Friday, March 14, 2008

Effect of processing on minerals

Effect of processing on minerals
When food is cooked, processed, or stored, minerals may combine with other food components and may become unavailable for digestion. Also, as with vitamins, natural variations in the raw food products and cooking methods result in variations in the final mineral contents of foods.

Minerals are generally not sensitive to heat during processing, but are susceptible to leaching into the processing or cooking water. More than 50% if the manganese, cobalt, and zinc may be lost during canning of spinach, beans, and tomatoes, if the liquid is not consumed.

Mineral losses during leaching can be minimized by use of a minimum amount of water and use if the cooking water in preparation of the food for consumption, such as in gravies, soups, and sauces. Losses in manganese, iron, copper, phosphorus, zinc, calcium, and manganese during the cooking of pasta may be as great as 86.5 – 100 %. Use of hard water for processing and cooking can result in an increase in the calcium or magnesium content of foods, while use of softened water can result in an increase in the sodium content. Mineral losses may also occur as a result of physical separation from the product during milling of grains, refining of sugar, and processing of legumes or seeds into oils. For example, significant losses of magnesium, zinc, iron, copper, and cobalt have been reported during milling of wheat to flour. However, nutrients can be added back to foods by restoration or fortification. Grain milling has positive nutritive benefits, as well. Phytate and fiber, which are present in the bran portion of the grain, are removed during this process, and they are no longer able to bind to minerals and render them unavailable. Therefore, iron and zinc deficiencies are not common in the U.S, whereas they may occur in populations which subsist on unmilled grains. Minerals are also susceptible to changes in bioavailability due to interactions with other food components. For, examples, oxalates may inhibit calcium bioavailability; while vitamin C enhances iron bioavailability.
Effect of processing on minerals
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