The effect of hydrothermal treatment on the physico-chemical properties of wheat bran and the rheological characteristics of the resulting dough

The consumption of healthy food has been on the rise for some years now and adding wheat bran to foodstuffs, especially bread, has played an important role in this context. Wheat bran a by-product of wheat milling, contains about 40–50% fiber and enjoys properties like reducing blood cholesterol and sugar as well as preventing heart disease, obesity, intestine and colon disease. This study reports an attempt to investigate the effect of hydrothermal treatment of wheat bran on the physico-chemical and rheological properties of the resulting dough. Hydrothermal treatment was carried out in an acetate buffer solution at 55°^C for 24h. Five doughs containing no bran, 15% raw bran, 9% hydrothermal bran, 15% hydrothermal bran and finally 15% hydrothermal bran with an excess amount of improver and sugar were investigated. The results showed that hydrothermal treatment affects the physico-chemical properties of bran namely a lower amount of glutathione and as a result, higher amount of disulfide bond formation in flour containing hydrothermal bran. The SEM micrographs showed that the rough surface with sharp protrusions of the raw bran could not be seen anymore after the hydrothermal treatment. The farinograph results showed that dough with 9% hydrothermal bran had considerably improved rheological parameters namely higher breaking time, stability, farinograph quality number as well as lower degree of softening. According to FTIR, the hydrothermal treated bran had a higher amount of amide I and III as well as a lower number of polysaccharides.

Moreover, the images of the dough after a fermentation duration of 2h showed that in comparison to 15% raw bran dough, the one with 9% hydrothermal bran enjoyed a higher height and better stability.