# Utilization of the Nutritional Potential of Wheat Bran Using Different Fractionation Techniques
## 2 Cereals and Their Potential Nutritional Benefits
Next, we shall look at the chemical composition of the various anatomical parts that become part of the bran as a by-product in the standard milling process. The pericarp, which forms the uppermost outer layer of the grain, is composed mainly of non-water-extractable fiber components such as cellulose, some hemicelluloses, and lignin. It also contains minerals, vitamins, and phenolic acids in bound form. Overall, this layer represents about 3-5% of the weight of the whole grain [18]. The seed coat is composed of non-starchy polysaccharides, mainly hemicelluloses, which are partly water-extractable. Furthermore, phenolic compounds, carotenoid dyes, alkylresorcinols, minerals, and vitamins are present at significant concentrations. This layer accounts for about 1% of the weight of the whole grain [11; 18]. The arabinoxylans of the \begin{table}
\begin{tabular}{c c c c c c} \hline
**Cereals** & **Moisture** & **Proteins** & **Lipids** & **Carbohydrates** & **Dietary Fiber** \\ \hline Wheat & 14.0 & 12.7 & 2.2 & 63.9 & 12.6 \\ Maize & 12.0 & 8.7 & 0.8 & 77.7 & 11.0 \\ Rice & 11.8 & 6.4 & 0.8 & 80.1 & 3.5 \\ Barley & 11.7 & 10.6 & 2.1 & 64.0 & 17.3 \\ Sorghum & 14.0 & 8.3 & 3.9 & 57.4 & 13.8 \\ Millet & 13.3 & 5.8 & 1.7 & 75.4 & 8.5 \\ Rye & 15.0 & 8.2 & 2.0 & 75.9 & 14.6 \\ Oat & 8.9 & 12.4 & 8.7 & 72.8 & 10.3 \\ \hline \end{tabular}
\end{table} 
Table 2: Chemical composition of selected cereals (per 100 g edible sample) [19]. hyaline layer, which lies between the awn and the aleurone layer, are usually sparsely cross-linked and therefore more easily extractable [20]. The aleurone layer, as noted, is located at the interface between the outer layers and the endosperm and constitutes about 6-9% of the grain weight [18]. It is essentially composed of a single layer of large cells with a diameter of 20-75 \(\upmu\)m. The aleurone cell walls contain 29% \(\upbeta\)-glucans, small amounts of proteins, and 65% arabinoxylans. They have a low ratio of arabinose to xylose and contain high amounts of the ester monomer ferulic acid. Inside the aleurone cells are spherical particles, called aleurone granules, that are 2-4 \(\upmu\)m in diameter. These granules can be composed of phytate inclusions or niacin and protein inclusions and are surrounded by a thin lipid layer. Overall, the aleurone layer is rich in nutrients. The cells forming the aleurone layer contain large amounts of proteins, minerals, phytates, B vitamins (especially niacin), and plant sterols. The aleurone layer contains 15% of the total amount of wheat protein and also 30% of the total amount of lysine, which is the first limiting essential amino acid in wheat. In addition, at least 80% of the total amount of niacin is present, as well as a significant amount of other B vitamins. Approximately 40-60% of the total mineral content of wheat is found here, making the aleurone layer a rich source of minerals [20]. The cell walls of cereal endosperm cells are important in germination and grain structure and are one of the sources of fiber. The endosperm occupies on average 80-85% of the grain and is composed mainly of starch, protein, and on average 2% dietary fiber. The predominant cell wall polysaccharides in wheat endosperm are mainly arabinoxylans, a mixture of \(\upbeta\)-glucans, and then a smaller amount of cellulose [18; 27]. The wheat germ makes up about 2.5-3.5% of the grain. The germ contains relatively high amounts of protein (25%), sugars (18%), lipids (13-16%), and ash (5%). It contains no starch but is relatively high in B vitamins and contains many enzymes. The sprouts also have a relatively high vitamin E content, reaching up to 500 ppm. Simple carbohydrates are mainly represented by sucrose and rafinose [5]. The main non-starch polysaccharides in wheat bran are arabinoxylans, cellulose, and \(\upbeta\)-glucans, which account for 73%, 24%, and 6% of starch-free bran, respectively. Arabinoxylan is classified as a hemicellulose. In cereals it is one of the main cell wall polysaccharides.