Raman spectroscopic study of the effects of microbial transglutaminase on heat-induced gelation of pork myofibrillar proteins and its relationship with textural characteristics

The effects of microbial transglutaminase (MTG) on heat-induced gelation of pork myofibrillar proteins (PMP) structural changes, textural properties were studied by Raman spectroscopy and texture profile analysis (TPA), respectively. And the relationships between the structural changes and textural characteristics were estimated by principal component analysis (PCA). Changes in the Raman spectra were interpreted as the occurrence of secondary structural changes in myofibrillar proteins with MTG added. Modifications in the amide I (1600-1700 cm(-1)) regions indicated a significant (p<0.05) decrease in alpha-helix content, accompanied by a significant (p<0.05) increase in beta-sheets, beta-turns and random coil content due to the addition of the enzyme. Obvious texture property changes were also determined by TPA. All these changes showed a strong, irreversible heat-induced gel formed due to the addition of MTG. The application of a dimensionality reducing technique such as PCA proved to be useful to determine the most influential properties of heat-induced gel. Significant (p<0.05) correlations were found between these structural changes and the textural characteristics (hardness) in PMP system with the addition of MTG by PCA. The hardness was related positively to fraction of beta-sheet, beta-turns and random coil, and negatively to normalized intensity of 760 cm(-1) and fraction of a-helix. The samples are closely grouped in a cluster defined by level of MTG. (C) 2011 Elsevier Ltd. All rights reserved.