蛋白质氧化对肉食用品质影响的研究进展

肉品质变化的内部因素从理化方面而言主要包括脂肪氧化以及蛋白质氧化,其中蛋白质氧化是近年来研究的热点。本文首先分析了肉蛋白质氧化机理（蛋白质的共价修饰）和蛋白质氧化表征（羰基化、巯基化以及交联等氧化修饰类型）;其次从可能的微观机理到宏观外在表现来说明蛋白质氧化对肉食用品质的影响;最后提出了在蛋白质氧化领域一些目前还未研究透彻的问题及可采用的解决方法,以期对肉蛋白质氧化机理及其对肉食用品质影响的研究提供思路。     

“科尔沁”气调保鲜牛肉

正冷鲜肉是一种近年来在国内市场兴起的肉类,它与传统的热鲜肉有着本质的区别。冷鲜肉的品质、安全卫生、销售方式与热鲜肉相比已经产生了革命性的提高。与此同时,也对冷鲜肉在生产阶段和零售阶段的品质管理提出了更高的要求。冷鲜肉的销售形式主要有无包装、普通保鲜膜包装、     

蛋白质氧化和翻译后修饰对肉品质的影响及机制研究进展

动物屠宰后，肌肉向可食肉转变的过程中涉及一系列的生化变化，它们相互影响并决定了肉的品质。其中氧化应激引起的蛋白质氧化以及蛋白质翻译后修饰对肉品质的形成具有重要影响，但鲜见对其机理系统的深入总结报道。本文综述了氧化应激与蛋白质氧化的关系，总结了动物屠宰后蛋白质氧化和翻译后修饰对肉的嫩度、持水性、肉色和营养价值等品质形成的影响及其作用机制，以期为未来肉品科学的研究提供理论参考。     

肉品中的蛋白质氧化机制及其影响因素

随着肉品加工技术的进步和人们生活方式的改变,丰富多样的加工肉制品越来越受到广大消费者青睐。但 加工肉制品的理化性质、营养成分和食用安全性易受各种加工及贮藏环境因素的作用而产生变化,如蛋白质氧化与 冷冻变性、脂质氧化、生物自身代谢、病原菌的滋生及致癌物产生等。其中蛋白质氧化对肉制品品质影响极大,它 被定义为一种共价键修饰作用,该作用对蛋白质分子结构造成破坏,引起蛋白质氨基酸侧链被修饰、蛋白质多肽 链的断裂、蛋白质分子间的交联聚合等,从而改变了蛋白质的凝胶、持水、消化、营养等特性,最终影响肉品的品 质。本文从蛋白质氧化机理、评估指标、影响因素等3 个方面出发,综述有关肉品蛋白质氧化的国内外最新研究进 展,归纳总结肉品中蛋白质氧化规律及其实际生产中的影响因素。     

活性包装对肉制品品质及货架期影响的研究进展

活性包装是一种新型包装方式,它能有效减少食品微生物污染,抑制蛋白质、脂质的氧化,使产品维持较高的品质,延长产品货架期。本文主要介绍了活性包装常用的活性物质及其作用机制,讨论了活性包装影响肉制品品质和货架期的最新研究成果,以期对活性包装在肉制品中的应用提供理论依据,并指导相关的科学研究。     

熏烧烤肉制品包装方式研究进展

如何延长货架期、提高肉品质量一直是肉类企业关注的焦点,对肉品进行恰当的包装销售已是一个势在必行的发展趋势。包装具有保护食品原有品质及延长食品货架期的作用。熏烧烤肉制品是受消费者喜爱的传统肉制品,在肉制品体系中占有相当重要的地位,但在储存和销售过程中易发生腐败变质,致使其营养价值降低,适口性及外观改变,同时还可能导致有毒有害物质的产生。该文主要基于熏烧烤肉制品的特点,同时通过与生鲜肉包装方式的比较,综述了不同包装方式对熏烧烤肉制品品质的影响,重点介绍了不同包装方式在熏烧烤肉制品中应用的利弊。     

