PSIII-A-10 - Effect of Grain Type and Wet-aging Time on Lamb Meat

Abstract: Visual appearance is critical for the consumer perception of meat quality. Color, as well as juiciness are key factors in determining consumer choice. The objective of this study was to evaluate the effect of grain type and different wet-aging periods on lamb meat. Eighteen castrated Merino x Corriedale lambs (± 40 kg) were randomly assigned to three dietary treatments: 60% corn grain (CG), 60% oats grain (OG) or all fescue hay (Control); diets were isonitrogenous (13% CP). After slaughter, pieces of Longissimus thoracis muscle from each animal were aged during 1, 4, 8 and 16 d. Treatments were arranged as a 3x4 factorial experiment, and color and water-holding variables were measured. No interactions were found (p > 0.05) between type of grain and aging time. Meat from CG showed the highest values for lightness, redness and yellowness (p= 0.0240, 0.0119, 0.0077, respectively), while meat from OG had the lowest values for redness and yellowness. Expressible juice was lowest (p= 0.0307) for Control, intermediate for CG and higher for OG. Meat cooking loss (p= 0.0157) resulted highest for Control, intermediate for OG and lowest for CG. Cooking loss, drip loss (48h) and expressible juice showed differences among aging periods (p= 0.002, 0.0001, 0.0015, respectively); the highest loss was found for 1d-aging, but no differences were detected for the other aging periods. The effect of aging period was greater than type of grain for cooking loss (F: 7.82, 4.48) and expressible juice (F: 5.88, 3.71) respectively. Purge-thaw loss showed no differences for diet type (p > 0.16) or aging period (p > 0.11). A more intense color developed by CG than OG might favor consumer perception of meat quality. Additionally, water-loss seems to be independent of these diets, showing that a longer aging period would be more relevant to get juicier lamb meat.