γ-Glutamyl transferase inactivation in milk and cream: A comparative kinetic study

The effect of heat treatment on γ-glutamyl transferase activity in non-bovine and bovine milk – A comparative kinetic and thermodynamic investigation

“…At lower temperature, GGT seems to be more heat stable in skimmed sheep milk, followed by goat and cow milk, whereas at higher temperatures (77 C) the GGT seems to be more heat stable in goat milk when compared with sheep and cow milk. Our results for cow milk are in good agreement with those reported elsewhere (St anciuc et al, 2011), but different than those obtained by Blel, Guingamp, Gaillard, and Humbert (2002). These authors obtained D-values of 7.2 min, 1.7 min and 0.34 min at 69 C, 73 C and 75 C respectively.…”

“…Also, these authors revealed that during lactation cycle over a period of 300 days, there is a small seasonal variation on both whole and skimmed milk. Piga, Urgeghe, Piredda, Scintu, and Sanna (2009) using chromatographic procedure for the determination of GGT activity in Sardinian sheep milk obtained values ranging from 2720 to 3460 U/L with a mean value of 3090 U/ L. Elsewhere, we reported mean values for GGT activities of 4010 and 3200 U/L in whole and skimmed cow milk (St anciuc et al, 2011). The results of this study are in fair agreement with those obtained by Zehetner et al (1995) who measured a GGT activity of 5920 U/L for raw cow milk.…”

Thermal inactivation of lactoperoxidase in goat, sheep and bovine milk – A comparative kinetic and thermodynamic study

“…Comparing these thermodynamic parameters with data from the literature (Dannenberg andKessler, 1988, Levieux et al, 2007;Stȃnciuc et al, 2011), it can be concluded that LPO is more heat stable when compared with other intrinsic indicators of heat treatments applied to milk, such as b-lactoglobulin, alkaline phosphatase and c-glutamyl transferase, respectively.…”

“…Thermal LPO inactivation was described by the first-order kinetics reaction as we reported elsewhere (Stȃnciuc et al, 2011).…”

Fluorometric Detection of Active Alkaline Phosphatase and Gamma-Glutamyl Transferase in Fluid Dairy Products from Multiple Species

“…F or exam ple, colorim etric analysis o f G G T activity indicates first-order inactivation o f G G T when raw milk is heated at 65 to 76°C for 5 to 1,000 s (31). In m any studies, G G T has been deem ed appropriate for estim ating the therm al treatm ent o f m ilk at 70 to 80°C, suggesting that G G T m ay be an appropriate m arker for liquid dairy products treated with high-tem perature, shorttim e pasteurization, or conditions o f 72°C for 15 s (2,6,10,15,16,19,23,24). Sim ilar kinetic studies o f G G T have revealed first-order inactivation at 60 to 85°C for 0 to 30 min (23).…”