**3. Arabinoxylans and viscosity in the process of malting**

Rye contains considerably higher amounts of arabinoxylans (AX), especially water-extractable arabinoxylans (WEAX), than barley. The rye AX structure and its properties were described [24]. AX are cell wall non-starch polysaccharides and are constituted by a chain of β-1,4 units of xylopyranose. The α-arabinofuranose chain can bind to the C(O)-2 and/or C(O)-3 of the xylose residues. It contains some arabinose substituents that are esterified with ferulic acid in C(O)-5 [25]. The molecular masses, the degree and the configuration of the arabinose branching, and the degree of esterification with ferulic acid exert an important influence on the properties of the AX. Since WEAX can bind to many water molecules, it can change the viscosity of the solutions making them more consistent. Gels can be formed by oxidative cross-linking of AX macromolecules through ferulic acid residues. The AX of the rye grains, during the process of the germination, suffer an enzymatic degradation. The inner bonds of the main chain of the xylan are divided forming a greater quantity of shorter-chain AX molecules by the action of

the endoxylanase enzymes. Xylose residues are released from the nonreducing end since the β-xylosidases, while keeping the number of macromolecules constant, slightly decrease the length of the chain. The enzyme α-l-arabinofuranosidase releases arabinose from macromolecules, whereas feruloyl esterase hydrolyzes the bond between ferulic acid and arabinose residues [26]. AX represent a large part of the rye's dietary fiber, a soluble dietary fiber with their known health benefits for the consumer [27, 28] described in two studies, the positive effects of AX on postprandial insulin response in healthy individuals and improved metabolic control in diabetes patients. AX breakdown products have also been shown to display prebiotic properties [29–32, 40]. Certain proteins restrict access to water and enzymes to the endosperm starch. This situation is reversed during germination, when proteins and other components of the cellular apparatus are degraded and allow the passage of enzymes to the cellular interior. In this way, the extraction of starch and other compounds is increased. In the brewing industry, it is associated with a high nitrogen level at low starch content. The total nitrogen content of the malts obtained varied when the germination conditions changed. The difference between the highest and lowest values measured was 0.2%. But changes in germination conditions do not justify changes in the measurements obtained. The protein content in barley and rye from the beginning of germination did not vary significantly [33]. Nitrogen-containing compounds, being insoluble, will not form part of the mass during processing. In addition, some fractions of the soluble nitrogen (SN), like enzymes and free amino nitrogen (FAN), play important roles in the mashing process and during the fermentation, respectively. It was studied that the variations in SN measured produced from rye malts were large with values ranging between 694 and 862 mg/100 g. The highest SN contents were found in samples germinated for 96 h at 18°C, 130 h at 15°C, and 144 h at 10°C. In the germination of barley, storage proteins are mobilized, and some structural proteins are degraded. An increase in soluble nitrogen is generated in the malt, due to the large amount of peptides and extractable proteins in water. Protease enzymes influence the content of nitrogen compounds during maceration, although the greater amount of SN is formed in the malting. In rye, the content of SN does not appear to be influenced by the action of the proteolytic enzymes of the germinated malt. Previous studies show that free amino nitrogen (FAN), as an essential nutrient, is relevant in the growth of yeasts in the initial stage of fermentation. It was observed that at longer germination times, the FAN contents increase [34, 35]. In the maceration process, the starch is degraded by two enzymes, α-amylase and β-amylase, which act mainly generating maltose. Then, the maltose is fermented by yeasts that generate ethanol as a primary product. An increase in enzymatic activity has been observed, proportional to the time of germination. An increase in the total content of AX in the final malt has been observed, probably due to the loss of other compounds in respiration and formation of rootlets. The results of this study show which quality parameter of rye malt can be optimized by varying germination conditions. One of the most important factors, in the use of malt in the brewing industry, is the viscosity due to high amounts of WEAX. When the malt is used as a raw material for functional foods, its nutritional properties are used as a function of the AX and its decomposition products. According to the selected germination parameters, it is possible to direct the breakdown of the AX in the malt.

## **4. Prebiotic effects of cereal arabinoxylans**

As reported before, in grains of wheat and related cereals, dietary fiber is predominantly composed of arabinoxylans (AXs). These cell wall components

**137**

*Fibers: Healthy Component in Whole Wheat and Rye Flours*

**5. Application of rye malt in the brewing industries**

typically consist of a linear backbone of β-(1–4)-d-xylopyranosyl units, which may be substituted by α-l-arabinofuranosyl units [36]. The structure and the physicochemical properties of AX from different layers in cereal kernels are very diverse. The cereal's arabinoxylans (AX) are the main dietary fibers in a balanced human diet. The physiological impact of AX consumption strongly depends on their structures and properties as different impacts on the microbial population and fermentation products in the intestinal tract of rats. The consumption of extractable arabinoxylan of wheat bran increases the mass of the cecal contents. It is known that the consumption of soluble fermentable fiber by rodents causes increase in the mass of the cecum content. Extensive fermentation of water-extractable arabinoxylan or arabinoxylan oligosaccharides reduce the pH, suppress relevant markers of the proteolytic breakdown, and induce a selective bifidogenic response [37].

The malting technologies were optimized for barley. The new materials must then be compared with the malt to establish identity in the processes. Wheat malt is also very important in large quantities in the western world. The contents of extract in rye malts were also higher than in barley malts (usually >81% [38]. As rye does not have a shell, which represents approximately 10% of the barley's dry weight [32], the fermentation capacities in the rye parts (73 and 77%) are lower than in 80% barley [38] or wheat parts (>78%, [39]), because they contain lower soluble nitrogen compounds and WEAX. However, the content of SN in rye malt turns out to be higher than in barley malt [38]. A higher viscosity of rye malt is the main drawback when using the brewing industry. This impediment can be reversed by modifying the temperature and the germination period (10°C and h) [40].

