微波条件下微波纸中邻苯二甲酸酯向食品模拟物Tenax的迁移

研究250W和600W微波加热功率条件下微波纸中5种邻苯二甲酸酯向食品模拟物Tenax迁移的规律,并与常规高温迁移实验的结果比较。结果表明:微波加热条件下的迁移受加热功率、加热时间、迁移物分子结构、相对分子质量和极性等因素影响。与常规高温迁移相比,微波加热能加速物质迁移,说明迁移过程也受加热方式影响,微波加热可作为加速纸质包装中有害物质迁移的实验方法。     

加热方式对聚碳酸酯中双酚A迁移规律影响

结合聚碳酸酯(PC)塑料的实际使用情况,以蒸馏水、自来水和矿泉水为食品模拟物,采用高效液相-荧光检测法测定PC塑料中双酚A在微波加热和恒温加热时向不同水质中的迁移量。结果表明:微波加热和恒温加热条件下,迁移率均随加热时间的延长而增加,其中蒸馏水中迁移率最低。微波加热比常规恒温加热达到平衡的时间缩短近12倍,说明微波加热能加速塑料中有害物质的迁移速率;蒸馏水和自来水在2种加热方式下的最大迁移率并无差别(P>0.05),矿泉水在微波加热时最大迁移率要高于恒温加热(P<0.01),因此,使用微波加热食品时,应注意容器所盛装食品的性质和控制加热的时间,以免引起PC容器中双酚A向食品的迁移。     

微波条件下纸包装油墨中增塑剂向食品（模拟物）的迁移

研究纸张印刷油墨中4 种增塑剂（3 种邻苯二甲酸酯类增塑剂和近年流行的环保增塑剂乙酰基柠檬酸三丁酯）向食品模拟物Tenax和奶粉的迁移,考察其在110、250、440、600、900 W微波功率下的迁移行为,探讨迁移影响因素,并与常规条件下的迁移行为做比较。结果显示在一定条件下微波功率越高,迁移量越大;且迁移行为受增塑剂的分子质量、极性等性质的影响;常规条件下的迁移影响因素也适用于微波条件。     

微波条件下聚烯烃抗氧剂向食用油迁移的扩散系数研究

实验研究不同微波加热功率条件下PE膜内三种不同分子量不同分子结构的抗氧化剂(BHT、Irganox 1076和Irgafos 168)向6 种食用油的迁移,计算相应的扩散系数并给出其与微波加热功率的关系图。鉴于微波加热条件下迁移的特殊性,提出构建新的扩散系数预测模型的设想。     

微波处理对花生蛋白功能特性和结构的影响

目的：探索阐述微波处理对花生蛋白功能特性和结构的影响。方法：微波处理(120、280、460、600 W和700 W,30 s)花生蛋白，对比微波前后花生蛋白溶解性、乳化性、起泡性、表面疏水性等指标的变化，并分析微波功率对花生蛋白二级结构和微观结构的影响。结果：当微波功率逐渐增大时，花生蛋白的溶解性、乳化性、起泡性和表面疏水性均显著提高(P<0.05)，且在较高功率600 W或700 W下达到最大值。其中，600 W时蛋白乳化性和表面疏水性最好；溶解性和起泡性较空白样分别提高了15.45%和11.11%，增幅虽不如700 W的16.33%和11.77%，但差距较小。红外结果显示，当微波功率较低时(120～460 W)，蛋白结构从有序向无序转变，而较高功率下(600～700 W)，结构从无序变得有序。微观结构表明花生蛋白在600 W下形成表面光滑平整、均匀分布的颗粒。结论：微波处理可以有效改善花生蛋白的功能特性和结构，且微波600W、30s为最佳处理条件。该结果可为花生蛋白的改性研究及其在食品工业中的应用提供一定的理论和实验依据。     

微波辐射辅助竹浆漂白研究

以漂后浆料白度、残氯为考察指标时,用微波辐射辅助竹浆次氯酸钠漂白的最佳工艺条件为:微波辐射功率640 W,辐射时间6 min,有效氯含量8%.竹浆白度达69.2%ISO,与相同条件下传统水浴加热90 min竹浆达到的白度(70.6%ISO)相当;残氯为0.221 7 g/L,比相同条件下传统水浴加热90 min稍高(0.203 4 g/L).微波辐射竹浆漂白可以缩短时间、提高生产效率、节约能源,在造纸工业中的应用值得进一步研究.     

