肌肽对牛肉糜肉色及脂肪氧化的影响

在牛背最长肌中添加肌肽(C_9H_(14)N_4O_3),研究在4±1℃冷藏条件下,不同浓度(0.05%、0.1%、0.5%、1.0%)肌肽对牛肉肉糜高铁肌红蛋白(MetMb)还原酶活性、色素含量、脂肪氧化及肉色稳定性的影响.结果表明:在7d的贮藏期内,添加不同浓度肌肽均可有效抑制肉糜MetMb含量上升、提高高铁肌红蛋白还原酶活性,并与无添加组有显著性差异(P<0.05),0.1%、0.5%浓度肌肽对抑制脂肪氧化、稳定肉色有显著作用,护色效果较理想     

乳酸盐对冷却牦牛肉色泽稳定性及高铁肌红蛋白还原的影响

以牦牛背最长肌为实验材料,通过向牦牛肉糜中添加三种不同种类的乳酸盐(乳酸钙,Ca L;乳酸钾,KL;乳酸钠,Na L)和不同浓度的Ca L(0.1%、0.3%、0.5%),研究了在(4±1)℃冷藏条件下乳酸盐对牦牛肉肉色稳定性和高铁肌红蛋白还原系统的影响。结果表明:经过7 d的贮藏,0.3%的乳酸盐可以抑制牦牛肉糜a*值的下降,但会使肉色变暗;可显著抑制牦牛肉贮藏过程中MbO_2的氧化(p0.05),抑制Met Mb含量的上升,提高MRA,且Ca L处理组的效果最显著(p0.05)。添加不同质量分数的Ca L后,0.3%Ca L处理组的a*值上升速度显著高于其他3组(p0.05),但会使肉糜L*值降低;不同浓度的Ca L均可抑制牦牛肉贮藏过程中Mb O2的氧化(p0.05)和Met Mb的生成(p0.05),并显著提高MRA(p0.05)和肉色稳定性,其中添加0.3%的Ca L对稳定和保持肉色的作用最明显。     

3种包装方式对宰后牛肉成熟过程中颜色影响的机制研究

选用真空包装作为对照,通过测定pH、颜色、总色素含量、脱氧肌红蛋白、氧合肌红蛋白和高铁肌红蛋白的相对比例、脂肪氧化以及高铁肌红蛋白还原酶活性,研究托盘包装和气调包装对宰后成熟过程中牛肉颜色的影响机制。结果表明:相对于真空包装,托盘包装牛肉样品的pH较高,而气调包装牛肉样品的pH较低,托盘包装和气调包装牛肉样品的L*值和b*值较高(P0.05),气调包装能够有效地维持牛肉样品颜色稳定性(P0.05),而托盘包装在维持颜色稳定性方面相对较差,托盘包装和气调包装的牛肉样品脂肪氧化程度较高(P0.05),脱氧肌红蛋白含量和高铁肌红蛋白还原酶活性相对较低。     

乳清分离蛋白水解物对猪肉糜抗氧化作用的研究

研究乳清分离蛋白(WPI)的碱性蛋白酶(alcalase)水解物的抗氧化能力,并将其应用于生肉糜中研究其抗氧化效果。实验分为6组,第1组为对照组,第2组加入2.0%的WPI未水解物,第3～5组中分别加入1.0%、1.5%、2.0%的水解物冻干粉(5h),第6组中加入0.02%的BHA,在冷藏过程中测定肉糜的红度值(a*)、硫代巴比妥酸值(TBARS)值、pH值、高铁肌红蛋白(MetMb)含量,并对产品的感官指标进行评定。结果表明,在贮藏7d内,与对照组相比,添加WPI水解物处理组能够显著抑制生肉糜脂肪的氧化(P<0.05),其中2%WPI水解物处理组效果最明显,能显著降低TBARS值、增加肉糜的红度值(a*)(P<0.05),且其高铁肌红蛋白(MetMb)含量仅为对照组的79%,与添加BHA处理组的水平相当。同时,WPI水解物处理组抑制脂肪的氧化效果比WPI未水解组好。因此,WPI水解物可以有效的抑制食物中脂肪氧化,且其抗氧化效果与水解物的使用量相关。     

