淡水鱼肉蛋白质组成及其在鱼糜制品加工中的变化

本文通过鱼肉蛋白质组成、鱼糜凝胶特性的测定及SDS-PAGE凝胶电泳,研究了鲢、鳙、草、鲫四种淡水鱼鱼糜凝胶特性及其凝胶形成过程中蛋白质组成的变化。四种淡水鱼肉粗蛋白质含量基本相同,但凝胶特性存在明显差异,其原因是四种淡水鱼肉的盐溶性蛋白含量不同。在鱼糜制品加工过程中,盐溶性蛋白质、水溶性蛋白的比例逐渐下降,而不溶性蛋白比例逐渐上升。弹性凝胶体的形成始于盐擂阶段,主要形成于低温凝胶化阶段。SDS-PAGE凝胶电泳图谱显示,肌球蛋白重链的量在鱼糜凝胶形成过程中明显减少,而肌球蛋白轻链和肌动蛋白的量几乎未发生变化。肌球蛋白重链在内源转谷氨酰胺酶作用下,发生分子间或分子内的ε-(γ-Glu)-Lys共价交联,形成了网络状的不溶性蛋白。     

嫩化时间对大口黑鲈半成品品质的影响

为改善淡水鱼加工和灭菌过程导致的肉质老化和嫩度下降问题,以大口黑鲈(鲈鱼)为研究对象,通过物性测定、十二烷基磺酸钠-聚丙烯酰胺凝胶电泳和扫描电镜系统考察复合嫩化剂(氯化钙1.2‰、复合磷酸盐1.2‰、木瓜蛋白酶1.8‰,均为质量分数)作用时间对鲈鱼半成品的嫩化效果。结果表明:用该嫩化剂嫩化鲈鱼半成品1.0~1.5 h,可显著降低鱼肉剪切力和硬度分别至(21.89±0.27)N和(111.98±3.46)g,提高鱼肉pH值和L*,并增加鱼肉肌原纤维小片化指数;上述指标均和对照组差异显著(P0.05)。凝胶电泳结果显示,嫩化后鱼肉肌原纤维中分子质量38 kD的蛋白和原肌球蛋白发生降解,在约37 kD和28 kD处产生了新的蛋白条带。扫描电镜结果表明,嫩化后鱼肉组织变得蓬松、肌纤维间连接物消失、肌原纤维发生断裂。该复合嫩化剂效果良好,嫩化1.0~1.5 h可显著提升鱼肉半成品品质。     

青海八眉猪与甘肃黑猪肉品质及营养成分比较

通过分析比较青海八眉猪和甘肃黑猪肉质性状、营养成分、氨基酸、脂肪酸、肌苷酸等含量差异,为研究青海八眉猪肉提供数据支撑,并为其资源保护提供一定依据。以10头青海八眉猪和10头甘肃黑猪为研究对象,采用国标法对其背最长肌的各个指标进行了系统比较分析。结果表明:八眉猪肉的失水率、熟肉率显著高于甘肃黑猪肉(P<0.05),大理石纹、肉色、脂肪色、pH在2个品种肉质上差异不显著(P>0.05);八眉猪肌肉中粗脂肪含量显著低于甘肃黑猪(P<0.05),蛋白、水分含量显著高于甘肃黑猪(P<0.05),粗灰分含量差异不显著。相对于甘肃黑猪肌肉中的7种脂肪酸,青海八眉猪肌肉含有14种脂肪酸,且饱和脂肪酸和多不饱和脂肪酸含量显著高于甘肃黑猪(P<0.05),不饱和脂肪酸及单不饱和脂肪酸显著低于甘肃黑猪(P<0.05);甘肃黑猪肌肉氨基酸总量(20.23 g/100 g)高于青海八眉猪(19.14 g/100 g),八眉猪肌肉鲜味氨基酸含量(8.76 g/100 g)高于甘肃黑猪(7.84 g/100 g)。八眉猪肌肉肌苷酸含量为2.44 mg/g,显著高于甘肃黑猪肌肉肌苷酸含量2.05 mg/g(P<0.05);八眉猪肌肉肌酐、次黄嘌呤含量依次为0.55、0.13 mg/g,均显著低于甘肃黑猪的0.81、0.55 mg/g(P<0.05)。由此说明,相比于甘肃黑猪,青海八眉猪肌肉氨基酸比例更合理,脂肪酸更丰富,肌苷酸含量更高,高蛋白、低脂肪,肉质更鲜美。     

