No abstract

The influence of prerigor temperature and pH on muscle chemistry of the inside semimembranosus (ISM) and outside semimembranosus (OSM) in relation to initial color and color uniformity and stability was investigated. Cold-boned ISM had a slower (p < 0.05) chill rate; faster (p < 0.05) pH decline; higher (p < 0.05) transmission values; and less (p < 0.05) metmyoglobin reducing ability, oxygen consumption, water holding capacity and color stability than the OSM. Cold-boned steaks were 2-toned in color and visually unacceptable at d 3 of display. Hot-boned ISM and OSM chilled at the same rate and had similar pH declines, similar chemical characteristics and uniform stable color for 5 d of display. Chilling beef ISM faster should produce uniform stable color.

Degradable films from spray-dried (SD) and flash-dried (FD) wheat gluten prepared at various pHs, salt levels, temperatures, and shearing times were compared. Differences were observed in properties of the films related to processing conditions. Films prepared from SD wheat gluten were thicker, and had higher tensile strengths and Young's moduli. SD wheat gluten solutions applied as coating material resulted in Grade Aquality shell eggs maintaining quality for 30 days at room temperature. Additionally, SD wheat gluten coating increased the water stability of starch-based packaging.

The relationships of 6 assays for metmyoglobin (Metmb) reducing ability to color stability and the chemical differences between the inside (ISM) and outside (OSM) beef semimembranosus (SM) muscle after 5 or 14 d storage were investigated. The ISM had less (p < 0.05) color stability than the OSM regardless of time post mortem, and both muscle portions were more color-stable when stored for 5 d rather than 14 d. Among the assays, aerobic reducing ability correlated best with visual color scores (r = -0.58) and Metmb accumulation (r = -0.61) in the SM. The ISM had less reducing ability than the OSM, which can be attributed partially to lower oxygen consumption rate and NAD concentrations (p < 0.05).

Color and microbiology of steaks and ground beef stored in 0.4% CO, 30% CO 2 , and 69.6% N 2 (but removed from the modified atmosphere before display) were compared with product displayed immediately after packaging in polyvinyl chloride film (only atmospheric oxygen). Storage of ground beef, loineye, inside round, and tenderloin steaks for up to 35 d in 0.4% CO resulted in typical initial bloomed color. Compared with product exposed to only oxygen, storage of ground beef and loineye steaks in 0.4% CO decreased color stability, whereas color life increased for tenderloin and inside semimembranosus muscles. No steaks having acceptable color had spoilage levels of microbes (Ն Ն Ն Ն Նlog 7). Thus, carboxymyoglobin formed from 0.4% CO did not mask microbial spoilage.