Aged Beef Research Articles

SEX OF CALF AND AGE OF DAM ADJUSTMENTS FOR SOME PERFORMANCE TRAITS IN TWO POPULATIONS OF BEEF CATTLE

Sex of calf and age of dam effects on birth weight, preweaning ADG, 180-day weaning weight; and age of dam effects on yearling weight, postweaning ADG in males, and 18-mo weight in females were studied in a Hereford and a beef Synthetic population. The effects of breed, sex of calf, age of dam and year were significant on preweaning traits. The superior milking ability of Synthetic cows over Herefords was more pronounced for male than female calves. Additive and multiplicative adjustment factors were calculated from the least squares analyses. Additive adjustments for age of dam and multiplicative adjustments for sex of calf were found most suitable for preweaning traits. Three methods of application of adjustment factors were studied. Multiplicative sex of calf adjustment followed by additive age of dam adjustment was found to be most effective as indicated by the reductions in mean squares for main effects and interactions. Additive and multiplicative age of dam factors are presented for yearling weight in males and 18-mo weight in females. Use of additive factors is recommended. Extending weaning weight age of dam adjustments for postweaning traits was not found suitable in this study. Key words: Beef cattle, age and sex, adjustment factors

Effects of Hot‐Boning and Particle Thickness on Restructured Beef Steaks

ABSTRACTRestructured steaks were made using hot‐boned or aged beef made from sliced particles (2.5 mm or 5.0 mm thick). Beef slices were formed to make restructured steaks. The steaks were evaluated for cooking characteristics, textural properties and sensory attributes. Restructured steaks made from hot‐boned beef were generally considered less tender and received lower texture desirability, flavor desirability and overall palatability ratings as compared to steaks made from aged beef. Restructured steaks made from larger meat slices (5.0 mm) were less tender and received lower texture desirability ratings than restructured steaks made with thinner slices (2.5 mm).

Reducing Postmortem Aging Time of Beef with Electrical Stimulation

ABSTRACTTwo studies (Study 1 = 23 forage‐fed steers; Study 2 = 20 grain‐fed steers and heifers) were conducted to determine relationships of electrical stimulation (ES) and/or postmortem aging (PA) to tenderness of beef. For Study 1, steaks from ES sides had lower (P < 0.05) Warner‐Bratzler shear (WBS) values than steaks from not‐ES sides for each PA period. In addition, the percentage reduction in WBS values was greater for the steaks from the ES‐Day 2 group (–29.5%) than for steaks from even the longest PA period (14 days) from the not‐ES group (–25.8%). For Study 2, during the fist three PA periods (1, 2 and 5 days), ES resulted in more desirable (P < 0.05) flavor ratings (Day l), higher (P < 0.05) tenderness ratings and lower (P < 0.05) WBS values (Day 1, 2, 5) and more desirable (P < 0.05) overall palatability ratings (Day 1, 2). During the last three PA periods (8, 11 and 14 days), ES resulted in higher (P < 0.05) tenderness ratings (Day 8), lower (P < 0.05) juiciness ratings (Day 11, 14) and lower (P < 0.05) WBS values (Day 8). Based on these results, ES had the greatest impact on beef palatability if the period of aging was 8 days or less; with additional aging time, ES effects on palatability were negated. When each treatment (ES, not‐ES) was divided into two groups based on median tenderness ratings for the not‐ES group, ES had the greatest impact on those carcasses in the “tough” group while ES had little impact on those carcasses in the “tender” group. ES will accelerate the postmortem aging of beef but the aging time reduction and extent of ultimate tenderization appears to be affected by the inherent tenderness of the beef.

The Limulus Lysate Endotoxin Assay as a Test of Microbial Quality of Ground Beef

The Limulus lysate test (LLT) for endotoxin assay has been found to be an excellent, simple and rapid test of microbial quality of refrigerated ground beef. In fresh ground beef held at 5°C for 7–12 d, LLT titres increased from 102–105 and correlated very highly with extract‐release volume (ERV) data and total viable Gram negative counts at both 5° and 30°C. The LLT was negative for fresh beef containing low numbers of bacteria and on aged beef in the absence of increasing numbers of Gram negative bacteria. Of 14 Gram negative meat isolates, all gave a positive LLT while none of eight miscellaneous Gram positive bacteria did. The use of this test provides objective information on the microbial quality of fresh refrigerated ground meats in 1 h. Based upon this study, it is suggested that a 0·1 ml inoculum from a 103 dilution of good quality ground beef should produce a negative lysate test and thus serve as an additional rapid screening test of meat microbial quality.

The temperature coefficient of beef ageing

AbstractA study has been made of the effect of holding temperature on the ageing of beef sternomandibularis muscle. Ageing rate increased exponentially up to 40°C, rose more slowly to a maximum at 60°C, and then decreased sharply to approach zero at 75°C. The temperature coefficient of ageing was 2.4 and was constant over the range 0–40°C. This high Q10 was reflected in the high positive enthalpy of activation, (61.5 kJ). The extent of ageing was also sensitive to holding temperature; maximal extent of ageing was achieved up to ∼60°C, above this, the extent fell to a minimum at ∼65°C, despite the fact that the initial ageing rate at this temperature was still quite high.

Predominant Psychrotrophic Bacteria on Fresh and Aged Ground Beef and Antelope

Predominant psychrotrophic bacteria on fresh and aged ground beef and antelope were identified. In addition, psychrotrophic bacteria were enumerated. The predominant bacteria on ground beef and antelope were similar. A change in the predominant bacteria before and after aging was noted.