腌制风干过程中卵形鲳鲹鱼肉性质、蛋白质氧化及游离氨基酸的变化

为探究卵形鲳鲹在腌制风干过程中蛋白质氧化及游离氨基酸的变化规律,对卵形鲳鲹鱼肉含水率、盐含量、质构特性、肌原纤维蛋白二级结构、羰基含量、巯基含量、蛋白质水解指数、十二烷基硫酸钠-聚丙烯酰胺凝胶电泳图谱和游离氨基酸等进行测定分析。结果表明：在腌制风干过程中,卵形鲳鲹鱼肉的盐含量整体呈上升趋势,含水率下降,硬度增加,而弹性则先上升后下降。鱼肉蛋白质在加工过程中发生氧化反应,羰基含量明显增加,而巯基含量明显下降,同时肌原纤维蛋白二级结构中α-螺旋含量减少,而无规卷曲含量增加。在加工过程中肌球蛋白重链条带和肌动蛋白发生明显变化,肌球蛋白重链条带变浅并在风干后消失,表明肌原纤维蛋白发生水解;鱼肉的蛋白质水解指数增加,非蛋白氮含量在腌制后下降而在风干过程中增加;游离氨基酸总量在干制1 d后达到最高,鲜味氨基酸和苦味氨基酸含量整体呈上升趋势。本研究可为腌制水产品加工过程中品质控制提供一定理论参考。     

俄罗斯鲟鱼不同部位肌肉营养组成分析与评价

以俄罗斯鲟鱼为对象,测定不同部位肌肉中的水分、粗蛋白、粗脂肪、灰分含量及氨基酸、脂肪酸组成,并进行营养评价。结果表明:鲟鱼鱼肉水分含量50.73%～57.93%,粗蛋白含量15.20%～17.25%,各部位间的差异不显著,粗脂肪含量与灰分含量越靠近鱼尾越高。靠近鱼头的鱼肉中氨基酸含量明显高于靠近鱼尾的鱼肉中氨基酸含量。不同部位间氨基酸组成成分差异不大,含量最高的氨基酸为谷氨酸,其次为赖氨酸、亮氨酸和天门冬氨酸,8种人体必需氨基酸占总氨基酸含量的39.87%～43.09%,高于FAO/WHO标准(35.38%)。以AAS评价作为标准,在1～6部位的第一限制性氨基酸为Val,7～8部位的第一限制性氨基酸为Met+Cys。靠近鱼头的鲟鱼肉EAAI为93.61,为良好蛋白源。从俄罗斯鲟鱼鱼肉中检测出22种脂肪酸,靠近尾部的俄罗斯鲟鱼鱼肉脂肪酸含量较高(18.66%～20.44%),EPA+DHA含量3.37%～4.26%。俄罗斯鲟鱼靠近鱼头的鱼肉是高蛋白、高氨基酸的优质肉类,具有较高的营养价值。     

