Sustained Effects of Muscle Calpain System Genotypes on Tenderness Phenotypes of South African Beef Bulls during Ageing up to 20 Days

The most important factor that determines beef tenderness is its proteolytic activity and the balance between calpain1 protease activity and calpastatin inhibition is especially important, while contributions could arise from calpain2 and possibly calpain3. These processes are however affected by the meat aging process itself. To determine whether genotypes in the calpaincalpastatin system can enhance tenderness throughout a 20 day aging period, South African purebred beef bulls (n=166) were genotyped using the Illumina BovineHD SNP BeadChip, through genebased association analysis targeting the cast, capn3, capn2 and capn1 genes. The WarnerBratzler shear force (WBSF) and myofibril fragment length (MFL) of Longissimus thoracis et lumborum (LTL) steaks were evaluated between d 3 d 20 of aging, with protease enzyme activity in the first 20 h postmortem. Although several of the 134 SNP associated with tenderness, only seven SNP in the cast, capn2 and capn1 genes sustained genetic associations, additive to agingassociated increases in tenderness for at least three of the four aging periods. While most genomic associations were relatively stable over time, some genotypes within SNP responded differently to aging, resulting in altered genomic effects over time. The level of aging at which genomic associations are performed is an important factor that determines whether SNP affect tenderness phenotypes.

Molecular Characterization of Microbial and Fungal Communities on Dry-Aged Beef of Hanwoo Using Metagenomic Analysis

Dry aging has been widely applied for the aging of meat to produce a unique flavor and tenderness of meat. A number of microorganisms are present, forming a community with interactions that affect the meat aging process. However, their comprehensive compositions are still not well understood. In this study, we analyzed longitudinal changes in microbial and fungal communities in dry-aged beef using a metagenomic platform. 16S rRNA sequencing revealed that dry aging led to an increase in bacterial diversity, and Actinobacteria and Firmicutes, which are mostly lactic acid bacteria, were dominant on dry-aged beef. However, prolonged dry aging reduced the diversity of lactic acid bacteria. Sequencing of the internal transcribed spacer (ITS) region showed that fungal diversity was reduced by aging and that Helicostylum sp. was the most common species. These results suggest that there are various microorganisms on dry-aged beef that interrelate with each other and affect meat quality. Understanding microbial characteristics during the aging process will help to enhance beef quality and functional effects.

The Influence of Mitochondria Enzyme Activity on Beef Tenderness

ObjectivesAmong all eating quality attributes, tenderness is often described as the most important factor dictating the overall acceptance of cooked beef, as well as, future decision to repeat purchase. While many intrinsic and extrinsic factors impact end-product tenderness, variation in tenderness is usually attributed to the extent of postmortem proteolysis occurring during meat aging. Evidence from the literature indicates that muscle fiber type composition is a major source of variation in the rate and extent of postmortem proteolysis. One of the major differences that distinguishes muscle fibers is the content of mitochondria. Typically, red muscle (slow-oxidative) is characterized by greater amounts of mitochondria than white muscle (fast-glycolytic). As part of the calcium buffering system, mitochondria sequester large quantities of calcium to maintain a constant cytosolic calcium level. We hypothesized that mitochondria may delay the activation of µ-calpain, the major protease responsible for postmortem proteolysis, through preventing the increase in cytosolic calcium concentration.Materials and MethodsTo test our hypothesis, beef longissimus thoracis muscle samples were collected at 30 min and 16 d postmortem. The 30 min samples were immediately snap frozen in liquid nitrogen and stored at – 80°C, while the 16 d samples were used to determine Warner-Bratzler shear force (WBSF) values. Based on WBSF values, the samples were allocated into less tender (average WBSF = 5.3 kg; n = 8) or more tender (average WBSF = 2.3 kg; n = 8) categories. Succinate dehydrogenase (SDH) abundance, citrate synthase (CS) activity, phosphofructokinase (PFK) activity, and glycogen phosphorylase (GP) activity were compared between the two categories using the 30 min samples. Collected data were analyzed using a Student’s t test and considered significant at P ≤ 0.05.ResultsOur results showed that SDH abundance and CS activity (mitochondrial biomarkers) were significantly greater (P = 0.01 and 0.003, respectively) in less tender samples when compared to more tender samples. On the other hand, PFK and GP activities (glycolytic biomarkers) were greater (P < 0.05) in the more tender than less tender steaks.ConclusionWhile not a cause and effect relationship, these data indicate that mitochondria content likely plays a role in development of beef tenderness.

The effect of aging and muscle type on the quality characteristics and lipid oxidation of lamb meat

The research carried out on meat from 45 ram lambs of the Polish merino breed allowed to determine the effect of meat aging and muscle type on physicochemical characteristics and oxidative stability of lipids. Analysis of physicochemical traits (pH, meat color, expressed juice, cooking loss, shear force, moisture, protein, fat and total collagen content) was performed on fresh and meat aged for 14 d in the longissimus lumborum (LL) and gluteus medius (GM) muscles. The meat aging determined all physicochemical characteristics except protein and fat content. More changes in pH and meat color parameters were defined in the GM muscle compared to the LL muscle. The increase in the tenderness of meat expressed as a reduction (P < 0.05) of shear force values was observed in both muscles aged for 14 d. A lower value (P < 0.05) of the shear force, despite the higher content of collagen, was determined in the GM muscle compared to LL. The investigated muscles differed in the degree of lipid peroxidation expressed as thiobarbituric acid-reactive substances (TBARS) in both fresh and aged meat. The TBARS value was lower (P < 0.05) in the LL muscle than in GM. In the longissimus lumborum muscle, the significantly lower content of polyunsaturated fatty acids (PUFAs) and PUFA n-6 has been recorded. The oxidation stability was not influenced by the meat aging.