微波消化面粉的关键步骤

微波消化法是消化面粉样品的较好方法之一。本文从取样量、样品的预处理、溶剂的选择、微波加热方式及加热时间、冷却方法等几个环节对面粉样品在微波消化过程中应注意的一些问题进行了探讨，总结出微波消化面粉样品时适宜的条件和操作方法：准确称取1．0g样品于消解罐内，加1mL去离子水将样品充分润湿，然后加入10mL硝酸和2mL过氧化氢，按250W（3min）→0W（5min）→250w（5min）→400W（5min）→600W（5min）的消解程序执行样品消化，消解程序执行完毕约5min后取出消解罐，在通风橱中通风冷却25min。     

微波复热时间和微波功率对预油炸牛肉串品质的影响

研究了微波加热时间(30、40、60、90、120s)和微波功率(350、490、700W)对预油炸牛肉串出品率、剪切力、色差和感官评价的影响.结果表明,在不同微波复热条件下,牛肉串的出品率、剪切力、色差变化和总体可接受性存在明显差异(p＜0.05).在同一微波功率条件下,随着微波加热时间的延长,肉串的出品率逐渐下降,亮度L*值降低,红色度a*值升高;除微波加热30s外,随着微波加热时间的延长,肉串的剪切力值增加,嫩度下降.牛肉串在700W加热40s、490W加热40s和60s时,不仅明显提高了肉串的出品率,而且改善了牛肉串的色泽,并使肉串保持较低的剪切力值.     

两种微波加热处理方式对白鲢鱼糜凝胶特性的影响

为提高鱼糜制品的品质,研究两种微波加热处理(单独微波和水浴微波联用)对白鲢鱼糜凝胶特性的影响。以凝胶强度、持水性、白度为检测指标,采用单因素和正交试验,优化得到单独微波加热和水浴微波联用加热的工艺条件;并采用凝胶溶解度、化学作用力、SDS-PAGE凝胶电泳、扫描电镜等检测方法,进一步研究不同加热处理方式对鱼糜凝胶蛋白质分子结构的影响。优化试验结果表明,单独微波加热的最佳工艺条件为微波功率600 W、微波时间60 s,此时凝胶强度608.64 g·cm,持水性83.64%,白度75.79;水浴微波联用加热的最佳工艺条件为水浴温度40℃,水浴时间1 h,微波功率450 W、微波时间60 s,此时凝胶强度627.37 g·cm,持水性85.37%,白度74.37。验证试验结果表明,在提高白鲢鱼糜凝胶特性方面,两种微波加热显著优于传统水浴加热(即水浴二段加热),且水浴微波联用加热比单独微波加热更好。     

微波加热预处理大豆对磷脂和豆粕品质的影响

应用频率2450MHz、功率650W之微波炉对整粒大豆进行预处理加热试验。在不同的加热时间条件下,对其提取的油脂与豆粕质量指标(水化脱胶油中NHP含量、PDI指数等)进行分析与测定。其结果初步表明:应用微波加热新技术,对钝化酶,提高豆粕蛋白质与油脂的品质行之有效。与传统热传导加热处理方式(蒸汽、热空气、导热油等)相比,微波加热具有时间短、选择性好的特点。并指出:本实验条件之最佳热处理时间为1 1/3min至2.5min。为兼顾豆粕与油脂品质的最优化,笔者提出:适当延长微波加热恒温阶段的时间、采用必要的低温处理作为工艺依据。相应的技术措施有如:调节水分、料层厚度与操作压力以及采取气流干热与微波真空干热预处理相结合的节能工艺等。     

食品加工新技术——微波灭菌

<正> 微波是辐射的电磁波,其波长约在10~(-3)～10~(-1)米数量级,频率为300兆赫～300秭赫,与电离辐射不同的是,微波用于食品加热已有一段时间,但微波用于食品灭菌处理则时间较短。 微波灭菌机理 微波与生物体的相互作用是一个极为复杂的过程。当生物体受到微波辐射后会吸收微波能,从而产生热效应,加上生物体在微波场中发生生理反应和变化,也会影响微生物的生存率。微波辐照细菌致死的原因是微波热效应和非热力生物效应共同作用的结果,两种效应相互依存、相互加强。     

Microwave Bumping: Quantifying Explosions in Foods During Microwave Heating

An apparatus was developed to quantify the degree of bumping due to the explosion of food particulates during microwave heating. The apparatus consisted of a sound recording device, a digital storage oscilloscope, and an electric filter. Degree of bumping for a product was defined by integration of the magnitude of an explosion over time of bumping. The sound spectrum of explosion was analyzed by Fast Fourier Transform (FFT) analysis. Frequency of bumping was usually in the range 1.6 kHz to 8 kHz. The character of microwave bumping varied according to localized microwave superheating effects, product formulations, and prior heat treatment of the food.     