肉类辐照保鲜技术的现状及前景

目前，我国的肉类销售仍以冷冻肉和市场开放式的热鲜肉为主。肉的冷冻虽然对延长肉的储藏期比较有效，但冷冻储藏是一个耗能的过程，不仅使肉在流通中成本大大增加，而且长期的冷冻储藏会使肉的质量发生明显变化，蛋白质变性及脂肪氧化则可能对人体造成潜在危害。因此，冷冻肉的消费呈逐年下降趋势。热鲜肉的销售从肉食品卫生及肉的成熟过程看，完全不符合肉品卫生要求。同时也与肉类工业的发展趋势不相适应，为了适应肉品新的消费趋势，因而关于鲜肉保鲜及包装储存的研究具有十分重要的社会意义。国外从20世纪30年代就开始了关于肉类气调保鲜的研究。近年来，国内关于延长鲜肉货架期及鲜肉保鲜的研究报道日益增加。鲜肉中肌红蛋白的氧化是鲜肉失去鲜红色泽的主要原因，脂肪的氧化间接地影响肉的色泽。消费者往往认为鲜肉失去鲜红色泽是肉品质量下降的主要标志。肉品质量的进一步下降是肉被微生物污染及肉本身酶活动的结果。因而鲜肉保鲜必须控制肉变色、微生物及酶活动。     

包装材料与方式对熟肉制品贮藏品质的影响

熟肉制品富含蛋白质等营养物质,是人们膳食中重要的组成部分。不同包装的熟肉制品在贮藏中对氧气、光照以及微生物的敏感性和抵抗能力不同,其品质变化也不同。主要综述了熟肉制品常用的包装材料(如金属、塑料、可食膜等)以及包装方法(如真空、气调和活性包装)对熟肉制品贮藏品质的影响。     

芬顿反应诱导的肉类蛋白质氧化及干预研究进展

肉及肉制品生产加工过程中伴随着蛋白质氧化的发生,这会导致肉制品营养性和可食用性降低,甚至产生有毒、有害物质,这些有害化合物严重威胁人体健康。蛋白质的氧化修饰改变其结构和理化特性（如构象、结构、组成、溶解性、流变性和反应性）,然而适度的修饰也可起到调控肉制品品质的作用。肉蛋白氧化过程中最主要和最有效的活性氧是羟自由基（·OH）,芬顿反应是产生高活性羟自由基的主要途径之一,因此本文综述芬顿反应中蛋白质氧化的基本原理、反应产物以及蛋白质氧化在肉品加工中对肉类色泽、嫩度、持水性等的作用,以期为肉制品的品质控制提供理论支撑。     

高氧气调包装肉类研究进展

肉类高氧气调包装通常是用含有70%~80%的氧和20%~30%的二氧化碳的混合气体对新鲜肉类进行包装的技术,其中的氧气可使肉类呈现稳定的红色,二氧化碳主要是抑制细菌的生长而延长贮藏期限。本文对近年来该技术在新鲜肉类中应用的研究情况进行了总结,从高氧包装对肉类颜色的影响、高氧环境下的微生物生长、高氧对肉类的脂类氧化和蛋白质氧化的影响以及提高高氧气调包装肉类品质的措施等方面进行了评述。肉类的颜色稳定性与肌肉类型有关,随O2浓度的增加而增大,随CO2浓度的增加而降低。另外,肉类颜色稳定性受肉类氧化特别是脂类氧化的影响。高氧气调包装肉类中的微生物受到CO2的抑制作用表现出比生长速率降低及生长的迟滞期延长。高氧气调包装会引起脂类和肌红蛋白的氧化以及蛋白质的交联,导致肉的嫩度和多汁性下降。高氧气调包装会导致肉类煮制时出现过早熟褐现象。添加某些防腐剂和抗氧化剂可以有效改善高氧气调包装肉类质量,延长肉类贮藏期限。     

冷链运输中不同包装方式对生鲜猪肉品质的比较分析

为了使生鲜肉类能够在冷链运输中保持良好的品质,分别研究了在冷链运输中三种不同包装方式下对生鲜猪肉品质的影响。本实验选取生鲜猪肉为研究对象,通过不同方法分别测定了不同包装方式下生鲜猪肉TVB-N含量、不同包装方式下生鲜猪肉p H值、不同包装环境下菌群数量的变化以及不同包装方式下生鲜猪肉的脂肪氧化程度(TAB)等。通过对这些参数的分析,得到不同包装方式冷链运输中生鲜猪肉品质的具体数据。通过实验分析可知,气调包装方式下生鲜猪肉TVB-N含量均在15mg/100g以下,三种不同包装方式下生鲜猪肉的PH值均在5~7之间,均在合理范围内,气调包装在生鲜猪肉冷链运输中可有效抑制菌群数量变化,菌群数量控制在10~3 CFU/g^10~4 CFU/g之间,而且在冷链运输过程中生鲜猪肉颜色等保持较好;真空包装方式下TBA的最高值为0.45mg/kg,能够效抑制肉类的脂肪氧化。     

