Employing moist heat methods while cooking foods can make foods soft & tender, improve its digestibility; but it can also result in loss of several heat labile, water soluble vitamins such as B-complex & Vitamin C. If retaining nutrition hold priority for you over taste, then employing these moist heat methods needs to be done smartly.
Moist Heat Cooking Methods
Cooking methods involving moist heat are as follows such as steaming, boiling, stewing, poaching, blanching, pressure cooking. These methods include water or liquid as a mode of heat transfer. Liquids perform the cooking of foods as they move in convection currents, distributing the heat & cooking the food uniformly.
Following are few of the main food groups & the effect moist heat has on the nutrients they contain.
Cereal & cereal products
The B-complex vitamins in rice are more prone to getting lost if washed & cooked in excess water. Vitamin B1 (thiamine) & nicotinic acid (vitamin B5) are lost if rice in cooked in excess water & the water is discarded. Parboiling rice & using it ensures more retention of nutrients as the gelatinized starch made around the grain prevents the loss of nutrients.
Pulses & legumes
Studies have shown that moist heat increased the total amount of available carbohydrates from whole beans & pulses. Dehulling the beans decreased their phytate & tannin contents, as a result increased the bioavailability of minerals such as zinc & iron, and also improved the protein digestibility. Discarding the water in which the pulses are soaked & cooking them in fresh water, enables to improve bioavailability of most nutrients in pulses.
Green Leafy veggies
Finely chopping green leafy veggies such as spinach, amaranth, fenugreek leaves followed by washing & boiling them later, can cause considerable loss of nutrients. Steaming or blanching them is the best way to cook them which minimum loss of vitamins such as folic acid, vitamin K and Vitamin C. Chop them coarsely and wash them before chopping, use the water they are cooked in, or best, steam them.
Root veggies such as potato, radish, carrot should be peeled after pressure cooking them. If chopped & boiled, use minimum water for boiling which can be further utilized later.
Meat & meat Products
Boiling fish is shown to preserve the omega-3 fatty acid content. Also, cholesterol content was observed to increase when canned & microwave heated tuna fish as compared to cooked tuna. Frying tuna reduced the cholesterol content due to cholesterol migrating into the frying oil.
Stephen N et.al., (2010) Effect of different types of heat processing on chemical changes in tuna. Journal of Food Science & Technology 47(2) : 174–181.
Gopalan G et.al, Nutritive Value of Indian Foods. (1989) Published by National Institute of Nutrition, ICMR, Hyderabad.