Year: 2012
Type: dissertation
Abstract: Phytosterols are plant-derived bioactive compounds known for their serum cholesterol-lowering ability and other health benefits. Phytosterols may occur as free sterols or various conjugates, e.g. ferulic acid esters. Cereals are an important source of natural phytosterols and sterol conjugates. However, the variation in occurrence and distribution of these compounds in cereal grains has not been adequately studied. As a part of the EU FP6 project HEALTHGRAIN, the effects of genotype, environment and dry fractionation on phytosterol and steryl ferulate contents in wheat kernels were studied. Wheat genotypes were grown at one location in Hungary over three consecutive years (2005 to 2007) and at three additional locations in Europe (Poland, France and the United Kingdom) in 2007. In 2005, 175 wheat lines were included in the diversity screen trial, and selected lines were further studied for environmental variation, focusing on bread wheat. Variation within wheat grains was studied by analysing wheat and bran fractions produced by novel and conventional dry fractionation processes. All genotypes and fractions were analysed for phytosterols using GC-FID and selected ones for steryl ferulates using HPLC-UV. The contents and compositions of sterol compounds in wheat were significantly affected by the genetic factors and growing location, whereas no considerable year-to-year variation was observed. The highest phytosterol contents were observed in ancient einkorn wheat and durum wheat genotypes and the lowest in bread wheat lines. Bread wheat contained 670 - 959 µg/g DM phytosterols, of which 7 - 9% occurred as steryl ferulate conjugates (79 - 123 µg/g DM), when grown at a single location during one year. Within various environments, the highest levels of sterol compounds were observed in genotypes cultivated in Hungary, and the lowest in those cultivated in the UK and France. Sitosterol was the main sterol species and the widest variation was observed in the stanol contents. Stanol species were the main compounds in the steryl ferulate fraction. Small kernels with a high bran content contained higher levels of sterol compounds than large ones. The contents and compositions of wheat fractions varied substantially, with the total contents of phytosterols and steryl ferulates ranging 6- and 120-fold, respectively. Phytosterols and steryl ferulates were concentrated in the bran. Within the bran layers, phytosterols were accumulated in the intracellular contents of the aleurone layer and intermediate layers, whereas steryl ferulates accumulated in the intermediate layers. Knowledge of the natural variation of phytosterol compounds in wheat enables the selection of wheat varieties and fractions with high and stable phytochemical content. Exploitation of such wheat grains or fractions in cereal foods would increase the intake of bioactive compounds and enhance public well-being and health in a natural way.
Source: Työväentutkimus Vuosikirja
Author: Tanja Nurmi
Language: English
Subfield: Nutrition and Dietetics
Field: Nursing
Domain: Health Sciences
SDG: Zero hunger
Open Access status: green
OpenAlex ID: W1606687869