Consumer preferences for beef color and packaging did not affect eating satisfaction.

We investigated whether consumer preferences for beef colors (red, purple, and brown) or for beef packaging systems (modified atmosphere, MAP; vacuum skin pack, VSP; or overwrap with polyvinyl chloride, PVC) influenced taste scores of beef steaks and patties. To test beef color effects, boneless beef top loin steaks (choice) and ground beef patties (20% fat) were packaged in different atmospheres to promote development of red, purple, and brown color. To test effects of package type, steaks and patties were pre-treated with carbon monoxide in MAP to promote development of red color, and some meat was repackaged using VSP or PVC overwrap. The differently colored and packaged meats were separately displayed for members of four consumer panels who evaluated appearance and indicated their likelihood to purchase similar meat. Next, the panelists tasted meat samples from what they had been told were the packaging treatments just observed. However, the meat samples actually served were from a single untreated steak or patty. Thus, any difference in taste scores should reflect expectations established during the visual evaluation. The same ballot and sample coding were used for both the visual and taste evaluations. Color and packaging influenced (P<0.001) appearance scores and likelihood to purchase. Appearance scores were rated red>purple >brown and PVC >VSP>MAP. Appearance scores and likelihood to purchase were correlated (r=0.9). However, color or packaging did not affect (P>0.5) taste scores. Thus, consumer preferences for beef color and packaging influenced likelihood to purchase, but did not bias eating satisfaction.

Evaluation of carbon monoxide treatment in modified atmosphere packaging or vacuum packaging to increase color stability of fresh beef.

Our goal was to obtain > 21 days red color stability for carbon monoxide (CO)-treated beef steaks in vacuum packaging (VP). In preliminary tests, pretreatment for 24 h in a 5% CO modified atmosphere package (MAP) was needed to maintain redness after re-packaging in VP. Pressure pretreatment with 5% CO for 2 h developed redness, but was impractical for large-scale application. Color stability and microbial load were then compared after treatment of steaks in 5% CO-MAP for 24 h, then VP; 100% CO-MAP for 1 h, then VP; steaks and ground beef in 0.5% CO-MAP; and steaks and ground beef in polyvinyl chloride (PVC) wrap. Steaks remained red for 5, 6, 8 and <1-week storage at 2°C, respectively. Steaks microbial load exceeded spoilage levels (>10(6)cfu/cm(2)) at 5, 6, 7 and <2-weeks, respectively. Thus, extended color stability in VP was achieved by pretreatment with 5% CO for 24 h or 100% CO for 1 h.

Minimum sodium nitrite levels for pinking of various cooked meats as related to use of direct or indirect-dried soy isolates in poultry rolls.

The relationship between sodium nitrite level and pinking was investigated in cooked meats, as measured by panel color score, acetone extraction of NO-hemochrome, and instrumental redness values. Beef was less susceptible than poultry breast meat to nitrite-induced pinking. Minimum sodium nitrite level for pinking was 14, 4, 2, and 1 ppm for beef round, pork shoulder, turkey breast, and chicken breast, respectively. By regression analysis, minimum ppm nitrite for pinking=0.092 (ppm total pigment)+0.53 (R(2)=0.99). High levels of nitrate (>250 ppm as sodium nitrate) and nitrite (>45 ppm as sodium nitrite) were found in direct-dried (DD) soy isolates. Chicken breast rolls formulated with >2% DD soy were pink, but control rolls with 156 ppm sodium nitrate were not pink. Thus, it was concluded that nitrite was the primary pinking agent in DD soy. Indirect-dried (ID) soy isolates contained <11 ppm sodium nitrite, which was insufficient for pinking in poultry rolls.

Effect of sodium phytate, sodium pyrophosphate and sodium tripolyphosphate on physico-chemical characteristics of restructured beef.

The effects of 0.5% sodium phytate (SPT), sodium pyrophosphate (SPP), and sodium tripolyphosphate (STPP), along with 1% NaCl, on physico-chemical properties of restructured raw and cooked beef were evaluated. In raw beef stored for 1 day at 4 ° C, the SPT, SPP, and STPP increased pH and salt-soluble protein level and decreased %MetMb and thiobarbituric acid reactive substances (TBARS), compared to the control with salt alone (p < 0.05). In cooked beef, SPT, SPP, and STPP increased bind strength, cook yield, moisture level, and pH, and decreased TBARS (p < 0.05). SPP and STPP increased orthophosphate in both raw and cooked beef (p < 0.05), compared to the SPT and control. SPT, SPP, and STPP decreased the Hunter color L and b values and increased a value in raw beef (p < 0.05) but had no effect on the Hunter color values in cooked beef. The binding value of SPP and STPP were similar over time, and the time to reach maximum binding strength was 10s longer than SPT and 25s longer than the control. These results indicate that SPT compares favorably with traditional phosphates for bind strength and cooked yield, but SPT was slightly more effective than other phosphates for reduction of TBARS 1 day after cooking.

Sodium hydroxide and sodium tripolyphosphate effects on bind strength and sensory characteristics of restructured beef rolls.

