Study On The Preservation Technology Of Steamed Bread For Circulation

Steamed bread is Chinese traditional food with good taste and rich nutrients, but it is susceptible to get aging and mildew during storage and its storage-life is only.1-2 days. To this point, the work evaluated the effects of quality improvement, biological preservatives, physical sterilization and modified atmosphere packing on steamed bread, in order to prolong the storage-life and postpone the aging of steamed bread, moreover maintaining the steamed bread in comparatively high quality during storage.The study of changes of the steamed bread quality and storage-life during storage by general packaging showed that, with the time increase the hardness of steamed bread increases and the springiness, cohesiveness and resilience decreases, especially during the 0-24 h the changes in amplitude of which are obvious and tend to be stable after 48 h. The results also showed that 37 ℃ for storage temperature is beneficial to postpone the aging of steamed bread that the increase of hardness is 75.13% at 24 h during storage, yet it will shorten steamed bread’s storage-life dramatically to 1 day. Likewise, though low temperature of 4℃ for storage could accelerate steamed bread’s aging process that the increase of hardness is 166% at 24 h during storage, the storage-life can be prolonged significantly to 8 days. It turned out that the main microbes in the surface of mouldy steamed bread are Penicillium and Aspergillus by microbiological assay.The study of quality improver for steamed bread showed that monoglycerides, xanthan gum, carrageenan enzyme and trehalose all could improve the sensory quality of steamed bread, and monoglycerides(0.8%), enzyme(75mg/kg) and trehalose (4%) could improve the specific volume and hardness of steamed bread obviousiy, besides xanthan gum (0.1%), carrageenan (0.1%) and trehalose (4%) could improve the springiness of steamed bread, moreover enzyme and trehalose could improve the cohesiveness and resilience of steamed bread. Compound modifying agent A (enzyme/trehalose=1/600,3%) could improve the quality of steamed bread in every item, and especially the hardness of steamed bread with compound modifying agent A in storage for 48 h is equal to which of blank group in storage for 12 h.The using of natamycin,sterilization by ultraviolet radiation, sterilization by Ozone fumigation can all prolong the steamed bread’s storage-life and especially, spraying natamycin 0.3 g/kg to surface of steamed bread could make the steamed bread’s storage-life extend 2 days, disinfecting by ultraviolet sterilization for 30 min could make the steamed bread’s storage-life extend 2.5 days,using ozone fumigation for 15 min with concentration of 10 mL/m3 could make the steamed bread’s storage-life extend 1 day.The results of the effects of modified atmosphere packing with vacuum bag on the quality of steamed bread showed that its storage-life can be increased significantly packing without air, and the result is getting better as the content of CO2 increases. Especially, when steamed bread is packed with 100% CO2, the storage-life can be prolonged to 12 days, which is 7 times longer than which by the ordinary packing way. When combined radiation of ultraviolet with modified atmosphere packing, storage-life of steamed bread can get up to 18 days, which is 11 times longer than which by the traditional packing way.