中国荷斯坦育肥公犊肉储藏过程中脂肪氧化对肌红蛋白稳定性的影响

本文通过参考国内外研究方法,测定中国荷斯坦育肥公犊和普通黄牛肉脂肪酸组成及其在有氧贮藏过程中脂肪和肌红蛋白的氧化程度,研究其脂肪氧化和肌红蛋白氧化之间的关系。结果表明,育肥公犊的饱和脂肪酸含量极显著高于黄牛(p0.01),多不饱和脂肪酸和单不饱和脂肪酸含量都极显著低于黄牛(p0.01)。在贮藏期间,两种牛都发生脂质氧化,且育肥公犊的氧化程度极显著低于黄牛(p0.01)。在有氧贮藏条件下,两种牛的肌红蛋白氧化程度增加。育肥公犊的高铁肌红蛋白含量与脂质氧化程度呈线性正相关,(r=0.945,p0.01),氧合肌红蛋白含量与脂质氧化程度呈线性负相关,(r=-0.906,p0.01)。黄牛的高铁肌红蛋白含量与脂质氧化程度呈线性正相关,(r=0.972,p0.01),氧合肌红蛋白含量与脂质氧化程度呈线性负相关,(r=-0.851,p0.05)。通过研究表明中国荷斯坦育肥公犊肉脂质氧化与肉色稳定性相关。     

高铁肌红蛋白还原酶与肉色关系研究进展

高铁肌红蛋白还原酶是肌肉中存在的可以还原高铁肌红蛋白的一类酶,它与肉色的关系是国内外研究的热点课题.本文对高铁肌红蛋白还原酶以及肉色稳定性关系的国外研究现状进行了概括,包括高铁肌红蛋白还原酶的概述、酶活力的测定方法、影响酶活力的因素、酶纯化的研究、还原过程的机理研究、酶活力和肉色稳定性关系等内容.最后分析了高铁肌红蛋白还原酶在肉品护色领域的研究所面临的问题,从而为以后的研究提供一些新的思路.     

托盘和真空包装对冷却猪肉中MetMb还原活性的影响

在冷却肉的贮藏过程中,其肌红蛋白(Mb)被氧化为高铁肌红蛋白(MetMb),导致了冷却肉的褐变。研究了托盘包装和真空包装条件下,冷却肉自身的还原系统活性变化规律及其对肉色稳定性的影响。在2周的贮藏期内,真空与托盘包装冷却肉糜肌浆蛋白粗提液的还原活性持续下降;但真空包装组MetMb还原酶粗提液还原活力第1天到第14天活性差异不显著,托盘包装组前后差异显著。真空包装组在贮藏期间MetMb含量持续下降,但托盘包装组MetMb含量则持续上升,说明无氧条件有利于MetMb的还原。托盘包装组TBA在贮藏期间持续上生,但真空包装组TBA变化不明显。结果表明,托盘包装不利于冷却肉自身MetMb还原能力的维持,而真空包装的无氧环境,有利于MetMb的还原和肉色的保持。     

光照条件对冷却猪肉MetMb还原活性及色泽稳定性的影响

冷却肉中的肌红蛋白很容易受到光的作用而发生褪色,导致颜色劣变.本文采用猪冷却肉为原料,在相同光照强度(40～ 80Lux)下,研究不同波长光照对冷却猪肉肉糜中MetMb还原酶活性及肉色稳定性的影响.结果表明:不论托盘包装还是真空包装,避光与其他光照条件(紫光、绿光、红光、白光)对肉的色泽影响差异显著(P<0.05);真空包装有利于保持肉中MetMb还原酶活性.     

甘油醛-3-磷酸对羊肉色泽稳定性和高铁肌红蛋白还原的影响

目的：甘油醛-3-磷酸（3-phosphoglyceraldehyde,GAP）是糖酵解过程的代谢产物,其能够在甘油醛-3-磷酸脱氢酶（glyceraldehyde-3-phosphate dehydrogenase,GAPDH）的催化下,生成还原型辅酶I（nicotinamide adenine dinucleotide,NADH）,而NADH会通过促进高铁肌红蛋白的还原而提高宰后肌肉色泽的稳定性。但GAPDH催化GAP产生的NADH能否直接作用于高铁肌红蛋白的还原并不明确。因此,该研究的目的在于探究添加GAP对肉色稳定性的影响及其作用途径。方法：采用原位模型和离体模型,在原位模型中将GAP添加到羊肉样品中,测定色差值及NADH含量;离体模型中,提取羊心肌中的线粒体,分别与高铁肌红蛋白、GAP等共同孵育,测定高铁肌红蛋白的占比。结果：原位模型中,向羊肉中添加GAP,显著升高了样品的红度值和NADH含量。离体模型中,GAP与GAPDH共同孵育显著降低了高铁肌红蛋白的占比,并且会增加孵育体系的氧气消耗率。结论：添加GAP提高羊肉的色泽稳定性,是由于GAP在肉中GAPDH催化下生成的NADH能够直接被用于还原高铁肌红蛋白,进而延缓了高铁肌红蛋白的累积,肉色稳定性较高。     

香辛料提取物对生肉糜的抗氧化作用

研究了迷迭香、肉桂、丁香提取物对生肉糜的抗氧化效果,测定了生肉糜在贮藏期间色差、pH、硫代巴比妥酸反应物值(TBARS)、高铁肌红蛋白(metMb)的变化,并与BHA进行比较,结果表明香辛料提取物能显著抑制肉糜中脂肪的氧化,增加肉糜鲜红的色泽,与0.02%BHA效果相当.     