Mild protein oxidation enhanced hydration and myofibril swelling capacity of fresh ground pork muscle packaged in high oxygen atmosphere

Abstract: This study investigated the influence of an oxygen‐enriched modified atmosphere packaging (HiOx: 80% O₂/20% CO₂) in comparison with air‐permeable polyvinylchloride (PVC) wrapping and partial vacuum (VP: 60%) packaging on the ability of myofibrils to imbibe water during retail display of fresh ground pork at 2 to 4 °C. Both HiOx and PVC muscles after 4 d showed maximum myofibril swelling and A‐band dissolution when isolated myofibrils were subjected to a graded series of salt solutions (0.2→0.4 M NaCl with 10‐mM sodium pyrophosphate, pH 6.2), while VP samples exhibited no remarkable change. Protein carbonyl content increased substantially from day 0 to 4 in all muscle samples. For HiOx, muscle hydration capacity increased linearly (P < 0.05) during storage up to 14 d, corresponding to protein carbonyl production. No significant changes in hydration properties were noted in VP muscle samples, which also maintained lower levels of protein oxidation, during storage up to 21 d. These results indicated that packaging in modified atmosphere with high levels of oxygen could result in increased protein oxidation but enhanced hydration capacity of fresh meat. Practical Application: Packaging of fresh meat, including ground pork, under an oxygen‐enriched atmosphere condition is widely used in the industry to preserve red color of meat. Results from the present study indicate that high oxygen packaging has a discordant effect on fresh ground pork: it enhances hydration but decreases water‐binding, and this seems to be caused by increased swelling of muscle fibers due to mild protein oxidation. Hence, it is advisable to employ a water‐binding agent in this type of packaging system so as to retain the moisture in stored fresh pork products while maintaining the color stability.     

不同包装方式对冷藏过程中水牛肉品质特性的影响

为研究不同包装方式对冷藏过程中水牛肉品质特性的影响。以水牛肉为原料,分别采用托盘包装、涂膜托盘包装和真空包装对肉样进行包装,并测定其在4 ℃冷藏过程中色泽、pH、离心损失、蒸煮损失、挥发性盐基氮（TVB-N）值、羰基含量、菌落总数和大肠菌群数等品质指标的变化。结果显示,随着冷藏时间的延长,三种包装方式水牛肉的L*值、a*值呈不断下降趋势,但蒸煮损失、b*值、TVB-N、羰基含量、菌落总数和大肠菌群数呈不断上升趋势,而pH、离心损失呈先下降后上升的动态变化。冷藏第6 d,托盘包装组的TVB-N值达17.56 mg/100 g,冷藏第10 d,涂膜托盘包装组的TVB-N值达19.17 mg/100 g,冷藏第15 d,真空包装组的TVB-N值达16.20 mg/100 g,超出国标限定值（15 mg/100 g）。3种包装方式中,真空包装不仅可以保持水牛肉的色泽和保水性,降低TVB-N、菌落总数和大肠菌群数,还能有效抑制蛋白质的氧化。因此,真空包装对水牛肉的品质保持效果最好,其保鲜效果优于托盘包装和涂膜托盘包装。     

Color, lipid oxidation, sensory quality, and aroma compounds of beef steaks displayed under different levels of oxygen in a modified atmosphere package

High oxygen modified atmosphere packaging (MAP) is currently used by the industry to maintain an attractive color in fresh meat. However, it can also promote lipid oxidation and sensory changes. The aim of this study was to compare the quality of beef steaks displayed under different levels of oxygen. For that purpose, meat was stored with 50%, 60%, and 80% of oxygen for 4 and 8 d at retail conditions. A control treatment with steaks vacuum packaged, without exposure to retail display, was included, and color, lipid oxidation, organoleptic characteristics, and aroma compounds were analyzed. Steaks displayed under high oxygen MAP with 50% of oxygen showed the lowest color stability, according to hue values. Higher oxygen levels did not necessarily correspond with higher rancidity levels in the raw meat. Thiobarbituric Acid Reacting Substances (TBARS) values were higher than 2.2 mg malonaldehyde (MDA)/kg muscle in all the samples displayed for 8 d at retail conditions. These samples exhibited the highest intensities of rancid and the least intense beef odors and flavors. The ketones: 2,3-butanedione, 2-octanone, 2,3-pentanedione, 2-heptanone, 4-methyl-2-pentanone, and the aldehydes: pentanal, 2-methyl-butanal, and 2-furfurylthiol, 1-octen-3-ol and 2-methylpropyl-acetate, were proposed as candidates for the aroma differences between the cooked beef steaks stored under vacuum and high oxygen packs. PRACTICAL APPLICATION: High oxygen modified atmosphere packaging (MAP) is used to increase shelf-life and color at the retail level. However, oxygen deteriorates faster some quality attributes, being a contributor to lipid oxidation that could be perceived at consumption. This study attempts to find the best gas composition in a MAP in order to maintain the color, minimizing the oxidation. Aromatically relevant chemicals have been analyzed by gas olfactometry-gas chromatography as a key to measure beef oxidation after display.     

