ABSTRACTWhey protein concentrate (WPC) was treated with sodium sulfite to achieve 4 levels of disulfide bond sulfonation (0%, 31%, 54%, and 71% mole/mole). The WPCs were blended with cornstarch to a 32% (weigh/weight) protein content and extruded into an expanded product. Extrudates were collected at 160 °C and 170 °C and analyzed for physical (air cell diameter, expansion ratio, breaking strength, and density) and chemical (water adsorption index [WAI], water solubility index, moisture content, soluble protein, and carbohydrates) properties. The control and 54% sulfonated samples had larger expansion ratios and air cell diameters and smaller densities and breaking strengths than the 31% and 71% samples. Expansion increased at 170 °C in the sulfonated samples. The WAI was influenced by both sulfonation and temperature, whereas the other chemical properties (except moisture content) were influenced only by sulfonation level. Soluble protein and carbohydrate were highest in the control and 54% samples. The anomalous behavior of the 54% sample may have been the result of significant structural and functional changes of α‐lactalbumin that are predicted to occur at approximately 50% sulfonation. Many functional properties of the WPCs were measured and were significantly correlated to the extrudate properties, particularly those related to protein unfolding and flexibility The increased ability for the proteins to become unfolded during extrusion may have promoted protein‐starch interactions, which led to decreases in expansion and overall quality Disulfide bond content did influence the chemical and physical properties of an extruded‐expanded whey protein products.

Case-ready fresh beef is typically packaged in a modified-atmosphere with approximately 80% oxygen and 20% carbon dioxide. Recently, USDA approved distribution of fresh meats in a master bag system using 0.4% carbon monoxide (CO). This study compared effects of packaging system (vacuum, 80% oxygen, 0.4% carbon monoxide), fresh meat storage time (7–21 days) and cooking temperature (49–79 °C) on extent of myoglobin denaturation, color and rancidity in cooked top sirloin steaks. Steaks packaged in 80% oxygen or CO retained desirable red color for 14 and 21 days storage, respectively. Steaks stored in 80% oxygen exhibited the greatest TBA values and myoglobin denaturation at all storage times and cooking temperatures. Steaks stored in high oxygen developed brown interior color at internal temperatures as low as 57 °C, the premature browning effect. Premature browning and rancidity associated with steaks packaged in 80% oxygen was prevented by packaging in 0.4% CO or vacuum.

ABSTRACT: Cooked meat color is an important quality attribute for consumers. This study compared color and thiobarbituric acid (TBA) values of cooked ground beef (internal temperatures of 49 to 79 °C), after storage of raw product in atmospheres of 0.4% carbon monoxide (CO), 80% oxygen, or vacuum at 2 °C for 7 to 21 d. Premature browning, observed as a brown cooked color at internal temperatures as low as 49 °C, was found in patties made from meat stored in 80% oxygen. At all cooking temperatures, samples stored in high oxygen had less internal red color, higher myoglobin denaturation values, and were more rancid with higher TBA values than CO or vacuum‐packaged ground beef. Raw ground beef held in 0.4% CO modified‐atmosphere packaging (MAP) remained bright red throughout the 21‐d storage period. Premature browning and high TBA values in cooked patties were avoided by use of this packaging system. However, internal patty color remained somewhat red even at the highest internal cooking temperature of 79 °C. The persistent pink color observed in CO‐treated patties cooked to 79°C internal temperature was likely due to development of heat‐denatured CO‐hemochrome, rather than the presence of undenatured CO myoglobin. The problems of PMB and high TBA values of cooked patties were also avoided by vacuum packaging. However, the development of dark purple color associated with vacuum packaging of raw beef limits the use of this packaging method for products in retail display. Keywords: beef, packaging, carbon monoxide, oxygen

ABSTRACTThis study compared the effects of 1.4% or 2.7% sodium levulinate or sodium lactate on aerobic plate count (APC), color, pH, and TBA values of fresh pork and turkey sausage. Both sodium lactate and levulinate inhibited growth of aerobic microorganisms during storage compared to controls. Antimicrobial effects of sodium lactate were dose‐dependent, where as 2.7% lactate was significantly more antimicrobial than 1.4% lactate. This was not the case for sodium levulinate where 1.4% sodium levulinate was as inhibitory to microbial growth as 2.7% sodium levulinate. Additionally. 1.4% sodium levulinate was as inhibitory to microbial growth CIS the higher level (2.7%) of sodium lactate. TBA values, color and pH were not affected by either sodium lactate or levulinate. In conclusion, sodium levulinate may have potential as an antimicrobial agent in fresh sausage if it can be obtained at a reasonable cost on a commercial basis.