Survival of Salmonella dublin and Salmonella typhimurium in Lebanon Bologna

Survival and destruction of Salmonella dublin and S. typhimurium added to Lebanon bologna was studied during manufacture of this sausage. During the aging period of salted cubed beef at 5 C, viable cell counts of S. dublin did not change over a 10-day period. Cell counts of S. Dublin were reduced 3 to 4 log cycles during the 4-day fermentation at 35 C; further reduction in the viable Salmonella count occurred during mellowing of the bolognas at 5 C. The number of S. typhimurium was usually reduced to an undetectible level before the end of the fermentation. Salmonella typhimurium was consistently more sensitive to the acid conditions of Lebanon bologna than was S. dublin. Introduction of an optional cooking step indicated that heating of bolognas to 51.7 C or above led to destruction of salmonellae. Unaged beef which was not inoculated with starter culture did not ferment and there was very little reduction in numbers of added salmonellae. Salmonellae were destroyed more rapidly in Lebanon bologna made from unaged beef with starter culture than in bologna made from aged beef (natural flora fermentation). Smoking also appeared to contribute to destruction of salmonellae. Four commercial Lebanon bolognas were tested for the presence of salmonellae but none were detected.

Lipid‐soluble components of meat flavors/odors and their biochemical origin

AbstractA review of the lipid‐soluble constituents important in the flavor‐odor, of various meats is presented. In addition, the focus of current research at The Pennsylvania State University in these areas is discussed. Special emphasis is given to the flavor of aged beef, swine sex odor, mutton flavor, turkey‐chicken skin flavor, and mechanically deboned turkey‐chicken flavor. The data presented include both chemical analyses and the results of sensory evaluation. Metabolic pathways and biochemical mechanisms in the formation of meat flavor‐odor components are presented and discussed.

Studies in Meat Tenderness 8. Ultra‐structural Changes in Meat During Aging

SUMMARY: During the aging of beef, the external loading required to stretch sterno‐ mandibularis muscle to its fullest extent declines 5‐10‐fold from the maximum of 2 Kg/cm2 muscle attained at rigor onset. This loss of tensile strength is due to a weakening of the myofibrillarstructures at the junction of the I filaments with the Z discs of the sarcomeres. The Z discs undergo progressive changes and lose ground substance as aging proceeds. There is no obvious structural change in the I filaments during aging although a weakening in the association of the constituent proteins of these structures apparently occurs.

Concentration of Inosine 5′‐Monophosphate in Meat

SUMMARYConcentrations of inosine 5′‐monophosphate (IMP) were not significantly different in the longissimus dorsi, biceps femoris, and semimembranosus muscles of six pork carcasses sampled 48 hr post‐mortem. On aging beef for 28 days at 0.1–1.5°C (33–35°F) the peak concentration of IMP (5.4 μM/g) occurred at 12.hr post‐mortem. Other values through the 4th day of post‐mortem aging were approximately the same. Following the 4th day, a gradual but steady decline in IMP content was observed until a value of only 0.75 μM/g or less than 15% of the peak IMP concentration remained after 28 days storage. A wide range of IMP concentration was observed between muscles obtained from different species, with beef sampled at 0 hr containing the highest amounts (4.71 μM/g) and pork heart muscle sampled at 0 hr containing the least (0.13 μM/g).

Response of the extract-release volume and water-holding capacity phenomena to microbiologically spoiled beef and aged beef.

The aging of ground beef was effected by storing in gas-impermeable, sterile plastic bags with incubation at 7 and 15 C. Control meat from the same preparations was wrapped in aluminum foil and stored at the same temperature. In three experiments where control meat was tested, aged meat did not attain a log bacterial number of ca. 8.4 per gram until an average of 6 days after this level was reached in control meats. This degree of difference was shown in values for both extract-release volume (ERV) and water-holding capacity. The previously reported ERV value of around 25, which was found to correspond to an average log bacterial number of ca. 8.5 per gram for ground beef allowed to spoil in aluminum foil and freezer paper, was approximated for aged meats, which required an average of 9.7 days to attain this number compared with 4.1 days for unaged meats. Plate count methods indicated the predominant flora of aged beef to be gram-negative, facultatively psychrophilic rods.

Studies in Meat Tenderness II. Proteolysis and the Aging of Beef

SUMMARYThe proteolytic changes which occur in the longissimus dorsi muscles of beef carcasses during 30 days' aging at 2°C give rise to a mean increase of nonprotein nitrogen of 0.045mM/g meat, representing a degradation of 2.3% of the meat protein. The tenderizing and proteolysis which occur during aging are not related, for differences in the rates of tenderizing among carcasses arc not paralleled by similar differences in the rates of proteolysis. Bacterial action is not responsible for the observed proteolytic and tenderizing changes.

Response of the Extract-Release Volume and Water-Holding Capacity Phenomena to Microbiologically Spoiled Beef and Aged Beef

The aging of ground beef was effected by storing in gas-impermeable, sterile plastic bags with incubation at 7 and 15 C. Control meat from the same preparations was wrapped in aluminum foil and stored at the same temperature. In three experiments where control meat was tested, aged meat did not attain a log bacterial number of ca. 8.4 per gram until an average of 6 days after this level was reached in control meats. This degree of difference was shown in values for both extract-release volume (ERV) and water-holding capacity. The previously reported ERV value of around 25, which was found to correspond to an average log bacterial number of ca. 8.5 per gram for ground beef allowed to spoil in aluminum foil and freezer paper, was approximated for aged meats, which required an average of 9.7 days to attain this number compared with 4.1 days for unaged meats. Plate count methods indicated the predominant flora of aged beef to be gram-negative, facultatively psychrophilic rods.