Off-campus UNL users: To download campus access dissertations, please use the following link to log into our proxy server with your NU ID and password. When you are done browsing please remember to return to this page and log out.
Non-UNL users: Please talk to your librarian about requesting this dissertation through interlibrary loan.
Factors affecting endogenous proteolytic enzymes and their relationship to meat tenderness
Abstract
Three studies were conducted with cattle and sheep to examine the activities of acidic proteases (cathepsin B and cathepsin B + L) and calcium dependent proteases (CDP) and their relationship to tenderness due to differences in growth rate, breed types and postmortem conditions. Differences in postmortem tenderness were achieved in the three studies by limiting protein or energy in growing lambs, selecting Bos taurus and Bos indicus breed types, and manipulating postmortem pH and temperature decline in beef carcasses. In study I, chops from growing lambs fed a control diet had higher (P $<$.05) Warner-Bratzler shears (WBS) than chops from lambs fed diets restricted in energy or protein. Dietary treatments and realimentation periods did not consistently differ in cathepsin B + L activity. In study II, at d 1 tenderness did not differ among breed types; however, by d 10 of aging, steaks from Angus steers were more (P $<$.05) tender than steaks from ${1\over2}$ Brahman and ${3\over4}$ Brahman. The Angus and ${1\over4}$ Brahman steaks had significantly more cathepsin B + L activity than the ${3\over4}$ Brahman. The CDP inhibitor was positively correlated to d 1 WBS (r =.41, P $<$.05) and cathepsin B + L activity was negatively correlated to WBS at d 10 (r = -.44, P $<$.05). In study III, time required for carcass sides to achieve pH 6.3 and muscle temperature at pH 6.3 were correlated (P $<$.05) with d 3 WBS (r =.40, r = -.56, respectively) d 9 WBS (r =.37, r = -.49, respectively), cathepsin B activity (r = -.34, r =.43, respectively) and cathepsin B + L activities (r = -.43, r =.34, respectively). CDP-I activity was correlated (P $<$.05) with d 3 WBS (r = -.53) and d 3 sensory panel tenderness (r =.47). Cathepsin B + L activities at d 3 were correlated (P $<$.05) with d 3 sensory panel tenderness (r =.37). Cathepsin B activity at d 9 was related (P $<$.05) to d 9 WBS (r = -.39) and d 9 sensory panel tenderness (r =.42). These studies suggest that differences in meat tenderness due to differences in breed types and postmortem conditions may be partially explained by differences in proteolytic enzyme activity.
Subject Area
Livestock|Food science
Recommended Citation
Johnson, Mark Haas, "Factors affecting endogenous proteolytic enzymes and their relationship to meat tenderness" (1990). ETD collection for University of Nebraska-Lincoln. AAI9121924.
https://digitalcommons.unl.edu/dissertations/AAI9121924