The ingredients of antioxidant activity waere separated and regulation of intestinal flora in diarrhea mice induced by antibiotics was carried out.The main contents and conclusions are as follows:(1) Nutritional components were analyed and evaluated on FSME. The content of protein and fat in FSME was57.26%and0.86%, respectively. FSME contained iron, magnesium and other minerals. Compared with soybean meal, the content of some amino acid specicies of FSME were changed, but the total amino acid content remained unchanged. Compared with fermented soybean meal, FSME in aspartic acid, glutamic acid, isoleucine, leucine, tyrosine, phenylalanine, lysine and proline content was dominant; the total amino acid content increased3%. There were8essential amino acids in FSME, especially leucine, lysine, tryptophan content were high.(2) The antioxidant activity of fermented low-temperature soybean meal in vitro was studied. Experiments were conducted using60%ethanol extracts prepared under the same conditions. The superoxide anion radical and DPPH radical scavenging activities, Fe3+reducing power, rat liver homogenate inhibitory ability of lipid peroxidation and red blood cells of hemolysis inhibitory ability were checked. The results shows that:compared with soybean meal extract, fermented low-temperature soybean meal extract(FSME) had strong scavenging activities of DPPH radical and superoxide anion radical, had strong Fe+reducing ability, inhibition of lipid peroxidation and red blood cells hemolysis, the IC50was0.321mg/mL,7.404rag/mL, 2.128mg/mL,0.737mg/mL,4.599mg/mL, respectively.(3) The antioxidant activity in vivo was investigated by using the D-galactose induced aging mice as models. Fermented soybean meal extract had increased SOD, GSH-Px, CAT activity in the serum and liver tissue of aging mice, decreased the content of lipid peroxide malondialdehyde. Fermented soybean meal extract had reduced MAO activity in brain tissue of aging mice, increased NOS, Na+-K+-ATPase and Ca2+-Mg2+-ATPase activity. The antioxidant activity of fermented soybean meal extract was better than that of soybean meal extract.(4) In order to separate antioxidant activity ingredient of fermented soybean meal extract, process conditions are optimized. Solid fermentation optimization result is: matrix water content73%, inoculation19%, fermentation time94.5h. Based on these results, the single factor and orthogonal tests were performed to determine the optimal extraction conditions:volume fraction of ethanol50%, the liquid-solid ratio10:1, extracting time90min, extracted three times.(5) The system separation and column chromatography was subjected to FSME, and an active substance was obtained and showed a single peak in HPLC. The maximum absorption wavelength was at260nra by ultraviolet scanning. Molecular weight of MS detection was270, and then genistein was identified by comparison of’H NMR and13C NMR spectra with literature data, formulas was C15H10O5.The analytic method with HPLC has been established for quantitation of genistein content in FSME. The chromatography conditions were:chromatographic column: Kromasil C18column (250mm x4.6mm,5u.m); Mobile phase:methanol-water (60:40); Flow rate:0.8mL/min; Detected wavelength:260nm; sample amount:20μL. The column temperature:room temperature (25℃). Genistein content of FSME is545.73±8.14μg/g, is0.055%; Genistein content of fermented soybean meal is0.024%. Genistein content of soybean meal is0.011%, which shows that Genistein content is increased by1.2times when soybean meal is fermented by Bacillus natto.(6) Regulation of intestinal flora in nomal mice and diarrhea mice induced by antibiotics was tested with FSME. It could significantly promote the growth of intestinal anaerobic bacteria; inhibit the proliferation of aerobic bacteria. The activity of FSME was better than non-fermented soybean meal. FSME was a potential substance, could be used as a prebiotics in Food or pharmaceutical industry.