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Experimental and computational analysis of microbial inactivation in a solid by ohmic heating using pulsed electric fields
Innovative Food Science & Emerging Technologies ( IF 6.3 ) Pub Date : 2020-07-24 , DOI: 10.1016/j.ifset.2020.102440
M.Á. Ariza-Gracia , M.P. Cabello , G. Cebrián , B. Calvo , I. Álvarez

Pulsed electric field technology (PEF) has traditionally been used as a technique to inactivate microorganisms in liquid foods at temperatures below those used in heat treatments; however, application of high-intensity PEF (E>1 kV/cm) at high frequencies (>10 Hz) can allow rapid and volumetric solid food electrical heating in order to replace traditional convection/conduction heating that progresses from the heating medium to the inside of the product. This investigation is the first one to evaluate the inactivation of Salmonella Typhimurium 878 in a solid product (cylinder of technical agar used as reference solid) by applying PEF treatments (2.5 and 3.75 kV/cm, and up to 9000 microseconds) at 50 Hz. The evolution of temperature in different locations of the agar cylinder was measured by observing the variability of heating rates depending on location and PEF intensity. Microbial inactivation was determined and compared with isothermal heat treatments that predicted similar inactivation values, but did not detect additional inactivation. Computational analysis enabled us to predict temperature and microbial inactivation for any spatial and temporal distribution of the cylinder agar by detecting the coldest point in the transition zone between the high-voltage electrode, the agar, and the plastic container of the treatment chamber. In order to evaluate the variability of the temperature, computational predictions were done each 0.5-mm. The difference between the coldest and the hottest point (e.g. at the center of the cylinder) resulted in around 10 C and 10 second variation in temperature and processing time, respectively. In any case, it was possible to obtain 5-log10-reductions after 60 s of PEF treatments when using 2.5 kV/cm and 50% reduction for 3.75 kV/cm. These results suggested the potential of PEF technology as a rapid heating system based on ohmic heating for microbial inactivation in solid food products.



中文翻译:

利用脉冲电场通过欧姆加热对固体进行微生物失活的实验和计算分析

传统上,脉冲电场技术(PEF)被用作使液体食品中的微生物在低于热处理所用温度的条件下失活的技术。但是,在高频率(> 10 Hz)下使用高强度PEF(E> 1 kV / cm)可以实现快速,定量的固体食品电加热,以代替从加热介质向加热介质进行加热的传统对流/传导加热。产品内部。这项研究是第一个评估沙门氏菌灭活的研究通过在50 Hz下进行PEF处理(2.5和3.75 kV / cm,最高达9000微秒),在固体产品(工业琼脂圆柱体用作参考固体)中的鼠伤寒878。通过观察加热速率随位置和PEF强度的变化来测量琼脂瓶不同位置的温度变化。确定了微生物失活并将其与预测相似失活值但未检测到其他失活的等温热处理进行比较。计算分析使我们能够通过检测高压电极,琼脂和处理室塑料容器之间的过渡区中的最冷点,来预测圆柱琼脂的任何时空分布的温度和微生物失活。为了评估温度的可变性,每个0.5毫米都进行了计算预测。最冷点和最热点之间的差异(例如,圆柱体的中心)导致大约10温度和处理时间分别变化∘C和10秒。在任何情况下,当使用2.5 kV / cm的电压和3.75 kV / cm的电压降低50%时,PEF处理60 s后都可能获得5-log 10的降低值。这些结果表明,PEF技术作为基于欧姆加热的快速加热系统的潜力,可以使固体食品中的微生物失活。

更新日期:2020-08-11
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