EFFECT OF AGING ON BEEF TENDERNESS OF ZEBU CATLLE AND ITS CROSSES GUALACA, PANAMA. 2002.

Abstract

Tenderness is considered as one of the most important factors that decrease the quality of the beef cattle in Panama, while post mortem aging is an enzimatic natural process that improve this organoleptic trait. The objective of this study was to determinate the effect of aging time and packing type on tenderness (Warner-Bratzler Shear) of beef from Zebu cattle and its crosses (crossbred). Longissimus dorsi samples were used and taken 24 h post mortem from both half carcass. Samples were storaged in a freezer at 0°C according with four aging time: 7, 14, 21 and 28 days. lt was evaluated two packing types: plastified conventional (EC) and vaccum packed (EV). Racial groups were: 23 Zebu (Brahman) and 27 crossbred animals (50% Charolais + 50% Brahman and 50% Simmental + 50% Brahman). Data were analyzed through a fixed cross classified generalized lineal model and adjusted means were compared using "t" test. The higher effect on beef tenderness was obtained at 7 days aging (P<0.05) on both types of packing; with a difference of 0.81 Kgf (21.3%) favourable to EV. There was an improvement of 22.7% (0.82 Kgf) using EV respect to EC in crossbred carcass, while in Brahman carcass the improvement was of 20.1% (0.80 Kgf). At day 7 of aging, between both racial groups, crossbred carcasses showed a positive-difference of 0.39 Kgf (12.2%) in EV and 0.37 Kgf (9.3%) in EC. Beef without aging can be classified as intermedia tenderness in Brahman and Crossbred (5.13 and 4.27 Kgf, respectively). lnitial pH was of 6.11 and could limit the proteolitic effect of endogenous enzimes. There was no differences (P>0.05) between racial groups at pH_1h and pH_24h. Bacteriological charges were within permissible parameters, so that aging does not imply risks for public health. It was concluded that aging improve tenderness of the Zebu cattle and its crosses, create aggregated value, increased it for the use of EV.