Minireview: β-Glucan extraction methods from oats
Whole grain oats contain several nutritionally advantageous constituents and many physiological responses have been linked to the intake of oat products. Most of the advantageous constituents are localized in the oat bran, which is a conventional milling product obtained from dehulled or naked oat groats by removing starchy endosperm particles. Oat bran is rich in dietary fibre, especially in water-soluble β-glucan, which is strongly linked to two specific physiological responses: 1) a reduction of serum cholesterol level and 2) a reduction of postprandial glycaemic response. The β-glucan concentration of regular oat brans is usually between 6-12 percent, which is often too low for food products aiming at β-glucan related health claims without jeopardizing the sensory and technical quality of the end product. This review highlights technologies and processes to produce ingredients rich in β-glucan. In addition, a new fractionation technology based on lipid removal and subsequent dry fractionation is presented, yielding 34 percent β-glucan concentration in the product.
Oat dietary fibre is characterized by a high concentration of mixed linked (1→3),(1→4)-β-D-glucan, generally referred as β-glucan (1). This water-soluble dietary fibre component has attracted significant nutritional interest during recent years, as several independent studies have shown that products containing oat β-glucan have a cholesterol-lowering effect (2-4). In addition, oat β-glucan has been reported to attenuate glycaemic response (5). In the U.S.A., the Food and Drug Administration (6, 7) has allowed a heart health claim for products containing oat or barley β-glucan. Based on the positive opinion of European Food Safety Authority (8), EU is expected to approve the health claim related to regular consumption of oat β-glucan and the maintenance of normal blood cholesterol levels.
The β-glucan concentration of whole grain oats is typically in a range of 2 to 8.5 percent and from 6 to 12 percent in oat bran products (5, 9, 10). Even higher β-glucan concentrations are present in products, which are usually referred to as β-glucan or oat bran concentrates. Oat β-glucan is located throughout the starchy endosperm, b ...