Simple truths on nutrition and heating in a microwave

“Most ready-to-eat meals provide only [meat] protein, [rice] carbohydrate and fat that can retain their nutrition even after being frozen and reheated. So the nutritional value in RTE meals is not very different from fresh cooking, regarding the three groups,” says Prapaisri Sirichakwal – a nutritionist from the Institute of Nutrition, Mahidol University.
“As the RTE is simpler, I think it helps people to have breakfast more conveniently and takes just a few minutes to get ready. The morning meal is important for our health but a lot of people skip it because they don’t have time,” she explains.
Compared to fresh-cooked food from cooked-to-order shops that can be found on every corner, Prapaisri says the RTE has an advantage in hygienic material and preparation, if it is from a certified company.
“Sanitation is important for frozen-food quality, and we found street-side cooking shops don’t have much concern for the sterilization of their utensils, raw ingredients and cooking process,” she said.
However, as minerals and vitamins are easily diluted by washing or any cooking process, the frozen meals have yet to equal fresh meals in keeping their nutritional value.
“What concerns me is people get a high salt intake from this food and saturated fat from the cooking process,” she explains.
Last year Thailand joined the five-year salt reducing campaign of the World Health Organisation. The nutritionist said the recommendation for salt intake is not more than 6 grams a day which equals two teaspoons of fish salt – the more common salt form in Thai kitchens.
“It is hard to change our habits because the sodium helps the food taste better. Actually we have a salt substitute substance like potassium, but it’s not widely used in Thailand,” she says.
Not every frozen food provides nutritional facts on its packaging. But the nutritionist said customers should read the label and take note of the nutrition facts for their own sake.
“We have to raise consciousness and learning of what the nutrition label means and compare between products,” she said.
The Thai Recommended Daily Intake should be around 480 calories per meal, fat not more than 1 gram, sodium not more than 640mg and sugar less than 2 grams.
Though saturated fat often isn’t indicated, Prapaisri says we should be careful and it should be around 6 grams per meal.
Besides the effects on its nutritional value, many worry that in reheating food in a microwave the wave will be absorbed in the food and collect in our body and cause cancer.
 “There is no research that indicates eating microwave food will increase the cancer risk. It works by sending a wave passing through the food and utensils which are not absorbed by the objects,” she says.
The microwave reheats by causing the food molecules to vibrate rapidly – an accelerated version of what ordinary cooking does. The wave can transmit through glass and plastic and wood. But it can’t go through metal utensils like stainless steel or aluminium.
However, though microwave utensils are widely available in supermarkets and department stores, a lot of people don’t know or are unaware of how to use suitable utensils in the microwave.
Many wash plastic dishes from ready-to-eat meals after they have eaten and keep them for use in the microwave oven again. Some also microwave food in plastic containers from the food stalls without knowing it is dangerous and the plastic will probably go up in flames.
“It’s better to use microwave ware and I rather recommend putting frozen food on simple china or ceramic ware without colourful designs or gold trim,” adds Prapaisri.
Parinyaporn Pajee
The Nation