Microwave digestion of proteins

 The time needed for a conventional acidic digestion of peptide bonds in proteins with 6 N HCl was reduced from 18–24 h to 2 h when microwaves were applied. The rate-determining step of the splitting of the peptide bonds depends on the amino acid composition of the proteins. Myoglobin, lysozyme and bovine serum albumin were tested as pure model proteins. The amino acid contents determined after ion-exchange HPLC and postcolumn derivatisation with ninhydrin correlated well with values obtained on the basis of known amino acid sequences. Tryptophan, methionine as well as cysteine/cystine were partly or completely destroyed under the hydrolysis conditions applied. Almost 95% of the thermolabile amino acids (based on theoretical values) could be recovered. The conditions were further applied for the hydrolysis of food proteins like casein, commercially available whey proteins as well as pea proteins, and a comparison with the results of the conventional hydrolysis (24 h) was made. Received: 26 February 1998 / Revised version: 20 March 1998     

Microwave digestion of proteins

 The time needed for a conventional acidic digestion of peptide bonds in proteins with 6 N HCl was reduced from 18–24 h to 2 h when microwaves were applied. The rate-determining step of the splitting of the peptide bonds depends on the amino acid composition of the proteins. Myoglobin, lysozyme and bovine serum albumin were tested as pure model proteins. The amino acid contents determined after ion-exchange HPLC and postcolumn derivatisation with ninhydrin correlated well with values obtained on the basis of known amino acid sequences. Tryptophan, methionine as well as cysteine/cystine were partly or completely destroyed under the hydrolysis conditions applied. Almost 95% of the thermolabile amino acids (based on theoretical values) could be recovered. The conditions were further applied for the hydrolysis of food proteins like casein, commercially available whey proteins as well as pea proteins, and a comparison with the results of the conventional hydrolysis (24 h) was made. Received: 26 February 1998 / Revised version: 20 March 1998     

Microwave Blanching of Vegetables

ABSTRACT: Three vegetables, spinach, carrot, and bell peppers were blanched conventionally in water and using pulsed microwave at 95 ± 2 C. The effect of various parameters like mass of the product, mobility of the product in the microwave field, and physical geometry on the temperature attained was evaluated. The study also included the kinetics of peroxidase inactivation, temperature, and power distribution during microwave blanching. The study highlights the potential application of microwave blanching in reducing the loss of valuable nutrients. The kinetics of peroxidase inactivation indicated that microwave blanching was comparable to water blanching with higher reaction rate in the case of water blanching. The temperature and absorbed power levels during microwave blanching was influenced by the vegetable itself, its quantity, shape, location in the oven, and the microwave power applied.     

Microwave phase control heating

Summary Food processors are increasingly looking towards new microwave-based technologies to deliver competitive advantage in the market place, reduce operational costs, allow greater product innovation and increase flexibility without the need for large capital investments. The technical barriers to the widespread exploitation of microwave heating, and opportunities for microwave heating in food processing, are discussed in the context of the need to understand the microwave field/material/process interaction. It is shown how a new application of interference techniques, called phase control microwave heating, may offer opportunities for enhanced heat transfer in food processing, especially for direct control of the spatial power deposition within a foodstuff. Simulations of phase control heating using a 3D FETD microwave model, validation of experimental findings and examples in other applications are presented.     

微波技术应用(英文)

As a new development technique microwave technology has applied widely in areas of food processing.This article summarized the principles and characteristics of microwave technology and applications of microwave processing technology in meat products, cereals, fruits and vegetables processing.Some problems existed in microwave applications were analyzed.The development trend of microwave processing technology in food industry was put forward.     

Microwave and Radio Frequency Processing

SCOPE OF DELIVERABLES: The use of microwave and radio frequencies to heat food for commercial pasteurization and sterilization in order to enhance microbial safety is discussed here. Although not under FDA regulations, use of microwave technology to enhance microbial food safety in the home is also discussed briefly. Mechanisms of heating food and destroying pathogens, and the validation of industrial processes are also discussed, followed by conjecture on handling deviations during industrial processing. This document summarizes information obtained through published literature and personal contacts with industry, academia, and government. Although radio frequency is covered whenever possible, very little information on radio frequency heating for commercial pasteurization or sterilization of food is available in the published literature and no commercial facility for this purpose could be located. The microbial inactivation mechanisms of radio frequency heating are also quite similar to those of microwave heating. Thus, this document refers mostly to microwave processing with the implicit assumption that the principles are generally applicable to radio frequency. Specific information on radio frequency is included whenever available.