蓝鳍金枪鱼脂质和肌红蛋白的氧化动力学研究

以蓝鳍金枪鱼赤身、中腹和大腹3个部位的肌肉为研究对象,对其脂质和肌红蛋白在-18,-30,-40,-50°C等冻藏温度条件下的氧化动力学进行研究。结果表明:各部位肌肉随着冻藏温度的升高,贮藏时间的延长,TBA值和高铁肌红蛋白含量逐渐增加;各部位肌肉在不同冻藏温度下脂质和肌红蛋白的氧化速率变化规律均符合0级化学反应动力学;各部位肌肉的脂质和肌红蛋白氧化反应速率常数随冻藏温度的变化规律均符合Arrhenius方程的描述,且具有很高的拟合精度(R20.9);脂质氧化的氧化速率对温度变化的敏感顺序是:赤身中腹大腹,与肌红蛋白氧化的变化恰好相反。     

在不同冻藏温度下黄鳍金枪鱼腹部肌肉的脂质氧化和肌红蛋白氧化的动力学研究

以冻藏在-18、-25和-30℃,并贮藏310d的黄鳍金枪鱼腹部肌肉为研究对象,理化指标分析发现,脂质氧化值和肌红蛋白氧化值随贮藏温度的升高,贮藏时间的增加呈现上升趋势。利用相应的反应函数,确立脂质氧化和肌红蛋白氧化反应级数为0级。化学品质动力学研究显示,脂质氧化值和肌红蛋白氧化值的增加随贮藏温度的变化对Arrhenius关系有很高的拟合精度,其拟合方程分别为:y=4.35×10-9exp(0.057t)、y=2.01×10-5exp(0.037t)。     

不同冻藏温度对金枪鱼肉肉色变化的影响

以黄鳍金枪鱼背部肌肉为研究对象,测定不同的冻藏温度(-18℃,-25,-55℃)对肌肉颜色(a*值)、高铁肌红蛋白的含量、脂肪氧化的影响。结果表明:随着冻藏时间的延长,a*值呈下降趋势;高铁肌红蛋白含量增加、脂肪氧化值增加;在不同的冻藏温度下,肌肉a*值变化显著(p<0.05);冻藏温度越低,a*值,脂肪氧化值变化越小,肌红蛋白氧化成高铁肌红蛋白的量越少。     

蓝鳍金枪鱼脂肪氧化和鱼肉色泽的变化研究

结合脂肪氧化和鱼肉色泽指标,观察蓝鳍金枪鱼赤身肉、中腹肉和大腹肉在低温冻藏条件(-18℃)下的变化情况,并对各指标进行相关性分析。结果显示:随着冻藏时间的延长,3个部位肌肉的TBA值和metMb%(高铁肌红蛋白含量)增加;a*值、总色素含量和感官评定值都呈下降趋势;大腹肉变色最快,中腹肉次之,赤身肉最不明显;metMb%与a*值呈极显著负相关(R=-0.943,P0.01),与TBA值呈极显著正相关(R=0.914,P0.01)。分析认为蓝鳍金枪鱼各部位肌肉虽都有褐变的趋势,但速率不同,脂肪含量越高的部位褐变越快;若要保证金枪鱼鱼肉的色泽,必须采取措施防止脂肪氧化和高铁肌红蛋白的产生。     

单色光照金枪鱼脂质和肌红蛋白氧化动力学研究

为探讨单色光照对金枪鱼生食产品脂质氧化和肌红蛋白(myoglobin,Mb)氧化的影响,优化其陈列展示光照条件,实验以大目金枪鱼(Thunnus obesus)赤身肉为研究对象,使用红、黄、绿和蓝4种单色LED(lightemitting diode)灯,以等功率、等光照强度和梯度光照强度3种方式施加光照,测定贮藏过程中金枪鱼肉硫代巴比妥酸反应产物值和高铁肌红蛋白含量变化。结果表明:贮藏期内,相较于暗室贮藏,单色光照显著促进了大目金枪鱼的脂质氧化,加速了Mb氧化;在相同光照强度下,单色光照的促氧化作用随波长减小而增大,但黄色光促氧化作用小于红色光;光照强度影响单色光促氧化作用,蓝色光和绿色光促氧化作用受光照强度的影响程度大于黄色光和红色光;脂质氧化和Mb氧化反应符合0级模式。因此,建议金枪鱼生食产品的陈列展示使用长波长的红、黄色光,避免短波长的绿、蓝色光。     

