Aged Beef Research Articles

Relationship between degradation of proteoglycans and weakening of the intramuscular connective tissue during post-mortem ageing of beef

Changes in proteoglycans (PGs) during post-mortem ageing of bovine m. semitendinosus were studied. Electron microscopic observations made it clear that there were two types of PGs in bovine m. semitendinosus immediately post-mortem: PGs were arranged regularly in the basement membrane and PGs associated with collagen fibrils in the perimysium. After 28 days ageing at 4 °C, no PG was observed in the basement membrane, and the greater part of PGs in the perimysium had disappeared. The total amount of PGs decreased with time post-mortem. SDS-polyacrylamide gel electrophoresis indicated that PGs with a high molecular weight disappeared within 7 days post mortem. These results suggest that PGs are degraded during post-mortem ageing of beef. The degradation of PGs seems likely to be the main factor in the weakening of intramuscular connective tissues, i.e., separation of collagen fibrils and fibres from the endomysium and the perimysium, which results in the partial tenderization of beef during post-mortem ageing.

Accelerated Postmortem Aging of Beef Utilizing Electronbeam Irradiation and Modified Atmosphere Packaging

ABSTRACTThe combined effects of electron‐beam irradiation and modified atmosphere packaging (MAP) with 25% CO2 and 75% N2 were examined. Steaks from prerigor beef longissimus (lumborum and thoracis) were prepared, placed in MAP, irradiated with 2 kGy, and stored at 15°C or 30°C. Postrigor longissimus steaks from the other half of each carcass were vacuum‐packaged and stored at 2°C. Analysis for tenderness, lipid oxidation, color, and microbial growth were conducted over 2 wk. Aging irradiated prerigor beef at 30°C for 2 days with MAP resulted in similar Warner‐Bratzler shear values as conventional wet aging at 2°C for 7 or 14 days, and steaks did not show discoloration, lipid oxidation, or microbial spoilage.

Effects of postmortem aging time, animal age, and sex on degradation of titin and nebulin in bovine longissimus muscle

This study was conducted to determine degradation of the giant myofibrillar proteins titin and nebulin in postmortem aged beef, with known tenderness values, from animals differing in sex (steers vs bulls) and age (cows vs steers and bulls). Ten bulls and 10 steers (both groups were approximately 14 mo old) and 10 cows (44 to 108 mo old) were slaughtered. Longissimus muscle samples were removed for determination of Warner-Bratzler shear force, sensory panel tenderness evaluation, and SDS-PAGE analysis at 3, 7, 14, and 28 d postmortem. The SDS-PAGE analysis of titin and nebulin revealed that titin often migrated as three closely-spaced bands (T1, T1-2, T2, in increasing order of migration) in 3-d postmortem samples. With increasing time post-mortem, intact titin (T1) decreased and degraded titin (T2) increased in all samples. Within a class (i.e., steers, bulls, or cows) the rate of conversion of T1 to T2 was slower in the less-tender samples. The T1 to T2 conversion postmortem was slower in the intact males (bulls) than in the castrated males (steers). The T1 to T2 conversion postmortem also was slower in the older animals (cows) in comparison to the younger steers, but not in comparison to the younger bulls. Nebulin was degraded by 3 d postmortem in tender samples from steers, but some nebulin remained in the less-tender 3-d samples from steers and in all of the 3-d samples from bulls and older animals (cows). Intact nebulin was absent in all 7-d samples, regardless of the class of animal. Our results suggest that titin and nebulin are degraded at faster rates in more tender beef samples within each of the three classes of animals examined. The rate of degradation seems to differ when sex and age classifications are compared.

Changes in the concentration of biogenic amines and application of tyramine sensor during storage of beef

The vacuum-packaged beef was stored at 10, 5 and 0 °C, and biogenic amines, viable counts and tenderness with the passage of time were measured. Of the biogenic amines analyzed, only tyramine was detected in viable cell counts in the order of 10 5~ 10 6 before the appearance of a faint putrid smell (initial stage of putrefaction) at all three storage temperatures. Cadaverine was detected before the initial stage of putrefaction only at 5 °C. The changes in tenderness ceased in 5 days (10 °C), 10 days (5 °C), 28 days (0 °C), and the meat retained freshness judging from the viable counts and organoleptic evaluation. To estimate bacterial spoilage conventionally, a tyramine sensor which was composed of a tyramine oxidase-immobilized column and an oxygen electrode was applied. The sensor first detected tyramine at 5 days (10 °C), 13 days (5 °C) and 32 days (0 °C). It was confirmed that the tyramine sensor was useful for estimating the bacterial spoilage in aging beef.

