Nutritional Composition of Grain and Seed Proteins

*Adeola Abiola Oso and Anofi Omotayo Ashafa*

#### **Abstract**

Grains including wheat, brown rice, millet, oat, and seeds from crops such as pumpkins, almonds, cashew, peas are important staple foods in many parts of the world. Grains and seeds contain proteins and bioactive peptides classified as nutraceuticals. Proteins and peptides are essential components in man's diet because they provide the raw materials needed for protein biosynthesis and are also a good source of energy. Incorporating grains and seeds into the human diet provide nutritional, functional health benefits, reducing contracting some chronic diseases. They avail the body with a balanced nutrient profile such as carbohydrate, fatty-acid, fibre, B vitamins, minerals and protein. The quest at exploring staples for their functional and health benefits, as well as reducing risks to diseases, has resulted in the investigation of the potentials of grains and seeds, especially the underutilised ones (African yam bean, pigeon pea, Bambara groundnut etc.) for consumption and as an alternative therapy against diseases. This chapter discusses grains and seeds as sources of nutrition protagonist, their nutritive property, health benefits, and the pharmacological properties of bioactive peptides in grains and seeds. However, some under-utilised grain and seed proteins would also be explored for their nutritive potentials.

**Keywords:** bioactive peptides, grain, nutraceutical, protein biosynthesis, and seed

### **1. Introduction**

Seventy-five per cent of the people in developing countries live in rural areas, especially sub-Saharan Africa and southern Asia [1, 2]. Despite intensification associated with the green revolution and expansion in agricultural production, many people remain food insecure, suffering from hidden hunger caused by protein deficiencies [3, 4]. The malnutrition problems could be addressed by exploring plant proteins as an economical and sustainable source of protein for a wholesome diet [5]. Grains and seeds are plant products containing proteins and peptides that can be classified as nutraceuticals. Nutraceuticals are any functional food extract with health and medical benefits, particularly to humans [6]. Grain and seed proteins are critical components in food systems that help combat protein-calorie malnutrition in developing countries [7]. They are referred to as the poor man's meat of the vast majority who cannot afford fish, meat and dairy since they provide nutritionally balanced protein diets [8]. Grain and seed proteins create windows of opportunities by reducing poverty level, improvement in nutrition and health status, improvement in food security and sustenance of natural resource base among

the resource-poor farming communities. Grain and seed proteins are a staple source of calories, carbohydrate, minerals, B-vitamins and proteins.

Proteins from grains and seeds are probable sources of a wide range of bioactive peptides that positively impact man's health [9]. Grain and seed high in protein include wheat, brown rice, millet, cornmeal, oatmeal, amaranth, buckwheat, couscous, teff, quinoa, whole-wheat pasta, flaxseeds, chia seeds, pumpkin seeds, peanuts, walnuts, almonds, sunflower seeds, cashews, date, kiwi, and cumin. However, the cultivation and utilization of some locally grown grain and seed proteins with potential food and nutrition security are grossly underexploited [10]. The locally underexploited grain and seed are tied to the cultural ancestry of their places of origin, acclimate to precise agroecological areas, and perform well in traditional farming systems with little or no external inputs [11, 12]. The new generation of farmers, especially in sub-Sahara Africa, have relegated the locally grown grain and seeds as crops of the older folks. Thus, the traditional farming system is exposed to genetic erosion of the germplasm of the traditional underutilized crops [13]. The formulation of production expansion strategies of the locally grown grain and seed proteins would be a step in the right direction for sustainable intensification and diversification in the global food base.

#### **2. Grain**

Grain is a member of the Poaceae family with approximately 780 genera and 12,000 species [14]. The family Poaceae is the fifth-largest plant family following the Asteraceae, Orchidaceae, Fabaceae, and Rubiaceae [15]. They possess a wide range of tolerance for climatic fluctuations; thus, they survive in almost all kinds of ecological niche [16]. The Poaceae are the most economically important plant family, providing staple foods from domesticated cereal crops [17] and feed for


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**seed**

important food additives.

*Nutritional Composition of Grain and Seed Proteins DOI: http://dx.doi.org/10.5772/intechopen.97878*

grasses from the family of Poaceae.

the popular grains is shown in **Table 1**.

