| Faba bean is one of the main beans cultured in China,and its output ranks first in the world.Faba bean has the advantages of high protein,reasonable amino acid composition,rich vitamin and mineral trace elements.However,the application of faba bean in animal feed is limited due to the existence of anti-nutrient factors(proanthocyanidins and phytic acid,etc.),which affects the development and utilization of faba bean.Various enzymes produced by microbial fermentation can effectively reduce the content of anti-nutritional factors,and the fermented faba bean has higher nutritional quality and antioxidant activity.In this study,Bacillus pumilus,Lactobacillus plantarum and Saccharomycopsis fibuligera were used as fermentation strains,and different fermentation strains were used to ferment faba bean at different times(12 hours,24 hours,36 hours,48 hours,60 hours and 72 hours).And under the same conditions,three different fermentation strains were used for mixed fermentation of faba bean in a ratio of 1:1:1.By measuring the physical state,nutritional components,antioxidant activity and anti-nutritional factors of faba bean before and after fermentation,the effects of fermentation at different times on faba bean were comprehensively evaluated.The main research contents of this paper are as follows:1.Analysis of physicochemical state,nutritional components,anti-nutritional factors and antioxidant properties of faba bean fermented by single bacteria.Physicochemical state: Microbial fermented faba bean,its color,odor,p H and microstructure have been changed.Unfermented faba bean powder is light yellow and white,tasteless;after fermentation by S.fibuligera,it is yellow-brown,with wine aroma;after fermentation by B.pumilus,it is yellow-brown,with mellow aroma;after fermentation by L.plantarum,it is dark brown,With a strong sour taste.The p H value of the fermented product decreased gradually with time.The p H value of the fermentation product was stable at 5.07 after fermentation by S.fibuligera,at 4.1 after fermentation by B.pumilus,and at 4.03 after fermentation by L.plantarum.The microstructure of unfermented faba bean flour was smooth and complete,while the microstructure of fermented faba bean flour was in a rough and irregular state.Nutrient components: The crude ash and crude fat of faba bean flour after single-bacteria fermentation by different microorganisms at different times were significantly higher than those of unfermented faba bean flour(P<0.05).After fermentation by B.pumilus,the total starch content decreased by 60.80% at 72 hours,the crude protein content increased by 4.54% at 72 hours,the acid-soluble protein increased by 61.02% at 60 hours,and the in vitro digestibility increased by 3.4% at 12hours;For faba bean fermented by L.plantarum,the total starch content decreased by61.86% at 72 hours,the crude protein content increased by 11% at 48 hours,the acid-soluble protein increased by 59.32% at 72 hours,and the in vitro digestibility at72 hours increased by 4.3%;For faba beans fermented by S.fibuligera,the total starch content decreased by 37.51% at 72 hours,the crude protein content increased by33.38% at 24 hours,the acid-soluble protein increased by 67.14% at 72 hours,and the in vitro digestibility at 12 hours increased by 2.8%.Analysis of the protein components of faba bean after single bacterial fermentation by protein electrophoresis showed that B.pumilus and L.plantarum basically decomposed macromolecular proteins in 36 hours and 24 hours,respectively.S.fibuligera decomposes macromolecular proteins to a certain extent within 24 hours,but the decomposition is incomplete.Anti-nutritional factors: Single bacterial fermentation can reduce the anti-nutritional factors of faba bean,and with the increase of fermentation time,the proanthocyanidins and phytic acid of the fermentation products show a downward trend,and both reach the highest degradation rate at 72 hours.The highest degradation rate of proanthocyanidins was 71.53% in B.pumilus fermentation,68.39%in proanthocyanidin fermentation by S.fibuligera,and 76.89% in L.plantarum fermentation.The highest phytic acid degradation rate was 10.31% by B.pumilus fermentation,32.85% by S.fibuligera fermentation,and 14.93% by L.plantarum fermentation.Antioxidant activity: In faba beans fermented by B.pumilus,the total phenolic flavonoids increased by 40.05% and 121.48% respectively at 60 hours,the DPPH free radical scavenging ability increased by 10.12% at 48 hours,and the hydroxyl radical scavenging ability was improved 9.40% in 24 hours,72 hours on superoxide anion free radical scavenging ability increased by 95.10%.In the faba beans fermented by L.plantarum,the total phenolic flavonoids increased by 35.02% and 86.83%,respectively,the DPPH free radical scavenging ability increased by 10.20%,and the hydroxyl radical scavenging ability increased by 16.58% in 36 hours.The free radical scavenging ability of superoxide anion was improved by 63.09% at 72 hours.In the faba beans fermented by S.fibuligera,the total phenolic flavonoids increased by54.68% and 99.07% respectively in 48 hours,the scavenging ability of DPPH free radicals increased by 11.84% in 36 hours,and the scavenging ability of hydroxyl radicals in 36 hours increased 17.88%,and the scavenging ability of superoxide anion free radicals increased by 86.76% within 48 hours.2.Analysis of physicochemical state,nutritional components,anti-nutritional factors and antioxidant activity of mixed fermented faba bean with strains(1:1:1).Physical and chemical state: After mixed fermentation,the color of faba beans changed from light yellow to yellowish brown,the smell changed from tasteless to a mixed smell of sour,wine and mellow,and the microstructure changed from smooth and complete to rough and broken.The p H gradually decreased and stabilized at 4.09.Nutrient components: crude ash and crude fat changed steadily and were significantly higher than unfermented faba bean flour at different times(P<0.05).The total starch decreased gradually and decreased by 40.61% at 72 hours.Crude protein trended parabolically,peaking at 24 hours,up 10.19%.Acid-soluble protein and in vitro digestibility gradually increased,increasing by 80.72% and 4.12%,respectively.Protein electrophoresis analyzed the protein components of faba bean after fermentation,and the macromolecular protein was basically decomposed within 24 hours.Anti-nutritional factors: Both proanthocyanidins and phytic acid showed a downward trend after fermentation.At 72 hours,the degradation rate of procyanidins was 82.44%,and the degradation rate of phytic acid was 32.57%.Antioxidant activity: After fermentation,both antioxidant substances and antioxidant activity were improved to a certain extent.At 60 hours,the total phenolic flavonoids increased by 43.74% and 100.66%,respectively,and the scavenging ability of DPPH free radicals increased by 10.18%.In 72 hours,the scavenging ability of hydroxyl radicals increased by 16.89%,and the scavenging ability of superoxide anion radicals increased by 89.01%. |
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