Beer is the most widely consumed low-alcohol beverage, and the annual per capita consumption, which is estimated to be 5.11 million hL/day, is increasing year by year [1]. Consumer interest in this beverage has increased due to unprecedented assortment diversification and the reinvention of craft beer ^[1][2][1,2]. Over the last 40 years, as scientific discoveries have continued to develop, amazing innovations have resulted in advances in the quality of the finished beer product. Innovation in the beer industry often involves the use of new mixtures of cereals and pseudocereals or the rediscovery of old cereals, new hop varieties or hop substitutes, new non-Saccharomyces yeast crops, fruit, vegetables, some spices, and other flavouring compounds to improve/modify the sensory characteristics of the finished product, customize a type of beer or offer a new type of different beer ^[3][4][5][3,4,5]. However, minimal progress has been made in considering raw ingredients, without malting, in the brewing process [6]. Moreover, there are few data in the literature on the use of unconventional raw materials in brewing recipes and on how they influence the physico-chemical and sensory characteristics of the finished product [7].

Conventional raw materials in beer processing include barley or wheat malt, water, hops, and yeast, to which unmalted cereals and possibly enzymatic preparations can be added in various proportions, through a technological process that includes four main operations: malting, mashing/filtration, boiling/hopping and wort pitching/fermentation ^[8][9][10][8,9,10]. Assortment diversification has been influenced by several factors, such as the rebirth of craft beer; increased consumer interest in functional beer; the concern of producers to reduce the costs of obtaining the finished product; development of gluten-free brewing; consumer demand for the unique experience of consuming authentic products of superior quality, with distinctive taste and aroma; and unfavourable conditions for growing barley or wheat in some parts of the world ^{[8][11][12][13]}[8,11,12,13]. These emerging trends and new developments in the beer market have led to the production of distinctive and unconventional products, which, together with traditional beers, make up many beer types (Figure 1).

Producers’ interest in making a non-traditional beer requires technical and empirical knowledge of the composition of the new ingredients in the production recipe, and knowledge of the variables of each stage of the technological process. For example, craft beer is a type of beer in which “anything is possible” in the world. Medicinal plants, herbs, fruits, and spices are a treasure trove of bioactive components, making them valuable antioxidant raw materials for beer [14]. The growing interest in craft beer has contributed to an increase in the number of microbreweries, which in 2017 accounted for 94% of the over 19,000 breweries worldwide [4].

The distribution of craft beer producers worldwide is as follows: the United States and Europe hold 46% and 43%, respectively, followed by Canada (4.5%), South Africa (4.5%), Australia (3%), Japan (1.6%) and New Zealand (1%). In 2019, the United States ranked 1st in the world in the number of small breweries (8386, with over 20,000 brands of craft beer), with the craft beer market accounting for 13.6% of the market share [3].

Craft beer brewers develop their beer with imagination and creativity and produce many different styles and amazing beers. Innovations in science and technology and the promotion of food for health, flavour, and quality are the engines of the development of new types of beer ^{[15][16][17][18]}[15,16,17,18].

The diversification of ingredients in beer production is also imposed by food allergies and intolerances, developing functional beers that aim to combine moderate beer consumption with health benefits [7]. For example, coeliac disease is an incurable disease, and the only therapy is a strict, rigorous, gluten-free diet throughout life [19]. According to Codex Alimentarius and EU Regulation 41/2009 for gluten-free foods, beers with less than 20 mg/kg of gluten can be declared as gluten-free beers [20]. Barley (Hordeum vulgare), wheats (Triticum aestivum, Triticum turgidum ssp. durum, Triticum turgidum ssp. turgidum, Triticum turanicum, hulled wheat: Triticum monococcum, Triticum dicoccum, Triticum spelta), rye (Secale cereale), and oats (Avena sativa, triticale (x Triticosecale) and tritordeum), respectively, can trigger coeliac disease ^{[9][21][22][23]}[9,21,22,23].

