Quality characteristics of ground round formulated with three fat sources

"December 2013.""A Thesis presented to the Faculty of the Graduate School at the University of Missouri--Columbia In Partial Fulfillment of the Requirements of the Degree Master of Science."Thesis supervisor: Dr. Bryon R. Wiegand.This research was performed to determine if changing the source of fat for inclusion in ground beef from the round will cause a change in the number of days that the ground beef has a viable shelf-life as influenced by oxidation. The objectives were to evaluate the color stability and degree of fat oxidation during retail storage of ground beef patties and to determine the influence of fatty acid profile on the extent of ground beef lipid oxidation and shelf-life of ground beef patties over 7 d of refrigerated retail storage. Beef carcasses (n = 30) were chilled for two days and then fabricated. Semimembranosus muscles (IMPS # 168), commonly referred to as top or inside round, were removed and closely trimmed. Within each carcass, three sources of fat (kidney and pelvic = KP, subcutaneous = S, or seam = I) were sourced to blend with the top round to achieve either 75 or 95% lean ground beef. Trim and fat blocks were individually ground through a coarse 10 mm plate. Final meat blocks (862 g lean and 45 g of fat) for 95% lean product and (680 g of meat and 227 g of fat) for 75% lean product were blended and finely ground through a 4.5 mm plate. The 907 g of viii product from each treatment within animal was then used to create four, 115 g patties to be used for the shelf study. Patties were placed on Styrofoam® trays and overwrapped with oxygen permeable, polyvinyl chloride and placed in refrigerated retail storage (4oC) where an instrumental measurement of color (L*, a*, b*) and thiobarbituric acid reactive substances (TBARS) were collected on d 1, 3, 5, and 7 of the study. The additional 447 g of sample was placed in a whirl-pack bag, stored at 4°C, and used for fat and moisture determination, oxymyoglobin concentration, fatty acid analysis, and calculated iodine value (IV). Data analysis indicated different (P = 0.0004) saturated fat (SFA) percentages (KP > I > S with means of 57.9, 53.5, and 52.1%, respectively). Calculated IV differed (P = 0.003) where KP < I = S with means of 33.9, 37.1, and 38.3Includes bibliographical references (pages 76-82)