Effect of accelerated aging on shelf-stability, product loss, sensory and biochemical characteristics in 2 lower quality beef cuts

The aim of this study was to determine the impact of accelerated aging (AA) on shelf stability, product loss, sensory and biochemical characteristics of 2 lower quality beef cuts. Triceps brachii (TB) and semimembranosus (SM) were collected and fabricated from 10 USDA Choice beef carcasses and assigned to 1 of 6 treatments: 3 d cooler aged (control), 21 d cooler aged, AA 49 °C for 2 h, AA 49 °C for 3 h, AA 54 °C for 2 h, and AA 54 °C for 3 h. The results showed that AA can decrease APC counts on steak surface and in purge and redness, but increase lightness and product loss of the steaks (P < 0.01). Lower shear force was also found for AA steaks compared to those from the control (P < 0.01), with the AA 54 °C treatments being comparable to 21 d cooler aging. However, the trained sensory panel determined AA steaks were less juicy and flavorful than those from the control and 21 d cooler aged samples (P < 0.05). There was no off-flavor detected in AA steaks though lipid oxidation was higher in AA samples than those in the control steaks (P < 0.01). The AA treatments stimulated cathepsin activity (P < 0.05), which may have enhanced the solubilization of stromal proteins and led to a different troponin-T degradation pattern compared to those from the 21 d aged samples (P < 0.01). Although AA is an economical and time-efficient method to increase tenderness of lower-quality beef cuts, further research is needed to determine strategies to mitigate the decrease in juiciness from AA treatments.

Structural changes in collagen and aggrecan during extended aging may improve beef tenderness

The aim of this study was to characterize structural and property modifications of intramuscular connective tissue (IMCT) during extended aging. Longissimus lumborum (LL), Gluteus medius (GM), and Gastrocnemius (GT) muscles were collected from 10 USDA choice carcasses, fabricated and assigned to one of four aging periods: 3, 21, 42, or 63 days (n = 120). As expected, tenderness improved, and IMCT texture weakened after 21 days of postmortem aging (dpm; P < 0.05). In addition, transition temperature of collagen decreased (P < 0.01) after 42 dpm. It is interesting to note the collagen structure was also altered where relative % of γ chain decreased after 42 dpm (P < 0.05), and the α1 chain % increased at 63 days (P < 0.01). Finally, The LL and GT had a decrease in the 75 kDa aggrecan fragments from 3 to 21 to 42 dpm (P < 0.05). This study provided evidence that IMCT weakens during postmortem aging due to the modifications of IMCT components such as collagen and proteoglycan.

An Investigation of the Altered Textural Property in Woody Breast Myopathy Using an Integrative Omics Approach

Woody breast (WB) is a myopathy observed in broiler Pectoralis major (PM) characterized by its tough and rubbery texture with greater level of calcium content. The objective of this study was to investigate the functionality/integrity of WB sarcoplasmic reticulum (SR), which may contribute to the elevated calcium content observed in WB and other factors that may influence WB texture. Fourteen Ross line broiler PM [7 severe WB and 7 normal (N)] were selected, packaged, and frozen at -20°C at 8 h postmortem from a commercial processing plant. Samples were used to measure pH, sarcomere length, proteolysis, calpain activity, collagenase activity, collagen content, collagen crosslinks density, and connective tissue peak transitional temperature. Exudate was also collected from each sample to evaluate free calcium concentration. The SR fraction of the samples was separated and utilized for proteomic and lipidomic analysis. The WB PM had a higher pH, shorter sarcomeres, lower % of intact troponin-T, more autolyzed μ/m calpain, more activated collagenase, greater collagen content, greater mature collagen crosslinks density, and higher connective tissue peak transitional temperature than the N PM (p ≤ 0.05). Exudate from WB PM had higher levels of free calcium than those from N PM (p < 0.05). Proteomics data revealed an upregulation of calcium transport proteins and a downregulation of proteins responsible for calcium release (p < 0.05) in WB SR. Interestingly, there was an upregulation of phospholipase A2 (PLA2), and cholinesterase exhibited a 7.6-fold increase in WB SR (p < 0.01). Lipidomics data revealed WB SR had less relative % of phosphatidylcholine (PC) and more lysophosphatidylcholine (LPC; p < 0.05). The results indicated that upregulation of calcium transport proteins and downregulation of calcium-release proteins in WB SR may be the muscle's attempt to regulate this proposed excessive signaling of calcium release due to multiple factors, such as upregulation of PLA2 resulting in PC hydrolysis and presence of cholinesterase inhibitors in the system prolonging action potential. In addition, the textural abnormality of WB may be the combined effects of shorter sarcomere length and more collagen with greater crosslink density being deposited in the broiler PM.

