Evaluation of xylanases from Aspergillus niger and Trichoderma sp. on dough rheological properties
Although starch is the main polysaccharide used in the fermentation of bread dough, wheat flour also contain some non-starch polysaccharides such as pentosans or hemicelluloses, which may contribute up to 3% of the total polysaccharide content of the flour. Despite being present in relatively low amounts, pentosans and hemicelluloses play an important role in dough rheology and bread properties. The aim of this work is to understand how the xylanases from Aspergillus niger and Trichoderma sp. influence dough rheology, such as elasticity, extensibility, strength and stability. When the extensograph parameters such as extensibility (E) and elasticity (R) were determined, it was possible to note that all dosages of xylanase from A. niger were capable of decreasing the dough elasticity in 21%. Depending on the dosage, the xylanase from Trichoderma sp. can decrease dough stability in the mixing and, consequently, the mixing time during the process. An increased dosage of Trichoderma xylanase decreased the elasticity in 32% and increased the extensibility by 8% following 45 min. It was also observed that raising dosages of Trichoderma xylanase in flour content affected the dough rheology more significantly than raising dosages of A. niger xylanase.
Key words: Xylanase, dough rheological properties, bread, Aspergillus niger, Trichoderma sp.