三种金枪鱼不同部位肌肉营养成分与风味物质比较

为科学评价大目金枪鱼、黄鳍金枪鱼和蓝鳍金枪鱼不同部位的营养成分与风味物质,采用国标法和Flavorspace?气相色谱-离子迁移谱仪检测了其基本营养成分、氨基酸组成、脂肪酸组成和挥发性风味物质,对比分析不同品种及不同部位间存在的差异。结果表明:三种金枪鱼肌肉的水分含量存在较大差异,不同部位肌肉水分含量为50.16~79.37 g/100 g,其中,蓝鳍金枪鱼肌肉的水分含量显著低于大目和黄鳍金枪鱼（P<0.05）。蓝鳍金枪鱼背部蛋白含量最高,达24.70 g/100 g;蓝鳍金枪鱼腹部脂肪含量高达30.29 g/100 g。大目金枪鱼背部肌肉符合FAO/WHO标准,属于优质蛋白;而大目金枪鱼腹部肌肉、蓝鳍背部和腹部肌肉均接近于FAO/WHO标准,也是良好的蛋白源。三种金枪鱼不同部位肌肉中谷氨酸含量最高,色氨酸含量最低。三种金枪鱼不同部位肌肉共检出31种脂肪酸,其中,二十碳五烯酸（Eicosapentaenoic acid,EPA）和二十二碳六烯酸（Docosahexaenoic acid,DHA）总量较高,二者总量占脂肪酸比例的27.61%~41.73%。共检测到醛类、酮类、醇类、酯类、酸类和烷烃及含氮化合物等40种挥发性风味物质;其中蓝鳍金枪鱼中种类最多,大目金枪鱼最少;同一品种不同部位肌肉中挥发性风味物质的相对含量也存在明显差异。三种金枪鱼不同部位肌肉均具有较高的营养价值,主体风味各不相同;其中蓝鳍金枪鱼背部肌肉必需氨基酸含量高,腹部肌肉不饱和脂肪酸含量丰富,且风味更佳。本研究结果为三种金枪鱼不同部位肌肉的精准加工与利用提供科学依据。     

营养食疗俱佳的金枪鱼

金枪鱼泛指金枪鱼属的鱼类,它们是大洋、高速、长距离洄游的鱼类,也是我国远洋渔业的主要渔获物之一,广泛分布于太平洋、印度洋、大西洋的温带、亚热带、热带海域中,已发现的37个种类:黄鳍金枪鱼(Tbunnus albacare)、金枪鱼(Tbunnus tbynnus)、青干金     

提取黄鳍金枪鱼眼窝肉鱼油的方法比较研究

以黄鳍金枪鱼(Thunnus albacores眼窝肉为研究对象,采用隔水蒸煮法、酶解法、碱水解法和超临界CO2(SC-CO2)萃取法提取鱼油,对所得鱼油的理化性质和脂肪酸组成进行分析测定。结果表明:SC-CO2萃取法和酶解法提取率无显著性差异,但明显高于隔水蒸煮法和碱水解法;SC-CO2萃取法获得的鱼油达到我国水产行业SC/T3502—2000精制鱼油一级标准,其他3种方法达到SC/T3502—2000粗鱼油二级标准;SC-CO2萃取法提取的鱼油不饱和脂肪酸含量最高(74.29%),其中含EPA5.99%、DHA27.12%。因此,SC-CO2较其他3种方法提取金枪鱼眼窝肉中鱼油具有显著优势。     