金枪鱼保鲜方法及其鲜度评价指标研究进展

金枪鱼肉鲜味美,富含肌红蛋白,易与氧结合发生变质,因此研究金枪鱼的保鲜方法及其鲜度评价指标意义重大。本文主要介绍了冷藏、冰鲜、微冻、冻藏、气调等金枪鱼的保鲜方法,综合了理化指标、感官指标和微生物指标等金枪鱼的不同鲜度评价指标,并展望了金枪鱼保鲜及鲜度评价方法的研究热点,同时也指出了目前金枪鱼保鲜需注意的一些问题。     

生食金枪鱼肉冷藏过程色泽变化

对解冻生食黄鳍金枪鱼肉0、2、4、6、8℃冷藏过程中色泽变化进行研究,用高铁肌红蛋白相对含量、色差等指标评价品质,获得生食金枪鱼肉冷藏色泽变化规律。结果表明:0、2、4、6、8℃冷藏过程中高铁肌红蛋白相对含量达到50%的时间分别为40、48、24、20、18h,同时与感官评定显著相关(p<0.01)。色泽变化配对T检验分析表明a*(红度值)和ΔE(色差值)与冷藏温度和时间有较高关联度,温度越高,色差值变化越大,6、8℃冷藏色差值变化显著,但0℃色差值变化却大于2℃。同时建立了高铁肌红蛋白含量随时间变化规律的动力学模型,模型符合一级动力学反应方程。冷藏温度对反应速率常数的影响用Arrhenius方程描述,有较高的拟合精度。     

因子和相关性分析在黄鳍金枪鱼腹部肌肉理化分析与感官鉴定的相关比较中的应用

从理化指标分析和感官鉴定上,研究了不同冻藏温度下黄鳍金枪鱼腹部肌肉随贮藏时间的增加而发生的品质变化,并对理化和感官测定值进行因子分析和相关距离分析.在实验中发现,相同的贮藏时间下,贮藏温度越低,黄鳍金枪鱼肉的品质保存得越好.通过测定感官指标可大体表征其理化指标的变化,也能反映黄鳍金枪鱼的品质变化.     

不同冻藏温度下鲣鱼暗色肉的品质分析研究

研究了远洋围网捕获鲣鱼的暗色肉在不同温度(-18、-25、-33℃)下冻藏9个月期间鲜度、肌纤维蛋白质、肌红蛋白等品质的变化规律。研究结果表明,-18、-25、-33℃下冻藏的鲣鱼暗色肉在第3、4、5个月后其鲜度品质(挥发性盐基氮值、TVBN)开始不被接受,低温延缓了K值的升高,组胺控制在规定范围内;冻藏温度对鲣鱼暗色肉肌原纤维易碎度(MFI)、剪切力、肌红蛋白氧化影响的差异性不显著(p>0.05),但对脂肪氧化的影响有显著性差异(p<0.05)。     

冻贮温度对生食金枪鱼品质变化的影响

研究普通冻贮条件下金枪鱼品质变化规律。以大目、黑鳍和红鳍3种金枪鱼前腹肉为研究对象,以高铁肌红蛋白含量、硫代巴比妥酸反应活性物质(thiobarbituric acid reaction substances,TBARs)值、鲜度指标K值、pH值为检测指标,研究其在-18、-30℃条件下金枪鱼品质随时间的变化规律。结果表明:随着贮藏时间的延长,3种金枪鱼的pH值、鲜度指标尺值、TBARs值及高铁肌红蛋白含量等指标均呈现上升趋势,且-18℃条件下贮藏的金枪鱼各项指标的变化速率明显高于-30℃条件下贮藏的金枪鱼;相较于TBARs和K值,高铁肌红蛋白含量更能反映金枪鱼生食产品的食用品质;-18℃冻贮金枪鱼14 d时高铁肌红蛋白含量已超过30%,金枪鱼颜色由红色向红褐色转变.感官品质明显劣化,而-30℃冻贮条件下则可达28 d。     

