基于脉冲电场处理技术低温原牛乳灭菌系统研究

Study on Low Temperature Raw Milk Sterilization System Based on Pulsed Electric Field Treatment Technology

为了建立高压脉冲电场(pulsed electric field,PEF)处理原牛乳的完整体系,达到促进PEF处理原牛乳工业化进程的目的。提出了以电场强度和脉冲处理时间为双因素,进行正交实验的方法。以原牛乳为实验原料,自行搭建高压脉冲电场系统,以PEF处理前后原牛乳的菌落总数以及原牛乳的理化性质进行对比研究,结果表明该系统对原牛乳有良好的灭菌效果,在场强35 kV/cm、脉冲数为2 000时,灭菌效率可达90.98%,且灭菌率与脉冲数和电场强度正相关。在此PEF条件下处理后,牛乳中的游离氨基酸含量增加24.56 mg/L,电导率上升0.05 ms/cm,温升为5.9℃,且随着脉冲数和电场强度的递增,此类变化愈加明显,而几乎不影响pH值。证明了PEF对牛乳确有冷灭菌效果,且对原牛乳的理化性质影响微弱,提高了原牛乳的营养价值,为PEF实现工业化提供了新的实验依据和技术支撑。

In order to establish a complete system of high voltage pulsed electric field(PEF) treatment of raw milk and promote the industrialization of PEF treatment of raw milk.An orthogonal experiment method was proposed with the electric field intensity and pulse processing time as two factors.Taking the raw milk as experimental material,using the self-built high-voltage pulsed electric field system,The total number of colonies,the physical and chemical properties of the original milk were compared with the original milk before and after PEF treatment.The results showed that the system had good sterilization effect.When the field strength was 35 kV/cm and the number of pulses was 2 000,the sterilization rate could reach 90.98% and was positively related to the number of pulses and electric field strength.Under this PEF condition,the free amino acid content in milk increased by 24.56 mg/L,the electrical conductivity increased by 0.05 ms/cm,the temperature rise was 5.9 ℃ and the change became more pronounced with the increase in pulse number and electric field strength,while pH did not change.It is proved that PEF has a cold sterilization effect on raw milk,and has little effect on its physical and chemical properties,which improves the nutritional value of raw milk and provides new experimental basis and technical support for the industrialization of PEF.