感应电场对连续流动蓝莓果泥理化特性的影响

采用非接触型感应电场(IEF)对蓝莓果泥进行连续加工,考察不同激励电压(100、150和250 V)、温度(65、75和85 ℃)下果泥阻抗和多酚氧化酶(PPO)活性随处理时间(9、18、27、30、36和45 min)的变化规律,并对比不同处理(鲜榨、常规热处理、IEF处理)后蓝莓果泥的色值、粒径分布、流变特性、风味和挥发性成分。结果表明,随着处理时间的增长和处理温度的升高,料液阻抗逐渐降低;250 V激励电压诱导形成的IEF对多酚氧化酶(PPO)的杀灭具有促进作用,经250 V、85 ℃和30 min的IEF处理后,蓝莓果泥 PPO活性完全丧失。IEF处理蓝莓果泥的L*和a*分别为30.37和6.42,显著高于鲜榨和常规热处理的果泥(P<0.05)。IEF处理的蓝莓果泥产品在粒径分布、黏度和风味上更接近鲜榨果泥。弱的感应电场/感应电流对蓝莓果泥中呈色物质、风味成分等具有一定的稳定作用,有利于减缓热处理导致的果泥颜色损失和风味变化。研究旨在为利用弱电效应实现果泥产品的高品质加工提供一定理论参考。

Effect of Induced Electric Field on Physical and Chemical Characteristics of Continuous-Flow Blueberry Puree

The non-contact induced electric field (IEF) was applied in the treatment of continuous-flow blueberry puree. Changes in impedance and polyphenol oxidase (PPO) activity of the sample with different treatment time (9, 18, 27, 30, 36, 45 min) at different excitation voltages (100, 150, 250 V) and temperature (65, 75, 85℃) were investigated. Meanwhile, the color, particle size distribution, rheological properties, flavor and volatile components of different (fresh, conventional-heating-treated, IEF-treated) blueberry puree products were analyzed and compared. It was found that the impedance of blueberry puree gradually decreased with the increasing of treatment time and temperature. The inactivation of PPO was enhanced by IEF. After 30 min of IEF treatment at 250 V and 85℃, PPO was completely inactivated. The L* and a* of the IEF-treated blueberry puree were 30.37 and 6.42 respectively, which were significantly greater than those of the fresh and conventional-heating-treated ones (P<0.05). Particle size distribution, viscosity and flavor of IEF-treated blueberry puree were much closer to those of the fresh sample, in comparison with the conventional-heating-treated one. Results indicated that the relative weak induced of electric field/current was potential to stabilize the color and flavor components in blueberry puree, which was beneficial to slow the color loss and flavor change caused by heat treatment. This investigation aims to provide a certain thermotical reference for the high-quality processing of fruit puree by using weak induced electric field.