黄鳍金枪鱼食用品质的研究

取斐济岛黄鳍金枪鱼背部肌肉,分别测定其营养成分,氨基酸及脂肪酸组成和游离氨基酸,对其进行营养价值与食用价值评价。结果显示,黄鳍金枪鱼背肉粗蛋白含量高达24．88％,脂肪含量仅为0．0387％,灰分含量为1．71％。根据1973年FAO／WHO推荐的必需氨基酸需要量模式对黄鳍金枪鱼背肉进行评价,氨基酸评分为95,第一限制性氨基酸为缬氨酸。赖氨酸含量为81．02mg／g,甲硫氨酸含量为54．81mg／g。游离的呈味氨基酸如组氨酸（肉香味）、甘氨酸（甜味）、谷氨酸（鲜味）,分别占氨基酸总量的75．94％、1．25％和1．73％。不饱和脂肪酸含量占总脂肪酸含量的60．95％,其中EPA和DHA分别占6．90％和36．38％。此外,还检测到奇数碳脂肪酸,如十五碳脂肪酸和十七碳脂肪酸。可见新鲜黄鳍金枪鱼背肉是营养丰富、味道鲜美的上等原料。     

3种金枪鱼头不同部位成分比较及营养学评价

分析黄鳍金枪鱼、大眼金枪鱼和马苏金枪鱼鱼头不同部位（鱼肉、鱼皮和鱼骨）的基本营养成分,并评价其营养价值。结果表明：3 种金枪鱼鱼头均含有丰富的粗蛋白、粗脂肪和灰分;3 种金枪鱼鱼头的鱼肉中必需氨基酸种类齐全,必需氨基酸与总氨基酸含量的比值接近40%,氨基酸评分较高,必需氨基酸指数大于86,属于优质蛋白;而鱼皮和鱼骨中蛋白质的营养价值相对较低;3 种金枪鱼鱼头的脂质中饱和脂肪酸、单不饱和脂肪酸、多不饱和脂肪酸的比例接近于1∶1∶1,富含二十二碳六烯酸（docosahexaenoic acid,DHA）和二十碳五烯酸（eicosapentaenoic acid,EPA）,其含量分别为15.69%～23.29%和4.02%～5.15%,DHA与EPA的比值为3.23～5.27,n-6与n-3多不饱和脂肪酸的比值为0.13～0.29,具有较高的营养价值;3 种金枪鱼鱼头中还富含对人体健康有益的Ca、Fe、Zn等矿物质元素。     

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。     

2种大洋性金枪鱼赤身营养价值分析与评价

对黄鳍和长鳍2种金枪鱼赤身部位肌肉的营养成分进行分析与评价。结果表明:黄鳍和长鳍金枪鱼赤身水分含量分别为72.43%和72.73%,脂肪含量分别为0.54%和0.19%,蛋白质含量为25.21%和26.63%,灰分含量为1.32%和1.53%,均含有丰富的矿物质元素;黄鳍和长鳍金枪鱼赤身多不饱和脂肪酸含量高,尤其是DHA含量可高达28.84%和29.83%。黄鳍和长鳍金枪鱼赤身氨基酸配比合理,必需氨基酸含量分别为40.70%和41.70%,必需氨基酸指数(EAAI)分别为92.62和95.00,并含有丰富的呈味氨基酸,其含量分别为40.81%和42.31%。因此,2种金枪鱼赤身肌肉蛋白含量高,脂肪含量低,具有较高的营养价值。     

金枪鱼乳化液中脂肪酸提取及组成分析

金枪鱼在加工过程中产生大量乳化液,严重影响产品的外观和风味。以脂肪酸提取率为指标,利用动物蛋白水解酶对乳化液进行处理并对提取脂肪酸的工艺条件进行了研究。结果表明,最佳酶解条件为:加酶量400 U/g,反应时间4 h,pH7.5,固液比1︰0.5。应用气相色谱分析所提脂肪酸的组成,其中饱和脂肪酸含量约为38%,不饱和脂肪酸约为60%。多不饱和脂肪酸(PUFA)的含量达32.80%,其中C20:5(EPA)和C22:6(DHA)的含量分别为8.32%和18.46%。该脂肪酸澄清透明呈淡黄色,略带鱼腥味,各项理化指标均达到SC/T3502-2000标准的鱼油一级要求,是一种潜在的功能性脂肪酸资源。     

