In this study, we compare the effects of single- and double-cycle HP treatments at 600 MPa on inactivation of the natural microflora and physicochemical properties of whole and skimmed milk of high bacterial load. The results show that two-cycled HP (2 × 2.5 min) was more effective (P < 0.05) on microbial inactivation, and caused similar or slightly less changes (P > 0.05) in physicochemical properties of milk in comparison to single cycled HP (1 × 5 min). In addition to the expected milk protein structure changes, HP at 600 MPa caused only slight effects on milk fat and lactose. Minor decreases in levels of short chain fatty acids were observed with the cycled treatments, and the volatiles in general decreased after HP treatment, depending mostly on the pressure time but also on cycling in skimmed milk. The study confirmed the superior effect of two-cycle HP on microbial inactivation, and shows a slightly better preservation of the physical-chemical milk quality.

Industrial relevance

Multi-cycling HP has been shown to be advantageous for microbial inactivation, but limited information is available regarding the effect on milk components in whole milk or skimmed milk. The present study compares the psychochemical properties of whole and skimmed milk processed by multi-cycling in comparison to single cycle HP treatment. Double cycled HP presented a superior effect on microbial inactivation and slightly better preservation of milk quality than one continuous HP.

中文翻译：

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全脂和脱脂牛奶的循环高静水压力处理：对理化性质的影响

在这项研究中，我们比较了600 MPa下单周期和双周期HP处理对高细菌负荷全脂和脱脂牛奶天然微生物区系失活和理化特性的影响。结果表明，两个周期的HP（2×2.5分钟）对微生物灭活更有效（P  <  0.05），并引起相似或稍少的变化（P  >  0.05与单周期HP（1×5分钟）相比，牛奶的理化特性）。除了预期的牛奶蛋白质结构变化外，600 MPa的高压仅对牛奶脂肪和乳糖产生轻微影响。在循环治疗中观察到短链脂肪酸的含量略有下降，HP处理后挥发物总体上减少了，这主要取决于加压时间，也取决于脱脂牛奶中的循环。该研究证实了两周期HP对微生物灭活的优异效果，并显示了理化牛奶质量的较好保留。

行业相关性

已显示多循环HP对微生物的灭活是有利的，但是关于对全脂牛奶或脱脂牛奶中的牛奶成分的影响的信息有限。本研究比较了与单周期HP处理相比，多周期处理的全脂和脱脂牛奶的心理化学特性。与一个连续的HP相比，双循环HP对微生物的灭活效果更好，对牛奶品质的保存效果更好。