Impact of pH on the high-pressure inactivation of microbial transglutaminase. (January 2019)

• Record Type: Journal Article
• Authors: Queirós, Rui P.; Gouveia, Sónia; Saraiva, Jorge A.; Lopes-da-Silva, José A.
• Is Part Of: Food research international. Volume 115(2019)
• Page Start: 73
• Page End: 82
• Publication Date: 2019-01
• Subjects: Microbial transglutaminase -- High pressure -- Inactivation kinetic -- pH -- Optimization -- Response surface methodology; Food -- Analysis -- Periodicals; Food industry and trade -- Periodicals; Food industry and trade -- Canada -- Periodicals; Food Technology -- Periodicals; Food -- Periodicals; Food-Processing Industry -- Periodicals; Aliments -- Industrie et commerce -- Périodiques; Aliments -- Industrie et commerce -- Canada -- Périodiques; Aliments -- Recherche -- Périodiques; Food industry and trade; Canada; Periodicals; Electronic journals; 664.005
• DOI: 10.1016/j.foodres.2018.08.002
• Languages: English
• ISSNs: 0963-9969

Abstract

Abstract: Microbial transglutaminase (MTG) is an enzyme largely used in the food industry, mainly to improve food texture. However, many globular proteins show low susceptibility to the action of this enzyme. High-pressure processing (HPP), being able to change protein conformation, may be a useful tool to increase the accessibility of globular proteins to the action of MTG. Nevertheless, HPP conditions need to be carefully optimized to avoid the expected decrease of enzymatic activity observed above certain conditions of pressure (P), treatment time (t) or temperature (T). Pressure inactivation of MTG under different HPP conditions (200–600 MPa; 20–40 °C; 10–30 min) was evaluated employing a face-centered composite design at four different pH values (4–7). The regression models obtained presented high coefficients of determination and high F values, although they could not explain some of the associated variability. At all the pH values tested, the three main factors (P, T, and t) significantly ( p < 0.05) affected the activity of MTG. At least 20% of MTG was inactivated when low pressures (200 MPa) were used at pH 4 and 5, whereas a higher pressure above 400 MPa was needed to obtain a similar inactivation at pH 6 or 7. MTG pressure-inactivation followed first-order kinetics under all tested conditions. Inactivation rate constants decreased with increasing pressure at constant temperature and pH 4, with a positive activation volume ( V a ), while the opposite was verified for the other pH values. Both activation energy ( E a ) and V a were dependent on pH, however, at the lower pH values, E a and V a did not vary significantly with pressure and temperature, respectively. Overall, MTG can be considered relatively resistant to pressure, particularly near its optimal pH. Graphical abstract: Unlabelled Image Highlights: Microbial transglutaminase is more sensitive to pressure at pH 4–5 than at pH 6–7. Pressure inactivation of microbial transglutaminase followed first-order kinetics. At pH 5, 6 and 7 inactivation rate constants increased with increasing pressure. Both energy and volume of activation were dependent on pH.