An investigation on the influence of various biochemical tenderness factors on eight different bovine muscles

This study's objective was to understand the relationships between biochemical tenderness components and subject/objective tenderness of eight muscles from beef carcasses. Longissimus thoracis (LT), pectoralis profundus (PP), supraspinatus (SS), triceps brachii (TB), gluteus medius (GM), rectus abdominus (RA), rectus femoris (RF), and semitendinosus (ST) were collected from 10 USDA upper 2/3 Choice beef carcasses and assigned to a two- or 21-day aging period (n=160). Troponin-T (TNT) degradation, desmin degradation, sarcomere length, collagen content, mature collagen crosslink density, intramuscular lipid content, pH, Warner-Bratzler Shear Force (WBSF) and trained sensory panel analyses were measured. A Pearson correlation analysis was conducted to determine the relationship between each tenderness contributor measured in this study with WBSF or the overall tenderness evaluated by the trained panelist for each of the eight muscles. In addition, multivariate regression models were constructed to confirm this relationship. The results showed that muscle anatomical locations and physiological functions driven by muscle fiber types may explain some of the biochemical/tenderness differences found in this study. The correlation analysis showed that each muscle had a specific tenderness factor(s) that contributed to the overall tenderness. For instance, tenderness for LT, TB, GM, RA, and ST may be influenced more by proteolytic degradation, while the collagen characteristics may primarily influence tenderness for PP. Also, lipid content has a significant influence on GM tenderness. Finally, the multivariate regression model showed that almost all of the biochemical measurements conducted in this study played a minor but important role as an overall tenderness predictor on a whole carcass basis. Increasing the knowledge base on the various tenderness components' level of contribution will allow end-users to develop specific tenderness management strategies to ensure consistent tenderness in beef products.

Meta-analysis of the relationship between collagen characteristics and meat tenderness

Meta-analysis methods were used to investigate the effects of collagen content, solubility and pyridinoline cross-link content on Warner-Bratzler shear force (WBSF) and sensory tenderness in major meat species. Data was collected from the literature on pork, beef and lamb and analyzed independently for each species. The beef data was categorized into subgroups according to muscle (loin and other muscle) and age (young, <18 months and old, ≥18 months). The results showed that in beef, collagen content and pyridinoline cross-link content were positively correlated with WBSF and negatively with sensory tenderness, while collagen solubility was negatively correlated with WBSF. The correlation coefficients were greater in other beef muscles than loin. Significant correlations between collagen content and tenderness attributes were observed in old beef animals. However, non-significant relationships and large variations were found in pork and lamb. More studies with various muscles and ages are required for an in-depth understanding of the relationship between collagen characteristics and meat tenderness.

Evaluation of skin-on goat meat processing on processing efficiency, carcass yield, meat quality, and sensory attributes

The objective of this study was to evaluate the properties of skin-on and skin-off goat processing and carcasses for processing efficiency, fabrication time, biochemical factors, and sensory attributes for stewed goat meat. Thirty-one goats were harvested in 2 separate experiments, either skin-on (n = 16) or off (n = 15). The carcasses were fabricated into four primals and each primal was cut into cubes. Processing efficiency, carcasses yield, collagen content, moisture, lipid, ultimate pH, and sensory attributes were measured, and multivariate regression analysis were conducted. The skin-on group had greater overall yield compared to the skin-off group (P < 0.01). Consumers rated goat shoulder meat with the highest overall liking compared to the other primals (P < 0.01), regardless of skin present (P > 0.10). Finally, lipid % was found to be the most essential palatability trait to American Asian consumers.