In recent years, studies investigating the use of 100% alternative ingredients instead of barley malt in gluten-free beer production have increased [24]. Raw materials that have been investigated for making gluten-free beer include cereals such as sorghum, maize, rice, and millet, and pseudocereals such as buckwheat, amaranth, and quinoa ^{[24][25][26][27]}[24,25,26,27]. However, techniques for producing beer from cereals (other than barley and wheat) and pseudocereals are not yet well developed. A crucial element in gluten-free beers is their taste, which for pseudocereals differs significantly from the taste of traditional beers [8].

Pseudocereals do not belong to the Poaceae family, which includes barley and wheats, so they do not contain gluten-generating proteins and can be used to make gluten-free beer [24]. Amaranth (Amaranthus spp.), buckwheat (Fagopyrum esculentum), and quinoa (Chenopodium quinoa), due to their high starch content, are recommended to be used in obtaining value-added foods ^{[24][28][29][30]}[24,28,29,30]. Pseudocereal malt is characterized by a high content of protein, carbohydrates, fibres, minerals, and vitamins. For example, in Poland, buckwheat, due to its high availability as well as its positive recognition among potential consumers, is used to obtain buckwheat malt, but its quality does not allow obtaining 100% buckwheat malt beer without enzymes addition [31]. Buckwheat is generally one of the most cited pseudocereals in the literature for the manufacture of gluten-free malts and beers, as it has shown excellent results over the years in terms of productivity and chemical composition of the finished product [27]. Buckwheat is also an important source of antioxidant compounds and its use in brewing considerably increases the antioxidant activity of the finished product. Constant consumption of buckwheat can prevent some “diseases of the civilization born of food” (indigestion, obesity, constipation, cholesterol, diabetes, hypertension, etc.) [25]. Buckwheat is currently attracting increasing interest as a raw material for functional foods and pharmaceuticals [1]. Due to its excellent nutritional value and the fact that it does not form gluten, buckwheat can be included in gluten-free diets for patients with gluten intolerance. Buckwheat is considered by specialists, due to its huge nutraceutical properties, to be the “golden culture” of the future ^[2][26][2,26].

Amaranth is a plant that has been a staple for about 8000 years. In America, it was considered a sacred food for the Inca, Mayan, and mainly Aztec civilizations due to its nutritional and therapeutic properties and ritual uses [32]. Today, it is an underused, rediscovered crop that includes species that are grown as leafy vegetables, grains, or ornamental plants, while others are weeds. Amaranth is one of those rare plants whose leaves are eaten as a vegetable, while the seeds are used as cereals, with a multipurpose potential that is worth exploring ^[33][34][35][33,34,35].

Buckwheat and amaranth are two pseudocereals that have multiple uses, including for obtaining of malt and beer, that are grown in different parts of the world.

2. Buckwheat and Amaranth: Raw Materials for Brewing

In the process of obtaining beer, the main raw materials currently used for malting are barley and wheat [36]. The many advantages of using these cereals for brewing are well known, one of which is the high starch/protein ratio [37]. The global trend is to replace barley malt or wheat malt with other unconventional raw materials. This is due to consumers’ desire to add new qualities to the finished product, to improve the brewing process, or to reduce the cost of production ^[38][38]. This review will detail two pseudocereals, buckwheat and amaranth, which are currently used in brewing, emphasizing the characteristics that recommend them in this regard.

2.1. Overview

Buckwheat is an annual crop with a short development cycle, from 30 to 90 days, which is part of the Polygonaceae family, the Fagopyrum genus comprising 30 species ^[39][40][41][39,40,41]. Buckwheat has similar characteristics to cereals such as barley or wheat in terms of chemical composition and edibility, but as it does not belong to the family Poaceae is a pseudocereal with differences in grain structure ^[27][42][27,42]. Barley and wheat are monocotyledonous plants, while buckwheat is a dicotyledonous plant. This implies that the triangular buckwheat fruits, similar to those of the beech, have the embryo with two S-shaped cotyledons instead of a cotyledon, and the core reserve compounds are located differently (Figure 2) ^[42][43][44][42,43,44]. Buckwheat is not related to wheat, and its name is probably related to its triangular seeds and the fact that it has similar uses to wheat [45].

Figure 2. Plant, flowers, and seeds of buckwheat.

Buckwheat has been grown for centuries for its grains, but also its leaves. However, its cultivation has been neglected during the 21st century due to the increased focus on the development of high-yielding varieties of other cereals, such as rice, wheat, and maize, which has led to a significant decrease in the cultivated area ^[40][41][40,41]. Global buckwheat production has steadily increased, reaching about 4 million tons by 2021 [46]. Buckwheat is widely grown, especially in the northern hemisphere, Asia, Europe and America, China, India, Korea, Bhutan, Nepal, Kazakhstan, Tajikistan, Russia, Ukraine, Lithuania, Estonia, Belarus, Moldova, Poland, Serbia, Croatia, Slovenia, Austria, Italy, United States of America, and Canada ^{[39][47][48][49]}[39,47,48,49].

The buckwheat plant is easily adaptable, so that it can be grown almost anywhere in the world and different habitats, from high altitude regions, with low rainfall and temperatures, even in nutrient-poor soils and has a higher resistance to pests in compared to other cereals ^[43][50][51][43,50,51].

Of the buckwheat species, the common buckwheat (Fagopyrum esculentum) and the tartar buckwheat (Fagopyrum tataricum) are the most cultivated and consumed species worldwide [39]. From an economic point of view, the most important species is the common buckwheat (Fagopyrum esculentum), which represents 90% of the world’s buckwheat production, which is generally grown in the temperate regions of the northern hemisphere [52]. Tartar buckwheat (Fagopyrum tataricum) has been called “bitter buckwheat” due to the bitter substances in the grains and has many advantages over other species, such as self-pollination, high grain yield, has better resistance to adverse climatic conditions, being mainly a high-altitude culture [41]. Additionally, tartar buckwheat is considered a healthy food due to the fact that it contains a higher amount of rutin compared to the common buckwheat [53]. There are also wild buckwheat species, the best known being the species Fagopyrum cymosum, used, for example, in traditional Chinese human and veterinary medicines. Wild buckwheat species are used by researchers to create newly cultivated species, like in the case of Fagopyrum giganteum Krotov species, which was originally defined by Krotov and Dranenko at the Ustymivska Experimental Station in Ukraine, obtained by intraspecific crossings between tartar buckwheat and wild Fagopyrum homotropicum [54].

The health benefits of buckwheat have been studied and recognized worldwide. In China, for example, it is said that “people who love buckwheat live a long time” and that “people who love buckwheat are healthy” [55]. The consumption of products containing buckwheat have a hypoglycaemic, hepatoprotective, anticancer, antihemorrhagic, anti-inflammatory, antioxidant, vasoprotective, antihypertensive, and cytoprotective effect, reduces the total triglycerides and total cholesterol in serum and liver, blood sugar, and blood pressure, prevents cardiovascular disease gallstones and cognitive impairments such as Alzheimer’s disease ^{[40][41][54][56]}[40,41,54,56]. It can also lead to weight loss as well as a lower risk of diabetes, stroke, and coronary heart disease ^[51][57][51,57]. Soluble and insoluble dietary fibre in buckwheat grains positively affects constipation and obesity [58]. Literature data have shown that long-term consumption of buckwheat products can prevent and control many chronic diseases, such as hyperglycaemia, hypertension and hyperlipidaemia [46].

Amaranth belongs to the order Caryophyllales, family Amaranthaceae, subfamily Amaranthoideae, genus Amaranthus, with about 65–70 species, divided into four classes (cereals, vegetables, ornamentals and weeds) which are naturally found in temperate and tropical regions worldwide, mainly on the American continent, at altitudes that vary between sea level and over 3000 m ^{[32][59][60][61][62]}[32,59,60,61,62]. Like buckwheat, it is a pseudocereal, and an annual dicotyledonous plant, with most species originating from Central and South America (Figure 3) ^[59][63][59,63]. Amaranth is currently widely grown all over the world, but mainly in Canada, Mexico, Russia, India, Nepal, China, Indonesia, Malaysia, the Philippines, Kenya, Argentina, Peru, and Australia ^[35][64][35,64]. The world’s largest producer is China ^[64][65][64,65]. Presently, the main consumer market for amaranth seeds is Germany [64].

Figure 3. Plant, flowers, and seeds of amaranth.

More than 500 g of seeds can be harvested from a single plant, which can contain 60,000–100,000 pieces [62]. Amaranth is a plant that adapts very well to soil and climate conditions, has a better resistance to biotic and abiotic stress than conventional cereal crops ^{[32][59][66][67]}[32,59,66,67]. Due to these advantages, amaranth may be a suitable alternative for cereals that are less tolerant of heat, high radiation, pests, and drought ^{[60][63][64][68]}[60,63,64,68].

The name amaranth comes from an ancient Greek word meaning “immortal”, “everlasting”, or “not withering” ^[35][60][35,60].

Among the many species of amaranth discovered, the main typical species grown for seeds are Amaranthus cruentus, Amaranthus caudatus and Amaranthus hypochondriacus, while the most cultivated species for leaves is Amaranthus tricolor [59].

The chemical composition and high nutritional value, as well as its great potential for use, have led to the recognition of amaranth by UN/FAO nutrition experts as the plant of the 21st century [59].

The amaranth plant can reach over 2.0 m in height; it has a pivoting root that ensures its survival during periods of water scarcity [32].

In addition to its nutritional value, amaranth has many health benefits. Studies have shown that regular consumption of amaranth has hypocholesterolaemic, antioxidant, antidiabetic, anti-inflammatory, antirheumatic, analgesic, antimalarial, antiemetic, laxative, improves appetite, is antileprotic, induces the decrease of free fatty acids, benefits people hypertension and cardiovascular disease, improves liver function and prevents cancer ^{[32][35][61][69][70][71]}[32,35,61,69,70,71]. The amaranth’s ability to provide health benefits is due to its bioactive compounds; for example, there is evidence that rutin slows down the aging process, quercetin prevents oxidation, and nictoflorin helps protect memory functions. In some countries, parts of the amaranth plant are used to treat various disorders in traditional medicine. In Zimbabwe, the consumption of amaranth grains has been reported to lead to significant improvements in children’s health, such as improved appetite, quick healing of mouth sores and weight loss. In Benin, the leaves of amaranth are recommended for young children, nursing mothers and patients with constipation, fever, bleeding, anaemia, or kidney problems. In Senegal, the roots are boiled with honey as a laxative for infants. In Ghana, water from macerated plants is used as a wash to treat limb pain. In Sudan and Gabon, the ash from the stems is used as a wound dressing. In Gabon, heated amaranth leaves are used on tumours ^[35][64][35,64].

2.2. Structure and Chemical Composition

Specialists’ attention has been directed towards the chemical composition of buckwheat seeds, confirming the unique nutritional value conferred by the various nutritional and bioactive components it contains [39]. The chemical composition is influenced by several factors, such as environmental conditions (especially climatic conditions), growing season, species and variety of origin, crop management practices, and so on [48].

Buckwheat seeds are made up of endosperm where starch is located (on average 70%) and a starch-free aleuronic layer ^[2][42][2,42]. The weight of a thousand grains varies between 17.6 and 25.9 g in commercially available buckwheat seeds, a weight that is directly proportional to the starch content, the useful component for brewing [68]. Buckwheat starch granules are irregularly shaped, in a compact package, measuring 2–6 μm, and contain 24% amylose and 76% amylopectin, which is the usual ratio of cereal starch [43].

