# Utilization of the Nutritional Potential of Wheat Bran Using Different Fractionation Techniques
## 4 Grain Finishing Options--Peeling  
Surface treatment has another major importance besides the issues we have discussed. The outer layers of the wheat grain are most exposed to contamination by natural and synthetic contaminants. These contaminants include mycotoxins, in wheat most commonly _Fusarium_ fungal products, especially deoxynivalenol or zearalenone, synthetic contaminants such as heavy metals cadmium and lead, and especially pesticides [46].  
One of the fractionation processes is the so-called \"peeling\" or \"debranning\" of the grain. This is a process in which the outer layers of the grain are removed by rubbing and abrasion [30]. The degree of peeling can be effectively controlled to separate those fractions of the outer layers of the grain that are technologically problematic and may also be a safety hazard. Thus, the middle fraction of wheat grain outer layers obtained by repeated peeling after removal of the uppermost layers could be used as a functional ingredient in order to enrich wheat-four-based products with bioactive substances but also to rid them of the risk of contaminants associated with the use of all outer grain layers [46].  
This peeling technology is well known for its use in rice milling and is sometimes used before milling durum wheat, but peeling has rarely been used for common wheat. Of particular interest for food purposes are bran fractions enriched with the aleurone layer, as this tissue is rich in soluble fiber and biologically active substances such as vitamins, minerals, and antioxidants, while being free of possible exogenous contaminants, as these are removed together with the peripheral layers of the grain [30]. [PERSON] et al. also report that the enrichment of flour with a selected fraction obtained by peeling (containing an aleurone layer) leads to an improvement in the nutritional profile of bread, with less adverse effects on bread volume and texture than bread made from flour with the addition of conventional wheat bran [30].  
The table below (Table 3) compares the distribution of certain components in the outer layers of wheat grain. The different fractions (always constituting 5% of the original grain weight) were obtained by successive abrasion of the wheat grain from the outer layers to the starch kernel of the grain using the technological method of \"peeling\" [42].  
Peeling or partial debranning, i.e., surface treatment of varying intensity, is a direct and relatively simple way to significantly improve the nutritional properties of flours and to compensate for the negative technological and sensory effects of using wholemeal flours. However, it is at the same time a relatively inaccurate method. The grain is irregular in shape, and the size of individual grains varies slightly. As a result, the efficiency of separating technologically problematic layers and, conversely, preserving nutritionally important grain layers is always rather imperfect [30; 41; 43].  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Peeling Fraction** & **Protein (\%)** & **Fiber (\%)** & \(\boldsymbol{\beta}\)**-Glucans (\%)** &
\begin{tabular}{c} **Free Phenolic Acids** \\ **(\(\boldsymbol{\mathfrak{g}}\)/kg)** \\ \end{tabular} \\ \hline
0-5\% & 11.7 & 58.3 & 1.4 & 788 \\
5-10\% & 17.4 & 37.8 & 1.9 & 572 \\
10-15\% & 19.6 & 24.4 & 1.5 & 500 \\
15-20\% & 18.2 & 19.7 & 1.1 & 395 \\
20-25\% & 17.5 & 12.9 & 0.9 & 261 \\ Remaining & 12.0 & 5.6 & 0.3 & 23 \\
25-100\% & & & & \\ \hline \hline \end{tabular}
\end{table}
Table 3: Distribution of selected grain components in wheat fractions obtained by peeling (content of compounds is expressed in weight %) [42].