Restructured beef rolls formulated with 1% NaCl (controls) or with 1% NaCl plus 0.07% NaOH or 0.375% sodium tripolyphosphate (STPP) had different (p < 0.05) relative bind strength and cooked yield, as follows: STPP > NaOH > controls. Percent cooked yield was inversely affected (p < 0.05) by added water level (5 > 10 > 20%). Bind values were lower (p < 0.05) in rolls with 20% added water. NaOH and STPP rolls had higher pH (p < 0.05) than controls (6.28, 6.22, and 6.07, respectively). Panel cohesiveness, juiciness, and acceptability scores were also generally higher (p < 0.05) for NaOH and STPP rolls, compared to controls. There was a high correlation (0.93) between panel cohesiveness scores and instrumental bind values. At 20% added water, STPP rolls were preferred, but at 10% added water, STPP and NaOH rolls were similar in overall acceptability. Thus, if added water level is not too high, NaOH alone or perhaps with other binding agents may be an alternative to phosphates in cooked beef rolls.

Effects of time on feed and post-mortem aging on palatability and lipid composition of crossbred Wagyu beef.

Twenty-seven Wagyu-sired steers were fed for 90 (14 steers) or 170 (13 steers) days to study the effects of time on feed on palatability and fatty acid composition, and the effects of post-mortem aging time (2, 4 or 10 days) on palatability. Hot carcass weight, fat thickness, longissimus dorsi muscle area, yield grade, estimated kidney, pelvic and heart fat and maturity score were increased (p < 0.05) by an additional 80 days on the high concentrate feed, but marbling was not changed (p > 0.05). Feeding the high concentrate diet for 170 days increased Warner-Bratzler shear force values (p < 0.05) and tended to decrease tenderness (p > 0.05), flavor intensity and connective tissue scores. For the 90 day feeding group, 4 days of aging improved connective tissue score (p < 0.05) and tended to increase (p > 0.05) tenderness scores and decrease shear force, compared with 2 days of aging. For the 170 day feeding group, 10 days of aging improved (p < 0.05) shear force and all sensory attributes except flavor intensity, compared to 2 days of aging. An additional 80 days on feed decreased (p < 0.05) stearic acid and total saturated fatty acids (SFA) and generally increased (p < 0.05) monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), MUFA:SFA, and PUFA:SFA in subcutaneous fat and longissimus dorsi muscle. The cholesterol content of fat and muscle increased (p < 0.05) as time on feed increased. Ninety days on a high concentrate diet was adequate for yearling crossbred Wagyu steers to produce highly acceptable carcasses. The additional 80 days on feed produced little or no overall benefit and the steers became overfinished and less tender. Ten days post-mortem aging improved (p < 0.05) all palatability attributes except flavor intensity.

Inactivation of clostridial ferredoxin and pyruvate-ferredoxin oxidoreductase by sodium nitrite.

Clostridial ferredoxin and pyruvate-ferredoxin oxidoreductase activity was investigated after in vitro or in vivo treatment with sodium nitrite. In vitro treatment of commercially available Clostridium pasteurianum ferredoxin with sodium nitrite inhibited ferredoxin activity. Inhibition of ferredoxin activity increased with increasing levels of sodium nitrite. Ferredoxin was isolated from normal C. pasteurianum and Clostridium botulinum cultures and from cultures incubated with 1,000 micrograms of sodium nitrite per ml for 45 min. The activity of in vivo nitrite-treated ferredoxin was decreased compared with that of control ferredoxin. Pyruvate-ferredoxin oxidoreductase isolated from C. botulinum cultures incubated with 1,000 micrograms of sodium nitrite per ml showed less activity than did control oxidoreductase. It is concluded that the antibotulinal activity of nitrite is due at least in part to inactivation of ferredoxin and pyruvate-ferredoxin oxidoreductase.

Nitrite inhibition of Clostridium botulinum: electron spin resonance detection of iron-nitric oxide complexes.

Vegetative cells of Clostridium botulinum were shown to contain iron-sulfur proteins that react with added nitrite to form iron-nitric oxide complexes, with resultant destruction of the iron-sulfur cluster. Inactivation of iron-sulfur enzymes (especially ferredoxin) by binding of nitric oxide would almost certainly inhibit growth, and thus is probably the mechanism of botulinal inhibition by nitrite in foods.

Bioavailability to anemic rats of iron from fresh, cooked or nitrosylated hemoglobin and myoglobin.

Bioavailabilities of heme iron prepared from lyophilized, fresh, cooked, nitrosylated hemoglobin and purified myoglobin in semipurified diets were investigated in two experiments. In experiment 1, the bioavailabilities of porcine and bovine hemoglobins were about one-third that for ferrous sulfate regardless of hemoglobin treatments. The efficiency of hemoglobin regeneration by anemic rats fed nitrosylated pork hemoglobin was significantly depressed compared with that by those fed unnitrosylated products. Cooking did not affect the availability of the heme iron, whereas washing tended to increase it. In experiment 2, the hemoglobin regeneration efficiency of the purified myoglobin diet was lower than reported by others for meat diets, and was even lower than that of the purified hemoglobin diet. The respective efficiency values for the basal, basal + FeSO4, hemoglobin, and myoglobin diets (experiment 2) were 0.073, 0.581, 0.199, and 0.125. The efficiencies of converting hemoglobin and ferrous sulfate iron into hemoglobin by the anemic rats were very similar to reported absorption values for these iron sources by iron-deficient human subjects.