不同包装方式对冷鲜鹿肉品质的影响

用出水率、菌落总数、挥发性盐基氮及pH值为指标,研究真空热缩包装、气调包装、真空贴体包装三种不同包装方式对冷鲜鹿肉在(0±2)℃条件下品质的影响。实验结果显示,在相同的冷藏条件下,真空热缩包装的鹿肉品质最佳,保鲜效果最好,产品的保质期最长达(70 d),气调产品色泽最好但包装保质期最短(7 d)。     

生产类群、性别及包装方式对冷藏牦牛肉肌浆蛋白氧化的影响

为了探讨冷藏条件下牦牛肉肌浆蛋白的氧化规律,本实验通过羰基含量、巯基含量、表面疏水性、紫外吸收光谱及十二烷基硫酸钠-聚丙烯酰胺凝胶电泳法研究了普通包装和真空包装方式下不同生产类群的公、母牦牛肉的肌浆蛋白氧化特性。结果表明：随冷藏时间的延长,两种包装的肌浆蛋白羰基含量呈波浪式上升趋势（P＜0.05）,总巯基含量下降;普通包装组表面疏水性上升（P＜0.05）,真空包装组表面疏水性先上升后下降;同一包装方式的不同生产类群之间肌浆蛋白羰基、总巯基含量及表面疏水性均有显著差异（P＜0.05）;公、母牦牛肉之间肌浆蛋白羰基、总巯基及疏水性差异均不显著（P＞0.05）。两种包装的肌浆蛋白紫外吸收光谱的二阶导数光谱在冷藏第3天谱图改变最明显。随着氧化的进行,肌浆蛋白分子质量降低,所有蛋白条带均有不同程度的弱化,普通包装组肌浆蛋白降解程度大于真空包装;相同冷藏时间,2 种包装方式的不同生产类群及性别的牦牛肉的肌浆蛋白紫外吸收谱图及电泳图趋于一致。该研究认为,在冷藏过程中,肌浆蛋白的蛋白氧化与包装方式、生产类群密切相关,与牦牛的性别无关。     

The effect of different atmospheric conditions on the changes in myoglobin and colour of refrigerated Eastern little tuna (Euthynnus affinis) muscle

BACKGROUND: Oxidation of myoglobin is responsible for the undesirable appearance and loss in acceptability of fish and fish products. The retardation of such a change by a modification of the surrounding atmosphere would be a means to maintain the quality of fish during the refrigerated storage. RESULTS: The changes in oxymyoglobin and metmyoglobin from dark muscle of Eastern little tuna (Euthynnus affinis) as affected by different atmospheric systems (closed system, opened system and flushed oxygen system) were determined. A saturated oxygen atmosphere more likely weakened the haem–globin complex, especially as the exposure time increased. Autoxidation of the oxy form proceeded rapidly in the presence of oxygen with the concomitant formation of the met form. When the oxygen was excluded, oxidation of oxymyoglobin was retarded. With flushed oxygen and increasing exposure time, conformational changes of globin occurred, mainly associated with protein oxidation. Generally, oxymyoglobin was more susceptible to oxidation and conformational change than did metmyoglobin. After keeping the samples at 4 °C for 3 days, dark muscle of tuna fillet kept in vacuum packaging had a slight decrease in redness and it was still acceptable. The fillets stored in exposed air or packed in 100% O₂ atmosphere turned brown, most likely due to myoglobin oxidation. CONCLUSION: The oxygen level of the packaging atmosphere had a profound impact on myoglobin alteration, which was governed by the forms of myoglobin. Copyright © 2011 Society of Chemical Industry     

Microbiological and physicochemical properties of fresh retail cuts of beef packaged under an advanced vacuum skin system and stored at 4 degrees C

