Bách khoa toàn thư - Dinh dưỡng và sức khỏe tốt - Vần W | W walnut Juglans spp. A popular commercial nut with a hard deeply furrowed shell surrounding the meat. The English walnut J. regia is the most important commercial walnut. It is native to southeastern Europe and western Asia and probably originated in Persia. The black walnut J. nigra is native to the Mississippi Valley and Appalachians of the United States there is limited commercial production of black walnuts however. The United States produces over half the world crop most of it comes from California. About 40 percent of the walnut crop is marketed in shells the remainder is processed. Machine-shelled nuts may be blanched to remove the inner skins which give walnuts their somewhat bitter aftertaste. They may be blanched to even out the color. Walnuts contain a large percentage of oil with 66 percent of it as polyunsaturated fatty acids. It is a good source of alpha linolenic acid an omega-3 fatty acid essential to the diet. Cholesterol-lowering diets in which meat and dairy products are substituted by walnuts may lower blood cholesterol levels because of their polyunsaturated fat. Shelled nuts are subject to rancidity they should be vacuum-packed or stored in sealed plastic bags in the freezer. On the other hand whole walnuts can be stored for months in a cool environment. If antioxidants are added to extend shelf life they are listed on the food label. Walnuts are used in baking and confections. The nutrient content of 1 cup 120 g of chopped English walnuts is 770 calories protein g carbohydrate 22 g fiber g fat g iron mg potassium 602 mg thiamine mg riboflavin mg niacin mg. water A clear colorless odorless liquid that is essential for all life forms. Water is the most abundant nutrient in the body. More water is needed daily than any other nutrient because cells contain mainly water. A human embryo represents about 98 percent water an infant s weight is about 75 percent water and water accounts for 50 percent to 65 percent of
