Effects of high-temperature conditioning on enzymatic activity and tenderness of Bos indicus longissimus muscle.
We studied the effects of high-temperature conditioning (HTC) on beef longissimus (LM) and semitendinosus muscles. Eleven 5/8 Sahiwal x Angus, Hereford or Angus x Hereford crosses (seven heifers and four steers) were slaughtered. Alternate carcass sides were held at 22 +/- 3 degrees C for 6 h, then chilled at -1 degree C for 18 h. The opposite, control (C) sides were chilled at -1 degree C for 24 h. Samples were removed only from the LM at various times to determine calcium-dependent protease (CDP) and CDP inhibitor (INH) activity, cathepsins B and B + L activity, shear-force, sensory panel traits, myofibrillar fragmentation index (MFI) and sarcomere length. Results were analyzed by least squares procedures; our model included fixed effects of temperature, sex and their interaction. The LM temperature remained higher (P less than .01) for the HTC treatment at 3, 6, 9 and 12 h postmortem. In addition, HTC increased the rate of pH decline which resulted in pH differences (P less than .01) at 6, 9 and 12 h. At d 1, LM steaks had lower (P less than .05) shear forces (8.3 vs 9.6 kg) from HTC than C carcasses. At d 14, LM shear forces tended (P = .13) to be lower for HTC (6.9 kg) than for C (7.7 kg) carcasses. At, 3, 7 and 14 d, MFI for LM were greater (P less than .07) for the HTC steaks. However, by 6 h postmortem, INH activity had decreased (P less than .10) 35% in HTC samples, but no change had occurred in C samples (P less than .10).(ABSTRACT TRUNCATED AT 250 WORDS)
Whipple
G
G
Dept. of Anim. Sci. and Ind., Kansas State University, Manhattan 66506.
Koohmaraie
M
M
Dikeman
M E
ME
Crouse
J D
JD
D000818:Animals; D002401:Cathepsin B / Q000378:metabolism; D056668:Cathepsin L; D002403:Cathepsins / Q000378:metabolism; D002417:Cattle / Q000502:physiology*; D003546:Cysteine Endopeptidases; D010450:Endopeptidases / Q000378:metabolism; D005260:Female; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008297:Male; D008460:Meat / Q000592:standards*; D009132:Muscles / Q000033:anatomy & histology / Q000201:enzymology / Q000378:metabolism*; D011180:Postmortem Changes; D012518:Sarcomeres / Q000648:ultrastructure
D002403:Cathepsins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; D002401:Cathepsin B; D056668:Cathepsin L