Mitochondrial Activity and Beef Muscle Color Stability

Concentration, oxygen consumption rate (OCR), oxygen consumption rate/g meat (OCRM) and metmyoglobin reducing activity (MRA) of muscle mitochondria were determined for beef longissimus dorsi and gluteus medius muscles of Holstein and crossbred steers which differed in color stability. OCR and OCRM decreased but no significant changes were observed in MRA during postmortem storage time. Significant effects of muscle and breed type on OCR, OCRM, and MRA were observed. Muscles and breeds of lower color stability had the highest levels of OCR, OCRM, and MRA. Differences in OCR of muscle mitochondria may be a contributing factor in the effects of muscle and breed on the rate of discoloration.     

宰后牛肉色泽稳定性及其影响因素

介绍了宰后影响牛肉色泽稳定性的主要因素及其机理,肌红蛋白的氧化状态是决定鲜肉产品的最主要因素,高铁肌红蛋白还原酶活力对于肌红蛋白氧化状态及肉色稳定性的影响最大,而在宰后储藏过程中各种内源性抗氧化成分对肉色稳定具有重要作用.并建议引入体外孵化和预测模型等相关研究方法.关于影响因子的精确研究对提高肉品色泽品质具有重要意义.     

Effects of Antioxidants in Polyethylene Film on Fresh Beef Color

ABSTRACT: BHA, BHT, rosemary extract, and α‐tocopherol were incorporated into low‐density polyethylene (LDPE) at the 0.1% level and thermoformed into 25‐mm‐dia, 0.25‐mm‐thick discs, which were exposed to the surface of fresh beef and held in contact with a polyvinyl chloride (PVC) overwrap. On d 0, the control treatment with only the PVC overwrap had greater “a” (redness) values, probably due to greater transmission of oxygen to the meat surface. However, by d 7, the control with only the PVC overwrap had lower redness values than any of the other treatments. By d 8 and 9, the meat packaged with the BHA‐impregnated film had higher “a” (redness) values than any of the other film treatments     

Variations in Internal Color of Cooked Beef Patties

Seventeen commercially prepared patty formulations were cooked to internal temperature 71°C. Pink cooked color occurred in eight of the products and was due to incomplete denaturation of myoglobin. Although there was some relation between pH and cooked color, other factors seemed to be involved. When products were re-analyzed after 1 yr storage at -27°C, sixteen products were red/pink when cooked to 71°C. This increase in redness after frozen storage could not be explained. Cooking to internal temperatures between 81 and 87°C was necessary for complete disappearance of red/pink color. Premature browning, where a product looks well-done at temperatures lower than 71°C, occurred in one formulation.     

高压处理对牛肉肌红蛋白及颜色变化的影响

室温下不同压力(200、400、600和800MPa)，20min处理对绞碎牛肉颜色及肌红蛋白的影响进行了研究。结果显示：随压力的上升，L^*值增加、a^*值下降，肌肉逐渐失去红色变为灰棕色。同时，肌红蛋白总量显著降低，高铁肌红蛋白的比例在压力400MPa以上时显著增加。真空包装不能减轻压力导致的变色，而添加亚硝酸钠能对色泽起到稳定作用。压力处理导致色泽变化的原因可能是由于二价铁的肌红蛋白氧化成三价铁的高铁肌红蛋白、球蛋白的变性及结构的变化所致，可通过处理前腌制形成亚硝基肌红蛋白来稳定色泽。     

Visual and Spectrophotometric Evaluations of Beef Color Stability

Slices of longissimus and gluteus medius muscles from 96 beef steers were displayed under simulated retail display conditions. Meat color display life was calculated by methods termed (1) change between days and (2) days to threshold. The days to threshold approach yielded estimates of color display life which were more consistent among slaughter groups of steers and within muscles. Longissimus had a longer color display life than gluteus medius. Reflectance measurements of beef color provided similar relative estimates of color display life as visual assessment. The accumulation of metmyoglobin at the onset of discoloration was associated with variances which were more homogeneous than those for percentage discoloration determined by visual assessment.     

氧化应激对牛肉肉色及其稳定性的影响研究进展

肉色作为衡量肉品质的关键指标一直是肉品产业关注的焦点。刚屠宰的牛胴体由于缺氧、缺血产生了大量活性氧,活性氧积累造成胴体氧化应激,进一步促进肌红蛋白的氧化,对肉色产生不利影响。但目前关于氧化应激对肉色及肉色稳定性的影响鲜有系统、深入总结。本文综述氧化应激通过调控脂质氧化、蛋白质氧化和降解以及线粒体的功能等途径对肉色及其稳定性的影响,以期为通过控制宰后氧化应激来保持牛肉良好的肉色提供理论依据。     

