棒状乳杆菌发酵秘鲁鱿鱼糜凝胶特性的变化及其形成机理

为阐明棒状乳杆菌（Lactobacillus coryniformis）Lz153发酵秘鲁鱿鱼糜的凝胶形成机理,通过质构仪测定棒状乳杆菌Lz153发酵秘鲁鱿鱼糜凝胶特性,分析凝胶形成过程中离子键、氢键、疏水相互作用、二硫键及非二硫共价键的变化,并利用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（sodium dodecyl sulfate-polyacrylamide gel electrophoresis,SDS-PAGE）方法观察肌原纤维蛋白变化情况。结果表明,棒状乳杆菌Lz153鱿鱼糜发酵24～36?h阶段凝胶特性最佳;离子键含量在发酵过程中呈逐渐减少趋势,氢键和疏水相互作用含量分别在发酵36?h和30?h达到最大值,二硫键和非二硫共价键含量随发酵时间延长而呈增加的趋势;氢键、疏水相互作用、二硫键和非二硫共价键是形成和维持凝胶网络的主要作用力。SDS-PAGE图谱显示,发酵后肌动蛋白和肌球蛋白重链均开始被降解,同时经发酵24?h后分子质量在100～135?kDa范围出现了新的盐溶性蛋白质条带,发酵至48?h也被降解。研究结果可为开发秘鲁鱿鱼为原料的乳酸菌发酵鱼糜制品加工提供参考依据。     

新西兰柔鱼与北太平洋柔鱼的品种特异性聚合酶链式反应鉴定

利用聚合酶链式反应(polymerase chain reaction,PCR)技术扩增新西兰柔鱼和北太平洋柔鱼的线粒体细胞色素C氧化酶亚基Ⅰ(cytochrome C oxidase subunitⅠ,COⅠ)基因,通过多重序列比对检测2种鱿鱼之间的多态性位点。根据2种鱿鱼的特异性位点分别设计2种鱿鱼的品种特异性引物,并利用多重PCR实现2种鱿鱼品种的特异性鉴定和区分。结果表明:建立的品种特异性PCR鉴别体系对新西兰柔鱼和北太平洋柔鱼分别扩增出214 bp和339 bp的品种特异性条带,该方法的检测限低至0.1 ng,且能检测出新西兰柔鱼中1%的北太平洋柔鱼掺入,并能有效检测市场上2种鱿鱼及其复配鱼糜制品的原料来源。     

Accelerated Cheddar Cheese Ripening with an Aminopeptidase Fraction from Squid Hepatopancreas

ABSTRACT: An aminopeptidase (AP) fraction from squid (Illex illecebrosus) hepatopancreas was added to Cheddar cheese at 2 levels, and its influence on ripening indices was determined for up to 3-mo storage at 11 °C. Two commercial enzymes (Neutrase ® and Flavourzyme ®) were similarly tested. Cheese with the higher level of squid AP contained more soluble N, amino acids, and Cheddar flavor after 1 mo, but it developed defects in texture and bitterness as ripening progressed. Cheese with less squid AP did not differ from the control with respect to all ripening indices over 3-mo storage. Ripening Cheddar contains cysteine protease inhibitor(s) that inhibit low levels of squid AP but not Neutrase ® and Flavourzyme ®.     

Distinctive characteristics of collagen and gelatin extracted from Dosidicus gigas skin

Squid skin, often discarded as processing by-product, is a good resource of collagen/gelatin. In this study, acid soluble collagen (ASC), pepsin soluble collagen (PSC) and water soluble gelatin (WSG) were extracted from squid (Dosidicus gigas) skin and physicochemically examined. The lowest yield of 33.5% was obtained for ASC extracted at 4 °C, and the addition of pepsin increased the collagen yield by around 35.0% (PSC). The highest yield of 81.9% (WSG) was achieved by thermal extraction at 60 °C. A low temperature can largely retain the native helix structures of ASC and PSC, contrariwise, thermal treatment converted collagen into gelatin with unordered and renatured structures. The proline and hydroxyproline contents of ASC, PSC and WSG were 183/1000 residues, 194/1000 residues and 175/1000 residues, respectively. In addition, WSG showed a denaturation temperature at 80.7 °C which was much higher than that of ASC (24.2 °C) and PSC (26.2 °C), while a significant lower resistance towards enzymatic digestion.     

新鲜鱿鱼超高压杀菌工艺试验

为确定新鲜鱿鱼超高压杀菌工艺的最佳工艺参数,以杀菌压力、保压时间、漂烫温度为条件,设计了新鲜鱿鱼超高压杀菌试验。试验结果表明,90℃漂烫10 min,在400 MPa压力下保压10 min,此为新鲜鱿鱼超高压杀菌的最佳工艺条件。     

Molecular identification of dried squid products sold in China using DNA barcoding and SYBR green real time PCR

ABSTRACT

Dried squid products are popular in China as a snack food, side dishes, or refreshments, and the market appeal can be reflected by the high price that occasionally reaches 497 RMB per kg. However, the absence of harmonisation around the definition of squid, as well as the problems with visual inspection for processed seafood products, make alternative species substitution for dried squid products a frequent occurrence. The aim of the present study was to apply a DNA barcoding approach for species identification of 48 dried squid products collected from the largest online shopping platform in China. Moreover, we also developed a novel SYBR green real-time PCR assay (simplex and duplex followed by a melting curve analysis) specific for Illex argentinus and Todarodes pacificus based on cytochrome C oxidase subunit I (COI) gene.