Quantification of beef myofibrillar proteins by SDS-PAGE

A semi-quantitative determination of beef myofibrillar proteins using sodium, dodecyl sulphate polyacrylamide gel electrophoresis is described. Bovine serum albumin was used as internal standard. Results indicate a linear relationship between densitometric readings after staining with Coomassie brilliant blue R 250 and protein content. Recoveries of four pure proteins, loaded within a range of 0·5−4 μg, were between 92 and 110%. Heating of beef myofibrillar protein samples during dissolution is shown to be unnecessary. The method allows the quantitative study of myofibrillar degradation during beef aging, without overlapping of troponin-T with tropomyosin bands.

Relationship of restriction fragment length polymorphisms (RFLP) at the bovine calpastatin locus to calpastatin activity and meat tenderness.

Restriction fragment length polymorphisms (RFLP) have been identified at the bovine calpastatin locus. The objective of the present study was to determine whether these polymorphisms are related to variations in calpastatin activity or beef tenderness in unrelated animals of mixed breeding. A sample of 83 crossbred steers from sires representing eight different breeds was examined to determine this relationship. A 2.2-kb cDNA coding for domains 2 through 4 plus a 3' untranslated region of bovine skeletal muscle calpastatin was used as a probe for calpastatin RFLP. Polymorphisms were found using the restriction enzymes BamHI and EcoRI. Polymorphic restriction fragments for BamHI were 9.0 and 5.0 kb and for EcoRI were 6.0 and 4.0 kb. Allelic frequencies for BamHI restriction fragments were .53 for the 9.0-kb allele and .47 for the 5.0-kb allele. Allelic frequencies for EcoRI restriction fragments were .43 for the 6.0-kb allele and >57 for the 4.0-kb allele. No polymorphisms were identified using the restriction enzymes BglII, DraI, or PstI. No associations between EcoRI and BamHI RFLP and 24-h calpastatin activity of Warner-Bratzler shear force at 14 d postmortem were detected. Therefore, the polymorphic EcoRI and BamHI restriction sites within the bovine calpastatin locus do not detect DNA sequence differences responsible for variation in calpastatin activity or tenderness of aged beef. Therefore, these polymorphisms cannot be used to predict tenderness of aged beef from unrelated animals of mixed breeding. These results do not exclude the possibility that other DNA sequences in or near the bovine calpastatin gene are responsible for variation in calpastatin activity or meat tenderness. The lack of a relationship between these calpastatin RFLP and meat tenderness must be distinguished from the well-documented relationship between calpastatin activity and meat tenderness. Therefore, further development of calpastatin-based methods for predicting beef tenderness in unrelated animals of mixed breeding should focus on basic factors influencing calpastatin activity at the molecular and cellular level.

Monitoring of beef aging using a two-line flow injection analysis biosensor consisting of putrescine and xanthine electrodes

A two-line flow injection analysis (FIA) biosensor was developed which can simultaneously detect bacterial spoilage and the progress of aging. This FIA biosensor was composed of a putrescine oxidase immobilized electrode and a xanthine oxidase immobilized electrode as detectors. The putrescine electrode measures putrescine and cadaverine which are produced by bacteria, and the xanthine electrode measures hypoxanthine and xanthine which accumulate in meat with aging. The analytical conditions for this system were set as follows; flow rate, 1 ml/ min; water bath temperature, 30 °C; flow buffer, 0.1 M phosphate buffer (pH 7.0); injection volume for putrescine electrode, 200 μl; injection volume for xanthine electrode, 40 μl; and measurement cycle, 2 min. The linear relationship for standard solution was between 20 and 800 nmol/ml in the putrescine electrode and between 0.1 and 3.0 μmol/ml in the xanthine electrode. The coefficients of variation in standard solutions were 2.14% with the putrescine electrode and 2.83% with the xanthine electrode. The coefficients of variation values in the specimen solution were 3.22% and 3.76%, respectively. This two-line FIA biosensor was applied to the vacuum-packed beef stored at 0, 5 and 10 °C. The progress of aging could be monitored at all temperatures, and the bacterial spoilage could be detected before the appearance of putrid odor at 5 and 10 °C. However, at 0 °C the putrid odor did not appear during storage, and neither putrescine nor cadaverine was detected. Thus, this FIA biosensor was confirmed to be useful for the quality control of beef aging at 5 and 10 °C, but not at 0 °C.