The effect of an advanced vacuum skin packaging system on the microbiological and physicochemical properties of fresh retail cuts of beef (including meat portions from six different anatomical regions) stored at 4 degrees C was compared with the effect of traditional vacuum packaging. The vacuum skin packaging system whose effect on meat quality was evaluated in this work displayed two remarkable features: (i) the instantaneous heating of the lower surface of the upper film of the package before the film descended over the meat surface and (ii) the tight disposition of the plastic film on the meat surface, which avoided wrinkles and purges. Throughout storage at 4 degrees C, rates of bacterial growth were statistically significantly slower in beef portions processed with the vacuum skin packaging system than in those processed with traditional vacuum packaging, with average differences of 2.07, 1.60, and 1.25 log CFU/g in counts of aerobic mesophiles, anaerobes, and lactic acid bacteria, respectively. pH values were statistically significantly lower for beef portions packaged with the vacuum skin system than for those that were vacuum packaged in the traditional manner, probably because of the relative predominance of lactic acid bacteria observed in such samples, which coincided with both higher meat firmness values and a slower meat tenderization process. The vacuum skin system prevented the appearance of undesirable coloration on the meat surface and also significantly improved the commercial color of the meat as determined on the basis of luminosity (L*) and the redness (a*). Overall, the quality (as determined by microbiological and physicochemical analyses and by visual examination) of fresh retail cuts of beef packaged with the vacuum skin system and stored at 4 degrees C was higher than that of meat samples processed with the traditional vacuum-packaging system.     

Irradiation effects on meat flavor: A review

Irradiating fresh meat, even at low doses, can result in off-odors and flavors which have been described as rotten egg, bloody, fishy, barbecued corn, burnt, sulfur, metallic, alcohol or acetic acid. The odors vary with the type of meat, temperature during irradiation, oxygen exposure during and/or after the irradiation process, packaging and presence of antioxidative substances. Irradiation can induce formation of isooctane-soluble carbonyl compounds in the lipid fraction and low molecular weight, acid-soluble carbonyls in the protein fraction of meat. Increasing irradiation dose increases these compounds however, cooking reduces them. Among the volatile components, 1-heptene and 1-nonene are influenced most by irradiation dose, and aldehydes (propanal, pentanal, hexanal) are influenced most by packaging type (aerobic vs vacuum). Sulfur-containing volatiles formed from sulfur-containing compounds (primarily amino acids) also contribute to irradiation odor. Dimethyltrisulfide is one of the most potent off-odor compounds, contributing fishy, putrid odors, followed by bismethylthiomethane (sulfurous). Reducing the temperature during the irradiation process reduces the effects on odor/flavor because free radical generation and dispersion are reduced. Ultimately, radiolysis of water into free radical species (OH,H, H(3)0(+), e(aq)(-)) may be the initiators of both lipid oxidation breakdown products and sulfur-containing volatiles responsible for irradiation odor. Methods to decrease the detrimental effects of irradiation include oxygen exclusion (vacuum packaging), replacement with inert gases (nitrogen), addition of protective agents (antioxidants), and post-irradiation storage to allow flavor to return to near-normal levels (re-packaging or double packaging in oxygen permeable film).     

Protein Oxidation: Basic Principles and Implications for Meat Quality

The involvement of oxidized proteins to the development of biological diseases has been studied for a few decades, but the effects and the mechanisms of protein oxidation in food systems are largely unknown. Protein oxidation is defined as the covalent modification of a protein induced either by the direct reactions with reactive oxygen species (ROS) or indirect reactions with secondary by-products of oxidative stress. ROS can cause oxidation in both amino acid side chains and protein backbones, resulting in protein fragmentation or protein–protein cross-linkages. Although all amino acids can be modified by ROS, cysteine, and methionine that are the most susceptible to oxidative changes due to high reaction susceptibility of the sulfur group in those amino acids. Oxidative modifications of proteins can change their physical and chemical properties, including conformation, structure, solubility, susceptibility to proteolysis, and enzyme activities. These modifications can be involved in the regulation of fresh meat quality and influence the processing properties of meat products. Oxidative stress occurs when the formation of oxidants exceeds the ability of antioxidant systems to remove the ROS in organisms. Increased levels of protein oxidation have been associated with various biological consequences, including diseases and aging, in humans and other animal species. The basic principles and products of protein oxidation and the implications of protein oxidation in food systems, especially in meat, are discussed in this review.