Studies On Bacillus Natto And Its Oxidation Peptide By Brewer’s Spent Grain Fermentation

The beer industry developing and expanding, China is discharging more and more industrial beer waste each year, its main by-products is brewer’s spent grain(BS-G).If BSG isn’t handled properly, direct emissions into the rivers, it will waste reso-urces and also threatens the ecological environment. At present, enterprises treat BSG to sell to farmers as feedstuff, it just brings to the enterprise to lower profits,at the same time, it also can’t better increase the potential value of the BSG. Bacillus natto is probiotic bacteria, it has many excellent properties, however, nowadays the production cost of Bacillus natto is higher, the unit output was not high, and research of Bacillus natto fermented residue existing inoxidizability was not very clear. In order to solve the above problems, the brewer’s spent grain was used as the main ferment raw material to obtain higher yield, cheaper Bacillus natto bacteria producti-on process, by the modern statistical principles and scientific experimental designed scheme,at the same time, it focused on antioxidant peptide of Bacillus natto fermented residue.In order to ferment Bacillus natto,BSG was used as mainly nutritive material through shaking flask scaled fermentation. On the basis of single factor experiments, initial pH, fermentation time, shaking speed was chosen as significant factors from the influence bean bacterial growth of nine factors in the Plackett-Burman experiment. The optimal proliferated Bacillus natto conditions:BSG additional amount120mg*m-L-1,glucose additional amount2%,NaCl additional amount2mg·mL-1, initial pH8.0, fermentation time24h, fermentation temperature34℃, shaking speed180r/min and water additional amount20mL, the growth of the amount of Bacillus natto was2.5×1012cfu/mL by steepest ascent methodical experiment and response surface methodical experiment.Antioxidant peptide was obtained, by-18℃acetone to precipitate fermented liquid,the antioxidant peptides can scavenge75.04%of superoxide anion at5mg. In order to research antioxidation stability of the peptide, the scavenging activity of superoxide anion as the index to investigate the effects of temperature, pH, ultraviolet ray, metal ions, Sugar source, antiseptic.The results show that the antioxidant peptides have a certain heat-resistance and light stability.It can keep high activity in the acidity and alkali environment; Ions had little effect on activity or promoting effect on the activity of the peptide,except for that Fe3+can considerably reduce the antioxidant activity of the peptide.Sodium nitrite made antioxidant peptide activity completely lost, but other preservatives and sugar were good influence together with the peptideUltrafiltration, gel chromatography, ion exchange chromatography, and RPLC were used to purify and identify the antioxidant peptides. It showed that the antioxidant activity of the antioxidant peptides mainly by three kinds of peptides, the ratio of that was about1:1:1.