New interest in barley raises technical issues

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Barley has great potential to regain its former popularity in food, says a new review, but there are some knowledge gaps about its functional properties for processing and product development.

Barley has a history of domestication dating back to around 10,000 years, but over time has come to be used less as a food and more for as a grain for animal feed, malting and brewing. In recent times, only about 2 per cent of the annual crop has been used directly for food. A raft of recent research has investigated barley on a health platform - particularly the role of barley beta glucan in lowering blood cholesterol levels, and the association between wholegrains and increased satiety. But according to the authors of a new review from Washington State University, food developers wishing to exploit these attributes in a promising new market face a number of technical challenges. Although it has remained an important staple in some countries, in the west barley largely fell out of favour in the 19th​ and 20th​ centuries as food products from wheat were seen to deliver better mouth feel and product quality. This meant that while great strides were made in optimising wheat processing and product development, barley has been somewhat left behind. "The quality requirements of barley for food use have not been well established, making it difficult for food manufacturers to select raw materials suitable for use in specific food products,"​ wrote Byung-Kee Baik and Steven Ullrich in the review, which has been accepted for publication in the Journal of Cereal Science​. Not only have there been few attempts to breed varieties that have attributes appropriate for food, but also, because barley is a genetically diverse cereal, the authors say it may be a challenge for processors to choose a barley grain that is suitable for their planned use since there are few guidelines out there. The review covers basic and general information on barley food use, and the processing of barley grain for food use. It also takes a more in-depth look at some other aspects, such as kernel hardness and colour, grain starch and beta-glucan content. Grain hardness​The authors say that our understanding of barley grain hardness and the factors that make barley hard is limited, since there has not been much need to consider this in the past. Now, however, more intensive and complex processing may be needed for its use in new food products. "It is crucial to produce and supply barley of appropriate grain hardness,"​ they wrote. They set out certain questions that need to be answered, in order for barley with the right hardness to be developed, such as the role of genotype and environment in grain hardness, the role of cell wall and endosperm cell structures, and the significance of the quantities and composition of the various constituents (starch, proteins, beta-glucans). Colour​Baik and Ullrich note that, while barley is generally bright light-yellow or off-white in colour, it can be discoloured by fungal infections or abnormal phenol metabiolism. Discoloured barley is also wont to develop unpleasant flavours and odours when malted. The best way to prevent discolouration is through the development of tolerant barley varieties, they say. While the usual light yellow grain is generally preferred for malting, brewing and food uses, there can be some wild variations in hue depending on levels of anthocyanins. Some grains can be purple, violet, blue and even black. Although these may be produced in small amounts, anthocyanin-coloured gtains are used for speciality foods because of their attractive appearance, and are also garnering interest for functional foods because of their high antioxidant content. The review authors spelled out the importance of colour in consumer acceptance. "The colour and appearance serve as indicators of the wholesomeness and quality of food products, and are the first factors considered by consumers before purchase and consumption."Consumers prefer a specific colour for each food product. If the food product loses or deviates from the expected colour, it loses favour regardless of other quality characteristics."Beta-glucan​The physical and compositional properties of barley grain have an effect on processing properties and the quality of food products from or using pearled barley or barley flour. Barley grains typically contain between 2 and 10 per cent beta-glucan. The authors note that whole beta-glucan is desirable for its health benefits, "little is known about the functional properties of beta-glucan for making food products".​ What is more, they say there has been little effort, so far, to develop quality requirements for food uses. SourceJournal of Cereal Science​ (online ahead of print) DOI: 10:1016/j/jcs/2008/02/002"Barley for food: Characteristics, improvement, and renewed interest"​Authors: Baik BK, Ullrich SE

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