Effect of Hydrolyzing Enzymes on Wheat Bran Cell Wall Integrity and Protein Solubility

Abstract

Cereal Chem. 93(2):162-171Wheat bran contains good quality protein, but given its location inside aleurone cells, this protein has restricted digestibility. The aim of this work was to liberate and solubilize wheat bran proteins via cell wall degradation by using carbohydrate-hydrolyzing and proteolytic enzymes without causing extensive protein hydrolysis. Bran incubated with water (without added enzymes) for 16 h increased the solubilized organic nitrogen content from 14.0 to 42.8%. Enzymes with solely carbohydratehydrolyzing activity increased the water-soluble pentosan and reducing sugar contents but did not significantly increase protein solubilization or protein release from the aleurone cells. Enzymes with proteolytic activity significantly increased the solubilization of protein to 58.2% already at 4 h. Significant protein hydrolysis was detected with a high dosage of protease. However, based on light microscopy, the enzymatic treatment mainly modified the proteins in the subaleurone layer, and it was less effective on proteins inside the aleurone cells. With optimized protease treatment (3 h, 35°C, and 550 nkat/g), effective protein solubilization (>48%) without extensive protein hydrolysis (free amino nitrogen content <45 mg/L) was achieved. In conclusion, intensive solubilization of proteins in the subaleurone layer of wheat bran is possible by using exogenous enzymes with proteolytic activities. † Corresponding

Biochemical characterization and technofunctional properties of bioprocessed wheat bran protein isolates

“…Viscoferm had xylanase activity of 33284 nkat/ml and -glucanase of 44317 nkat/ml. Viscoferm had also side activities of acidic protease 2.5 nkat/ml (pH 5.5), cellulase 13036 nkat/ml (FPU, pH 5.5) and endoglucanase 149 nkat/ml (pH 5.0) (Arte et al, 2016). Phytase had a phytase activity of 25005 nkat/g according to the manufacturer.…”

“…Bioprocessing with lactic acid fermentation and enzymes is an effective tool to alter the dietary fiber and protein composition of cereal brans, and to enhance the bran overall nutritional quality (Coda et al, 2014;Nordlund, Katina, Aura & Poutanen, 2013). In our previous work, treatment of wheat bran with carbohydrases and proteases increased the protein solubilization to 58% (Arte, Katina, Holopainen-Mantila & Nordlund, 2016).…”

Cereal Side-Streams as Alternative Protein Sources

“…Bioprocessing with enzymes or microbes can be utilized to modify bran structure through the action of both endogenous and microbial enzymes, thereby affecting the technological functionality, bioactivity, and bioavailability of bran components (4,5,38,41,50). Treatment of wheat bran with carbohydrases and proteases resulted in increased protein solubilization of up to 58% (4,5), and activation of bran endogenous enzymes resulted in increased solubility of up to 75%.…”

“…Treatment of wheat bran with carbohydrases and proteases resulted in increased protein solubilization of up to 58% (4,5), and activation of bran endogenous enzymes resulted in increased solubility of up to 75%. Enzymatic processing still needs to be improved by, for example, decreasing the treatment time using new or current enzymes.…”

“…Dietary fiber makes up more than half of the bran (56), and 8. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19].3% of the bran is protein (47). The bran proteins are composed primarily of albumins (23.5%), globulins (15.5%), prolamins (18.5%), and glutelins 25.5% (28).…”