Dietary administration of 4 ppm of the beta-agonist L-644,969 (Merck Sharpe and Dohme Research Laboratories) to finishing lambs induced a decrease (10 to 14%, P less than .05) in extractable calpain I activity in the longissimus muscle (LD) at death (d 0). At 4 d postmortem (d 4), extractable calpain I levels in the LD of both control and treated lambs were reduced (P less than .001) from those present at d 0, but the extractable activity in the LD was reduced to a greater extent in control than in treated lambs. Calpain II activity was increased 42% (P less than .005) in LD of treated lambs; however, no significant differences were observed between d 0 and d 4 calpain II activity within treated or control LD samples (P greater than .1). Calpastatin activity was higher in the LD of treated lambs (74% on d 0, P less than .001 and 430% on d 4, P less than .001) than in the LD of control lambs. Measurable cathepsin B activity was decreased (29% on d 0, P less than .05) and measurable cathepsin H activity was increased (10% on d 0, P less than .05 and 10% on d 4, P less than .05) in the LD of treated lambs compared with controls. On d 2, 4 and 6 postmortem, degradation in myofibrils isolated from the LD was lower for treated than for control lambs. Warner-Bratzler shear values for loin chops from treated lambs were higher on both d 3 (111%) and 6 (108%) postmortem than for chops from control lambs (P less than .001). L-644,969-induced decreases in muscle proteolytic capacity may limit postmortem myofibril degradation and contribute to the reduced tenderness observed. This decreased proteolytic capacity may contribute to increased muscularity of L-644,969-treated lambs.

Wild rice hulls (WRH) have not been utilized in any valuable manner. Minnesota WRH have been shown by us to possess antioxidant properties. The methanol extract of hulls showed antioxidant activity when added to ground beef, as evaluated by the content of thiobarbituric acid reactive substances (TBARS). The results of an ammonium thiocyanate assay also showed that some fractions of the hull methanol extract (MeOH:H 2 O, 75:25) have strong antioxidant activity. The yield of the evaporated methanol extract was 2.51% of WRH. The crude methanol extract was fractionated according to hydrophobicity. The antioxidant assay revealed that eluates of MeOH: H 2 O (50:50, 75:25) and absolute methanol have the strongest antioxidative activity in ground beef, as measured by the content of TBARS. Antioxidants were isolated from the 75:25 eluate and identified by mass spectrometry as 2,3,6-trimethylanisole (anisole); m-hydroxybenzaldehyde; 4-hydroxy-3-methoxybenzaldehyde (vanillin); and 4-hydroxy-3,5-dimethoxybenzaldehyde (syringaldehyde). Another compound identified, 2,3-dihydrobenzofuran, was a prooxidant.

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Cooked Minnesota wild rice was added at 0, 15, and 30% to low-, intermediate-, and high-fat ground beef patties. Proximate analyses of raw and cooked patties indicated proportional decreases in cholesterol, % fat, % protein, and % ash and increases in % carbohydrate and % moisture, as level of wild rice increased. Sensory evaluations indicated a preference for patties with wild rice over controls (~~0.05). Thiobarbituric acid reactive substances were significantly reduced during storage (~~0.05) by addition of wild rice. Cooking yields were significantly higher for patties containing wild rice over controls.

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