Louise J. Cleary - Department of Biological Sciences, University of Plymouth

Summary

Barley is the second most important crop in the UK, however in recent years there has been a rapid decline in its ex-farm price, with the majority of the crop used for animal feed products, attracting no premium. The high beta-glucan content of barley is viewed as deleterious to both the malting (1-2) and feed sectors (3-5). As such, the value of barley crops with high levels of beta-glucan are severely reduced, and growers may encounter difficulty in selling such crops at cost effective prices. However, in recent years there has been increasing interest in the health benefits of cereals (namely oats and barley) containing beta-glucan and therefore potential exists to market them as ingredients in nutraceutical foods.

Background and scientific justification

Beta-glucan is a complex carbohydrate classified as a dietary fibre. The high viscosity of beta-glucan poses problems for the malting and brewing industry, where it is responsible for reducing the rate of wort filtration, recovery of malt extract and haze formation in beer (1-2). In the feed sector beta-glucan reduces feed digestibility and metabolisable energy as well as increasing the occurrence of sticky droppings (3-5). However, beta-glucan has been illustrated to have therapeutic and preventative nutritional properties in humans. The most widely known nutritional benefits of beta-glucans (from both oat and barley grains) are the attenuation of blood glucose and insulin (6-7), and hypocholestrolemic properties (8-9). Other documented effects of beta-glucan include, delayed gastric emptying (10), prolonged satiety (11), relief of constipation (12) and possible prevention of colorectal cancer (13).

In the USA, the FDA (14) has permitted health claims to be made that beta-glucan from oat may reduce the risk of heart disease. The functional similarities between oat and barley beta-glucan allows for the possibility of barley beta-glucan being awarded a similar health statement, which in turn has the potential to add value to the UK barley crop.

Cereal products, namely bread and pasta, are ideal foods for enrichment with barley beta-glucan, due to their popularity and frequency of consumption. However quality specifications for such products are high and changes to formulation can result in negative sensory attributes and reduced consumer acceptance. Therefore, a need exists to investigate how feed barley crops may be used as a resource to refine beta-glucan for use in pasta or bread production, and to research how beta-glucan may be utilised in cereal foods with minimal changes to product quality. An additional challenge, is the preservation of beta-glucan molecular weight during milling, isolation and food processing. Such conditions may cause mechanical and enzymic degradation of beta-glucan and a subsequent loss of nutritional function.

Overall project aim

To improve the utilisation of beta-glucan rich barley grains by creating a novel human food market.

Specific project objectives

1. Isolate and characterise barley beta-glucan fractions from beta-glucan rich barley varieties.
2. Investigate the effects of barley beta-glucan inclusion in model cereal foods.
3. Determine the nutritional benefit of barley beta-glucan inclusion in food material.
4. Appraise the effect of food processing on the degradation of beta-glucan.
5. Assess the market cost benefits and acceptance of such products in the food industry.

Outcomes

The output of this project will include preliminary modelling of barley beta-glucan material in cereal foods and optimisation of this new added value product from grain otherwise suitable for animal feed only. Outcomes of the project are expected to contribute to the generation of a new market for undervalued cereals, thus adding value to the farming/agri-food sector.