黄颡鱼和大鳍(鳢)肌肉及鱼卵中脂肪酸组成的比较

采用GC测定了黄颡鱼和大鳍(镬)的脂肪酸组成.结果表明:在两种鱼的肌肉和鱼卵中含有22种脂肪酸.在黄颡鱼肌肉中饱和脂肪酸占34.90%;不饱和脂肪酸中,单不饱和脂肪酸占51.37%,多不饱和脂肪酸占13.74%.在黄颡鱼卵中,饱和脂肪酸占26.76%,单不饱和脂肪酸占49.51%,多不饱和脂肪酸占23.73%.从大鳍(镬)来看,肌肉中饱和脂肪酸占26.97%,单不饱和脂肪酸占48.8l%,多不饱和脂肪酸占24.23%;鱼卵中饱和脂肪酸占30.75%,单不饱和脂肪酸占44.08%,多不饱和脂肪酸占25.17%.研究揭示了黄颡鱼和大鳍(镬)的肌肉脂质中以不饱和脂肪酸为主,是理想的食品.两种鱼的鱼卵还含有较高的花生四烯酸(C20:4n-6,ARA)、廿碳五烯酸(C20:5n-3,EPA)和廿二碳六烯酸(C22:6n-3,DHA)的比例,鱼卵的食用、加工值得进一步研究和开发.     

6种鲤科鱼肌肉脂肪的脂肪酸组成比较及相关性分析

为研究鲤科鱼肌肉脂肪中脂肪酸组成及含量的差异,以鳙鱼、缩骨鳙鱼、翘嘴红鲌、鲢鱼、青鱼和脆肉鲩6种鲤科鱼为研究对象,利用气相色谱-质谱联用仪(GC-MS)测定其肌肉脂肪的脂肪酸组成及含量,再采用IBM SPSS Statistics 22. 0对各脂肪酸组成进行相关性分析和聚类分析。结果表明:6种鲤科鱼肌肉脂肪的饱和脂肪酸(SFA)含量为23. 83%～36. 35%,单不饱和脂肪酸(MUFA)含量为30. 87%～54. 34%,多不饱和脂肪酸(PUFA)含量为17. 92%～35. 07%,C20∶5+C22∶6(EPA+DHA)含量为0. 58%～16. 27%;主要组分间的相关性分析结果表明,C18∶0与EPA呈极显著正相关(相关系数r=0. 900～1. 000),EPA与DHA呈显著正相关(r=0. 800～0. 899),C18∶1与DHA呈极显著负相关,与EPA呈显著负相关;聚类分析将6种鲤科鱼分为2组,第一组为缩骨鳙鱼、翘嘴红鲌、青鱼和脆肉鲩,第二组为鳙鱼和鲢鱼。6种鲤科鱼肌肉脂肪中均含有较多的不饱和脂肪酸,具有较高的营养价值和开发利用潜力。     

Identification of tuna species by a real-time polymerase chain reaction technique

Tuna are highly priced fishes that are often used in processed products. For effective fishery management and protection of consumers’ rights, it is important to develop a molecular method to identify the species of the tuna products. In this study we have developed a molecular method based on real-time polymerase chain reaction (real-time PCR) technology for the rapid identification of four tuna species. Four species-specific TaqMan probes were designed to identify bigeye tuna (Thunnus obesus), Pacific bluefin tuna (Thunnus orientalis), southern bluefin tuna (Thunnus maccoyii), and yellowfin tuna (Thunnus albacares). A SYBR green system was also designed to enhance the authentication of T. obesus. Both systems can distinguish target species from others in an efficient and high-throughput manner and can be applied to species identification of tuna products.     