The effects of germination and subsequent oven-drying or freeze-drying on folate content in a number of wheat and rye cultivars were studied for producing folate-rich flour ingredients. As reported in previous studies [41–43], germination of wheat and rye resulted in a four- to sixfold higher folate content than untreated cereals, mainly due to an increase in 5-CH3-H4 folate (w4-fold). The increased folate content has been attributed to de novo synthesis of folate being accelerated because of increased demand for methyl groups (one carbon unit) during germination [43]. Oven-drying (50°C) did not significantly affect the folate content, which is in agreement with our previous findings that oven-drying of germinated grains is suitable for the production of folate-rich candidate ingredients [44]*.* It has recently reported that by addition of germinated wheat flour to native wheat flour, bread with a 65% higher folate content compared with conventional Egyptian baladi bread could be prepared [45]. Germinated cereal grains and flour could also serve as functional ingredients for the European bread-baking industry. Here, the folate content in the rye cultivars studied was approximately 25% higher than that in the wheat cultivars. This confirms findings by [46] that rye flour contains more folate than flour from other cereals such as wheat, triticale, barley, and oats. The folate content quantified in the four Swedish wheat cultivars tested (23–33 mg/100 g dry matter DM) is also similar to HPLC data (34–40 mg/100 g DM) reported for four Polish wheat cultivars [48]. In comparison to data from microbiological assays [47–49], the mean folate content in untreated wheat and rye cultivars was 30–40% lower in this study. HPLC methods generally tend to provide folate values which are around

*DOI: http://dx.doi.org/10.5772/intechopen.83341*

**6. Folate in germinated cereals**

*Food Engineering*

the endoxylanase enzymes. Xylose residues are released from the nonreducing end since the β-xylosidases, while keeping the number of macromolecules constant, slightly decrease the length of the chain. The enzyme α-l-arabinofuranosidase releases arabinose from macromolecules, whereas feruloyl esterase hydrolyzes the bond between ferulic acid and arabinose residues [26]. AX represent a large part of the rye's dietary fiber, a soluble dietary fiber with their known health benefits for the consumer [27, 28] described in two studies, the positive effects of AX on postprandial insulin response in healthy individuals and improved metabolic control in diabetes patients. AX breakdown products have also been shown to display prebiotic properties [29–32, 40]. Certain proteins restrict access to water and enzymes to the endosperm starch. This situation is reversed during germination, when proteins and other components of the cellular apparatus are degraded and allow the passage of enzymes to the cellular interior. In this way, the extraction of starch and other compounds is increased. In the brewing industry, it is associated with a high nitrogen level at low starch content. The total nitrogen content of the malts obtained varied when the germination conditions changed. The difference between the highest and lowest values measured was 0.2%. But changes in germination conditions do not justify changes in the measurements obtained. The protein content in barley and rye from the beginning of germination did not vary significantly [33]. Nitrogen-containing compounds, being insoluble, will not form part of the mass during processing. In addition, some fractions of the soluble nitrogen (SN), like enzymes and free amino nitrogen (FAN), play important roles in the mashing process and during the fermentation, respectively. It was studied that the variations in SN measured produced from rye malts were large with values ranging between 694 and 862 mg/100 g. The highest SN contents were found in samples germinated for 96 h at 18°C, 130 h at 15°C, and 144 h at 10°C. In the germination of barley, storage proteins are mobilized, and some structural proteins are degraded. An increase in soluble nitrogen is generated in the malt, due to the large amount of peptides and extractable proteins in water. Protease enzymes influence the content of nitrogen compounds during maceration, although the greater amount of SN is formed in the malting. In rye, the content of SN does not appear to be influenced by the action of the proteolytic enzymes of the germinated malt. Previous studies show that free amino nitrogen (FAN), as an essential nutrient, is relevant in the growth of yeasts in the initial stage of fermentation. It was observed that at longer germination times, the FAN contents increase [34, 35]. In the maceration process, the starch is degraded by two enzymes, α-amylase and β-amylase, which act mainly generating maltose. Then, the maltose is fermented by yeasts that generate ethanol as a primary product. An increase in enzymatic activity has been observed, proportional to the time of germination. An increase in the total content of AX in the final malt has been observed, probably due to the loss of other compounds in respiration and formation of rootlets. The results of this study show which quality parameter of rye malt can be optimized by varying germination conditions. One of the most important factors, in the use of malt in the brewing industry, is the viscosity due to high amounts of WEAX. When the malt is used as a raw material for functional foods, its nutritional properties are used as a function of the AX and its decomposition products. According to the selected germination parameters, it is possible to

**136**

direct the breakdown of the AX in the malt.

**4. Prebiotic effects of cereal arabinoxylans**

As reported before, in grains of wheat and related cereals, dietary fiber is predominantly composed of arabinoxylans (AXs). These cell wall components typically consist of a linear backbone of β-(1–4)-d-xylopyranosyl units, which may be substituted by α-l-arabinofuranosyl units [36]. The structure and the physicochemical properties of AX from different layers in cereal kernels are very diverse. The cereal's arabinoxylans (AX) are the main dietary fibers in a balanced human diet. The physiological impact of AX consumption strongly depends on their structures and properties as different impacts on the microbial population and fermentation products in the intestinal tract of rats. The consumption of extractable arabinoxylan of wheat bran increases the mass of the cecal contents. It is known that the consumption of soluble fermentable fiber by rodents causes increase in the mass of the cecum content. Extensive fermentation of water-extractable arabinoxylan or arabinoxylan oligosaccharides reduce the pH, suppress relevant markers of the proteolytic breakdown, and induce a selective bifidogenic response [37].
