A substantial amount of vitamins in foods can be lost from the time a fruit or vegetable is picked until the time it is eaten. Heat, light exposure to the air, cooking in water all contribute to nutrient loss.
The sooner a food is eaten after harvest, the less chance there is of nutrient loss.
The following 6 suggestions will assist you in preserving the vitamins in your food:
1) Go frozen rather than canned when buying vegetables: Freezing helps retain vitamin content much more efficiently than canning. *Frozen vegetables are often as nutrient-rich as fresh picked ones.
2) Keep your fruits and veggies cool: Enzymes in food begin to degrade vitamins once the fruit or vegetable is picked. Refrigerate fresh produce (except for potatoes, tomatoes, onions, and bananas) until consumed
3) Minimize reheating of food: Prolonged reheating reduces vitamin content
4) Microwave or steam: More nutrients are retained when there is less contact with water and a shorter cooking time.
5) Cut, trim, or peel fruits and vegetables minimally : just enough to remove inedible or rotten parts: Oxygen breaks down vitamins faster when more surface is exposed. Potato skins and Apple skins have more vitamins and minerals than their inner parts. Outer leaves of lettuce and other greens posses more vitamins and minerals than the inner, tender leaves or stem portion.
6) Store canned foods in a cool place and use them wisely: Canned foods often vary in the amount of nutrients lost, mostly because of differences in storage time and temperature. To obtain the optimal amount of nutritional value from canned goods, serve any liquid packed with the food whenever possible