available literature showed that vitamin retention in microwaved foods is equal

Available literature showed that vitamin retention in

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available literature showed that vitamin retention in microwaved foods is equal or better than conventionally prepared foods because of the shorter heating time of microwave cooking 1,25 . Minerals 29. Minerals are generally not destroyed during cooking including microwave cooking. However, they might be lost in cooking water or meat drippings. Nevertheless, a study comparing microwave and conventional braised beef found that significantly more phosphorus and potassium were retained in microwave cooking 1 . 14
30. Therefore, it can be concluded the nutritional values of food cooked by microwave would be comparable with those by conventional methods. FOOD CONTACT METERIALS FOR MICROWAVE COOKING 31. Nowadays, common materials for packaging or containing foods are plastic, paper, glass, ceramics and metal. However, not all of these materials are suitable for microwave cooking. Materials like plastics, paper, glass and ceramics are generally transparent to microwaves. Nevertheless, some of them may absorb certain amount of microwave energy and hence reduce the amount of energy to be absorbed by food. 32. On the other hand, there have been concerns on the possibility of chemical migration from such food contact materials (e.g. plastics, etc.) into food during microwaving. Safety issues on the application of common food contact materials for microwaving are detailed below: Plastics 33. Plastic containers are commonly used for microwave cooking and re-heating food and it is getting popular nowadays for carrying take-away meals. Not all types of plastic materials are suitable for microwave cooking. Even though high density polyethylene can be used for foods with high water content, it cannot be used for foods with high fat or high sugar content as these foods may reach temperature above 100 o C during microwave cooking. Among plastic materials, the most commonly used ones for microwave cooking are 15
polypropylene and crystalline polyethylene terephthalate (CPET), which have melting points of 210-230 o C 1 . 34. For plastic wraps, commonly used materials are poly-vinyl chloride (PVC) and polyethylene. To enhance the flexibility of PVC films, plasticisers like di-(2-ethylhexyl) adipate (DEHA) may be added. There have been concerns regarding the potential carcinogenicity of DEHA which may migrate into foods. IARC evaluated the carcinogenicity of DEHA and concluded that there was no data relevant to the carcinogenicity to human and limited evidence for its carcinogenicity to animals. It was therefore not classifiable as to its carcinogenicity to humans (Group 3) 26 . Very low level of DEHA exposure occurs when ingesting certain types of fatty foods wrapped in plastics, for example, meat and cheese. The levels of plasticiser that might be consumed as a result of the use of plastic wrap are well below the levels showing toxic effect in animal studies 27,28 . However, a study conducted in the UK in 1986 found that DEHA migration from PVC films to food cooked in microwave oven might be higher under certain conditions and considered that it might not be appropriate to use PVC films for lining dishes or wrapping foods in a microwave oven

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