Effect of microbial transglutaminase on dough rheological properties of wheat flour supplemented with hull-less barley flour

Microbial transglutaminase (MTG) catalyzes the formation of ε – (δ glutamyl -) - lysine cross links in proteins via an acyl transfer reaction. In this study، the impact of microbial transglutaminase (MTG) on dough rheological properties of wheat flour supplemented with 20، 35 and 50% of hull-less barley flour was investigated. The MTG was added at five different levels (0. 0. 5%، 1%، 1. 5% and 2%; w/w) to increase the concentration of lysyl residues and possibly enhance the extent of cross-linking of protein matrix by MTG، a commercial soy protein isolate (SPI) was added at a level of 3% (w/w) in combination with MTG. Extensography results showed that increasing MTG concentration increases the resistance to extension and decreases the extensibility. Farinography results indicated that in flours with 35 and 50% of hull-less barley flour، with increasing MTG doses، dough development time was increased. Addition of MTG in a concentration of 1% in 20% of hull-less barley led to an increase in dough stability time in farinograph. In 50% of hull-less barley treatment، addition of MTG in concentration up to 1. 5% and 2% caused an increase in dough stability time. Mixing tolerance index was decreased with increasing MTG up to 0. 5%. In overall، MTG can improve the rheological properties of dough when it is used in an optimum level.