Thursday, December 3, 2015

Microwave heating of foods-Some concerns about its ill effects

Have we not come a long way since our ancestors started cooking their foods in open fire created by friction between two stones? Unfortunately this progress in our knowledge and modern practices are still not ensuring that the nutrients in the food are not degraded or lost during any of the cooking practices in vogue to day. Some extreme preachers promote the concept of eating food in its raw form ignoring the dangers involved in such practices. Raw milk consumption is still being practiced in some parts of the world and for these practitioners heating is a taboo fearing the loss of the original goodness inherent in the food. Similarly the habit of salad eating also presupposes that heating reduces its nutrition besides the eating quality. But to day's growing methods are radically different from what they were hundred years ago and industrial agriculture involving heavy use of chemical fertilizers and powerful insecticides and pesticides. Industrial scale cultivation became inevitable to meet the food needs of a vast expanding population. Similarly industrial scale cooking using a variety of heating modes in modern restaurants and other mass catering places are making kitchen a redundant place, to be visited occasionally for light cooking. Naturally the question arises whether modern cooking technologies destroy the nutrients present in our foods very significantly compared to yesteryear? Recent debate about microwave heating and its impact on nutrient retention is a typical case where there is no unanimity among experts. Read further below:  

"The microwave has gotten a bit of a bad rap about its effects on nutrients. Cooking and heating food by any method can result in some degradation of nutrients. Vitamins C and B12, for instance, degrade quickly when a food is heated. But other nutrients may actually benefit from the rise in temperature. For example, carotenoids, the antioxidants found in colorful vegetables like carrots and tomatoes, increase when the proteins that bind them break down during heating, said Guy Crosby, the science editor for America's Test Kitchen and an adjunct associate professor at the Harvard T.H. Chan School of Public Health. The Harvard Health Letter recently concluded that microwaving may be preferable to other methods for heating food. "Because microwave cooking times are shorter, cooking with a microwave does a better job of preserving vitamin C and other nutrients that break down when heated," it reported. "The cooking method that best retains nutrients is one that cooks quickly, heats food for the shortest amount of time, and uses as little liquid as possible. Microwaving meets those criteria. Using the microwave with a small amount of water essentially steams food from the inside out. That keeps more vitamins and minerals than almost any other cooking method." However, Ashim Datta, a professor of food engineering at Cornell University, cautioned that because microwaves heat food unevenly, nutrients are more likely to be broken down in spots that get extremely hot. In some cases, Dr. Datta said, microwaving could lead to more degradation over all than another warming method. To help avoid these problems, put a lid on food in the microwave to retain moisture, and keep the power relatively low to ensure that food is cooked rapidly, but not overheated, said Rebecca Solomon, director of clinical nutrition at Mount Sinai Beth Israel hospital in New York City.But for people who eat a balanced diet, microwave heating is unlikely to have a meaningful effect positive or negative, on nutritional intake."

Microwave heating was frowned upon in the beginning in early years of its introduction into the kitchen places because of the mistaken impression that it emits dangerous radiation reminding one of atom bomb and hydrogen bomb. Fortunately out weighing this perception, house wives started believing that microwave is a very convenient mode of cooking and hence it has become one of the most conspicuous fixtures in many modern kitchens. Scientists are always curious in following up their "feelings" about any subject through laboratory research and naturally microwave heating also raised curiosity among some of them whether nutrient loss or retention in the heated foods is worse or better than that happening in conventional cooking processes. The result is on the expected line in that there is no unanimity about this issue. What ever is said the basic principles of food technology tell us that damage to heat sensitive nutrients will always be less when duration of cooking time is less. Thus microwave heated foods exposed to cooking temperatures for a few minutes cannot be expected to suffer significantly vis-a-vis nutrients. The argument that there are hot spots in the food cooked due to nonuniform heating in the microwave owen probably cannot take away the merits inherent in this mode of heating. Suggesting covering the dish during "nuking" is a welcome one and easy to adopt to ensure uniformity of heat transfer in the the food matrix.  


No comments: