# Properties and Functionality of Cereal Non-Starch Polysaccharides in Breadmaking
## 2 Definition and Occurrence of Cereal NSPs  
Arabinoxylans (AXs) are built from a skeleton composed of xylose residues which may be substituted with arabinose residues at the positions of C(O)-3 (monosubstituted xylose residues) and C(O)-2 and C(O)-3 (disubstituted xylose). The arabinose residues in AX molecules can be further substituted with phenolic acid molecules, in particular ferulic acid. In cereal grains (Table 1), the highest AX contents were found in rye grain (8-12%), but AXs are also present in relatively high amounts in grains of wheat 0.8-9%, corn 4.8-5.6%, rice 2.97-6.84%, barley 1.2-10.5% and oats 1.2-11.6% [2; 3; 4; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15]. \(\beta\)-glucans consist of long, linear chains composed of glucose residues linked in the cell walls of cereal grains and seeds by \(\beta\)-(1\(\rightarrow\)4) and \(\beta\)-(1-3) glycosidic bonds, while in the cell walls of fungi by \(\beta\)-(1\(\rightarrow\)3) and \(\beta\)-(1\(\rightarrow\)6) glycosidic bonds [16; 17; 18; 19]. Generally, there are trimomomeric and tetramomeric segments in \(\beta\)-glucan molecules, i.e., containing three or four \(\beta\)-(1\(\rightarrow\)3) linked glucose molecules. In cereal grains, trimomomeric segments of \(\beta\)-glucans account for 58-72%, while tetramomomeric segments account for 20-34% [20]. Fungal \(\beta\)-glucans are composed of segments consisting mainly of three \(\beta\)-(1\(\rightarrow\)3) linked glucose molecules and, in small amounts, segments of two or four \(\beta\)-(1\(\rightarrow\)3) linked glucose units [21; 22]. As summarized in Table 1, the highest number of \(\beta\)-glucans (6.6%) was determined in the grain of cereals such as oats and barley [13; 18; 23; 24; 25; 26]. \(\beta\)-glucans are especially abundant in the outer parts of the grain. Therefore, their content in bran is especially high (Table 1). These polymers are found in smaller amounts of 0.12-2.6% in rye and wheat grains in amounts of 0.4-1.3% in corn and rice grains [16; 27; 28; 29]. \(\beta\)-glucans are also found in the cell walls of fungi in the amount of 4.71-56% d.b. of dried mushrooms [19; 30; 31; 32; 33; 34]. Suitake mushrooms (_Lentinus edodes_) and some members of the oyster mushroom family, especially _Pleurotus_ spp., are considered to be among the most important sources of \(\beta\)-glucans, and their content in these mushrooms ranges from 10-56% d.b. [19; 32; 33; 34]. Cellulose is formed by long linear chains of glucose linked by \(\beta\)-(1,4) glycosidic bonds. Due to its linear structure, cellulose is insoluble in water and resistant to digestive enzymes. The average cellulose content reported in the literature in barley grain is 1.4-4.7%, in rye 1.3-11.8%, and 1.67-14.1% in wheat grain [35; 36; 37; 38; 39]. It must be noted that the determination of cellulose content is complicated due to complex structure, poor solubility, and application of non-specific analytical methods for the determination of their content. Therefore, the reported values should be considered proximate. Galactomannans are heterogeneous polysaccharides composed of a backbone of mannose residues linked by \(\beta\)-(1-4) glycosidic bonds with attached galactose residues via \(\alpha\)-(1-6) glycosidic bonds. They differ in the ratio of mannose to galactose content. Galacto-tomannans are mainly obtained from the endosperm of the seeds of many dicotyledonous plants, especially species of plants within the Leguminosae family. The highest amounts of galactomannans are found in carob gum (27-33%), fenugreek seed gum (25.5-32.8%), and guar gum (28.6-34.6%) [2,40-44]. Galactomannan content in cereals has not been reported. Glucomannans have been found as a minor component in cereal grains. These NSPs are composed of glucose and mannose units [2]. Arabinogalactans consist of galactan chains with attached arabinose residues. Arabinogalactans are present in the cell walls of cereal grains, and their content (Table 1) ranges from 0.3% to 1.5% [45-47]. There are two types of arabinoagalactans: type I and type II.