Cereals and Cereal-Based Foods

Functional Benefits and Technological Advances for Nutrition and Healthcare

Megh R. Goyal, Kamaljit Kaur, Jaspreet Kaur, Megh R. Goyal, Kamaljit Kaur, Jaspreet Kaur

• Editorial: Apple Academic Press
• Año: 2021
• ISBN:
  9781000164350
• Edición: 1
• Categoría: Médecine
• Categoría: Médecine alternative et complémentaire

This book volume sheds light on the health benefits of selected cereal grains, processing technologies of cereals, specific roles of bioactive compounds of cereals in chronic disease prevention, and traditional and latest technologies to improve the functional benefits of cereal-based products. It presents a thorough review of the functional components of some lesser known or forgotten cereals and their role in maintaining good health.

With advancements in cereal science and technology, new methods of processing have emerged that help to preserve or even enhance the health-benefitting properties of cereal grains. Further, plant breeding and biotechnology have contributed greatly in improving nutritional quality and functionality of these grains. This book provides comprehensive information on the simple as well as advanced methodologies for enhancing the properties of cereals that benefit human health. Some new approaches such as bio-fortification and extraction of bioactives from cereals are also included in the text.

PART I
Functional Benefits of Cereal Grains

CHAPTER 1

BARLEY-BASED FUNCTIONAL FOODS

PRABHJOT KAUR, JASPREET KAUR, KAMALJIT KAUR, and JYOTI BOHRA

ABSTRACT

Barley (Hordeum vulgare) is nutritious, and it is rich in carbohydrates, good quality proteins, fats, vitamins, and minerals. It is particularly a good source of soluble fiber, that is, β-glucan, which on regular consumption has several positive effects on human health. Barley is used to prepare several products, such as, barley bread, cookies, and beverages. It can be fermented and malted. Barley malt is used in beer production. Barley grain has lost its importance in recent years due to consumer preference for other cereals, such as wheat and rice. Recently, however, barley is fast emerging as a base material for health foods due to increased awareness of the nutritional and health benefits of this grain.

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.

1.2 TYPES OF BARLEY

Barley can be classified on the basis of number of rows of grains on the head [9]:

• Barley with two rows of grains on the head is called two-row barley.
• Barley with four rows is called four-row barley.
• Barley with six rows is called six-row barley.

Six-row type is the most cultivated barley and two-row barley is the wild variety. The protein content of six-row barley is higher than two-row barley. This makes six-row barley more suitable for animal feeding. Malt barley has lower protein. Another way of classification of barley is by describing its beards (awns) covering the kernels. Barley can also be classified based on hull as hulless (naked) or hulled; based on usage as feed or malt type; based on seed color as white, yellow, blue, and colorless; and based on height. Following is the list of some varieties of barley:

• (Normal) hooded.
• Awnless or awnletted in central rows and lateral rows.
• Elevated hooded.
• Elevated hoods in central row, and awnless in lateral rows.
• Long awned.
• Long awned in central row, awnletted or awnless in lateral rows.
• Short awned.
• Short awned in central row, awnletted or awnless in lateral rows.
• Subjacent hooded.

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].

TABLE 1.1 Chemical Composition (Per 100 g Edible Portion) of Barley Grain

Component	Unit	Value	Component	Unit	Value
Moisture	g	9.77	Water-soluble vitamins
Protein	g	10.94	Thiamine	mg	0.36
Ash	g	1.06	Riboflavin	mg	0.18
Total fat	g	1.30	Niacin	mg	2.84
Carbohydrate	g	61.29	Pantothenic acid	mg	0.14
Energy	kJ	1321	Biotin	μg	2.38
Dietary fiber			Total folates	μg	31.58
Total	g	15.64	Carotenoids
Insoluble	g	9.98	Lutein	μg	5.39
Soluble	g	5.66	Zeaxanthin	μg	1.90
Minerals			Total carotenoids	μg	69.87
Magnesium	mg	48.97	Minerals
Manganese	mg	1.24	Selenium	μg	18.61
Phosphorus	mg	178	Sodium	mg	7.56
Potassium	mg	268	Zinc	mg	1.50

Source: Indian food composition tables, 2017 [40].

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).

1.4 BIOACTIVE COMPONENTS OF BARLEY

1.4.1 β-GLUCAN

Dietary fiber can be classified into two groups according to their water solubility: insoluble and soluble. The β-glucan, a soluble fiber in cereals, is a branched polysaccharide having glycosidic bond at β-(1-3 and 1-4) of glucopyranose units. Barley contains the highest level of β-glucan (2%–10%) among other cereal grains. β-Glucan is present in endosperm, which encloses matrix protein, starch, and lipids reserves of grain. The cell walls of endosperm cells are high in β-glucan. Endosperm cell walls in barley contain approximately 75% β-glucans, 20% protein, and arabinoxylans [24, 25, 30]. β-Glucan influences the functional and nutritional properties of food. Soluble dietary fibers are known for their hypocholestrolemic effects. β-Glucans in barley grains have important role in controlling diabetes.

1.4.2 PHENOLIC ACIDS

The major phenolic acids in barle...