Evaluation of beef aging by determination of hypoxanthine and xanthine contents: application of a xanthine sensor

The changes of ATP-related compounds were measured during the aging of sirloin meat of eight bullocks, together with changes in myofibrillar fragmentation index (FI) and inosine-5-monophosphate (IMP) content. The increase in hypoxanthine (Hx) content, (Hx + 1 2 Xanthine (X)) content and K value correlated well with the observed increase in FI ( R 2 = 0.804, 0.819 and 0.801, respectively) and decrease of IMP content ( R 2 = 0.809, −0.839 and −0.965, respectively). An immobilized xanthine oxidase biosensor was tested for its usefulness as a convenient method for measurement of (Hx + 1 2 X ) content. Also, organoleptic evaluation and measurement of FI, free amino acids and ATP-related compounds were carried out. The findings suggested that the xanthine sensor could provide accurate measurements of the (Hx + 1 2 X ) content, and was useful for assessing the progress of aging by the estimation of the changes in tenderness and IMP content.

Japan - no more tough old beef : In FOOD CHEM. (52/4 (439–445) 1995) Y. Yano, N. Kataho, M. Watanabe, T. Nakamura and Y. Asano of Ctr Research Inst Itoham Foods Inc report on “Evaluation of beef aging by determination of hypoxanthine and xanthine contents: Application of a xanthine sensor”.

Japan - no more tough old beef : In FOOD CHEM. (52/4 (439–445) 1995) Y. Yano, N. Kataho, M. Watanabe, T. Nakamura and Y. Asano of Ctr Research Inst Itoham Foods Inc report on “Evaluation of beef aging by determination of hypoxanthine and xanthine contents: Application of a xanthine sensor”.

Assay and Storage Conditions Affect Yield of Salt Soluble Protein from Muscle

ABSTRACTPork and beef muscles were used to evaluate assay and storage condition effects on yields of salt soluble protein (SSP). Assay conditions included pH (5.5, 6.0 or 6.5), extraction volume (6, 9, 12 or 15 X sample weight), homogenization time (30, 60, 90 or 120 set) and centrifugal force (2500, 4000 or 5500 ×g). Storage conditions included postmortem aging (4°C for 0, 7 or 14 days) and freezing conditions (rapid freezing, slow freezing, and freezing‐thawing‐freezing). Highest yield of SSP was obtained using pH 6.0, extraction volume 15 X sample weight, centrifugation at 4000 ×g and homogenization time 90 to 120 set for both pork and beef. Freezing conditions did not affect measurement of SSP. Aging beef for 7 and 14 days postmortem reduced the yield of SSP; however, such differences were not observed for pork.

Changes in Textural Properties of Beef Longissimus Dorsi Muscle During Aging

The effects of vacuum packaging, chilling rate (slow or fast) and fat cover thickness (⩽4 mm or 7-8 mm) on the textural profile analysis properties of longissimus dorsi muscle were assessed during beef aging. The longissimus dorsi muscle was aged on the carcass or in vacuum packaging. Muscle samples were taken on days 0 (24 h post mortem), 2, 4, 8, 12 and 16 to measure the textural properties. The most tender meat was observed on aging days 4 or 8. The aging time influenced cohesiveness and springiness whereas packaging affected gumminess. Similarly, aging time, chilling rate, packaging and fat thickness influenced chewiness through their synergistic effects chill x fat and time x packaging interactions.

Changes in pH and water holding properties of Longissimus dorsi muscle during beef ageing

The effects of vacuum packaging, chilling rate (slow or fast), and fat cover thickness (≤ 4 mm or 7–8 mm) on pH and water-holding properties of longissimus dorsi muscle were assessed during beef ageing. The longissimus dorsi muscles were aged on the carcass or in vacuum packaging. Muscle samples were taken on days 0 (24 h post-mortem), 2, 4, 8, 12 and 16 to measure these properties. Ageing time significantly influenced muscle pH and cooking loss; however, interaction fat × chill × time affected press juice. The pH was also influenced by vacuum-packaged ageing. Press juice positively correlated with cooking loss and pH.

