Two cases of microwave drying are possible, drying at atmospheric pressure and that with applied vacuum conditions. Microwave energy has found general, commercial application in very few areas. Nevertheless in order to estimate results of microwave heating applications and to check roughly the numerical results, knowledge of simple solutions of the one-dimensional wave propagation like the exponentially damped wave is of practical (and also educational) relevance. The quantum energy of a photon of f = 2.45 GHz is defined by E = h f ≈ 1*10-5 eV, the typical energy of a photon radiated from a body of 25°C ≈ 298 K equals E = k T ≈ 0.26 eV and the energy of molecule bonds are in the eV-range. Microwave vacuum dehydration is used for the concentration or even powder production of fruit juices and drying of grains in short times without germination.Newly and successfully applied is the combination of pre-air-drying, intermittent microwave vacuum drying (called puffing) and post-air-drying. While more conventional temperature probe systems, like fibre optic probes, liquid crystal foils or infrared photographs only give a kind of incomplete information about the temperature distribution within the whole sample, probably magnetic resonance imaging has the potential to give very useful information about the heating patterns. However, inherent in thawing is a major problem that does not occur in the freezing operation. They are − Wireless Communications. One difficulty to be overcome was a microwavable baking pan, which is sufficiently heat resistant and not too expensive for commercial use. You may need to download version 2.0 now from the Chrome Web Store. A moderate heating process such as blanching may also release carotenoids and make them more extractable and bioavailable (Arroqui et al., 2002). Microwave heating is attractive for heating of foods due to its origin within the material, fast temperature rise, controllable heat deposition, and easy clean-up. That is why we are cautious in predicting the future of microwaves in industrial use. But still the best test for numerical calculations is experiments, which yield the real temperature distributions within the product, which is really important especially in pasteurization and sterilization applications. The temperature distribution within the food product is affected by additional factors. As shown in Fig.1, a typical drying curve of a foodstuff can be subdivided into three phases. If we look specifically at the retention of aroma, it becomes necessary to distinguish between two basic cases. Among these are the finish drying of potato chips, pasta drying, snack drying, and the finish drying of biscuits and crackers. Of these factors, thawing time is the principal criterion that often governs selection of the system. • The microwave oven is a device with a high-power electron tube (magnetron) that generates and radiates electromagnetic energy into food to be prepared. Help us write another book on this subject and reach those readers. Sub-atmospheric pressure, when applied to the steam blanching process, reduces the amount of oxygen and therefore results in a lower degradation of vegetable pigments and nutrients. If you are at an office or shared network, you can ask the network administrator to run a scan across the network looking for misconfigured or infected devices. This is the minimum temperature at which the meat can be boned or other products cut or separated by hand. Venkatesh and Raghavan (2004) dried rosemary in a household microwave oven with good aroma retention. The possible avoidance of case hardening, due to more homogeneous drying without large moisture gradients is another advantage. There are many reasons for its limited use: the technical problems described above were not well- understood in the past. The most common application of Microwave is its use in RADAR and SONAR. -5 to -2 0C) are acceptable for product that is destined for mechanical chopping, but such material is `tempered' rather than thawed. The latter disadvantage has been partly overcome by the exponentially growing calculating power which makes it possible to compute more and more realistic models by numerical methods. This way of product enhancement is called product engineering or formulation. The combination of microwave and vacuum drying also has a certain potential. When heating rapidly, the quality of fruits and vegetables such as flavor, texture, color and vitamin content is better kept (Dorantes-Alvarez et al., 2000). The combination of air drying and microwave-vacuum puffing is being used in Germany and Poland for fruits and vegetables. The last objective can also be helped by a careful control of the food composition (Anantheswaran and Ramaswamy, 2001). Only a relatively low number of microwave applications can be found in actual industrial production, compared with their indisputable high potential. In this chapter an overview of microwave heating as one method of thermal food processing is presented. As a result, the losses of water and aroma are coupled. The spraying of cold water at the end of the blanching process allows a better nutrient retention than the immersion of the food in cold water. Considering the fact that we perceive aroma -as opposed to taste - with our noses, it is quite clear that aroma molecules are normally volatile; otherwise they would stay in the food during eating and not contribute to the aroma. By 1982 patents had been issued overcoming this problem by using metal baking pans in microwave ovens (Schiffmann et al., 1981 and Schiffmann, 1982). Appearance, bacteriological condition and weight loss are important if the material is to be sold in the thawed condition but are less so if it is for processing. Correspondingly sensorial and nutritional damage caused by long drying times or high surface temperatures can be prevented. Built by scientists, for scientists. Reasons mentioned for the failure of industrial microwave applications range from high energy costs, which have to be counterbalanced by higher product qualities, over the conservatism of the food industry and relatively low research budgets, to the lack of microwave engineering knowledge and of complete microwave heating models and their calculation facilities. When the microwave energy is turned off and the food is removed from the oven, there is no residual radiation remaining in the food. Applications of Microwaves Communication • Before the advent of fiber-optic transmission, most long distance telephone calls were carried via microwave point-to-point links through sites like the AT&T Long Lines. On a smaller scale, Microwave Research has a long track record of supplying microwave heating equipment at 2450 MHz for both industrial and laboratory applications. Food processing and rubber manufacture involve relatively high-volume, continuous processing. There are a wide variety of applications for Microwaves, which are not possible for other radiations. © 2012 The Author(s). Another advantage of this technique is the valuable by-product namely rendered fat of high quality, which is used as food flavoring (Schiffmann, 1986). Applications of Microwaves in the field of Power A microwave passes (non-ionizing) microwave radiation (at a frequency near 2.45 GHz) through food, causing dielectric... Microwave heating is used in industrial processes for drying and curing products. In this situation, the volatility of the aroma molecule in water is essential. However, rapid heating can also lead to problems of non-uniform heating when excessively high energy transfer rates are used (Ohlsson, 2000). Moreover, the existing regulation does not always allow all kind of waste material to be recycled, especially if harmful or hazardous materials are involved (Oda et al., 1992). “Because the microwave energy is changed to heat as soon as it is absorbed by the food, it cannot make the food radioactive or contaminated (O.S.H.A, 2012). However, this operation has also some inconvenient effects such as losses in product quality (texture and turgor), environmental impact, and energy costs. Microwaves are the main energy source, to render the fat and coagulate the proteins by an increased temperature. Compared to the development of traditional blanching systems, it is still a challenge to design appropriate equipment for microwave blanching. In commercial practice there are relatively few controlled thawing systems. When the process temperature is not adequate, the enzymatic deteriorative action may prevail or even increase in some cases.