微波加热鸡肉和土豆的传热仿真分析研究

为了更好地了解与研究家用微波炉微波加热过程中即食食品的传热特性,本文建立了电磁与传热耦合的仿真模型,研究鸡肉和土豆的空间温度和瞬态温度变化规律,并通过实验研究在-5~95℃范围内,鸡肉在频率为2450 MHz时的介电特性和热物理特性。基于温度对鸡肉介电和热物理特性的分析,将温度可分成两个范围:-5~0℃和0~95℃,各温度范围内的鸡肉特性变化趋势不同。仿真模型包括加热腔、波导以及可旋转的转盘和物料。通过比较不同转速对仿真结果的影响,综合考虑仿真所用时间以及物料的均匀性,选用7.5 r/min作为转盘转速。当微波功率为700 W时,组合样品的仿真结果显示,经过90 s的微波加热,空间温度场分布和瞬态温度曲线与实验结果保持一致,微波仿真组合样品的模型是可行的,研究结果为优化微波加热冷藏快餐的均匀性研究提供一定依据。     

用微波炉热食物

由于微波炉的加热原理同一般的烹饪器具不同,所以用微波炉的食品再加热时,应注意以下几点：1如需再加热的食品数量较多时,最好在加热过程巾停机,取出食物充分搅拌一下再加热,这样可以使食品受热更加均匀。2蔬菜类食品再加热时,不要加盖子或覆保鲜膜,以免使蔬菜色泽变黄。3由于面食（馒头、包子、面包等）多次加热后会发于发硬,再加热时,最好在其表面覆盖上一层带气孔的保鲜膜,以免水分的蒸发,同时也可缩短加热时间。4热牛奶时,如果是袋装奶,则应将其倒入广口瓶或瓷碗中。如果是瓶装奶进行整装加热,则应取掉盖子,并将瓶上部包…     

家用微波炉自制蛋糕的研究

探讨了采用家用微波炉加热制作蛋糕的新思路和新方法,着重研究家用微波炉自制蛋糕的膨松剂的用量及自制微波蛋糕时对微波炉加热强度和时间的控制,初步建立了微波蛋糕的基础配方、生产工艺、自制蛋糕方法.从而增加了蛋糕销售的常规模式.     

谷物防虫防霉专用微波炉的设计

研究开发一套可连续稳定工作的谷物防虫防霉专用微波炉,采用磁控管交互垂直的布置方法,并设计磁控管水冷循环系统和磁控管变压器油冷循环系统。性能测试结果表明:谷物防虫防霉专用微波炉稳定性好,温度分布均匀,偏差小于3℃,微波炉物料出口处温度在55~65℃范围可调,可连续工作24h,设定温度低于60℃时,经微波处理后大米平均增碎率小于0.2%,裂纹率增加量低于0.45%,大米各类害虫及虫卵致死率均在98%以上。     

食品微波加热过程中的传热模型

微波加热是一种快速简便的食品复热手段,但此种方法通常会导致受热不均匀。为了更好的将微波加热技术应用于食品的复热过程,解决受热过程"冷点"的出现,作者综述了食品微波加热过程传热模型的研究进展,并针对数值计算方法、模型理论和功率吸收进行了详细阐述,探讨了微波能在食品中转化成热能的机制,并分析了研究过程中存在的问题和发展方向。     

冷冻食品射频解冻技术研究

正射频加热解冻是一种新型的冷冻食品解冻方式。其利用食品的介电特性,使食品在射频腔内受热升温,达到解冻的目的。与其他解冻方式相比,射频加热解冻的解冻速度快,显著降低了解冻汁液流失率,物料各处同时产生热量,射频解冻后物料内的温度分布更均匀,对食品的品质影响较小,且易于控制。目前国内外已有功率为30 k W左右,频率为27.12 MHz的高频解冻设备投放到市场,可以迅速大量地对冻肉或其它冻制品进行解冻。并且,国内外科学家对射频加热的机理以及食品内部的温度分布及其变     

产品推介

微波炉加热包装 产品结构NY／PE等产品特点独特的产品设计使包装具有在微波炉加热中自动排气的功能。将装有食品的密封包装袋直接置于微波炉中加热．随着食品温度的升高．食品中的水分迅速气化,袋内气体压力的升高使袋子迅速膨胀,此时,包装袋能够自动在某个位置产生放气口,释放出袋内多余的水蒸气．防止袋子炸开和食物飞溅,同时可有效保留食物的风味和水分。     

网上食坛

据英国《新科学家》杂志介绍,有关科学家正在研制的一种智能微波炉,可自动控制加热时间和温度,使烹任大为简化.鲁特格尔斯大学食品系的研究人员说,目前大多数微波炉的控制面板设计不够科学,这导致微波炉的操作仍较复杂,而他们正在研制的新型微波炉有望解决这个问题.这种智能微波炉的奥妙之处,在     