The effects of ante-mortem feed and water withdrawal, ante-mortem electrolyte supplementation, and post-mortem electrical stimulation on the palatability and consumer acceptance of bull beef after ageing (6 days at 1°C)

A total of 120 bulls each weighing approximately 500 kg were used to evaluate the effects of withholding feed and water for various intervals pre-slaughter, ante-mortem supplementation with an electrolyte solution, and post-mortem electrical stimulation on the cooking and palatability attributes and consumer acceptance of boneless rib steaks aged for 6 days at 1°C. The results clearly showed the detrimental effects of withholding feed and water pre-slaughter and the beneficial effects of post-mortem electrical stimulation on the eating quality of bull beef aged for 6 days at 1°C. Taste panel ratings of palatability attributes between electrolyte-treated and untreated animals did not differ significantly. However, consumer evaluations indicated a lower overall palatability rating for electrolyte-treated bulls. The results clearly indicate that feed and water deprivation is detrimental to the palatability attributes and consumer acceptance of aged bull beef.

Effects of manures and fertilizers on asparagus yield, fern mineral content and soil fertility

Asparagus ( Asparagus officinalis L.) growth and soil fertility experiments were initiated with the transplanting of crowns at two locations in Nova Scotia. The objectives of the study were to determine the response of asparagus to different rates and sources of organic and inorganic fertilizers. Annual amendments were applied to provide a total of 80 kg N ha −1. Treatments were the recommended soil test rate of P 2O 5 (100 and 160 kg ha −1 for 1985 and 1986 respectively) and K 2O (40 and 160 kg ha −1 for 1985 and 1986 respectively), one-half of each year's recommended rate of P 2O 5, B at 2.4 and 7.2 kg ha −1, Mg at 54 and 162 kg ha −1, fresh beef manure and aged beef manure (‘compost’). Spear yield, fern tissue and soils were sampled from 1985 through the 1988 harvest season. Tissue analysis of 10 elements was reported. In general, asparagus response to both manure amendments was equivalent to that of the commercial fertilizer treatments. Asparagus yield and fern mineral analysis seemed to reflect differences between the two sites in soil fertility.

Ineffectiveness of Three Added Mold Species to Enhance the Rapid Aging of Beef

Paired beef short loin sections from four U.S. Good and four U.S. Choice carcasses were used to determine the effects of the mold Thamnidium elegans on cooking and palatability characteristics. The longissimus muscle from each section was treated with mold spores and aged for 2 or 4 d or left untreated and aged for 2 or 14 d at 4°C. Sensory panel ratings revealed that mold treatment had no significant effect (P<0.05) on tenderness, juiciness, detectable connective tissue amount, or beef flavor intensity of the loins aged for 2 d. Thawing loss, cooking loss, cooking time, Instron shear force and work force values were not affected (P>0.05) by treatment with T. elegans. Aging untreated meat for 14 d significantly improved (P<0.05) sensory panel ratings for tenderness. No significant difference (P>0.05) was noted between mold treatments (2 and 4 d) when compared to the 14-d untreated aging, for beef flavor intensity, detectable connective tissue amount, shear and work force values. Significant grade effects were noted with U.S. Choice samples having higher (P<0.05) sensory panel ratings for juiciness and beef flavor intensity, and decreased (P<0.05) ratings for connective tissue amount when compared with U.S. Good samples. The data indicate that treatment of sub-primal cuts with T. elegans has little or no effect on palatability and cooking characteristics.

CHANGES IN TENDERNESS DURING AGING OF VACUUM-PACKAGED BEEF

The variation of tenderness during aging of vacuum-packaged beef at different storage temperatures (0, 4, 10 and 13°C) was determined. Tensile and Warner Bratzler (WB) shear measurements were used to assess the tenderness of raw and cooked beef (M. semitendinosus). Coefficients of variation corresponding to each method demonstrated the usefulness of the WB shear test with cooked beef. An exponential decay equation was used to quantify changes in beef tenderness during aging; rate constants and activation energies for each method were calculated. The model was adequate to represent the time dependence of different aging indicators: Biochemical Index of Myofibrillar Aging (BIMA) and Yield Point (YP).