Evaluation of the Antioxidant Potential of Hyssop (Hyssopus officinalis L.) and Rosemary (Rosmarinus officinalis L.) Extracts in Cooked Pork Meat

ABSTRACT: The objective of this work was to study the ability of rosemary and hyssop extracts to inhibit lipid oxidation and metmyoglobin formation in pork meat, thereby stabilizing meat color. We also evaluated their effects on iron release from the heme moiety of pork meat. Meat samples were blended with hyssop and rosemary extracts and cooked. The cooked meat was chopped into pieces and stored for 8 d at 4 °C. Heme iron, TBA values, metmyoglobin percentage, and meat color were calculated. Hyssop and rosemary were seen to inhibit lipid oxidation and degradation of heme pigments caused by cooking and storage. Both spices delayed metmyoglobin formation and stabilized the red meat color during storage of the cooked meat.     

Effects of frozen storage temperature on the quality and oxidative stability of bigeye tuna flesh after light salting

Effects of frozen storage temperature on the quality and oxidative stability of lightly salted tuna were investigated. The bright and vivid colour became totally brown after 4 weeks at −20 °C and 8 weeks at −30 °C, where the a^*/b^* value decreased from 1.35 to 0.38 and 0.58, respectively. Discoloration and lipid oxidation occurred concurrently in lightly salted tuna flesh, and it was speculated that the oxidation of oxymyoglobin to metmyoglobin exacerbated lipid oxidation and vice versa. Storage at −40 °C or lower temperatures effectively suppressed the discoloration and maintained the high water-holding capacity and unique textural properties of lightly salted flesh. It was attributed to the reduction in the conformational changes and particularly hydrophobic interactions among proteins, protecting the myoglobin from oxidative damages during frozen storage. Considering the quality maintenance and energy savings, storage at −40 °C was appropriate for lightly salted tuna flesh.     

SOME OBSERVATIONS ON MYOGLOBIN AND LIPID OXIDATION IN FROZEN BEEF

SUMMARY –The observed curvilinear correlation between metmyoglobin formation and lipid oxidation in beef gluteus medius samples (3 mm thick) stored in polyethylene at -5°C was dependent (P < 0.001) on initial treatment, namely freeze-thawing, delayed freezing or mincing. However, these initial treatments accelerated both metmyoglobin formation and lipid oxidation. In slices initially held in 1% oxygen at 0°C to increase the relative amount of metmyoglobin, the concentration of this pigment was first reduced during frozen storage at -5°C before increasing again. High initial metmyoglobin concentrations had no effect on the rate of lipid oxidation.     

迷迭香对生鲜猪肉颜色变化与抗氧化稳定性的影响

选用鼠尾草酸质量分数分别为5%和20%的迷迭香(CAP05、CAP20),分别以一定质量浓度梯度喷射到生鲜猪肉表面,并将猪肉置于超市标准荧光灯下冷藏8d。检测迷迭香对猪肉贮藏期间CIE a*值、色相、氧合肌红蛋白、正铁肌红蛋白、TBARS值、蛋白质羰基和感官评价的影响。实验发现,5%鼠尾草酸的抗氧化效果总体优于20%鼠尾草酸的作用效果,其中r500、r1000和R500组较大程度上延缓了肉品的变色及脂肪和蛋白质的氧化,且r500组肉品在第8天变色最轻、异味最少。统计分析发现猪肉的氧合肌红蛋白、正铁肌红蛋白、TBARS值和蛋白质羰基与颜色CIE a*值之间具有极显著的相关性(P0.01)。     