乳酸钙对牛肉糜色泽稳定性的影响

为研究乳酸钙对牛肉糜色泽稳定性的影响,将牛背最长肌绞碎成肉糜,分别添加0.1%、0.3%、0.5%的乳酸钙溶液,研究在(4±1)℃的冷藏条件下,肉糜肉色稳定性、色素含量、脂肪氧化及高铁肌红蛋白还原酶活性随时间的变化。结果表明：在7d的贮藏期内,添加不同质量分数乳酸钙均可有效抑制高铁肌红蛋白的生成和脂肪氧化的发生,并显著提高高铁肌红蛋白还原酶活性和肉色稳定性,但会使肉糜L*值显著降低(P＜0.05)。其中0.3%的乳酸钙对稳定肉色有显著作用,护色效果明显。     

Effects of Metmyoglobin Reducing Activity and Thermal Stability of NADH‐Dependent Reductase and Lactate Dehydrogenase on Premature Browning in Ground Beef

Premature browning is a condition wherein ground beef exhibits a well‐done appearance before reaching the USDA recommended internal cooked meat temperature of 71.1 °C; however, the mechanism is unclear. The objectives of this study were: (1) to determine the effects of packaging and temperature on metmyoglobin reducing activity (MRA) of cooked ground beef patties and (2) to assess the effects of temperature and pH on thermal stability of NADH‐dependent reductase, lactate dehydrogenase (LDH), and oxymyoglobin (OxyMb) in‐vitro. Beef patties (lean: fat = 85:15) were packaged in high‐oxygen modified atmosphere (HiOX‐MAP) or vacuum (VP) and cooked to either 65 or 71 °C. Internal meat color and MRA of both raw and cooked patties were determined. Purified NADH‐dependent reductase and LDH were used to determine the effects of pH and temperature on enzyme activity. MRA of cooked patties was temperature and packaging dependent (P < 0.05). Vacuum packaged patties cooked to 71 °C had greater (P < 0.05) MRA than HiOX‐MAP counterparts. Thermal stability of OxyMb, NADH‐dependent reductase, and LDH were different and pH‐dependent. LDH was able to generate NADH at 84 °C; whereas NADH‐dependent reductase was least stable to heat. The results suggest that patties have MRA at cooking temperatures, which can influence cooked meat color.     

熟制牛肉肉色问题和影响因素研究进展

近年来,我国消费者尤其是逐渐扩大的中产阶级群体对牛排、牛肉饼、汉堡包、烧烤牛肉等西式牛肉制品的消费越来越多,对牛肉品质和安全的要求也越来越高,但是该类牛肉制品熟制过程中存在一些肉色问题。本文综述了牛肉加热过程中常见的肉色问题,包括未完成熟制前肉色提前褐变现象、达到熟制温度后肉色仍然呈现粉红现象和熟制结束后肉色恢复红色的现象;分别阐述了其产生机制、主要影响因素和相关控制措施,概括了影响熟制牛肉肉色的主要因素,并对熟制牛肉肉色问题产生的分子机制研究提出展望,以期为我国熟制牛肉肉色的控制提供思路。     

苹果多酚对鲜肉色泽稳定性及脂肪氧化的影响

本文研究了苹果多酚对透氧保鲜膜包装的鲜猪肉的色泽稳定性及脂肪氧化的影响。结果表明,苹果多酚能明显抑制肉中脂肪的氧化,并能提高鲜肉红色的稳定性。单独使用0.05%的苹果多酚,有较好的护色效果。苹果多酚与抗坏血酸或烟酰胺配合使用,抗氧化与护色效果明显增强。0.05%苹果多酚与0.05%烟酰胺配合使用可以使鲜肉在5±1℃条件下贮藏7d后,仍保持稳定的鲜红色,TBA值为0.3mg/kg,TVB-N值为14.7mg/100g。     

Influence of Cooking Rate, Endpoint Temperature, Post-cook Hold Time, and Myoglobin Redox State on Internal Color Development of Cooked Ground Beef Patties

ABSTRACT: Three experiments investigated cooking rate, endpoint temperature, post-cook holding time, and raw myoglobin redox-state effects on ground beef internal cooked color. In Experiment 1, patties were cooked to endpoint temperatures of 65.6°C, 71.1°C, 76.7°C, 82.2°C, or 87.8°C rapidly (1°C/s), slowly (0.2°C/s), or rapidly with 6-min post-cook holding time at 104°C. Patties cooked slowly to less than 76.7°C were more well done ( P < 0.05) in appearance than those cooked rapidly. Rapidly-cooked patties cooked to less than 82.2°C and held for 6 min after cooking had less pinkness, more myoglobin denaturation, and a more well-done appearance than did rapidly cooked patties with no holding time ( P < 0.05). In Experiment 2, increasing post-cook holding time (1, 3, 6, or 12 min) after rapid cooking to 71.1°C, 76.7°C, or 82.2°C decreased pinkness and increased myoglobin denaturation ( P < 0.05), with no benefit beyond 6 min ( P > 0.05). In Experiment 3, patties cooked rapidly to 71.1°C, 76.7°C, or 82.2°C from a predominantly raw oxymyoglobin state were less pink and had more denatured myoglobin than did those cooked from a predominantly deoxymyoglobin state ( P < 0.05). Prediction equations determined that 80% of myoglobin must be denatured to create a well-done appearance. Using a slow cooking rate, post-cook holding time, or cooking from a highly oxygenated state will increase myoglobin denaturation and foster a well-done appearance.     

