Study On The Effect Of Ozone Gaseous On The Preservation Of Steamed Bread

Steamed bread,as a Chinese traditional fermented staple food,is enduring for its unique advantages such as its delicate structure,good taste,low price,and rich wheat aroma.However,due to its high moisture content(35-45%)and highly water activity(0.93-0.97),it is rich in nutrients such as protein and carbohydrates and can easily breed spoilage microorganisms,especially in high-temperature and high-humidity environments.The storage time is extremely short.In view of this phenomenon,this paper studied the effect of ozone on the preservation of taro products by combining the efficient bactericidal activity of ozone.(1)This experiment studied the bactericidal effect of ozone gas treatment on the total number of bacterial colonies,molds and yeasts on the surface of steamed bread products.Control ozone gas fumigation steamed bread surface time for 1,10,30 and 60 min,the results show that with the ozone gas fumigation time prolonged,the total amount of bacteria on the surface of steamed bread increased,the minimum reduction of 0.4 Log CFU/g,the maximum reduction 1.6Log CFU/g,the maximum reduction of mold is 0.53 Log CFU/g.At the same time,the surface quality indicators of Taro samples,TPA,color difference,p H value,CQMG pulse sequence and porosity were measured.The results showed that the ozone gas fumigation at different times,TPA physical properties of the indicators,hardness,adhesion,resilience,no significant changes(p<0.05);L * value with ozone fumigation time increases,but with for the blank control,there was no significant difference.The values ? ? of a and b showed a certain degree of decreasing trend with the increase of the ozone fumigation time,but there was no significant difference with the blank control(p<0.05);the p H value increased with the ozone fumigation time However,the CQMG pulse sequence measurement showed that the binding ability of the steamed bread sample surface to both bound water and free water increased.However,there was no significant change in the surface porosity of the steamed bread.(2)The control sample storage temperature was 37?,25?,15?,and 4?.The different storage temperatures were combined with the ozone gas fumigation at different times and the changes of the microbiological indicators and quality indicators during sample storage.The results showed that the growth rate of microorganisms on the surface of steamed bread was different at different storage temperatures,and the results of quality indicators were also different.At 37? and 25? under high temperature,the total number of bacteria on the surface of the samplereached the maximum at 24 h and 72 h,respectively,and there was obvious bacterial spoilage on the surface of the steamed bread.The bacterial count on the surface of the sample was the largest difference between the treated and control groups.1.7 Log CFU/g;15 and 4 ? storage environment,the steamed bread sample storage time is relatively prolonged,but the surface of the sample mold corruption is more obvious,the maximum difference in mold surface counts were 1.0and 1.2 Log CFU/g.At the same time,the sample quality index was measured.The results showed that TPA changed significantly during storage,p H value and color difference did not change significantly(p<0.05);CQMG decreased the relaxation time T2,and the ability of bound surface water on the sample decreased.(3)To study the storage stability of taro samples with ozone gas treatment combined with oxygen-absorbing packaging.The treated steamed bread samples were stored at 37,25,15 and4?,and the total number of bacteria and mold yeast were measured on the surface of steamed bread samples.The shelf life of the samples was investigated through the growth of microorganisms.The results showed that the ozone gas treatment time was controlled to 1,10,30 and 60min,the storage temperature was 37?,and the oxygen storage bag was added.The shelf life of the sample was extended to 3 days.The sample was stored at 25? and the shelf life could be extended to 6 days at 15?.The sample shelf life is 9 days.When the sample is stored at 4?,the best storage period of the sample is 15 days.Which shows that ozone sterilization treatment of samples after oxygen packaging,can extend the sample's optimal shelf life.(4)The method of artificially contaminating steamed bread was used to study the bactericidal effect of ozone gas on different strains of microorganisms.The results showed that the inoculation of Bacillus subtilis,Staphylococcus aureus 6538,and Staphylococcus aureus 8325 had similar bactericidal effects to ozone gas.At the same time,through the amplification and identification of microorganisms in the sample,it was concluded that the main corrupt microorganisms in the surface of the steamed bread at 37? and 25? are Bacillus,mainly including Bacillus licheniformis,Bacillus amyloliquefaciens,and Bacillus subtilis;15 and The main spoilage strains on the surface of the samples at 4? were fungi,there are Bipolaris_sorokiniana,Cladosporium_herbarum and Fusarium_graminearum so on.