广西本地鲢鱼和长丰鲢肌肉营养成分分析与品质评价

为比较分析广西本地鲢和长丰鲢肌肉品质差异,选取这两个鲢鱼群体中体质量相近的雌雄个体各5尾,测定这4组鱼肉的营养成分、系水力、酸度以及质构特性等相关指标,并进行肌肉营养评价。结果显示:4组鱼肉中粗蛋白含量丰富(17.34%~18.57%),本地鲢雌雄鱼肌肉粗脂肪、粗灰分显著高于长丰鲢,但硬度、弹性和咀嚼性均显著低于长丰鲢雄鱼(P<0.05)。本地鲢雄鱼的回复性显著高于其余3组鱼肉,但粘性显著低于长丰鲢雌鱼(P<0.05),两种鲢鱼雌雄个体间的大部分质构指标差异不明显。4组鱼肉检测出的17种氨基酸中,Asp含量最高,其次为Glu和Lys,His和Cys的含量最低,EAA/TAA和EAA/NEAA的比值分别在39.61%~41.11%和65.60%~69.80%之间,与WHO/FAO要求的40%和60%的理想蛋白质比值接近;氨基酸指数(EAAI)均高于85分(86.13~100.00)。本地鲢雄鱼的∑TAA、∑EAA、∑FAA及EAAI均为最高。4组鱼肉检测出的脂肪酸种类均多于20种,且∑UFA和∑PUFA分别占脂肪酸总量在80%和40%以上。除长丰鲢雄鱼外,其余3组鱼肉的DHA含量均为最高,分别为30.40%、40.36%和24.01%。本地鲢的∑PUFA以及EPA+DHA含量均高于长丰鲢,而∑SFA略低于长丰鲢。结论:两种鲢鱼肌肉营养含量和组成比例均能较好地满足人体需求,本地鲢肌肉较长丰鲢更嫩,多不饱和脂肪酸含量更高。     

大豆素丸和三种肉丸的营养成分与质构特性比较

比较以大豆拉丝蛋白为主要原料、经棕榈油炸制的大豆拉丝蛋白素丸子,与自制猪肉丸子、市售鱼肉和牛肉丸子的营养成分与质构特性,探讨其应用价值。采用国标法检测丸子的营养成分,质构仪检测四种丸子的质地。蛋白质含量从高到低依次为拉丝蛋白丸子39.06 mg N/g、猪肉丸子30.11 mg N/g、牛肉丸子19.91 mg N/g、鱼肉丸子12.79 mg N/g。胆固醇含量从高到低依次为牛肉丸子28.71 mg/100 g、猪肉丸子25.27 mg/100 g、鱼肉丸子14.83 mg/100 g、拉丝蛋白素丸子1.21 mg/100 g。猪肉丸子的脂肪含量显著高于其他三种丸子(p0.05)。大豆拉丝蛋白素丸子的总氨基酸、必需氨基酸、鲜味氨基酸含量最高,分别为15.44±0.59、5.33±0.20、8.89±0.34(g/100g)。四种丸子的不饱和脂肪酸比例很高,占各自总脂肪含量的59%到73%。大豆拉丝蛋白素丸子的弹性、回复性最好,分别为96.84%±1.43%、52.77%±0.56%。研究表明大豆拉丝蛋白素丸子的蛋白质含量高、胆固醇低、氨基酸含量高、有丰富的不饱和脂肪酸、营养价值高、口感佳,可以作为传统肉丸的替代品。     

野生和养殖乌鳢肌肉的成分分析及营养评价

本文对野生和养殖乌鳢肌肉中的营养成分进行了分析和营养评价。结果表明:野生乌鳢肌肉中粗脂肪含量显著低于养殖乌鳢(P0.05)。野生乌鳢n-3多不饱和脂肪酸含量和c22:6(DHA)含量均高于养殖乌鳢,野生和养殖乌鳢肌肉中n-3/n-6的比例分别为1.21和0.65。两种乌鳢肌肉都检测到了17种氨基酸,养殖乌鳢肌肉中氨基酸总量、鲜味氨基酸含量、必需氨基酸含量均高于野生乌鳢,野生和养殖乌鳢肌肉中必需氨基酸/总氨基酸(EAA/TAA)的比值分别为42.66%和42.28%,必需氨基酸/非必需氨基酸(EAA/NEAA)的比值分别为74.40%和73.26%,均高于FAO/WHO推荐的理想蛋白质模式,野生和养殖乌鳢肌肉的必需氨基酸评分(EAAI)分别为63.48和70.82。两种乌鳢肌肉中矿物质元素均以钾最高,养殖乌鳢微量元素含量显著高于野生乌鳢(P0.05)。因此,以低值野杂鱼饵料为食物来源的养殖乌鳢具有良好的开发前景。     

