1.1 INTRODUCTION
The cereal grains are important food commodities for consumption and income generation. These are main energy sources for majority of the world population. Barley (Hordeum vulgare) is a historic cereal grain, which is mainly cultivated for animal feed. After wheat, maize, and rice crops, barley is the world’s fourth largest grain crop in terms of quantity produced. As human food, it is also consumed as meal and is used for brewing and malting for manufacture of beer. In regions of extreme climate like Ethiopia, Morocco, and Himalayas, barley is principal source of food. It is also used for bread making [36].
Archeological evidence suggests that barley was domesticated around 8000 BC in the Himalayan region, Morocco, and Ethiopia. Barley is hardier than wheat and can inherently adapt itself admirably well under limited inputs, marginal lands, and dry climates. It is more suited to cooler and drier climates. Its growing period is about 5 months in the plains and lasts for about 6–7 months in high hills. It is an important cereal in the world with an annual production of around 148 million metric tons, ranking next to maize, wheat, and rice. Russia is the leading producer of barley with a production of 20.6 million metric tons. It is grown widely in several European countries and Canada. In India, it is an important winter season (Rabi) cereal crop grown in Punjab, Rajasthan, Madhya Pradesh, eastern Uttar Pradesh, and Bihar. It occupies an area of 47 million ha. Annual production of barley in India was 1.75 million metric tons in 2017 [22].
This chapter focuses on the nutritional and bioactive components of barley and its health benefits. The chapter also provides an insight into the traditional and new functional food products from barley.
1.3 NUTRITIONAL COMPOSITION OF BARLEY
Barley has gained increased attention among researchers and consumers due to its nutritional composition. As for other cereals, the major components of barley grain include carbohydrates (e.g., starch and fiber), high-quality protein, lipids, and minerals (Table 1.1), which vary with the type of barley. For instance, the hull-less varieties of barley have higher content of protein, starch, and β-glucan compared to hulled barley. Barley is a good source of soluble fiber and β-glucan [14].
Barley grain has a high content of carbohydrates with an average of 61.29 g carbohydrates per 100 g of edible portion of grain (Table 1.1). It has 60%–64% of starch, 1%–2% sucrose, and 1% of sugars in different forms. The starch in barley is easily digestible and is a source of energy. Out of total starch, the amylose content is 20%–30%. In high-amylose barley, amylose content can be as high as 45% [55]. Glacier barley has nearly 42% of amylose content. In barley, carbohydrates occur both in soluble and insoluble forms. It contains higher amount of insoluble fiber. Among cereals and millet groups, barley has the highest content of total fiber. It contains 8%–10% of insoluble fiber and 1%–1.5% of water-soluble polysaccharides [41]. Milled barley contains about 25.12% total dietary fiber and 6.72% of β-glucan, which is higher than the dehulled barley [39]. β-Glucan is a soluble fiber and its content in barley is highest among cereal grains. The amount of protein and water-soluble polysaccharides in barley is proportional to the content of β-glucan in grains of barley [31].
The protein content of barley is comparable to other cereals, such as wheat. The whole grain contains 8%–20% protein. The protein quality is good with amino acids, such as, lysine (an essential amino acid), which is deficient in wheat [19]. Barley proteins may be classified as storage and nonstorage types. Storage proteins include prolamins (hordeins) and globulins (as per Osborne protein classification) [50]. In barley, range of protein content is nearly the same as present in pearl millet and wheat, but higher than ragi, rice, and maize. The total content of globulins and albumins protein is about 3.5%, whereas glutelins and hordeins content is 3%–4% each [41].
Barley contains 2%–3% lipids, which are mostly concentrated in the germ. The major fatty acids in barley are [13] palmitic (16:0), linoleic (18:2), and oleic (18:1).
Barley is a good source of niacin (2.84 mg/100 g), thiamine (36 mg/100 g), and riboflavin (0.18 mg/100 g). The amount of these in barley is even more than milk. Compared to other cereals and millets, it contains moderate amount of biotin (2.38 μg/100 g) but a lower amount of panthothenic acid (0.14 mg/100 g). Barley is a poor source of vitamins C and D (Table 1.1).
On average, barley contains 2% of minerals, which include magnesium, manganese, potassium, phosphorus, selenium, zinc, and sodium (Table 1.1).