**3. Seed**

meat-producing animals. A grain is the tiny edible fruit of the plant, usually hard on the outside harvested from grassy crops. Grains are either referred to as true cereal grains or pseudo-cereal grains. The true cereal grains are the edible seeds of specific

Examples of true grain cereals include wheat, oat, maize, barley, rye, sorghum, and millet. The pseudo-cereal grains are not really grains but seeds from different plant species with a nutritional composition similar to the true grains. Amaranth, buckwheat, and quinoa are examples of pseudo-cereal grains. Grain foods are consumed for their higher fibre content as well as for dietary proteins. The three critical parts of grains include; the bran (outermost layer), the germ (embryo), and the endosperm [18]. The bran is made up of fibre and B vitamins; the germ contains oils, vitamins, proteins, minerals, and antioxidants; and carbohydrates and protein are found in the endosperm. Grain foods are categorized either as whole or refined grains. Whole grains have been minimally processed and still contain the bran, germ, and endosperm [19]. Whole-grain foods are higher in B vitamins and fibre. Consumption of a whole-grain diet is associated with a lower risk of several diseases [20]. Refined grains are processed grains containing only the endosperm [21]. Refined grain foods are lower in B vitamins and fibre but higher in foliate. However, vitamins and minerals (specifically iron and folic acid) lost during processing are added to the refined grain to make it healthier [22]. The protein content in most of

A *seed* is an embryonic plant covered in a seed coat formed from the ripened ovule of the plant after fertilization. The seed comprises three major parts - the embryo, seed coat, and the endosperm [23]. The embryo is the most crucial part because the various tissues that make up the plant are developed from its cells. The endosperm contains the nutrients while the seed coat protects the embryo. The plant seed is not only an organ of propagation and dispersal but also a significant source of dietary protein [24]. The seed contains the complete profile of amino acids needed for the formation of complete and digestible protein. The amount of protein present in seeds vary from ̴ 10% (in cereals) to ̴ 40% (in particular legumes and oilseeds) of the dry weight. Although the individual protein in seeds either play structural or metabolic roles, seed proteins generally provide a store of amino acids available during germination and seedling growth [25]. Seeds also contain vitamins A, B, C, and E and the minerals calcium, magnesium, potassium, zinc, iron, selenium and manganese. Seeds are edible, and they form the primary source of the majority of human calories when consumed as legumes, cereals and nuts [26]. *Plant seeds* are a versatile food, used to flavour a stew, as a garnish, in salads and soups. Seeds are a low gastro-intestine (GI) food and help to keep blood sugar level stable. Seeds provide many beverages and spices, cooking oils and some

**4. Nutritional properties and health benefits of some selected grain and** 

The nutritional property of food is the measure of a well-balanced ratio of the essential nutrients, carbohydrates, fat, proteins, minerals, and vitamins with the nutrient requirements of the consumer. A healthy diet supports average growth, development and ageing. It also helps to maintain a healthy body weight and

**Table 1.**

*The protein content of some grains.*

meat-producing animals. A grain is the tiny edible fruit of the plant, usually hard on the outside harvested from grassy crops. Grains are either referred to as true cereal grains or pseudo-cereal grains. The true cereal grains are the edible seeds of specific grasses from the family of Poaceae.

Examples of true grain cereals include wheat, oat, maize, barley, rye, sorghum, and millet. The pseudo-cereal grains are not really grains but seeds from different plant species with a nutritional composition similar to the true grains. Amaranth, buckwheat, and quinoa are examples of pseudo-cereal grains. Grain foods are consumed for their higher fibre content as well as for dietary proteins. The three critical parts of grains include; the bran (outermost layer), the germ (embryo), and the endosperm [18]. The bran is made up of fibre and B vitamins; the germ contains oils, vitamins, proteins, minerals, and antioxidants; and carbohydrates and protein are found in the endosperm. Grain foods are categorized either as whole or refined grains. Whole grains have been minimally processed and still contain the bran, germ, and endosperm [19]. Whole-grain foods are higher in B vitamins and fibre. Consumption of a whole-grain diet is associated with a lower risk of several diseases [20]. Refined grains are processed grains containing only the endosperm [21]. Refined grain foods are lower in B vitamins and fibre but higher in foliate. However, vitamins and minerals (specifically iron and folic acid) lost during processing are added to the refined grain to make it healthier [22]. The protein content in most of the popular grains is shown in **Table 1**.