Color and Its Stability in Restructured Beef Steaks during Frozen Storage: Effects of Various Binders

Color and its stability were evaluated in restructured steaks made with various binders (calcium alginate, crude myosin extract, whey protein concentrate, wheat gluten, soy isolate or surimi) vs controls (intact ribeye muscle, restructured steaks with no additives or with NaCl and sodium tripolyphosphate). Steaks made with various binders showed similar effects on initial surface metmyoglobin concentration and sensory color attributes, except steaks made with calcium alginate or soy isolate protein. During 12-wk frozen storage, steaks made with various binders (except soy protein isolate) had similar color stabilities.     

Effects of Carbon Monoxide Packaging on Color and Lipid Stability of Irradiated Ground Beef

ABSTRACT: The effects of packaging atmosphere (aerobic, vacuum, or modified atmosphere with carbon monoxide) on ground beef treated with ionizing radiation were investigated. Measurements of color (CIE L*, a*, b*), lipid oxidation (TBA value), and sensory quality were conducted during 28 d of storage at refrigerated (0 to 2°C) temperatures. Irradiation significantly ( p > 0.001) decreased color scores and increased TBA and off-odor scores. The MAP + CO treatments increased the L* and a* values ( p < 0.001), regardless of irradiation dose. The TBA values for MAP + CO-packaged samples were well below the levels considered "rancid" (about 1.0). In addition, sensory scores indicated minimal production of irradiation off-odors with MAP + CO packaging.     

线粒体对肉色及其稳定性影响的研究进展

肉色是评价肉品品质最直观的指标,能够直接影响消费者的购买意愿。近40 年有较多学者对影响肉色及 其稳定性的因素进行了概述,但较少涉及线粒体对肉色及肉色稳定性的影响。线粒体与肌红蛋白的氧化还原状态密 切相关,它主要通过影响氧气消耗和高铁肌红蛋白还原来改变肉色及其稳定性,因此影响线粒体结构和功能的因素 也会影响肉色。本文对目前关于线粒体与肉色及其稳定性关系的研究进行综述,概括线粒体对肉色及其稳定性的直 接影响和基于线粒体影响肉色及其稳定性的因素,并阐述其影响机理。     

Color Stability and Microbial Growth Relationships in Beef as Affected by Endogenous α-Tocopherol

Longissimus muscle from Holstein steers supplemented with vitamin E at 500 or 2000 mg/head/day showed less surface metmyoglobin accumulation than controls during 12 days storage at 4°C. Temperature abuse at 25°C for 24 hr increased metmyoglobin formation; vitamin E supplementation diminished the adverse effect of temperature abuse. No differences (P > 0.05) in bacterial load were observed among the 3 vitamin E treatments during storage. Sensory panelists preferred vitamin E-supplemented beef steaks in visual acceptance. Panelist assessment of discoloration correlated highly with a value and hue angle. In general, elevated α-tocopherol concentrations in beef steaks did not affect panelist assessment of meat spoilage.     

Pasture and Grain Finishing Affect the Color Stability of Beef

ABSTRACT: We determined the effect of pasture feeding (P0) or sorghum feeding with 2500 IU/head/d; (G2500) or without (G0) vitamin E supplementation on the color stability of gluteus medius (GM), longissimus lumborum (LL) and semimembranosus (SM). Diets did not affect the total pigment concentration of the muscle. Color stabilities were G2500 > P0 > G0 for fresh GM and SM and G2500 > G0 > P0 for fresh LL. Color stabilities of aged beef from the P0 and G2500 treatments were similar and higher than those from unsupplemented animals. Color stability of minced beef ranked as: P0 aged > G0 and G2500 fresh > P0 fresh > G0 and G2500 aged.     

Contributions of Muscles of Various Color Stabilities to the Overall Color Stability of Ground Beef

ABSTRACT:  Ground high (HCS), intermediate (ICS), and low color stability (LCS) cow muscles were used to investigate effects of blending muscles of different color stabilities on ground beef display color. Six formulations at 90% and 80% lean points combining HCS, ICS, and LCS muscles were: 50% HCS + 50% ICS; 50% HCS + 50% LCS; 50% ICS + 50% LCS; 33.3% HCS + 33.3% ICS + 33.3% LCS; 75% HCS + 25% LCS; and 25% HCS + 75% LCS. Patties were packaged in a high oxygen (80% O₂, 20% CO₂) modified atmosphere, held in dark storage for 5 d, then displayed for 4 d. The 80% lean patties containing ≥ 50% HCS had the brightest red initial visual color. During display 75% HCS + 25% LCS at both lean points had the most cherry-red display color. Patties containing a greater proportion of HCS had greater metmyoglobin reducing ability throughout display. HCS, ICS, and LCS muscle can be mixed without adverse color affects, provided LCS muscle is ≤ 25%, and HCS muscle is ≥ 50% of the blend.