草鱼肉冷藏条件下肌肉蛋白的变化

采用十二烷基磺酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)和差示扫描量热法(DSC),研究了草鱼肉在4℃冷藏过程中肌肉蛋白的变化.结果表明:汁液流失随贮藏时间的延长而逐渐增加;SDS-PAGE表明草鱼肌肉主要蛋白没有发生显著性的降解,但盐溶性蛋白的提取率呈先增加、然后保持稳定、最后减少的趋势,而不溶性蛋白提取率的变化趋势正好与盐溶性蛋白相反;DSC表明随着贮藏时间的延长,草鱼肌肉中肌球蛋白的变性峰变得越来越尖锐,肌浆蛋白的变性峰逐渐消失,而肌动蛋白的变性峰无显著性的变化.     

蛋白质降解指示冷藏罗非鱼片品质劣变研究

通过测定蛋白分解菌、蛋白降解产物、蛋白溶解性以及肌原纤维蛋白和肌浆蛋白的十二烷基硫酸钠-聚丙稀酰胺凝胶电泳(SDS-PAGE)条带变化反映蛋白降解作用对冷藏罗非鱼片腐败进程的影响。结果表明:蛋白分解菌、pH值、氨基态氮含量的变化与肌肉蛋白降解程度具有良好对应关系。当蛋白分解菌少于6.10(lg(CFU/g))时,pH值呈弱酸性,氨基态氮含量无明显增加,肌原纤维蛋白和肌浆蛋白的SDS-PAGE条带模式无明显变化。当蛋白分解菌不少于7.60(lg(CFU/g))时,pH值呈中性至弱碱性,氨基态氮快速增加,SDS-PAGE条带开始扩展分解,蛋白降解作用持续增强。当肌原纤维蛋白SDS-PAGE中中45～29kD处第3条带消失,并在小于等于29kD处出现新条带时是鱼肉腐败的重要标志。     

Nutritional value of acid stabilised silage and liquefied fish protein

Fish silage made by a conventional method (pH 4.0) contained a variety of active enzyme systems which not only hydrolysed fish proteins to short peptides and free amino acids, but also caused the degradation of free amino acids to ammonia and other metabolic products. Acid-stabilised fish silage (pH 2.0) contained only those polypeptides released by endogenous pepsins with only slight accumulation of free amino acids and degradation products. Liquefied fish which was autolysed for less than 1 h at 60°C at physiological pH (6.2–6.6) and then pasteurised and acidified to pH 4.0 contained polypeptides of intermediate length which remained stable. These processes provide a means for adjusting the peptide and free amino acid content of autolysed fish protein to suit the nutritional requirements of a variety of aquatic and terrestrial species.     

Studies on fish protein concentrate and fish meal from river Nile bolti fish (Tilapia nilotica)

Fish protein concentrate (FPC) from river Nile bolti fish (Tilapia nilotica) was prepared and compared with commercial FPC and fresh bolti fish flesh. Fish meal (FM) from bolti fish offals was prepared and compared with commercial FM and also fresh bolti fish flesh. FPC from bolti fish showed a higher crude protein content but less fat, ash, calcium and sand than the commercial sample, while FM from bolti fish showed a higher content of ash and phosphorus than commercial FM but was nearly similar in crude protein, fat, calcium and sodium chloride. FPC from bolti fish had a higher content of lysine, arginine, aspartic acid, glycine and glutamic acid and a lower content of the other free amino acids. The bolti fish FM had a lower content of total amino acids and the contents of the free amino acids cysteine, glycine, aspartic acid, serine, alanine, valine, and methionine increased slightly. The yield was 12% for FPC and 19.5% for FM. Coliform bacteria were not present in both FPC and FM from bolti fish. Low moisture contents of FPC and FM were essential for preventing microbiol growth and to attain a good keeping quality. The FPC and FM from bolti fish reached moisture equilibrium and stopped increasing in weight within 144 to 192 h.     