ABSTRACT: : We extruded a dry mix of 2 parts whey protein concentrate (80% protein) and 1 part cornstarch using water, 0.1 N HCl, or 0.2 M NaOH as the liquid, or adding calcium (1.69% w/w) to the dry mix with water as the liquid. The functionality and acceptability of textured whey protein (TWP) extrudates was determined. Ground beef patties containing up to 40% (w/w) of hydrated TWP extrudates made with base (TWPbase) were as acceptable to a consumer panel as all beef patties. Additionally, patties containing 40% (w/w) TWPbase incurred less cook loss and less diameter reduction after cooking, but were less cohesive than all beef patties.

ABSTRACT: The quality of ground beef stored in high‐oxygen modified atmosphere packaging (MAP) (80% O2 and 20% CO2) was evaluated and compared to controls stored in oxygen‐impermeable chubs. Patties were formed from the stored ground meat at d 1, 6, and 10. Color, microbial load, thiobarbituric acid (TBA) number, and sensory acceptability were measured. Patties from both treatments bloomed to red with a* values > 16. Aerobic plate counts increased to 9 × 105CFU/gby 10 d storage, but were not different (p < 0.05) between treatments. TBA number of high‐oxygen samples increased to 2.1 after 10 d, compared to 0.8 for controls. The flavor of samples in high‐oxygen were rated less desirable after 6 or 10 d.

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.

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.

Calcineurin (Cn; protein phosphatase 2B) is a calcium-activated phosphatase that is highly conserved among eukaryotes. Calcineurin dephosphorylates a wide variety of substrates making it a versatile second messenger for intracellular calcium signals in many tissues. In muscle, Cn transduces signals that determine fiber type, hypertrophy, and commitment to the myogenic lineage. Calcineurin-mediated fiber transitions of fast to slow involve the nucleocytoplasmic shuttling of the transcription factor, NFAT. Less is known about the Cn-mediated signaling pathways that promote muscle hypertrophy and expression of the fast phenotype, although they are undoubtedly intertwined with a variety of other signaling pathways. This paper reviews Cn-dependent signaling in muscle with special emphasis on the role of Cn in mediating fiber type transitions and muscle hypertrophy. To open the door on the role and extent of Cn-mediated signaling in livestock, evidence is presented that in callipyge lambs Cn actively mediates muscle hypertrophy in a fiber type-specific manner. Increased understanding of Cn-dependent signaling in livestock will enhance our ability to control and select for extent of muscling and meat quality attributes. Key words: Calcineurin, signal transduction, muscle, review

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.

ABSTRACT The effectiveness of the Hydrodyne process and low voltage carcass electrical stimulation (ES), either alone or in combination, for tenderizing muscle from callipyge and normal lambs was evaluated. One hundred grams of explosive was used for the Hydrodyne treatment. Reductions in shear force with magnitudes of 33 to 67% were observed for the Hydrodyne treatment for the longissimus (LM) muscle from callipyge and normal lambs, respectively. Carcass ES had no effect (P>0.05) on either callipyge or normal lamb shear values. However, ES improved the response (48%) of the Hydrodyne treatment in the LM of callipyge lamb. Shear force for semitendinosus muscles averaged 3.53 kg and showed no response to either tenderizing treatment. Results suggest successful tenderization of lamb LM with the Hydrodyne technology.

The effects of dietary fat type and iron level on colonic lipid peroxidation were studied in male Sprague-Dawley rats. Sixty rats were fed a basal diet for 1 week, weighed, and randomly assigned to 1 of 6 diet groups. Each group was fed for 6 weeks 1 of 6 AIN-based diets formulated to contain either 15% (w/w) corn oil (C), 1% corn oil + 14% beef tallow (B), or 1% corn oil + 14% menhaden oil (M), and 35 or 880 mg iron/kg diet as ferrous fumarate. Feces were sampled at both the start and end of the trial and thiobarbituric reactive substances (TEARS) were measured. Rats were weighed, then sacrificed, at the end of the trial. Samples of mucosa were taken for TEARS measurement and for immunohistochemical staining to detect proliferating cell nuclear antigen (PCNA). Dietary fat type affected (P < 0.05) TEARS in both the feces and mucosa (B < C < M) in the same order expected for unsaturation of the fat types. Greater dietary iron increased fecal and mucosal TEARS only in rats fed diets containing menhadden oil. Body weights did not differ throughout the experiment among rats fed the different diets, nor were any changes observed in mucosal sections stained for PCNA. Previous evidence which lipid peroxidation causes cellular damage resulting in increased cellular proliferation, and possibly cancer, and results of this research suggest that supplementation of iron in high unsaturated fat diet is unfavorable for health because of extensive lipid peroxidation. (C) 1997 Elsevier Science Inc.

