Post-Harvest Strategies to Improve Tenderness of Underutilized Mature Beef: A Review.

Beef muscles from mature cows and bulls, especially those originating from the extremities of the carcass, are considered as underutilized due to unsatisfactory palatability. However, beef from culled animals comprises a substantial proportion of the total slaughter in the US and globally. Modern consumers typically favor cuts suitable for fast, dry-heat cookery, thereby creating challenges for the industry to market inherently tough muscles. In general, cull cow beef would be categorized as having a lower extent of postmortem proteolysis compared to youthful carcasses, coupled with a high amount of background toughness. The extent of cross-linking and resulting insolubility of intramuscular connective tissues typically serves as the limiting factor for tenderness development of mature beef. Thus, numerous post-harvest strategies have been developed to improve the quality and palatability attributes, often aimed at overcoming deficiencies in tenderness through enhancing the degradation of myofibrillar and stromal proteins or physically disrupting the tissue structure. The aim of this review is to highlight existing and recent innovations in the field that have been demonstrated as effective to enhance the tenderness and palatability traits of mature beef during the chilling and postmortem aging processes, as well as the use of physical interventions and enhancement.

Beef quality, biochemical attributes, and descriptive sensory scores of gluteus medius, biceps femoris, and tensor fasciae latae muscles subjected to combined tumbling and postmortem aging.

This study assessed how fresh beef tumbling without brine inclusion combined with aging would affect quality, biochemical attributes, and descriptive sensory scores of sirloin muscles. Paired gluteus medius (GM), biceps femoris (BF), and tensor fasciae latae (TFL) muscles from beef carcasses (n = 16) at 5 days postmortem were assigned to 0 or 120 min of tumbling, after which sections were aged 0 or 10 days. Tumbled GM (p < 0.001) and TFL (p < 0.01) muscles had increased objective tenderness compared to respective controls. Greater cook and initial purge losses were induced in all muscles with tumbling (p < 0.05), while thawing loss and purge loss with aging were similar (p > 0.05). Fragmentation of myofibrils was increased with tumbling and aging main effects (p < 0.001), although degradation of troponin T and desmin were primarily affected by aging only. In general, neither tumbling nor aging affected properties of collagen. Trained panelists assessed muscles aged 10 days for descriptive sensory scores including tenderness (myofibrillar, connective tissue, and overall), flavor (beef flavor identity, bloody/serumy, fat-like, liver-like, oxidized, umami, metallic, and sour), and juiciness (overall). Tumbled GM had greater myofibrillar tenderness than the control group (p < 0.05). Most sensory scores were unaffected by tumbling; however, tumbling increased oxidized and liver-like flavors of GM and TFL, respectively, as well as decreased overall juiciness of BF (p < 0.05). These findings indicate tumbling combined with postmortem aging can improve tenderness of certain sirloin muscles like GM, although some impairments to flavor and juiciness could also occur. PRACTICAL APPLICATION: The findings of this study are applicable to the beef industry to develop postharvest strategies to ensure sufficient tenderization of fresh beef sirloin muscles is achieved. However, the effectiveness of this process would differ between individual cuts, and minimizing possible impairments to flavor and juiciness would be critical.

Tumbling and subsequent aging improves tenderness of beef longissimus lumborum and semitendinosus steaks by disrupting myofibrillar structure and enhancing proteolysis.