内源酶在鱼肉和猪肉热胶凝过程中作用的比较研究

以鲢鱼和猪背肌肉为原料,采用质构仪、SDS-PAGE和溶解率测定等仪器和方法比较研究了内源性转谷氨酰胺酶(TGase)、蛋白酶在两种肉糜热胶凝过程中的作用。结果表明,鱼肉TGase于40℃催化蛋白质形成的非二硫共价键促使了其凝胶化,导致鱼糜凝胶劣化的主要是半胱氨酸蛋白酶。猪肉TGase在40℃下活性较低,或该温度下猪肉蛋白质分子链伸展程度偏低不适于被TGase交联;猪肉蛋白酶在60℃也会导致蛋白质的降解,然而该温度下形成的二硫键和疏水相互作用强于水解作用,故猪肉糜未表现出低温(40℃)凝胶化和60℃的凝胶劣化现象。两段加热显著提高了鱼肉糜凝胶的硬度和咀嚼性,而对猪肉糜凝胶性能的影响较小。     

Fish protein hydrolysates: Proximate composition,amino acid composition,antioxidant activities and applications: A review

The fish processing industry produces more than 60% by-products as waste, which includes skin, head, viscera, trimmings, liver, frames, bones, and roes. These by-product wastes contain good amount of protein rich material that are normally processed into low market-value products, such as animal feed, fish meal and fertilizer. In view of utilizing these fish industry wastes, and for increasing the value to several underutilised fish species, protein hydrolysates from fish proteins are being prepared by several researchers all over the world. Fish protein hydrolysates are breakdown products of enzymatic conversion of fish proteins into smaller peptides, which normally contain 2–20 amino acids. In recent years, fish protein hydrolysates have attracted much attention of food biotechnologists due to the availability of large quantities of raw material for the process, and presence of high protein content with good amino acid balance and bioactive peptides (antioxidant, antihypertensive, immunomodulatory and antimicrobial peptides).     

罗非鱼肉分离蛋白的营养成分分析

以罗非鱼鱼肉为原料,采用pH值调节法(pH-shifting),制备鱼分离蛋白,主要探讨提取条件和沉淀条件对提取蛋白得率及其应用特性的影响.结果表明:在极端酸性(pH<3)和极端碱性(pH>10)条件下,鱼肉蛋白的溶解性较好,而在pH值5-6时溶解性较差,由此选择pH值2、3、11和12条件下溶解,pH值5.5条件下沉...     

6种野生鱼肌肉营养成分分析与评价

为探讨同一水域生长野生鱼的营养成分,采用生化分析方法对密云水库鲤鱼（Cyprinus carpio）、鲫鱼（Carassius auratus）、草鱼（Ctenopharyngodon idella）、青鱼（Mylopharyngodon piceus）、翘嘴鲌（Erythroculter ilishaeformis）和鳊鱼（Parabramis pekinensis）肌肉的常规营养成分、矿物质、氨基酸和脂肪酸含量进行分析。结果表明,青鱼粗蛋白含量最高（21.25%）,鲫鱼含量最低（17.70%）;翘嘴鲌粗脂肪含量最高（5.73%）,鳊鱼含量最低（1.18%）。6种鱼富含矿物质K、Na、Ca、Mg、P及Fe、Mn、Zn、Se,为优质的高钾低钠膳食来源。人体必需氨基酸均占氨基酸总量的40.00%以上,鲜味氨基酸占37.53%~39.21%,谷氨酸含量均为最高。鲤鱼、鲫鱼、草鱼、青鱼、翘嘴鲌和鳊鱼肌肉中分别检出22、17、20、22、24和19种脂肪酸,饱和脂肪酸、单不饱和脂肪酸和多不饱和脂肪酸相对含量差异较大。结果表明6种鱼均为优良的蛋白质来源,氨基酸组成合理,有益矿物质和脂肪酸丰富,营养价值高。     