Characterization of Mexican Fishes According to Fatty Acid Profile and Fat Nutritional Indices

The fatty acid profile of crevalle jack was compared with that of Atlantic bluefin tuna, Atlantic Spanish mackerel, red snapper, and Nile tilapia. Crevalle jack and Atlantic Spanish mackerel showed similarities in their fatty acid profiles, with the saturated fatty acid > monounsaturated fatty acid > polyunsaturated fatty acid pattern. Atlantic bluefin tuna and red snapper followed a similar pattern to each other, with the polyunsaturated fatty acid > saturated fatty acid > monounsaturated fatty acid pattern, and the pattern for Nile tilapia was saturated fatty acid > monounsaturated fatty acid ≈ polyunsaturated fatty acid. In winter, the DHA+EPA content of crevalle jack (493.2 mg/100 g fillet) was 37% lower than Atlantic bluefin tuna and Atlantic Spanish mackerel, 35% higher than for the red snapper, and 2.8 fold higher than for the Nile tilapia. The best nutritional indices were for Atlantic bluefin tuna > red snapper > Atlantic Spanish mackerel > crevalle jack > Nile tilapia.     

Use of the Mitochondrial Control Region as a Potential DNA Mini-Barcoding Target for the Identification of Canned Tuna Species

In this study, a DNA mini-barcoding methodology was developed for the differentiation of species commonly found in canned tuna. Primers were designed to target a 236-base pair (bp) fragment of the mitochondrial control region (CR) and a 179-bp fragment of the first internal transcribed spacer region (ITS1). Phylogenetic analysis revealed the ability to differentiate 13 tuna species on the basis of the CR mini-barcode, except in a few cases of species introgression. Supplementary use of ITS1 allowed for differentiation of introgressed Atlantic bluefin tuna (Thunnus thynnus) and albacore tuna (Thunnus alalunga), while differentiation of introgressed Atlantic bluefin tuna and Pacific bluefin tuna (Thunnus orientalis) requires a longer stretch of the CR. After primer design, a market sample of 53 commercially canned tuna products was collected for testing. This mini-barcoding system was able to successfully identify species in 23 of the products, including albacore tuna, yellowfin tuna (Thunnus albacares), and skipjack tuna (Katsuwonus pelamis). One instance of mislabeling was detected, in which striped bonito (Sarda orientalis) was identified in a product labeled as tongol tuna (Thunnus tonggol). PCR amplification and sequencing was unsuccessful in a number of products, likely due to factors such as the presence of PCR inhibitors and DNA fragmentation during the canning process. Overall, CR and ITS1 show high potential for use in identification of canned tuna products; however, further optimization of the assay may be necessary in order to improve amplification and sequencing success rates.     

Risk-benefit analysis of fish consumption: Fatty acid and mercury composition of farmed southern bluefin tuna, Thunnus maccoyii

The docosahexanoic acid (DHA) and eicosapentaenoic acid (EPA) contents and total mercury concentration were measured in whole tissue composites of all edible tissues of wild caught and farmed southern bluefin tuna (Thunnus maccoyii, SBT) and each of the marketed tissue cuts (akami, chu-toro and o-toro) of these fish. Rapid lipid accumulation during culture resulted in a net reduction in mercury concentration of SBT composite tissues and an increase in the concentration of the dietary essential fatty acids. Moreover, the increased affinity of lipid for certain tissue cuts (o-toro) over that of others (e.g. akami), resulted in cross carcass variation in the mercury concentration of fish muscular tissue. Results highlight the potential for farming to be used as a tool to improve the flesh quality of fish species which could otherwise provide limited dietary essential fatty acids to consumers and potentially contain elevated contaminant levels.     

