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Processing Technologies for Healthy Grains: Introduction

Milica Pojic1 and Uma Tiwari2

1 Institute of Food Technology, University of Novi Sad, Novi Sad, Serbia

2 School of Food Science and Environmental Health, Technological University Dublin, City Campus, Dublin, Ireland

1.1 Healthy Grains: What Are They?

Cereal grains have been a principal part of humans' daily diet, consumed in different forms and/or products, for many years. Cereals are traditionally utilized as a breakfast meal or as a main meal of the day, not only to provide carbohydrates, but also to increase the level of dietary fiber. Nowadays, the increase in awareness of health and demand for healthy products by consumers are becoming a challenge for the food industry to develop new and nutritious cereal products. However, when it comes to nutrition, health, and wellbeing, one might think cereal grains inadequate foodstuffs, considering that they have been attributed as a major contributor to obesity due to their high content of easily digestible carbohydrates. Thus, in the early 2000s a decline in wheat consumption was observed in the USA, attributed to the "low carb" diet craze. Moreover, protein, iron, zinc, and vitamin A deficiencies are observed in developing countries with the highest per capita consumption of refined cereal grains, which are low in micronutrients. On the other hand, a vast number of scientific studies that have been emerging demonstrate protective positive effects of whole grains against cardiovascular disease, cancer, diabetes, obesity, and other chronic noncommunicable diseases, which have resulted in a growing consumption of whole-grain products (Awika 2011). The consumption of gluten (and "gluten-like") proteins from major cereals - wheat (including khorasan and spelt), barley (including malts), rye, and triticale - as well as gluten-containing food additives (in the form of flavoring, stabilizing, or thickening agents) and foods contaminated with gluten-containing products (such as oat) causes gastrointestinal problems and malabsorption syndrome in approximately 0.5-1.0% of the world's population, i.e. those diagnosed with celiac disease (El-Chammas and Danner 2011). Gluten-free diets, although predominantly designed for patients with celiac disease and nonceliac gluten sensitivity, have been gaining increasing popularity in recent years. A growing demand for gluten-free food is not only due to the increasing number of diagnosed patients, but also due to the higher availability of different gluten-free foods in the market (e.g. salty snacks, crackers, fresh bread, pasta, ready-to-eat cereals, baking mixes, cookies, flour, frozen bread/dough, etc.) and due to the advertising campaigns, press coverage and promotion of this type of diet (Newberry et al. 2017). As a result, in the period 2004-2011 the sale of gluten-free products had an annual growth of nearly 28% and in 2012 was close to US$2.6 billion (Asbran 2017; Remes-Troche et al. 2020). Moreover, a survey conducted in 2015 in the US, whose results were published in the report Gluten-Free Foods in the US (5th Edition), showed varying attitudes of the population toward these products. The survey indicated that 36% of respondents consumed gluten-free products for reasons other than gluten sensitivity: 65% because they thought it was healthier, 27% because they thought it helped in weight loss, 7% to reduce inflammation, and 4% to fight depression, whilst only 5.7% of respondents claimed the consumption of gluten-free products due to formal medical conditions (Békés et al. 2017). Therefore, in recent years the utilization of pseudocereals, being gluten-free, has captured consumers' interest and more research is now focused on partial or full utilization with cereals to produce "healthy" grain products. Furthermore, health and wellness retail showed growth in healthy products of 3.3% in Asia and the Pacific and 4.2% in the Middle East and Africa (Mascaraque 2018). Similarly, in Europe, the sales of healthy grain products reached ?12.8 billion in 2018, with a projection for the market value to increase about 6% from the previous year (CBI 2019). Globally, over the last few years an increase in market demand was observed for products perceived as more natural and "healthier" - a product group consisting of organic, "free-from", and naturally "healthy" products (Mascaraque 2018).

