猪胴体冷却过程中表面微生物的时空分布研究

为了研究在猪胴体冷却过程中风速、温湿度及微生物数量的变化情况,建立猪胴体在冷却期间微生物的时空变化的模型,从而为冷库防治污染提供依据,本文采用热敏式风速仪测量夏季冷库内的风速、温湿度,利用擦拭法测定猪胴体表面微生物菌落总数,最终得到猪胴体冷却过程中微生物的时空变化情况,结果表明:在冷却前期(冷却时间0~8 h),由于冷库门的开启、猪胴体本身散热等原因导致冷库内的风速并非均匀分布,温湿度也逐渐上升,从而导致冷库内不同位置处猪胴体表面微生物的菌落总数均有不同程度的增加,其中冷库中间位置的猪胴体表面菌落总数显著增加(P<0.05),其余位置的猪胴体表面菌落总数增加不显著(P>0.05);在冷却后期(冷却时间8~14 h),冷库门关闭,不再有猪胴体进入冷库,冷库内的温湿度迅速下降,使猪胴体表面微生物的菌落总数显著减少(P<0.05)并趋于稳定;猪胴体迎风面的菌落总数略高于背风面,其中前腿、胸腹腔的微生物较多;相关性分析结果表明猪胴体表面菌落总数与温度、湿度、冷却时间、采样部位有极显著的相关关系(P<0.01),与风速有显著的相关关系(P<0.05)。总之,随着冷却时间的延长,猪胴体表面菌落总数有显著差异(P<0.05),冷库内不同位置的猪胴体表面菌落总数不同,同一猪胴体的不同部位之间也有差异,这为冷库的改进布局和污染控制奠定了基础。

Temporal and Spatial Distribution of Surface Microorganisms during Cooling of Pig Carcass

In order to study the changes in wind speed, temperature, humidity, and the number of microorganisms during the cooling process of pig carcasses, a model of the spatiotemporal changes of microorganisms in pig carcasses during cooling was established to provide a basis for the prevention and control of pollution in cold storage. In this paper, a thermal anemometer was used to measure the wind speed, temperature and humidity in the cold storage during the summer. The total number of microbial colonies on the surface of pig carcasses was measured by the wiping method. The spatiotemporal changes of microorganisms during the cooling process of pig carcass were obtained. The results showed that in the early stage of cooling (cooling time was 0 to 8 h), due to the opening of the cold storage door and the heat dissipation of the pig carcass itself, the wind speed in the cold storage was not uniformly distributed, and the temperature and humidity were gradually increased (P<0.05).And the total number of microbial colonies on the surface of pig carcasses at different locations in the cold storage increased to varying degrees. The total number of colonies on the surface of the carcass in the middle of the cold storage increased significantly (P<0.05), and the total number of colonies on the surface of the carcass in the other positions did not increase significantly (P>0.05).In the late stage of cooling (cooling time was 8 to 14 h), the cold storage door was closed, and no pig carcass entered the cold storage. The temperature and humidity decreased rapidly, resulting in a significant decrease in the total number of microbial colonies on the surface of the pig carcass and tending to be stable (P<0.05). The total number of colonies on the windward side of the pig carcass was slightly higher than the total number of colonies on the leeward side, among which the microorganisms in the front leg and the thoracic cavity were more. The results of correlation analysis showed that the total number of colonies on the surface of pig carcasses had extremely significant correlations with temperature, humidity, cooling time, and sampling locations (P<0.01), and significant correlations with wind speed (P<0.05).In conclusion, with the extension of the cooling time, the total number of colonies on the surface of the pig carcass was significantly different (P<0.05). The total number of colonies on the surface of the pig carcass at different locations in the cold room was different, and there were differences between different parts of the same pig carcass. This laid the foundation for the improved layout of the cold storage and pollution control.