The availability of starch varies between 70–91%, an important aspect for the use of buckwheat as a raw material in the beer industry. Starch is also a useful substance that will be the content of fermentable carbohydrates in beer wort [8]. 33% of starch is in the form of resistant starch, which recommends buckwheat as a potential ingredient for the formulation of foods with low glycaemic index ^[26][72][26,72]. Buckwheat contains large amounts of soluble and insoluble dietary fibre, which have a positive effect on constipation and obesity [52].

Buckwheat is recognized as a good source of high biological value proteins that do not form gluten and a balanced amino acid composition (high levels of lysine and arginine, compared to cereals), lipids, antioxidants, organic acids, dietary fibre, mineral substances, and vitamins ^{[2][25][41][42][73]}[2,25,41,42,73].

The protein content of buckwheat is 11–19%, 55% of which is in the embryo and 35% in the endosperm, while the rest is in the shell. Compared to buckwheat, cereal proteins are 10–20% found in the embryo and 80–90% in the endosperm [43]. Buckwheat proteins are easily digested by the human body and are more valuable compared to cereal proteins and by their nutritional value is not inferior to legume proteins [73]. The main protein in buckwheat is a 13S globulin considered a rare vegetable protein with a blood cholesterol lowering effect. Buckwheat also contains lectins with a role in reducing the proliferation of spontaneous and induced tumours [40]. Interestingly, buckwheat protein has a higher amino acid score of 100 compared to cereals [48].

Buckwheat also contains essential fatty acids that are not synthesized in the human body and must come from theour diet. The lipid content of buckwheat (0.75–7.4%) is higher than that of wheat, being characterized by a high degree of unsaturation, which is preferable from a nutritional point of view [74]. Buckwheat lipids are resistant to oxidation, which means that buckwheat and processed products, can be stored for a long time [73]. It is also valuable for its phospholipids content, especially lecithin ^[73][75][73,75].

Several biofunctional compounds have also been identified in buckwheat, such as: phenolic acids, phytosterols, bioactive inositols (D-chyrosinitol and myo-inositol), condensed tannins, flavonoids, such as rutin, orientin, homoorientin, vitexin, quercetin, isovitexin and isoorientin ^{[49][56][76][77][78]}[49,56,76,77,78]. Fagopyrum tataricum has been found to taste much bitterer than Fagopyrum esculentum due to its higher content of phenolic compounds and flavonoids, such as rutin and quercetin ^[53][57][53,57]. Buckwheat also contains phagopyrins and phagopyritol with a huge potential in glycaemic control in people with type II diabetes ^{[40][49][55][79]}[40,49,55,79]. Buckwheat rutin is a bioflavonoid with important physiological and biological properties, for example, it keeps capillaries and arteries strong and flexible, in addition to acting as a shield against gastric damage, prevents bleeding, improves vision and hearing, protects against UV light, X-rays, oxidative stress ^{[55][72][80][81]}[55,72,80,81]. It should be noted that rutin is not found in any cereals and pseudocereals, so buckwheat can be used as a good source of dietary rutin ^[2][76][2,76].

Buckwheat grains are an important source of minerals (2.0–2.5%), namely zinc, copper, manganese, selenium, phosphorus, potassium, sodium, calcium, iron and magnesium ^[39][78][39,78]. The literature shows differences in the amount of mineral substances of the two cultivated species Fagopyrum esculentum and Fagopyrum tataricum. While Fagopyrum tataricum contains higher concentrations of sulfur, calcium, copper, and molybdenum, Fagopyrum esculentum has higher concentrations of selenium, zinc, iron, cobalt and nickel [48]. Buckwheat contains several B vitamins, B₁ (3.3 mg/kg), B₂ (10.6 mg/kg), B₃ (18.0 mg/kg), B₅ (11.0 mg/kg), B₆ (1.5 mg/kg), vitamins A, C and E ^{[40][47][78][82]}[40,47,78,82].