Effects of N-nitrosopyrrolidine, nitrite and pyrrolidine on tumour development in mice as related to ingestion of cured meat.

The incidence of tumours in mice fed a standard chow diet and given either N-nitrosopyrrolidine (NPyr), nitrite (NO(2)) or nitrite plus pyrrolidine (NO(2) + Pyr) in the drinking water for 12 months at 100mg, 1 g and 1 g plus 100mg/litre, respectively, was compared with that for a control group (C) receiving no additives. Differences between groups in weight gain and feed consumption were not significant. Group 3 (NO(2)) drank less water (P < 0·05) than those in groups 1 (C) and 2 (NPyr). Water intake of mice in group 4 (NO(2) + Pyr) did not differ from that of any of the other three groups. Survival rates were: 94% (C), 80% (NPyr), 92% (NO(2)) and 83% (NO(2) + Pyr); but the differences were not statistically significant. Gross examination upon autopsy revealed that the incidence of all tumours in group 2 (NPyr) was 10- to 20-fold higher than that in any other group. Histological examination confirmed that NPyr induced more (P < 0.05) malignant tumours in liver and lungs with any other treatment; otherwise there were no significant differences. Results indicated that NO(2) + Pyr (nitrite plus a secondary amine) did not increase the frequency of carcinogenic tumours in mice.

Relationship of mitochondria and sarcoplasmic reticulum to cold shortening.

Sarcoplasmic reticulum and mitochondria preparations from beef and rabbit muscle were shown to bind and release appreciable quantities of Ca(++). Differences between rabbit and beef muscle in Ca(++) binding and release by SR and mitochondrial preparations were not sufficient to account for the massive shortening in chilled beef as compared to little or no shortening in chilled rabbit muscle. Results substantiate the theory of Buege & Marsh (1975) that cold shortening is related to differences in mitochondrial concentration in red and white muscle rather than to differences in the Ca(++)-accumulating ability of SR. In order to explain the reversibility of cold shortening upon rewarming pre-rigor red muscle, a role for both SR and mitochondria is postulated and discussed.

Ultrastructural changes in pre- and post-rigor beef muscle caused by conventional and microwave cookery.

Examination of cooked pre-rigor muscle by TEM (transmission electron microscopy) and SEM (scanning electron microscopy) revealed that all cookery methods resulted in the development of supercontraction bands alternating with areas showing tissue fragmentation and tearing. Microwave cookery produced smaller and less dense supercontraction nodes in pre-rigor muscle with less tearing and fragmentation but more fibre separation. Although cold-shortened pre-rigor muscle cooked by all methods also exhibited supercontraction bands with some tearing and fragmentation in adjacent sarcomeres, the samples cooked by microwaves showed a more uniform repeating pattern of small stretched areas alternating with dense contracted areas. Cooking of muscle in full rigor resulted in myofibrillar protein coagulation and shrinkage but supercontraction nodes were absent. Cold-shortened bicarbonate treated muscle was relatively intact after cooking, exhibiting fusion of the myofibrils and an absence of intermyofibrillar spaces. Results are discussed in relation to possible effects upon tenderness.

M-line protein: Presence of two non-equivalent high molecular weight components.

M-line enriched protein preparations were prepared from glycerated rabbit muscle myofibrils by means of three alternate procedures and analysed with SDS-polyacrylamide gel electrophoresis. A doublet corresponding to polypeptides with molecular weights of 193,000 and 182,000 was obtained in a ratio of2:3, respectively. The two bands are evident in SDS-gels of purified myofibrils, indicating that the proteins represent intrinsic M-line structural peptides. Transmission electron micrographs of the extracted myofibrils confirmed the effectiveness of the extraction procedures for removing M-line proteins. The possible significance of the M-line proteins to meat science is discussed.

Comparison of isolated sarcoplasmic reticulum from bovine and rabbit muscle.

Comparison of the ultrastructure of purified bovine sarcoplasmic reticulum (SR) vesicles isolated from bovine sternomandibularis muscle before and following cold shortening indicates that the decreased Ca(2+)-accumulating ability and increased release of Ca(2+) in cold shortened muscle are not associated with any apparent structural alterations. Sodium dodecyl sulphate (SDS)-gel profiles revealed that the major constituent in both bovine and rabbit SR was Ca(2+)-activated ATPase with a molecular weight of 100,000-105,000. Both SR preparations also showed a proteolipid band at a molecular weight of approximately 10,000. Purified rabbit SR contained three protein components with molecular weights of 75,000, 60,000 and 53,000, whereas bovine SR exhibited a series of five components with molecular weights of 80,000, 66,000, 63,000, 50,000 and 45,000. Although the functions of these isolated proteins were not determined, it is assumed that at least some of them bind Ca(2+) ions in the SR.