Submitted to: Lipids Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/2/2004
Publication Date: 12/10/2004
Citation: Lampi, A., Moreau, R.A., Piironen, V., Hicks, K.B. 2004. Pearling barley and rye to produce phytosterol-rich fractions. Lipids, V.39, NO. 8.P.783-787. Interpretive Summary: During the last five years, several phytosterol (plant sterol(PS)) enriched functional foods have been approved by the FDA. These foods have been well received by US consumers because of the convincing clinical evidence of the ability of PS to lower serum cholesterol levels. Cereals and whole grains are sources of PS in human diets but the levels of these compounds in whole grains are so low that one would have to consume large quantities of grains (and calories) in order to ingest enough PS to significantly reduce cholesterol levels. We have found that the PS in grains are concentrated in the outer layers of the kernels. In this study, we have used 'pearling', an industrial process to remove outer layers of grains, to remove these outer, PS- and fiber-enriched layers of hulless barley and rye. The results of these studies show that the layers (fines) removed from the kernels contained 2 to 3 times as much PS per unit weight as did the whole kernels. Pearling fines could thus potentially be used as a feedstock from which to extract plant sterols or as a grain processing fraction that could be added as a low calorie, 'health promoting' ingredient in foods to increase their levels of PS and fiber.
Technical Abstract: Due to the positive health effects of phytosterols, phytosterol-enriched foods and foods containing elevated levels of natural phytosterols are being developed. Phytosterol contents in cereals are moderate, while their levels in the outer layers of the kernels are high. In this study, pearling of hulless barley and rye was investigated as a potential process to make fractions with higher levels of phytosterols. The grains were pearled with a laboratory scale pearler to produced pearling fines and pearled grains. Lipids were extracted by accelerated solvent extraction, and non polar lipids were analyzed by normal phase HPLC with evaporative light scattering and UV detectors. Total sterol analyses were also performed by GC. After a 90 second pearling, the amounts of pearling dusts from hulless barley and rye were 14.6% and 20.1%, respectively. During pearling, higher levels of phytosterols and other lipids were fractionated into the fines. Contents of free sterols and sterols esterified with fatty acids were at least doubled in the fines in comparison to the whole grains. Pearling fines of hulless barley and rye contained > 2 mg/g phytosterol compounds which makes them a good source of cereal phytosterols and thus valuable raw materials for health promoting foods.