Amaranth grains, although quite small compared to other cereals, have been widely studied, and there is currently a large volume of literature on the chemical content and nutritional qualities of amaranth ^[59][60][59,60].

Amaranth seeds have a diameter of 0.9–1.7 mm, lenticular in shape, with a weight of 1000 seeds of 0.6–1.3 g ^{[33][59][60][69][83]}[33,59,60,69,83]. The weight of 1000 seeds is an important index for the beer malt industry, as their size is directly proportional to the starch and protein content ^[59][60][84][59,60,84].

As in the case of cereals, the chemical composition of amaranth seeds is dominated by carbohydrates, of which starch is found in a proportion of 50–60% in relation to the total mass of the seeds or over 90% in relation to the carbohydrates included in the seeds. Starch granules, located mainly in the endosperm, are polygonal in shape and have a high swelling power ^[59][85][59,85]. The amylose content is lower than that of other cereal starches, with values between 0.1% and 11.1%. For this reason, due to the small size of the starch granule, it has specific properties, such as higher solubility, high water binding capacity and susceptibility to enzymes, higher sorption capacity at high water activity range [61]. Amaranth seeds contain higher quantities of dietary fibre (4–8%) than those found in most cereals (2%) ^[32][86][87][32,86,87].

Amaranth seed proteins are nutritionally valuable, with a high digestibility of about 90%, being rich in essential amino acids, in a proportion close to that recommended by the World Health Organization ^[60][88][89][60,88,89]. Amaranth grains contain three major proteins, namely, albumin (40%), globulin (20%) and glutelin (25–30%), and only 2–3% prolamine [69]. They do not generate gluten, so amaranth flour is recommended in the diet of people suffering from coeliac disease. Amaranth grains contain lysine, the limiting amino acid in cereals (wheat, rye and triticale), in the amount of 363–421 mg/g N, identical to that contained in soy. Amaranth proteins also contain a considerable amount of amino acids with sulphur (2–5%), methionine, cystine and cysteine, higher than in basic legumes (1.4% on average), such as peas, beans and soybeans ^{[32][59][60][64][85]}[32,59,60,64,85].

Amaranth grains contain 2–3 times more lipids than wheat or rye grains, almost twice as much as maize grains, and contain as many lipids as oat grains ^[59][60][59,60]. Unsaturated fatty acids represent about 76%, the largest share of total fatty acids (unsaturated and saturated), being held by linoleic acid (25–62%), oleic acid (19–35%), palmitic acid (12–25%), stearic acid (2–8.6%) and linolenic acid (0.3–2.2%) [83]. Amaranth oil has been reported as the richest source of squalene in the plant world (with amounts of 7–11% in refined oil) [60]. Squalene has a high content of antioxidants, which prevents oxidative damage induced by free radicals, especially on the skin, and helps to renew the protective layer of the skin ^[32][64][83][32,64,83]. Amaranth oil is also a rich source of tocotrienols, which is very effective in lowering LDL cholesterol and phytosterols with hypocholesterolaemic effects ^[32][69][32,69]. Among these phytosterols are beta-sitosterol (607 μg/100 g) which is 95% of the total phytosterols, campesterol (8.8 μg/100 g) and stigmasterol (5.6 μg/100 g) ^[32][90][32,90].

The excellent antioxidant capacity of amaranth compared to cereals is conferred by phenolic acids (caffeic acid, p-hydroxybenzoic acid, ferulic acid), flavonoids, phytosterols, squalene and bioactive peptides. These substances give amaranth, among other things, antidiabetic, antihypertensive, immunomodulatory, antitumor, and antimicrobial activities ^[63][90][91][63,90,91]. Amaranth seeds contain polyphenols in the amount of 14.72–14.91 mg/100 g ^[61][91][61,91].