液态食品连续通电加热的加热速率与温度分布

利用自行研制的小型液态食品通电加热装置研究了自来水在连续通电加热过程中的温度分布。实验结果表明,该系统能实现液态食品的连续加热。整个加热过程可分为三个阶段,在加热初始阶段各加热室的加热速率随电场强度的降低而减小：加热室的平均温度与装置长度呈线形关系;在同一极板表面中心处和0．5R处的温度基本相同;加热室极板表面出现了轻微“过热”现象。     

食品的通电加热技术研究

从食品热加工手段玫手,追溯了食品通电加热的历史沿革,阐述了食品通电加热的基本原理及相关的数学模型如电场、温度的分布以及发热量等。讨论了食品的电导率、温度、组成、形状等影响通电加热的因素;论述了实施通电加热的工艺设计的重要参数及系统设计的总体要求;阐述了通电加热在食品加工工业中的特点。应用范围、现状及其发展前景关的工艺设计的重要参数及系统设计的总体要求;阐述了通电加热在食品加工业中的特点、应用范围、     

Frequency Distribution in Domestic Microwave Ovens and Its Influence on Heating Pattern

In this study, snapshots of operating frequency profiles of domestic microwave ovens were collected to reveal the extent of microwave frequency variations under different operation conditions. A computer simulation model was developed based on the finite difference time domain method to analyze the influence of the shifting frequency on heating patterns of foods in a microwave oven. The results showed that the operating frequencies of empty and loaded domestic microwave ovens varied widely even among ovens of the same model purchased on the same date. Each microwave oven had its unique characteristic operating frequencies, which were also affected by the location and shape of the load. The simulated heating patterns of a gellan gel model food when heated on a rotary plate agreed well with the experimental results, which supported the reliability of the developed simulation model. Simulation indicated that the heating patterns of a stationary model food load changed with the varying operating frequency. However, the heating pattern of a rotary model food load was not sensitive to microwave frequencies due to the severe edge heating overshadowing the effects of the frequency variations.     

SDS-PAGE电泳法对微波加热猪肉终点温度的鉴定及其品质特性的研究

在食品烹饪的应用方面,微波加热技术具有节约时间、无异味和营养成分保留率高等特点,是一种理想的烹饪技术。本研究以猪背最长肌切成5 cm×5 cm×1.5 cm的方块为材料,用聚丙烯酰胺凝胶电泳(SDS-PAGE电泳)法对微波和水浴加热的样品进行蛋白变性终点温度鉴定,并对加热至终点温度之后的样品从蒸煮损失、色差、持水能力、剪切力及加热至终点所耗电量进行对比分析及方差分析和显著性分析。结果表明,对于变频微波炉,900 W与700 W加热均需70 s,500 W加热需120 s,而对于非变频品微波炉,100%功率加热需80 s,80%功率加热需100 s,50%功率加热需140 s。在此基础上,对加热至终点温度之后的样品品质及加热至终点所耗电量进行对比分析,得出700 W功率加热的样品质量最佳,消耗电能最少。     

微波解冻猪里脊肉过程的优化设计研究 Key words:

猪肉在我国是最重要的肉类之一,而为了储存更长时间,通常采用冷冻的方式保存。因此,在进一步加工之前就需要经过解冻这一过程,传统的解冻方式耗时长,严重制约了生产效率。微波加热作为一种常用的加热方式,与传统加热方式相比,具有加热速度快、省时节能等突出优点。本文利用家用变频微波炉对冷冻猪里脊肉块进行解冻处理,对解冻程序进行了优化设计,并与微波炉自带的解冻程序进行了对比研究,对肉汁渗出率、色泽以及质构特性进行分析。结果表明：两种优化程序的解冻效果要优于微波炉自的解冻程序,样品能基本解冻完全,肉汁渗出率较低,能较好维持鲜肉的颜色,经过优化后的微波解冻猪里脊肉温差更小,质构特性更佳,同时也缩短了解冻时间。     

模糊控制技术在微波炉中的应用

通过模糊控制技术在烹调过程中自动判定食物量和相应烹调容器确定相应的控制程序，得到相应各阶段的加热功率和时间及其变化规律，用于微波炉的烹调控制，使微波炉的操作得以简化，开拓了微波炉的烹调功能，提高了产品档次     

Assessment of the migration potential of nanosilver from nanoparticle-coated low-density polyethylene food packaging into food simulants

