Effect of Microbial Transglutaminase on Spaghetti Quality

To examine the potential application of microbial transglutaminase (MTG) on semolina dough properties
and quality of raw and cooked spaghetti, the effects of various MTG addition levels on the solubility of proteins,
SDS-PAGE pattern of semolina dough proteins, and textural and structural properties of raw and cooked
spaghetti were investigated using semolina from a high-protein good variety (MACS 1967) and a low-protein poor
variety (PDW274) durum wheat. 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, and its effect on semolina dough properties and spaghetti quality was investigated. The addition
of MTG significantly decreased the solubility of semolina dough proteins. SDS-PAGE results showed that with
increasing levels of MTG, a progressive decrease in the intensity of the bands corresponding to molecular weight of
around 66 kDa was observed. Protein cross-linking reaction catalyzed by MTG resulted in changes in dough properties,
dry spaghetti quality, cooking quality characteristics, and microstructure of cooked spaghetti. However, the
quality improvements were more evident in spaghetti from the poor variety PDW 274 than from the good variety
MACS 1967. The results also showed the ability ofMTG in the formation of heterologous polymers between SPI and
durum wheat proteins to improve the quality of spaghetti samples.