Probiotics which can provide potential health benefits for consumers and prevent disease, is the most important research field for functional food in the future. It is the key point that how much the count of bacteria...Probiotics which can provide potential health benefits for consumers and prevent disease, is the most important research field for functional food in the future. It is the key point that how much the count of bacteria and how long it can preserve. Freeze-drying skill is one of the best preservation methods, but it＇s defect that damage to biological systems can be attributed to changes in the physical state of membrane lipids or/and changes in the structure of sensitive proteins and the decreased survival rate. This work used pretreatment methods-cold shock and hot shock to reduce the damage to bacteria during freeze-drying. Using unpretreated samples as control, aspects of cold shock or heat shock. The response of Enterococcous faecalis A31 was investigated during lag phase, the middle of exponential growth phase and the terminal of exponential growth phase. The results suggested that when cold shock, the shock protein concentration produced by treated sample within 2 h during the middle of exponential growth phase was higher than 4, 8, 24 h, The concentration of shock protein produced by treated sample at 10 ℃ was higher than 20℃, The concentration of sample protein at the middle of exponential growth phase was higher than that at the terminal of exponential growth phase. After one-month storage, the survival rate at 10℃ was better than 20 ℃ and 4 ℃comparatively. The survival rate at （6 h） 4 ℃/24 h （lag period） was higher than （10 h） 4 ℃/24 h （the middle of exponential growth phase）, and the effect of 10℃/8 h shock treatments was best during the middle of exponential growth phase, when hot shock, The concentration of heat shock proteins produced was not obvious, and survival rate was higher at 45 ℃, 30 min than at 45 ℃, 60 min.展开更多
基金Supported by National Agricultural Translation Fund (02EFN212301073)
文摘Probiotics which can provide potential health benefits for consumers and prevent disease, is the most important research field for functional food in the future. It is the key point that how much the count of bacteria and how long it can preserve. Freeze-drying skill is one of the best preservation methods, but it＇s defect that damage to biological systems can be attributed to changes in the physical state of membrane lipids or/and changes in the structure of sensitive proteins and the decreased survival rate. This work used pretreatment methods-cold shock and hot shock to reduce the damage to bacteria during freeze-drying. Using unpretreated samples as control, aspects of cold shock or heat shock. The response of Enterococcous faecalis A31 was investigated during lag phase, the middle of exponential growth phase and the terminal of exponential growth phase. The results suggested that when cold shock, the shock protein concentration produced by treated sample within 2 h during the middle of exponential growth phase was higher than 4, 8, 24 h, The concentration of shock protein produced by treated sample at 10 ℃ was higher than 20℃, The concentration of sample protein at the middle of exponential growth phase was higher than that at the terminal of exponential growth phase. After one-month storage, the survival rate at 10℃ was better than 20 ℃ and 4 ℃comparatively. The survival rate at （6 h） 4 ℃/24 h （lag period） was higher than （10 h） 4 ℃/24 h （the middle of exponential growth phase）, and the effect of 10℃/8 h shock treatments was best during the middle of exponential growth phase, when hot shock, The concentration of heat shock proteins produced was not obvious, and survival rate was higher at 45 ℃, 30 min than at 45 ℃, 60 min.