Distribution of heme and total iron in heat-processed poultry products was investigated with light and dark chicken meat in the form of deep fried chicken breasts and legs purchased from fast food restaurants and grocery stores. Heme iron content was determined by the Hornsey method, and total iron was determined with Ferrozine on a wet-ashed digest. The heme and total iron were respectively, 1.7 +/- 0.5 and 6.5 +/- 2.0 mu g Fe/g meat (mean +/- SD) for light chicken meat and 7.6 +/- 1.6 and 19.3 +/- 2.2 mu g/g for dark chicken meat. Heme iron values averaged 29 and 40% for light and dark chicken meat, respectively.

The accuracy, specificity, and precision of several methods normally used to analyze iron in meats were assessed. The most reliable and practical methods were then used to determine the total, nonheme, and heme iron contents of various meats before and after cooking. Total iron was determined by using Ferrozine to detect the iron in wet ash digests. The wet-ashing technique was a novel procedure in which nitric acid was used to digest most of the solids and peroxymonosulfuric acid was used to complete the oxidation. Nonheme iran was determined by using Ferrozine to detect the iron in HCl-trichloroacetic acid extracts. Heme iron content was based on heme extracted into acidified acetone. Total iron values of the meats were consistent with those previously reported, but the percent of total iron present as heme in in many meats was much greater than commonly assumed. This has important dietary implications since heme iron is the more bioavailable form of iron for humans.

This study was designed to determine whether gastric acidity, added phytate or iron status significantly influenced the effects that dietary proteins have on iron absorption. Rats were fed test meals of wheat cereal, with and without an added dietary protein (beef, pork, chicken, fish or egg white), by gavage. The influences of phytate and gastric acid were investigated by adding sodium phytate to the test meals and by treating the rats with cimetidine to inhibit gastric acid production. Iron status was altered by dietary regimens. Significant (P < 0.05) effects of the proteins were determined by comparison of the various protein-containing meals to control meals of cereal or cereal + phytate, as appropriate. Gastric acidity, phytate and iron status were all confirmed as factors significantly affecting iron absorption. Beef, pork and chicken enhanced iron absorption, but only when phytate had been added to the meals and only in iron-deficient rats. Enhancement by meat was sufficient to overcome the inhibition by phytate. Fish was an inhibitor or enhancer in cimetidine-treated, iron-deficient rats, depending on the absence or presence of phytate, respectively. Egg white inhibited absorption from cereal meals in cimetidine-treated, iron-deficient rats.

ABSTRACTColor stability and various biochemical properties were determined in bovine longissimus dorsi and psoas major at different times postmortem (8 hr to 21 days) and during retail display. Surface metmyoglobin accumulation, metmyoglobin reductase activity and oxygen consumption rate were affected by muscle type, postmortem aging, and fabrication method (p < 0.01). Psoas steaks had greater metmyoglobin accumulation, lower metmyoglobin reductase activity, and greater oxygen consumption than longissimus steaks. However, color stability of muscles was similar after grinding, which increased oxygen consumption. Color was most stable in steaks fabricated at 4 or 7 days postmortem. The order of color stability was knife‐cut steaks > saw‐cut steaks > ground muscle.

Dietary iron is present in food both in inorganic forms as ferrous and ferric compounds, and in organic forms, the most important of these being heme iron. The purpose of this review is to evaluate the contributions of both heme and nonheme iron in establishing and maintaining a healthful iron status. The human requirement for iron, bioavailability of heme and nonheme iron, and amounts of heme and nonheme iron in the diet are individually estimated after reviewing the relevant literature in Sections II, III, and IV, respectively. In Section V, the contribution of heme and nonheme iron to human nutrition, as compared to the human requirement for iron (Section II), is estimated after attenuating the amounts of heme and nonheme iron found in the diet (Section IV) by their bioavailabilities (Section III).