Discoloration and lipid deterioration of farmed giant catfish (Pangasianodon gigas) muscle during refrigerated storage

ABSTRACT:  Discoloration and lipid deterioration of farmed giant catfish ( Pangasianodon gigas) muscle during 14 d refrigerated storage were investigated. Lipid deterioration, lipolysis, and lipid oxidation in both dorsal and ventral muscles increased as storage time increased. A progressive formation of primary lipid oxidation products monitored by the increase in conjugated dienes (CD) was observed ( P < 0.05) and the increase in thiobarbituric reactive substances (TBARS), an index of secondary lipid oxidation products, was noticeable throughout the storage ( P < 0.05). The pH of both dorsal and ventral muscles tended to increase as storage time continued ( P < 0.05). A gradual increase in free fatty acid (FFA) formation was found within the first 10 d of refrigerated storage ( P < 0.05), suggesting hydrolysis induced by lipases and phospholipases. However, a sharp decrease in FFA content was observed at the end of storage. Refrigerated storage also resulted in changes in redness index of both dorsal and ventral muscles. These changes were coincidental with the changes in metmyoglobin content. Therefore, the discoloration and lipid changes in giant catfish muscle during refrigerated storage depended on the muscle type and might be related to the difference in composition between dorsal and ventral muscles.     

Changes in Bovine Myoglobin Due to Interaction with Methyl Linoleate in a Model System

Changes in myoglobin due to lipid oxidation were studied in a model system, consisting of a mixture of metmyoglobin and methyl linoleate (2:1), which was mechanically emulsified, freeze-dried and stored at 37°C. After storage, samples were reconstituted, centrifuged and lipid fractions were separated and tested for degree of oxidation. The protein was recovered in two fractions: “soluble fraction” (supernatant) and “aggregates” (precipitated proteins). Absorption spectroscopy confirmed protein insolubilization due to formation of aggregates. SDS-PAGE of metmyoglobin recovered from both fractions indicates gradual formation of covalently bound polymers upon storage. Isoelectric focusing (IEF) shows formation of new bands and zones with a drastic acidic shift of isoelectric points. Two-dimensional IEF/SDS-PAGE shows that the newly formed bands on IEF correspond to covalently bound myoglobin polymers.     

Lipid and myoglobin oxidation in pork stored in oxygen- and carbon dioxide-enriched atmospheres

The formation of malonaldehyde and metmyoglobin in pork muscles stored in oxygen- and carbon dioxide-enriched atmospheres at 1°C was followed. The formation of metmyoglobin at the surface of the muscles was independent of carbon dioxide concentration. However, increased oxygen concentration caused a significant decrease in the rate of metmyoglobin formation; the surface concentration of metmyoglobin was below 30% even after 15 days' storage in 80% oxygen/20% carbon dioxide. Lipid oxidation, as measured by malonaldehyde production (TBA Number), occurred at the same rate in air an mixtures containing 80, 90 and 100% oxygen. In some muscles, the rate was such that rancidity was apparent within 6 days at 1°C and, for pork, lipid oxidation, and not bacterial spoilage or metmyyoglobin formation, may be the limiting factor in the use of oxygen-containing atmospheres for storage.     

Effect of dietary vitamin E on pigment and lipid stability of frozen beef: A kinetic analysis

The effect of vitamin E supplementation on pigment and lipid stability was evaluated with beef wrapped in high or low oxygen permeability films and stored in the dark or under constant illumination at -20°C. Dietary vitamin E supplementation improved pigment and lipid stability in both cases. Illumination increased metmyoglobin accumulation but did not affect lipid oxidation rate in both control and supplemented beef. A predisplay dark storage period of 30 days delayed metmyoglobin accumulation during subsequent display. Kinetic analysis showed that vitamin E supplementation stabilized the oxymyoglobin complex by enhancing the deoxymyoglobin oxygenation rate and by decreasing oxymyoglobin autoxidation rate.