Study On The Separation And Control Of Spoilage Microorganisms In Wheat Gluten

The wheat gluten is rich in nutrition, especially in protein.It is easy to cause short shelf lifeby spoilage as the sterilization in the processing is incomplete or storage conditions isimproper.The industry development of wheat gluten is restricted by spoilage.As a result,separating the spoilage microorganisms and choosing suitable preservative is of greatsignificance to extend the shelf life of wheat gluten.The microorganisms from spoilage wheat gluten were separated and analyzed on thephysiological and biochemical identification and the effect of different sterilization temperatureand time were studied.The storage conditions and the pH value on wheat gluten microorganismsgrowth characteristics were studied.The storage duration of wheat gluten was extended bychoosing the effective preservatives and combining with the heat treatment and low temperature.Wheat gluten sterilized at100℃for30min had serious deterioration in24hours at37℃,while wheat gluten sterilized at110and120℃for30min can maintain good.18strains separated from spoilage wheat gluten are all bacteria and all strains can causedeterioration within24hours at gluten corruption trial, so these strains are all spoilagemicroorganisms of wheat gluten. The18kinds of gluten microorganisms grow well and had aclose colony morphology on nutrient agar medium. They were gram-positive bacteria.Accordingto the results of the biochemical identification, they were Bacillus licheniformis, Bacillus subtilis,Bacillus megatherium and Bacillus mycoides Flugge.Four kinds of microorganisms had a large difference in the rate of survival under differentsterilization temperature, the sterilization effect had a proportional relationship with sterilizationtemperature and time.The range of growth temperature of bacteria was28-42℃, reaching themaximum at37℃. They grow well at the pH=6.0-7.0and grow slowly at pH in less than6.0andlarger than8.0.The minimum inhibitory concentrations of4kinds of antibacterial agents were studied.Theminimum concentration were respectively: lysozyme was0.04g/100mL, nipagin composite ester0.02g/100mL, Nisin0.02g/100mL, garlic oil was0.1%. Through the response surface method forformulation optimization, optimized combination was lysozyme0.030g/100mL,nipagincomposite ester0.021g/100mL,Nisin0.022g/100mL,inhibitory rate to spoilage microorganismsreached100%. The wheat gluten can keep10days under the condition of37℃,50days under25 ℃, more than60days under the condition of4℃when the complex were used to wheat gluten.The shelf life was greatly extended.