Some vitamins are more stable than others. Water soluble vitamins are more unstable than fat soluble vitamins during food processing and storage.
The most unstable vitamins include:
The most stable vitamins include:
PROCESS AFFECTING FOOD NUTRIENT CONTENT:
A variety of things can happen during the growing, harvesting, storage and preparing of food that can affect its nutritional content. Process that expose foods to high levels of heat, light or oxygen cause the greatest nutrient loss.
FERTILIZERS: Most plant crops are produced with the aid of fertilized soils. High use of nitrogen fertilizers tends to reduce Vitamin C content in many fruit and vegetable crops. It does not seem to make any difference to the plant’s nutrient value whether the fertilizer is organic or not
BLANCHING: Before the food is canned or frozen, it is usually heated very quickly with steam or water. The water soluble vitamins, including vitamin C and B complex, are sensitive and easily destroyed by blanching.
CANNING: Food is heated inside the can to kill any dangerous micro-organisms and extend the food’s shelf life. Some type of micro-organisms require severe heat treatment and this may affect the taste and texture of the food. Making it less appealing. Preservatives are generally not needed or used in canned foods. Water soluble vitamins are particularly sensitive to high temperature. Many people believe that canned foods are not as nutritious as their fresh counterparts, but this is not always the case, as fresh food often deteriorates more rapidly than canned foods.
FREEZING: The nutrient value of a food is retained when it is frozen. Any nutrient losses are due to the processing prior to freezing and the cooking once the frozen food is thawed.
DEHYDRATING: Drying out foods such as fruits can reduce the amount of Vitamin C they’re eating, but it can also concentrate other nutrients, particularly fiber in plant foods. Dehydrating food also makes food products more energy dense, which may contribute to weight gain. If a dehydrated food is reconstituted and cooked with water, further nutrients are leached out of the food and lost in the cooking water.
MILLING: Cereals such as wheat can be ground to remove the fibrous husks. The husks contain most of the plant’s dietary fiber, B-Group vitamins, phytochemicals and some minerals. That is why products such as white bread are less nutritious than whole meal varieties, even if they have been artificially fortified with some of the nutrients that were lost after milling.