Cloudy apple juice has been treated by thermosonication in batch mode as an alternative processing to thermal treatment. Thermosonication was found to be effective to inactivate polyphenol oxidase; however, pectinmethylesterase was found to be more resistant. An increase of the working ultrasound amplitude and the amount of energy supplied to the juice led to lower enzyme residual activities.

Enzyme inactivation kinetics were determined at different temperatures (from 44 to 67 °C). Inactivation data were described by the first order kinetic model and the Weibull model, both models yielding good fitting. Thermosonication treatment caused a homogenization effect reflected in the shifting of the particle size distribution towards smaller diameters. The effect of the nature of dissolved gases in the juice on enzyme inactivation was studied by displacing the air dissolved in the juice by bubbling nitrogen or carbon dioxide, previous to the thermosonication experiments. Higher inactivation rates were obtained by displacing the air with nitrogen.

Industrial relevance

Consumers demand of natural and fresh-like products has driven the food industry to investigate alternative technologies to replace conventional food heat treatments that may affect food quality. Among these technologies, thermosonication treatment is an attractive technology that can inactivate microorganisms and enzymes. This work shows that some enzymes that cause deleterious effect on cloudy apple juice can be more effectively inactivated by thermosonication than by thermal treatment, in the same temperature range, reducing the damages caused by heating.

中文翻译：

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分批热超声处理对浑浊苹果汁酶失活动力学及其他质量参数的影响

混浊的苹果汁已通过分批方式进行热超声处理，作为热处理的替代方法。发现热超声可有效灭活多酚氧化酶。然而，果胶甲基酯酶被发现具有更高的抵抗力。工作超声振幅的增加和提供给果汁的能量的增加导致较低的酶残留活性。

在不同温度（44至67°C）下测定酶的失活动力学。一阶动力学模型和Weibull模型描述了失活数据，这两个模型都具有良好的拟合性。热超声处理引起均质化效果，反映在粒度分布向较小直径的偏移中。在热超声实验之前，通过鼓泡氮气或二氧化碳置换汁液中溶解的空气，研究了汁液中溶解气体的性质对酶失活的影响。通过用氮气置换空气可获得更高的灭活率。

行业相关性

消费者对天然和类似新鲜产品的需求驱使食品行业研究替代技术，以替代可能影响食品质量的常规食品热处理。在这些技术中，热超声处理是一种可以使微生物和酶失活的有吸引力的技术。这项工作表明，在相同温度范围内，热超声处理比热处理能更有效地灭活一些对混浊苹果汁产生有害作用的酶，从而减少了加热造成的损害。