INFLUENCE OF BEEF MARBLING SCORE ON QUALITY INDICATORS DURING MEAT AGING

In the experiment, beef samples were used with the marbling scores «moderate» and «good» (n = 4). Half of the samples were packaged in a plastic film under vacuum, while the rest ones were left unpackaged. Aging was carried out for 4, 16, and 28 days in a storage chamber at a temperature of 2 ± 1 °C and a relative humidity of not more than 90 %. During beef aging, pH, sensory indicators of quality and freshness, microstructural indicators, and shear force were evaluated. Regardless of the marbling score, on day 28, sensory indicators of unpackaged beef had the signs of non-fresh meat, while the packaged samples had no deviations. Regardless of the marbling score, sensory evaluation indicated the high quality of boiled meat and broth during the entire aging period for packaged beef and during 16 days for unpackaged beef. Histological studies found that with the increase in beef aging period, the destructive changes in tissues increased as well. On days 16 and 28, samples of packaged beef, both with marbling score «good» and «moderate», corresponded to the second and third stage of meat aging. Changes in unpackaged beef at the corresponding days of aging were less pronounced. The results of a shear force study indicated that, during the entire observed aging period, a gradual decrease in shear force occurred.

The effects of dry or wet aging on the quality of the longissimus muscle from 4-year-old Hanwoo cows and 28-month-old Hanwoo steers

This study was conducted to discover the differences in physicochemical and sensory qualities of beef from 4-year-old Hanwoo cows and 2-year-old Hanwoo steers after undergoing different meat aging methods. Additionally, the possibility of using 4-year-old cows as value-added aged meat was investigated. Loins from eight cows (average 51 months old) and eight steers (average 28 months old) of quality grade 2 were aged for 28 days using dry and wet aging. Analyses were conducted to evaluate meat quality, including moisture content, pH, cooking loss, shear force, nucleotides, free amino acids (FAA), and sensory evaluation. After 28 days of aging, the moisture and shear force for loins from steers and cows were reduced compared with those of non-aged meat (P < 0.05). Cooking loss was reduced by dry aging. Regardless of aging method and gender, aging decreased inosine-5ʹ-monophosphate content but increased FAA content (P < 0.05). Dry aging increased glutamic acid content in meat, and aging the meat of steer increased the content of aspartic acid and glutamic acid (P < 0.05). Before aging, sensory scores for juiciness, tenderness, flavour, and overall acceptance between cow and steer were significantly different (P < 0.05), but the differences disappeared after aging. Therefore, the quality of lower grade meat from 4-year-old cows is comparable to that of meat from 2-year-old steers after aging, regardless of the aging method used.

Effect of breed and aging time on physicochemical and organoleptic quality of beef and its oxidative stability

In this experiment we used the meat of 16 Polish Red-and-White and Simmental bulls slaughtered at the age of 24 months. Physicochemical and organoleptic analyses were carried out on meat aged for 2, 7, 14 and 21 days and subjected to heat treatment. In addition, the effect of aging on oxidative stability and fatty acid profile of meat lipids was examined after 21 days of aging. The meat aging process determined all the physicochemical characteristics except for heating loss, as well as most of the sensory properties of meat. During aging, lightening of muscle colour, increased redness and chroma, and improved tenderness were observed. High scores were given for aroma intensity and taste desirability. The highest scores were awarded to meat aged for 7 and 14 days. The evaluation showed that meat tenderness and delicate texture steadily improved until day 14, after which they remained at a similar level or slightly deteriorated after 21 days of aging. Meat from the conserved breed generally had better scores, which could be influenced by better component scores for delicate texture and juiciness, as well as taste intensity. This study revealed no significant effect of breed on the degree of lipid peroxidation expressed as thiobarbituric acid-reactive substances (TBARS). The amount of malondidehyde was higher in meat aged for 21 days than in fresh meat. Aging did have an effect on the fatty acid profile of longissimus dorsi muscle (MLD) intramuscular fat. Wet aging of meat for 21 days was found to alter the content of capric (C10 : 0), palmitoleic (C16 : 1) and stearic acids (C18 : 0).

How does the dietary cottonseed hull affect the carcass characteristics and meat quality of young bulls finished in a high-concentrate diet?

This study evaluated the effects of diets composed by cottonseed hull and meat aging on carcass characteristics and meat quality from young bulls fed on a high-concentrate system. Thirty crossbred bulls were assigned in a complete randomized experimental factorial design with three diets (CH21: cottonseed hull 210 g kg-1on a DM basis, CH27: cottonseed hull 270 g kg-1on a DM basis and CH33: cottonseed hull 330 g kg-1on a DM basis) and different aging times (24 hours and 3, 7 and 14 days). Meat from CH27 diets presented smaller LM moisture content (p < 0.05). Total lipids were smaller in CH33 diet (p <0.05). At 24 hours, CH21 diet presented smaller LM cooking loss than other diets. The increasing aging time reduced the shear force (p < 0.001) on the LM. Meat from CH27 diet presented the highest luminosity (p < 0.05) and yellowness values (p < 0.001). Three or seven aging days presented smaller values of LM luminosity. Likewise, the increasing aging time presented greater (p < 0.05) yellowness within the LM. Lipid oxidation was lower from CH21 diet (p < 0.001). The fatty acid composition on LM was similar among diets. The use of cottonseed hull could be useful strategies to improve the meat quality and lean beef production.