1.2 Cereals and Pseudocereals: Production, Nutritional Value, and Utilization

Cereals (monocotyledonous) and pseudocereals (dicotyledonous) are species that are taxonomically not closely related to each other, but share certain characteristics, such as the structure and composition of their kernels, especially in terms of starch and protein content in approximately the same relative proportions. Moreover, they are cultivated, harvested, processed, and used in the same manner as cereals (Rosentrater and Evers 2018).

Although the increasing worldwide demand for pseudocereals in recent years caused their increased production, they are still considered underutilized feedstock. Their significance is increasing due to high-quality allergy-free proteins and large amounts of micronutrients and bioactive compounds, which increases their market price. Although the worldwide interest in pseudocereals is a relatively recent phenomenon, some of the species were cultivated as traditional crops in certain part of the world for centuries (Rosentrater and Evers 2018). Among pseudocereals, amaranth, quinoa, and buckwheat are of the highest commercial potential. On the other hand, traditional cereals are considered major and minor based on the volume of their production and utilization. Wheat, maize, rice, and barley are classified as major cereals, while sorghum, millet, oats, rye, spelt, and primitive and wild wheat species are minor cereals. The differences between major and minor cereals are not only in the quantity of production, but also in the nutritional profile, with higher levels of certain antioxidant substances, which makes minor cereals useful in preventing a wide range of diseases linked with oxidative damage (Akkoc et al. 2019).

According to the Food and Agriculture Organization of the United Nations (FAO) Statistics Database (FAOSTAT), the total production level of cereal crops worldwide significantly increased from the year 2000 to 2018. For example, crop production increased by 80% for wheat, 52% for maize, and 77% for rice, followed by barley, sorghum, millet, oats, and rye. Similarly, FAOSTAT also estimated pseudocereal production of buckwheat decreased slightly, while quinoa production increased over the 18?years to 2018 (Figure 1.1). Additionally, FAOSTAT also showed that production increased by 67% for quinoa, but reported a significant decrease by 30% for buckwheat (FAO 2020). However, due to the growing demand to feed the growing world population, the estimated world buckwheat utilization is expected to increase to 7 million tonnes by 2020 (FAO 2020). They predicted that wheat consumption will increase by 12 million tonnes, while world rice utilization will increase to 514 million tonnes in the year 2019-2020.

The major nutritional components of cereals are starch and nonstarch carbohydrates accounting for approximately 87%, while their protein content ranges from 6 to 15% (Goldberg 2003). The major storage proteins present in the cereal grains are gliadins and glutenins for wheat, oryzenin for rice, zeins for maize, kafirins for sorghum and millet, and hordeins and glutelins for barley, while in oats the main proteins are albumins and globulins (Kulp and Ponte 2000). Pseudocereal grains mainly consist of starch and proteins accounting for 55-75% (Venskutonis and Kraujalis 2013) and 12-16% (Mota et al. 2016), respectively. Unlike true cereals, pseudocereals contain high amounts of essential amino acids, particularly methionine, lysine, arginine, tryptophan, and sulfur-containing amino acids (Schoenlechner et al. 2008). Additionally, cereals and pseudocereals also contain good amounts of bioactive compounds including dietary fibers, phenolic acids, carotenoids, ß-glucans, as well as other phytochemicals such as tocopherols, alkylresorcinols, and flavonoids associated with the prevention of diseases (Akkoc et al. 2019).

Figure 1.1 Global production of cereals and pseudocereals from 2000 to 2018.

Source: FAO (2020).

Based on the healthy and nutritive value of cereal and pseudocereal grains, consumers are attracted toward increasing their consumption of the combination of these grains. For this reason, the popularity of healthy grains in many countries has gained importance and researchers are focused on creating new and innovative products.

1.3 Cereal Byproducts for Food and Feed Utilization

The increased demands for sustainability of food production, climate change, and limited natural resources for food for an increasing global population reaching 10 billion by 2050 impose the need to improve the efficiency of food systems and find alternative food solutions (Fasolin et al. 2019; Galanakis 2020). One of them is valorization of byproducts and side streams, and when it comes to cereals and pseudocereals, they are...