The mineral content of amaranth seeds is about twice as high as in other cereals [61]. They are a rich source of iron (72–174 mg/kg), calcium (1300–2850 mg/kg), sodium (160–480 mg/kg), magnesium (2300–3360 mg/kg) and zinc (36.2–40 mg/kg) [60]. That is why amaranth flour can reduce the deficiency of calcium, magnesium and iron in gluten-free products and in the gluten-free diet, which can be deficient in these minerals ^[85][92][85,92].

Amaranth seeds contain several vitamins, such as riboflavin (0.19–0.23 mg/100 g), ascorbic acid (4.5 mg/100 g), niacin (1.17–1.45) mg/100 g), thiamine (0.07–0.1 mg/100 g), vitamin E, β-carotene ^[60][61][63][60,61,63].

The chemical composition of the raw materials is particularly important for the beer industry. Table 1 summarizes the physicochemical characteristics of the two pseudocereals and wheat, one of the conventional raw materials for the beer industry.

Table 1. Physico-chemical characteristics of buckwheat, amaranth, and wheat.

Grain	Moisture [%]	Protein [%]	Fat [%]	Carbohydrate [%]	Fibre [%]	References
Wheat	12.8	11.8	2.5	71.2	12.5	[39]
	-	10.91	1.82	75.56	2.2	[64]
	13	14.0	2.0	69.0	1.0	[61]
	-	10.7	2.0	75.4	12.7	[32]
	12.6	11.7	2.0	71.0	2.0	[93]
	-	9–18	2.5–3.3	75–80	2.0–2.5	[94]
	-	8–13	3–4	85	12	[95]
	13	13.7	1.9	72.6	12.2	[96]
	-	11–14.1	1.4–2.1	81.3–83.1	2.1–2.9	[97]
	-	12.9–19.9	1.5–2.0	80	7.7–11.4	[98]
Buckwheat	13.4–19.4	10.4–11.0	2.4–2.8	67.2	8.6	[99]
	-	9.5–14.1	1.8–3.1	80.5–84.1	-	[73]
	-	12–19	1.5–3.7	60–70	1.7–8.5	[55]
	-	10–12.5	4.7	65–75	-	[82]
	11	12	7.4	72.9	17.8	[39]
	-	13.3	3.4	71.5	10.0	[32]
	-	13.9–16.4	3.43–3.86	67.8–78.3	3.55–5.86	[66]
	-	12.28–15.61	1.72–2.24	77.36–81.38	20.32–21.45	[100]
	10.8–11.6	8.51–18.87	1.5–3.7	60–70	2.7–21.3	[101]
	11.2	12.3	2.3	73.3	10.9	[102]
Amaranth	6–9	13–18	6–8	63	4–14	[99]
	-	15.7	7.2	62	4.2	[59]
	-	16	7	62	10	[32]
	-	13.1–21	5.6–10.9	48–69	3.1–5.0	[60]
	6.23–6.71	13.58–17.6	6.3–8.1	58.6–68.9	3.4–5.3	[34]
	-	13.6 ± 0.8	7.3 ± 0.3	69.0 ± 0.2	11.0 ± 0.2	[88]
	11.29	13.56	7.2	65.25	6.7	[64]
	6–9	13–18	6–8	63	4–14	[61]
	-	13.6	7.0	65.3	6.7	[32]
	-	15.1–16.4	6.47–7.25	57.3–65.5	6.53–11.16	[66]

From the data presented in Table 1, it can be observed that, compared to wheat, which is a conventional raw material for the production of malt or beer, buckwheat has for the carbohydrate content values of 60–84.1%, very close to those of wheat, of 69–85%. The values taken from the literature for the carbohydrate content of amaranth are lower than those for buckwheat, between 48% and 69%. Regarding the protein content, both buckwheat and amaranth have values of 9.5–18.87% and 13.1–18%, respectively, which are close to those of wheat, 8–19.9%.