Composition of Surimi-like Material from Beef or Pork

A surimi-like material was made from finely minced beef or pork by water washing followed by screening to remove connective tissue. Changes in component proteins, amino acid composition and vitamin, mineral and cholesterol content occurring during preparation were investigated. Total amino acid nitrogen contents of water-washed beef and pork were higher than those of the respective muscle by 7% and 6.5%. Among 16 amino acids measured, histidine and glycine decreased in both water-washed beef and pork, while others increased compared to original muscle. Thiamin content decreased after washing. Surimi-like beef and pork had less cytoplasmic minerals (K, Na, Mg) but more minerals associated with proteins or subcellular organelles (Ca, Cu, Zn, Fe). Fat content decreased, although cholesterol concentration was not changed by washing.     

非标记液质联用法测定市售鸡肉和猪肉的蛋白组

采用非标记液质联用法对市售鸡肉和猪肉样品进行蛋白组测定,比较两种肉在新鲜和熬煮后的小肽种类、量的相对变化。结果显示新鲜鸡肉的蛋白主要是大于100kD的蛋白,pI值范围为6～11;而鸡肉汤中蛋白主要是10～150kD,pI值范围为4～9;新鲜猪肉的蛋白主要是大于100kD的蛋白,pI值范围为6～11,与鸡肉相似;而猪肉汤中蛋白主要是10～100kD,pI值范围为3～9。显示了不同肉材质在相似加工中,其蛋白组的变化会有所不同,根据这些不同,提示由蛋白组测试提取出的指标可为肉质量的评价提供新的评价方式。     

Differential Scanning Calorimetry of Fish Muscle: The Effect of Processing and Species Variation

Differential Scanning Calorimetry (DSC) has been used to study the thermal properties of fish muscle proteins and to measure the extent of their denaturation under various processing conditions. Fish myosin was susceptible to denaturation by frozen storage and dehydration. Denaturation of certain fish proteins was partially reversible. Although fish myosin was very unstable, its thermal stability was found to increase in species adapted, to higher environmental temperatures.     

The role of collagen in the quality and processing of fish

Collagen in the muscles of fish constitutes the main component of the connective tissue membranes joining individual myotomes and is responsible for the integrity of the fillets. The content of collagen in fish muscles is from about 0.2 to 1.4% and in squid mantel about 2.6%. Fish and invertebrata collagens contain slightly more essential amino acids than intramuscular bovine connective tissue collagen. The invertebrata collagens are exceptionally rich in sugars linked mainly O-glycosidically to hydroxylysine residues. During maturation of fish the proportion of collagen to total protein in the muscles increases while the extent of crosslinking does not change significantly. The thermal properties of fish collagens depend significantly on the content of hydroxyproline and proline residues which in turn is correlated to the temperature of the habitat. Generally the shrinkage temperature of fish skin collagens is about 20 degrees C lower than that of mammalian hide collagens. In several species of fish the weakening of the connective tissues post mortem may lead to serious quality deterioration that manifests itself by disintegration of the fillets, especially under the strain of rough handling and of rigor mortis at ambient temperature. Thermal changes in collagen are the necessary result of the cooking of fish, squid, and minced fish products and contribute to the desirable texture of the meat. However, they may lead to serious losses during hot smoking due to a reduction in the breaking strength of the tissues when heating is conducted at high relative humidity. Because of the high viscosity of gelatinized collagen, it is not possible to concentrate the fish stickwaters, a proteinaceous byproduct of the fish meal industry, to more than 50% dry matter. Better knowledge of the contents and properties of fish collagens could be helpful in rationalizing many aspects of fish processing.