微囊包被处理屎肠球菌制粒耐受性的评价

Evaluation of the Pelletizing Stability of Micro-encapsulated and Coated Enterococcus faecium

【目的】通过对比微囊包被与普通粉末状屎肠球菌在不同热处理条件下的活菌数,观察微囊包被处理对屎肠球菌在高温环境下的保护效果,并通过实验室模拟热处理试验,评价微囊包被屎肠球菌制粒时的耐受性。【方法】热处理方法为烘箱干热法,温度分别为65和85℃,热处理时间分别为5、10、15、30及60 min;仔猪饲料中添加0.01%的微囊包被屎肠球菌制剂,分别在55和65℃进行制粒。检测经热处理和制粒后屎肠球菌的活菌数,计算存活率。【结果】微囊包被型屎肠球菌经65℃加热60 min,其活菌数显著高于同条件下的普通粉末型(P=0.037);而在85℃条件下加热30或60 min,微囊包被型的活菌数极显著高于普通粉末型(P=0.002)。与直接加热活菌制剂相比,将其添加到仔猪配合饲料中后进行相同热处理其存活率显著降低(P<0.05);制粒的过程对微囊包被屎肠球菌的破坏作用,要远大于实验室条件下单纯的温度破坏;饲料在55℃制粒时屎肠球菌的存活率与饲料在65℃加热28 min或85℃条件下加热11 min相当;而在65℃制粒时屎肠球菌的存活率,相当于饲料在65℃加热48 min或85℃条件下加热23 min。【结论】微囊包被处理可以在一定程度上保护屎肠球菌的活性,提高其对高温和制粒的耐受性;直接对屎肠球菌活菌制剂进行干热处理时的存活率不能准确反映其制粒时的稳定性,但可以采用将微囊包被屎肠球菌添加到饲料中进行实验室模拟热处理试验,估测制粒过程中屎肠球菌的耐受性。

【Objective】The viable count of the micro-encapsulated and coated Enterococcus faecium was compared with its normal freeze-drying powder under different heat treatment conditions to observe the protective effect of micro-encapsulation.And the pelletizing stability of the micro-encapsulated and coated E.faecium were evaluated through a laboratory heating trial.【Method】Two probiotics products were treated at 65℃ or 85℃ heated air for 5,10,15,30 and 60 min.The preparations of 0.01% micro-encapsulated and coated E.faecium were supplemented in piglet diets and being pelletized at 55℃and 65℃.【Result】The viable count of the micro-encapsulated and coated products,heated at 65℃ for 60 min,were higher（P=0.037） than the normal powder under the same condition.When the two products were heated at 85℃ for 30 or 60 min,the survival rates of the micro-encapsulated and coated ones were higher（P=0.002） than the normal powder.The Enterococcus faecium supplemented in piglet diet was more fragile than itself directly in heat air.The destruction of being pelletized in factory was much higher than being heated in the lab.The survival rate of E.faecium after being pelletized at 55℃ equivalent to that of being air-heated at 65℃ for 28 min or at 85℃ for 11 min in the same diet,while the survival rate after being pelletized at 65℃ equivalent to that of being air-heated at 65℃ for 48 min or at 85℃ for 23 min.【Conclusion】The micro-encapsulation and coating process could improve the thermal stability of E.faecium in a certain extent.Directly air-heated treatment of E.faecium probiotics couldn＇t represent their thermal stability during pelletizing,but it could be quickly evaluated through air-heated treatment to diets supplemented with them.