Cereal B-Glucans: The Impact of Processing and How It Affects Physiological Responses

Abstract

Cereal β-glucans are dietary fibres primarily found in oats and barley, and have several positive effects on health, including lowering the postprandial glucose response and the improvement of blood cholesterol levels. Cereal β-glucans have a specific combination of β-(1→4) and β-(1→3) linkages into linear long-chain polysaccharides of high molecular weight. Due to their particular structure, cereal β-glucans generate viscosity within the intestinal tract, which is thought to be the main mechanism of action responsible for their positive health effects. However, cereal grains are rarely consumed raw; at least one cooking step is generally required before they can be safely eaten. Cooking and processing methods more generally will modify the physicochemical characteristics of β-glucans, such as molecular weight, extractability and the resulting viscosity. Therefore, the health impact of β-glucans will depend not only on the dose administered, but also on the ways they are processed or converted into food products. This review aims at summarizing the different parameters that can affect β-glucans efficacy to improve glucose and lipid metabolism in humans.

Dietary Fibre from Whole Grains and Their Benefits on Metabolic Health

“…The higher viscosity also slows the gastric emptying process down and reduces the rate of starch digestion (and associated mono- and disaccharide production) and, hence, causes a delay in glucose absorption [ 114 ]. The slower digestion rate can also be the result of the formation of a ‘thick layer’ around the food bolus, that reduces the access digestive enzymes have to the inner part of the food bolus and hinders contact with absorbing surfaces in the gastrointestinal tract [ 115 , 116 ]. Even though SDF are considered to display anti-diabetic effects, it has been found that IDF are more potent in reducing the risk of type 2 diabetes [ 117 , 118 ].…”

Impact of processing degree on fermentation profile and chemopreventive effects of oat and waxy barley in LT97 colon adenoma cells

“…But, there is no sufficient information available on how processing, such as flaking, affects the chemopreventive effects of oat and barley products. The effects of processing on physicochemical properties such as viscosity and the resulting impact on physiological effects such as cholesterol and glycaemic response-lowering capacity have been extensively studied for different types of oat and barley products and in different types of studies [14][15][16][17][18][19][20]. For example, flaking involves heat-moisture treatments, which modify the physicochemical characteristics of β-glucan such as molecular weight and viscosity [21].…”

Low Molecular Weight Barley β-Glucan Affects Glucose and Lipid Metabolism by Prebiotic Effects

“…Barley and oats are rich in β-glucan, which has several positive effects on inhibiting a postprandial glucose rise [ 1 , 2 , 3 ] and improvement in serum cholesterol concentrations [ 4 , 5 , 6 , 7 , 8 ]. Barley and oat β-glucans have β-1,3 and β-1,4 glycosidic polysaccharides with high molecular weight [ 9 , 10 ]. It is generally recognized that β-glucans in barley and oats with higher molecular weights are essential for a reduction in postprandial blood glucose rise and incremental area under the blood concentration curve (IAUC) [ 11 , 12 , 13 ].…”