Other process heating in food industry

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1. OBJECTIVE


This unit operation category includes typical processes in the food industry that are not complicated in terms of equipment and are based on a simple heat transfer principle. Pre-heating of food streams, soaking and thawing are included in this category. The objective in all cases is to increase the energy content of the food stream so that it can be further processed. In the case of soaking, seeds are moistened and softened using water in order to reduce the cooking time or enhance the seed coat removal. In case of thawing, frozen food can be de-frozen before it can be further processed.


2. FIELD OF APPLICATION


Pre-heating, soaking and thawing can be applied in many food industry sectors, including dairies, breweries, fruit and vegetable industries, meat production and chocolate, cacao and coffee production (BAT in the Food, Drink and Milk Industries, June 2005).


3. DESCRIPTION OF TECHNIQUES, METHODS AND EQUIPMENT


Heat transfer in these cases can be accomplished either by direct or indirect heating. Water or steam can be used as an auxiliary feed for the process. In the case of soaking, seeds are in direct contact with the water in tanks. In the case of thawing, frozen food is placed in water baths. In the case of pre-heating, water or steam can be in direct or indirect contact with the food. Pre-heating can be accomplished in heat exchangers or in compartments where steam or water can be sprayed (BAT in the Food, Drink and Milk Industries, June 2005).


4. COMPETITIVE TECHNOLOGIES AND ENERGY SAVING POTENTIALS


Depending on the heating process, different methods can be used to achieve energy savings. Typically, the re-use of waste water streams of the process for heat recovery is an effective way to reduce the energy consumption. Re-use of condensates produced by evaporation leads to considerable heat recovery and minimization of boiler steam use, when it comes to direct pre-heating of food. In the case of thawing, microwave energy can be used to de-freeze food consuming less energy. Additionally, recovered heat from cooling systems can be used in the case of thawing deep frozen food (BAT in the Food, Drink and Milk Industries, June 2005).


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