Tocopherols in wheat and rye : a review of research within the subject

Abstract: This thesis focuses on tocols or vitamin E found in wheat and rye. Content and structure of tocols, the effects of some types of processing and their health benefits are discussed. The two most common tocols in wheat and rye are tocopherols and tocotrienols. α-Tocopherol has the highest vitamin E activity, while tocotrienols has better antioxidant properties. There are four kinds of tocopherols and tocotrienols, α, β, γ and δ, which have different vitamin activity and antioxidant function. The most abundant tocol in com-mon wheat, einkorn, durum wheat and spelt wheat (Triticum aestivum, Trit-icum monococcum, Triticum turgidum and Triticum spelta) is β-tocotrienol. Almost only α- and β-vitamers is the forms present in wheat. The most abundant tocol in rye (Secale cereale) is α-tocotrienol, but it varies among varieties. Only α- and β-vitamers are present also in rye. In general tocotri-enols are more abundant than tocopherols in both wheat and rye. Tocopher-ols are most abundant in the germ and tocotrienols are most abundant in the bran. They are labile in the presence of oxygen and heat, mainly because of their ability to act as antioxidants. Baking has been shown to cause moder-ate losses of tocols. Malting has no significant effect on tocol content. Mill-ing is a process which separates the bran, germ, hull and endosperm into different fractions. The tocopherols are found mostly in the germ fraction and tocotrienols in the bran fraction. Steaming treatment has been shown to cause a migration of tocotrienols from the bran to the endosperm. Tocols have been shown to be beneficial for the health, for example they can re-duce the level of blood cholesterol which is good for the prevention of heart disease. They also have effect in the prevention of neurodegeneration and of some type of cancers.