Evaluating nutritional quality of pacific fish species from fatty acid signatures

Eight fish species common to the Pacific Northwest coastal waters were categorised according to total lipids in a ranking from lean fish (e.g. walleye pollock) to oily fish (e.g. herring) species. Comprehensive fatty acid signatures were compared on both the relative proportion of total fatty acids and the proportion of total carcass lipid content. Generally, fish species from the Pacific coast had a relatively high proportion of n-3 highly polyunsaturated fatty acids (n-3 HUFAs), of which more than 80% was accounted for by C20:5n-3 (EPA) and C22:6n-3 (DHA), with species-specific and lower proportions of oleic acid (C18:1n-9) and palmitic acid (C16:0) also dominating. The MUFA contents of fish were lower (P < 0.05) in the lipids of lean and low-fat fish compared to those of fattier species. In contrast, higher (P < 0.05) proportions of polyunsaturated fatty acids (PUFAs) existed in the low-fat species with DHA contents ranging from 18% to 29% in the low-fat fish and from 8% to 10% in the fattier fish, such as herring and capelin. Expressing the same fatty acid content data in terms of absolute amount of fatty acids (e.g. gFA/100 g wet tissue) showed that both EPA and DHA contents in the flesh of pollock and hake were indeed many fold lower than those found in fatty fish, such as herring. The findings confirm that it is important that both the total lipid content and the fatty acid composition of these Pacific fish food sources be considered when making evaluations on the nutritional quality.     

2 种低值金枪鱼赤身肉的营养成分分析与评价

以青干金枪鱼和鲔的赤身肉为研究对象,通过气相色谱、液相色谱和原子吸收光谱等理化检测方法对其进行营养成分分析并作出评价。结果表明：1）青干金枪鱼和鲔赤身肉水分含量分别为71.13%和72.27%;粗脂肪含量分别为0.63%和1.47%;粗蛋白质含量分别为24.56%和23.44%;灰分含量分别为1.56%和1.38%;2 种金枪鱼均含有丰富的矿物质元素。2）青干金枪鱼和鲔赤身肉多不饱和脂肪酸含量高,尤其是二十二碳六烯酸含量高达28.53%和21.56%。3）青干金枪鱼和鲔赤身肉氨基酸配比合理,必需氨基酸/总氨基酸分别为39.86%和39.97%,必需氨基酸指数分别为96.23和96.66。因此,2 种金枪鱼赤身肌肉蛋白含量高,脂肪含量低,具有较高的营养价值。     

A 13C-NMR study of lipid alterations during fish canning: Effect of filling medium

Carbon-13 nuclear magnetic resonance spectroscopy was applied to study the effect of the filling medium on lipid modifications occurring during the industrial canning of tuna (Thunnus alalunga). In the two media studied—brine and soybean oil—increases in the free fatty acid level were observed with preferential hydrolysis of polyunsaturated fatty acids esterified in the sn-2 position of the glycerol moiety. The extent and mechanism of lipolysis seem to be independent of the filling medium used. Quantitative results obtained for the main lipid classes showed dilution of the natural lipids of muscle by triacylglycerols from the filling medium in oil-filled cans.     

Total mercury levels in muscle tissue of swordfish (Xiphias gladius) and bluefin tuna (Thunnus thynnus) from the Mediterranean Sea (Italy).

This study was carried out to determine the current levels of total mercury in the muscle tissue of swordfish (Xiphias gladius) and bluefin tuna (Thunnus thynnus) caught in the Mediterranean Sea with the purpose of ascertaining whether the concentrations exceeded the maximum level fixed by the European Commission Decision. In addition, specimens of each species were divided into different ranges of weight to investigate the influence of size on mercury accumulation in order to provide data upon which commercial fishing strategies and marketing of swordfish and bluefin tuna may be based. Higher mean levels of total mercury were found in bluefin tuna (1.02 microg g(-1) wet wt) than in swordfish (0.49 microg g(-1) wet wt). In 4.3% of swordfish and in 44.3% of bluefin tuna analyzed, total mercury concentrations exceeded the maximum level fixed by the European Commission Decision (Hg = 1 microg g(-1) wet wt). Besides, for bluefin tuna the total mercury level variability observed, due to size, suggests that there should be greater regulatory control by the authorities.