喷雾冷冻干燥对葛仙米藻胆蛋白抗氧化特性的影响

研究喷雾冷冻干燥对葛仙米藻胆蛋白抗氧化特性的影响,并与冷冻干燥技术进行比较。主要测定ABTS+ ·、铁还原抗氧化能力(FRAP)、对羟自由基( ·OH)清除作用和H2O2诱导的脂质过氧化的抑制作用,结果发现,喷雾冷冻干燥(SFD)对葛仙米藻胆蛋白的抗氧化特性有一定的影响,在基于电子转移和氢原子转移的抗氧化测定方法中,SFD与冷冻干燥(FD)制备的样品差异不明显,但在基于活性氧自由基清除的测定方法中,SFD显著优于FD。表明SFD非常适合于高活性成分的干燥。     

Effects of calcium salts on beef longissimus quality

The objective of this research was to evaluate the effects of injection marination with calcium salts on beef longissimus quality traits. Strip loins were injected (11% by weight) with distilled water or a 0.1, 0.2, or 0.3 M solution of calcium ascorbate, calcium chloride, or calcium lactate. Non-injected loins served as controls. Visual and instrumental color evaluations indicated that calcium ascorbate accelerated myoglobin oxidation, and increasing molar concentration of any calcium salt caused faster (P<0.05) discoloration. Aerobic microbial plate counts were lower (P<0.05) for treatments containing calcium lactate than those with calcium chloride or calcium ascorbate. Calcium ascorbate inhibited lipid oxidation whereas calcium lactate and calcium chloride appeared to be pro-oxidants of lipid oxidation. No differences for Warner-Bratzler shear force or sensory panel tenderness were found among the calcium salts; however, 0.3 M treatments had lower shear values and were judged more tender than 0.1 M treatments. Calcium ascorbate and calcium chloride treatments resulted in less (P<0.05) beef flavor and more (P<0.05) off-flavors than calcium lactate treatments. In addition, 0.1 M treatments had higher (P<0.05) beef flavor scores while 0.3 M treatments had higher (P<0.05) off-flavor scores. Considering the effects on color life, microbial inhibition, shear force, and sensory traits, we recommend injecting beef longissimus with a 0.1 M solution of calcium lactate to enhance both uncooked and cooked quality.     

Antioxidative/Antimicrobial effects of galangal and alpha-tocopherol in minced beef

The antioxidant and microbial stabilities of galangal (Alpinia galanga) extract in raw minced beef were examined at 4 +/- 1 degree C. Raw minced beef containing galangal extracts (0 to 0.10%, wt/wt) were prepared. Lipid oxidation during refrigerated storage was assessed by monitoring malonaldehyde formation, using the thiobarbituric acid reactive substances method. In minced beef, added galangal extract improved oxidative stability. Galangal extract at higher concentrations of 0.05% and 0.10% (wt/wt) were also found to extend the shelf-life of minced beef. Addition of alpha-tocopherol (0.02%, wt/wt) to galangal extract (0.05%, wt/wt) were observed to increase the oxidative but not the microbial stability of minced beef during the storage of 7 days. Galangal extract may prove useful in inhibiting lipid oxidation and increasing microbial stability of minced meat.     

Factors in Various Fractions of Meat Homogenates That Affect the Oxidative Stability of Raw Chicken Breast and Beef Loin

ABSTRACT:  The fractions of meat homogenates were analyzed to find the factors that determine the susceptibility of raw chicken breast and beef loin to lipid oxidation. The fractions used in this study were meat homogenate, precipitate, and supernatant of homogenate after centrifugation, and high and low molecular weight fractions from the supernatant. Chicken breast showed greater oxidative stability than beef loin during 10-d storage ( P < 0.05). All fractions from chicken breast showed lower amounts of free ionic iron and myoglobin and higher total antioxidant capacity (TAC) than those from beef loin during storage. The TAC level of chicken breast maintained during storage. This suggested that the oxidative stability of chicken breast was ascribed to high, stable total antioxidant capacity with low level of catalysts for lipid oxidation. The water-soluble high molecular weight fraction, which contained myoglobin, was responsible for the high lipoxygenase-like activity and lipid oxidation potential (LOP) in beef loin. TAC in all fractions from beef loin decreased during storage. This suggested that high myoglobin content in beef loin caused the imbalance between pro- and antioxidant factors leading to the high susceptibility of beef loin to lipid oxidation. Myoglobin served a major source of catalysts, ferrylmyoglobin, hematin, and/or free ionic iron, for lipid oxidation.     