An experimental nanosilver-coated low-density polyethylene (LDPE) food packaging was incubated with food simulants using a conventional oven and tested for migration according to European Commission Regulation No. 10/2011. The commercial LDPE films were coated using a layer-by-layer (LbL) technique and three levels of silver (Ag) precursor concentration (0.5%, 2% and 5% silver nitrate (AgNO₃), respectively) were used to attach antimicrobial Ag. The experimental migration study conditions (time, temperature and food simulant) under conventional oven heating (10 days at 60°C, 2 h at 70°C, 2 h at 60°C or 10 days at 70°C) were chosen to simulate the worst-case storage period of over 6 months. In addition, migration was quantified under microwave heating. The total Ag migrant levels in the food simulants were quantified by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Mean migration levels obtained by ICP-AES for oven heating were in the range 0.01–1.75 mg l^?1. Migration observed for microwave heating was found to be significantly higher when compared with oven heating for similar temperatures (100°C) and identical exposure times (2 min). In each of the packaging materials and food simulants tested, the presence of nanoparticles (NPs) was confirmed by scanning electron microscopy (SEM). On inspection of the migration observed under conventional oven heating, an important finding was the significant reduction in migration resulting from the increased Ag precursor concentration used to attach Ag on the LDPE LbL-coated films. This observation merits further investigation into the LbL coating process used, as it suggests potential for process modifications to reduce migration. In turn, any reduction in NP migration below regulatory limits could greatly support the antimicrobial silver nanoparticle (AgNP)-LDPE LbL-coated films being used as a food packaging material.     

食品的微波加工研究新进展

近年来,微波技术因其加热速度快、效率高等优势,在食品加工中得到了广泛的应用。本文从微波技术的原理着手,对微波技术在食品加热或烹饪、干燥、杀菌以及有效成分提取等方面的最新应用进展加以阐述,并探讨微波对食品颜色、质地、营养成分、生物化学成分、复水性、微观结构等食品品质的影响,以期为微波技术在食品领域的进一步开发及规模化应用提供参考,进而促进食品行业的发展。     

Multiphysics Modeling of Microwave Heating of a Frozen Heterogeneous Meal Rotating on a Turntable

A 3‐dimensional (3‐D) multiphysics model was developed to understand the microwave heating process of a real heterogeneous food, multilayered frozen lasagna. Near‐perfect 3‐D geometries of food package and microwave oven were used. A multiphase porous media model combining the electromagnetic heat source with heat and mass transfer, and incorporating phase change of melting and evaporation was included in finite element model. Discrete rotation of food on the turntable was incorporated. The model simulated for 6 min of microwave cooking of a 450 g frozen lasagna kept at the center of the rotating turntable in a 1200 W domestic oven. Temperature‐dependent dielectric and thermal properties of lasagna ingredients were measured and provided as inputs to the model. Simulated temperature profiles were compared with experimental temperature profiles obtained using a thermal imaging camera and fiber‐optic sensors. The total moisture loss in lasagna was predicted and compared with the experimental moisture loss during cooking. The simulated spatial temperature patterns predicted at the top layer was in good agreement with the corresponding patterns observed in thermal images. Predicted point temperature profiles at 6 different locations within the meal were compared with experimental temperature profiles and root mean square error (RMSE) values ranged from 6.6 to 20.0 °C. The predicted total moisture loss matched well with an RMSE value of 0.54 g. Different layers of food components showed considerably different heating performance. Food product developers can use this model for designing food products by understanding the effect of thickness and order of each layer, and material properties of each layer, and packaging shape on cooking performance.     

A test procedure to characterise the heating performance of domestic microwave ovens

A test procedure has been developed and used to characterise the performance of domestic microwave ovens in relation to the heating of chilled ready meals. The procedure uses reproducible test loads, which simulate the heating and weight loss characteristics of a chilled ready meal under consumer use. The temperature distribution after heating from 5 °C to a defined minimum temperature of 70 °C is measured in the food simulant using a purpose designed multipoint thermocouple ‘hedgehog’ probe. The temperature, weight loss and heating time data from the test are entered into a spreadsheet analysis program, which provides a simple oven performance ‘score’ and/or comprehensive heating performance data.     

模糊集在微波炉控制器中的应用

采用单片机与模糊控制技术相结合的方法,研制出了以东芝公司的ＴＭＰ８７Ｃ８４６Ｎ为核心的微波炉控制器．该控制器采用热释电温度传感器检测食物温度,采用热敏电阻型湿度传感器检测食物湿度,通过模糊推理,根据食物的温度、湿度、重量、烹调功率自动推断加热时间,从而避免了因操作者经验不足、设定时间不准而造成的烹调失败．     

Microwave Heating Uniformity of Ready Meals as Affected by Placement, Composition, and Geometry

The importance of chemical and physical modifications in a ready meal on microwave heating uniformity was investigated. Experimental materials were four-component chilled ready meals which were heated in a domestic microwave oven. The experiment was set up by using 2⁵ factor design and data were evaluated by analysis of variance. Temperatures during and after microwave heating were measured. Heating uniformity could be mainly modified by arrangement and geometry of components and type of tray. In contrast, chemical modifications had no effect or some combined effects with other factors.