Tenderness is an important sensory attribute to the overall eating experience of beef. Identifying novel methods to ensure consistent tenderness, especially in inherently tough cuts, is critical for the industry. This study investigated if tumbling without brine inclusion could be an effective method to improve the quality and palatability attributes of beef longissimus lumborum (LL) and semitendinosus (ST) steaks. Furthermore, interactions with postmortem aging were evaluated to determine how tumbling might affect protein degradation and muscle ultrastructure. At 5 d postmortem, pairs of LL and ST muscles from beef carcasses (n = 16) were bisected, vacuum packaged, and tumbled for 0, 40, 80, or 120 min. Sections were divided and subsequently aged an additional 0 or 10 d at 2 °C. Tumbling for any duration improved instrumental tenderness of LL (P < 0.001) but not ST (P > 0.05) steaks, regardless of aging time. Tumbling exacerbated moisture loss in both muscles shown by greater purge and cooking losses (P < 0.05). Myofibrillar fragmentation was induced through tumbling in both muscles (P < 0.001), which was supported by transmission electron microscopy images. Tumbling for 120 min followed by 10 d of aging resulted in less abundant intact troponin-T in both LL and ST (P < 0.05), as well as less intact desmin in ST (P < 0.05); however, calpain-1 autolysis was not affected by tumbling (P > 0.05). No effects of tumbling, aging, nor the interaction were found for the content and solubility of collagen (P > 0.05). Consumer panelists (n = 120/muscle) rated LL steaks tumbled for any duration higher for tenderness and overall liking compared to control steaks (P < 0.05). For ST, significant interactions were found for consumer liking of tenderness and juiciness. In general, tumbling without subsequent aging resulted in poorer juiciness than non-tumbled (P < 0.05), while at 10 d no differences in juiciness were found between treatments (P > 0.05). For ST steaks that were aged 10 d, 120 min of tumbling resulted in greater tenderness liking than non-tumbled steaks (P < 0.05). These results suggest that tumbling would result in myofibrillar fragmentation and may benefit the degradation of myofibrillar proteins; however, there would be negligible impacts on collagen. Accordingly, tumbling without brine inclusion alone may be sufficient to improve tenderness and overall liking of LL steaks, while combined tumbling with subsequent postmortem aging would be necessary to improve tenderness liking of ST.

Tenderness is a primary driver to the overall eating experience of beef. Postmortem aging is applied to improve beef tenderness through the activity of endogenous proteolytic enzymes; however, certain inherently tough cuts may not reach acceptable levels of tenderness through aging alone. This study investigated if tumbling in the absence of a brine solution, coupled with subsequent postmortem aging, would be an effective strategy to improve the quality and palatability attributes of fresh beef loin (longissimus lumborum; LL) and eye of round (semitendinosus; ST) steaks. Regardless of aging, tumbling for 40, 80, or 120 min improved instrumental tenderness of LL but not ST steaks. Consumer panelists rated tumbled LL steaks to be more tender with greater overall liking compared to those that were not tumbled. Tumbling alone was insufficient to affect consumer liking of tenderness of ST steaks, although tumbling combined with subsequent aging improved tenderness liking. The results supported that tumbling would physically disrupt and fragment the myofibrillar structure, which may aid in the degradation of myofibrillar proteins during postmortem aging.

Impacts of in Utero Heat Stress on Carcass and Meat Quality Traits of Market Weight Gilts.

This study evaluated the impacts of in utero heat stress (IUHS) on the carcass and meat quality traits of offspring when market weight was reached. Twenty-four F1 Landrace × Large White gilts were blocked by body weight and allocated among thermoneutral (IUTN) or IUHS treatments from d 6 to d 59 of gestation. The offspring were raised under identical thermoneutral conditions, and gilts (n = 10/treatment) at market weight (117.3 ± 1.7 kg) were harvested. At 24 h postmortem, the loins (M. longissimus lumborum) were obtained, and sections were allocated among 1 d and 7 d aging treatments at 2 °C. Carcasses from IUHS pigs had lower head and heart weights (p < 0.05), as well as decreased loin muscle area (p < 0.05) compared to IUTN pigs. Loins from the IUHS group had a higher shear force value than the IUTN group (p < 0.05). Treatments had no other impacts on carcass and meat quality traits (p > 0.05), and Western blots suggested increased toughness of IUHS loins would not be attributed to proteolysis. These results suggest minimizing IUHS during the first half of gestation may be beneficial in improving pork yield and quality, though in general the effects of IUHS would be minimal.