洋葱皮乙醇提取物对冷却牛肉颜色、脂质和蛋白质氧化稳定性的影响

将牛肉切片在3种浓度（0.5 %、1.0%、2.0%）的洋葱皮乙醇提取物（Ethanol Extract of Onion Skin,EEOS）溶液中浸渍后在4 ℃条件下冷藏12 d,并与空白对照组和添加了抗坏血酸（ascorbic acid,V_C）的处理组进行比较,分析EEOS对牛肉在冷藏期间的颜色褐变、脂肪和蛋白质氧化以及腐败程度的影响。结果表明:EEOS总酚含量较高,具有很强的自由基清除活性;添加EEOS可延缓牛肉pH上升,提高颜色稳定性,减少高铁肌红蛋白的生成,同时延缓脂肪和蛋白的氧化进程。2% EEOS有效降低了牛肉样品硫代巴比妥酸反应物（Thiobarbituric acid reactive substances,TBARS）和蛋白质羰基含量,与空白对照组相比分别降低56.9%和17.6%。此外,2% EEOS还可显著降低挥发性盐基氮（Total Volatile Basic Nitrogen,TVB-N）的含量（P<0.05）。因此,添加2% EEOS可抑制牛肉冷藏期间的颜色褐变和脂肪、蛋白质的氧化,可在牛肉冷藏保鲜中作为天然抗氧化剂。     

The combined effect of antioxidants and modified atmosphere packaging on protein and lipid oxidation in beef patties during chill storage

Effect of rosemary extract and ascorbate/citrate (1:1) in combination with modified atmosphere packaging (100% N(2), 80% O(2)/20% N(2)) on protein and lipid oxidation in minced beef patties during storage in the dark for up to 6 days at 4°C was investigated. A high level of oxygen in the packaging atmosphere was found to increase both lipid and protein oxidation during storage as evaluated by TBARS analysis of secondary lipid oxidation products and by 2,4-dinitrophenylhydrazine derivatization of protein carbonyls. Both antioxidant systems tested were found to inhibit lipid oxidation but not protein oxidation. In contrast, ascorbate/citrate was found to promote protein oxidation. Rosemary extract was found to regenerate or protect α-tocopherol whereas the packaging atmospheres had no effect on α-tocopherol stability. In high oxygen atmospheres both antioxidants protected the fresh red meat colour with ascorbate/citrate being more efficient than the rosemary extract, whereas no effect of antioxidant on meat colour was found in beef patties stored in 100% nitrogen.     

Effects of pyruvate on lipid oxidation and ground beef color

Our overall objective was to better understand the effects of added pyruvate on enhanced beef color stability. The 2 possible mechanisms assessed were the role of pyruvate in lipid oxidation and direct interaction between pyruvate and beef myoglobin. Microsomes were incubated with pyruvate at pH 5.6, 25 °C, and lipid oxidation was measured hourly for 3 h. Bovine oxymyoglobin at pH 5.6 was incubated with pyruvate and used to quantify both redox stability (metmyoglobin formation) and pyruvate-myoglobin adduction using mass spectrometry analysis. Surface color and lipid oxidation were measured on ground beef patties stored for 6 d in polyvinyl chloride over-wrap (PVC) or high oxygen. Addition of pyruvate to microsomes decreased lipid oxidation compared with controls (P < 0.05). Conversely, no effect on myoglobin was observed (no changes in redox stability and no peaks corresponding to pyruvate were observed; P > 0.05). However, pyruvate increased color stability and decreased lipid oxidation of ground beef patties packaged in PVC and high oxygen. Pyruvate decreased nitric oxide metmyoglobin-reducing capacity and oxygen consumption of patties compared with controls (P < 0.05). This research suggests that pyruvate may improve beef color stability primarily through its antioxidant effect on lipids. Practical Application: Discoloration of meat often results in significant revenue loss. This study suggests that pyruvate can improve the color stability of patties packaged in high oxygen and PVC primarily through its antioxidant effect on lipids.     

Sodium lactate influences myoglobin redox stability in vitro

Injection-enhancement of beef with lactate improves color stability; however, the mechanism is unclear. Thus, our objectives were to assess the effects of sodium lactate on equine myoglobin redox stability in vitro. Oxymyoglobin at pH 5.6 (50 mM sodium citrate) and pH 7.4 (50 mM sodium phosphate) was incubated at 4 °C with lactate (0, 5, 10, 100, or 200 mM) and myoglobin redox form was determined using absorbance spectra. Metmyoglobin formation at pH 5.6 and 7.4 was significantly (P < 0.05) decreased by lactate at concentrations of 100 and 200 mM. In general, increasing lactate concentration from 100 to 200 mM increased (P < 0.05) oxymyoglobin redox stability. This effect of lactate on myoglobin redox stability could be partially responsible for the improved color stability associated with lactate injection-enhanced beef products. Further work should determine the effect of lactate on beef myoglobin.     

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.