Zinc Cooking and Storage
Since zinc is a water-soluble mineral, substantial losses—about 50%--are possible when cooking with large amounts of water for prolonged periods of time. Browning also reduces the bioavailability of zinc.
Another cooking factor that can affect a food’s zinc content is the type of utensil. The use of clay pots for cooking in some Middle Eastern countries has a detrimental effect because the clay chelates to the zinc in the food and makes it non-absorbable.
Another problem relates to the switch from zinc and iron water pipes to copper water pipes. Since zinc is a water-soluble element and copper and zinc are antagonists, this technique also means less efficient zinc absorption.