Effects of electrical stimulation and ageing of beef on the gelation properties and protein extractability of isolated myofibrils

The gelation properties of bovine myofibrils, as evaluated by dynamic rheological measurements, were shown to be very sensitive to the variables investigated: stimulation and/or ageing of the meat used, presence of 5 m M pyrophosphate and 5 m M MgCl 2 (PP) and concentration of NaCl (0·3 or 0· M). Statistical evaluation of final gel storage moduli (determined at 70°C) revealed ageing to have a consistent detrimental effect. Fresh, stimulated processing of meat), gave gels of about 40% lower elasticity (storage modulus) than did non-stimulated myofibrils; when PP was included in the gel-forming mixture no effect from electrical stimulation was seen. In spite of the negative effects observed for gel elasticity, the myofibrils in question displayed enhanced protein extractability prior to heating. Electrophoretic results suggest myosin degradation to be partly responsible.

Antibacterial Nature of Molds Isolated from Aged Beef

The antibacterial and competitive nature of the molds Thamnidium elegans, Mucor mucedo and Chaetostylum fresenii, commonly isolated from beef aging at refrigeration temperature for extended periods, were examined to determine if their presence on meat would inhibit bacterial growth. An agar plate method revealed no growth inhibition of six strains of meat spoilage bacteria by the molds examined. Eye round (semitendinosus) roasts were inoculated with spore suspensions containing nine strains of the three fungal species and incubated for 48 h at 4 or 18°C. Initial aerobic bacterial counts (35°C) on the meat samples were 2.4 × 104 CFU/cm2. Mold treatment had no significant effect (P>0.05) on reduction of aerobic bacterial counts (35 and 7°C), coliforms or fecal streptococci when compared with uninoculated controls. No surface fungal growth was evident after 48 h at 4°C, the normal storage temperature for meat, whereas appreciable mycelial development was apparent after 48 h at 18°C. T. elegans, M. mucedo and C. fresenii were not capable of reducing or controlling bacterial growth on meat surfaces at refrigeration or elevated temperatures.

Post-mortem electrical stimulation and high temperature ageing of hot-deboned beef

The effects of electrical stimulation (80–100 V, 15 pps) of hot-deboned, bovine Longissimus dorsi muscles, followed by ageing at 30° or 40°Cfor 5, 7 or 10 h, on the solubility of sarcoplasmic and myofibrillar proteins, soluble non-protein nitrogen, and on the water-holding capacity, colour, tenderness and microbiological status of the meat, was assessed. Comparisons were made with the same traits measured on non-stimulated controls (average muscle temperature, 5°C), which were cold-deboned post rigor, and with hot-deboned, electrically stimulated muscles, subsequently held at 2°C. For each treatment and its corresponding control, six muscles each were studied. Such electrical stimulation produced a typical acceleration of pH fall post mortem and enhanced ageing changes at both 30°C and 40°C. It significantly increased tenderness over non-stimulated, cold-deboned controls. The higher temperature of ageing, however, was significantly associated with adverse colour development, loss of water-holding capacity and increased microbial growth. Electrical stimulation alone would not obviate the need for immediate refrigeration in hot-deboning operations with ambient temperatures of ∼ 40°C.

Proteolytic and Lipolytic Activity of Molds Isolated from Aged Beef

This study evaluated the proteolytic and lipolytic activity of several strains of Thamnidium elegans, Mucor mucedo and Chaetostylum fresenii on selected test proteins and lipids. At 18°C, the zone of hydrolysis to colony size ratio on skim milk agar, representing proteolytic activity after 4 d, was 0.92, 0.80 and 0.67 for M. mucedo, C. fresenii and T. elegans, respectively. A similar trend was noted after 4 d of incubation at 24°C. There was positive lipolytic activity on Tween 80 at 18 and 24°C for the same three molds. The proteolytic and lipolytic activity decreased with decreasing temperatures so that at 4°C, the temperature of most probable use if applied to meat, the effect was negligible unless long incubation times were used. The absence of proteolytic activity of the molds at 4°C and the impracticality of aging beef at 18 or 24°C suggest that treatment of meat with molds to enhance tenderness may not be feasible.