Results highlighted the successful DNA extraction and PCR amplification of a 655 bp COI gene fragment from all products. A maximum similarity value in the range of 98-100% was obtained for all readable sequences using the BOLD and BLAST public databases and four species (Dosidicus gigas, Uroteuthis edulis, I. argentinus, and T. pacificus) were identified. The specificity of the designed primer sets was confirmed against 23 non-target species, and the newly developed methods were successfully applied to screen I. argentinus and T. pacificus in dried squid products.

Overall, DNA barcoding is a robust tool for seafood species identification and the novel method is effective in screening I. argentinus and T. pacificus in food products.     

秘鲁鱿鱼皮酸溶性胶原蛋白提取工艺优化及其特性

以秘鲁鱿鱼皮为原料,通过单因素试验及响应面优化法得到秘鲁鱿鱼皮酸溶性胶原蛋白（acid soluble collagen,ASC）最佳提取工艺,并对ASC的理化特性进行研究。结果表明：最佳提取工艺为在4 ℃条件下,冰醋 酸浓度0.47 mol/L、液料比24.5 mL/g,浸泡43 h后,ASC提取率为31.76%;紫外全波长扫描结果表明,所得ASC在 231 nm波长处有最大吸收峰,符合Ⅰ型胶原蛋白特征;凝胶电泳分析表明,提取的ASC含有α1、α2和β链;拉曼光 谱分析表明,所得ASC结构完整,三螺旋结构未受到破坏;ASC的相变温度为50.07 ℃。     

秘鲁鱿鱼和日本海鱿鱼营养成分分析与评价

以秘鲁鱿鱼（Dosidicusgigas）和日本海鱿鱼（onychotellmisborealijaponicusokada）为原料,对其胴体的营养成分进行了分析比较与评价。研究表明,秘鲁鱿鱼和日本海鱿鱼都是低脂肪高蛋白食品,两者的蛋白质、脂肪、灰分含量均相近,水分含量前者显著高于后者（P〈0．05o两者的磷P、锌Zn、铜Cu含量没有显著性差别,日本海鱿鱼钙Ca的含量为（2.31‰）高于秘鲁鱿鱼（1．64％0o秘鲁鱿鱼的氨基酸总量、EEAA／ZAA均高于日本海鱿鱼,按照FAO／WHO建议的氨基酸评分标准模式,两者均属于优质蛋白质。两种鱿鱼含量最高的氨基酸均为谷氨酸,以AAS模式来看,虽然两种鱿鱼必须氨基酸指数不同,但都大于0．5,说明鱿鱼胴体营养丰富且符合人体对氨基酸的需求。秘鲁鱿鱼含有10种不饱和脂肪酸,日本海鱿鱼含有7种。与其他海产品相比较,鱿鱼的DHA含量较高,营养丰富,是具有较高开发前景的优质海产品。     

北太平洋鱿鱼(Todarodes pacificus)内脏自溶液总氨基酸组成质量评价和体外抗氧化性分析

采用自溶法水解鱿鱼内脏,测定鱿鱼内脏自溶液(squid viscera autolysates,SVAs)的蛋白质提取率、可溶性氮含量、游离氨基酸含量和水解度,分析SVAs总氨基酸组成,评价其营养价值,并对SVAs的体外抗氧能力进行分析。结果表明:SVAs的蛋白质提取率为(53.89±1.17)%、可溶性氮质量分数为(78.47±1.16)%、游离氨基酸质量浓度为(0.22±0.03)mg/m L、水解度为(14.73±2.02)%。SVAs中必需氨基酸含量占氨基酸总量的37.03%,呈味氨基酸(天冬氨酸、谷氨酸、丙氨酸和甘氨酸)含量占氨基酸总量的42.40%。氨基酸组成与联合国粮农组织/世界卫生组织推荐氨基酸评分标准模式和全鸡蛋蛋白质氨基酸模式相比较,得出SVAs是一种营养丰富、且氨基酸组成合理的优质蛋白源。研究还表明,SVAs具有良好的体外抗氧化能力,其中清除1,1-二苯基-2-三硝基苯肼自由基和羟自由基的IC50值分别为0.24 mg/m L和0.74 mg/m L,还原能力强于相同质量浓度的L-肌肽。     

Effect of pH and chitosan concentration on gelation of protein concentrate from giant squid mantle (Dosidicus gigas)

Jumbo squid (Dosidicus gigas) is characterised by its low commercial value, lean and white meat without bones or scales and high muscular yield. Therefore, it is an attractive species for the production of protein concentrates. However, the gelling ability of squid proteins is low due to the inherent characteristics of the proteins. Different hydrocolloids can be used to improve the gelling ability, where pH and concentration of the hydrocolloids are very important to stablish. Therefore, this study aimed to obtain a protein concentrate from Dosidicus gigas and evaluate the effect of pH and chitosan concentration on its gelation and conformational changes. Treatment at pH 7.0 with 2% chitosan improved the water‐holding capacity, elasticity and agglomeration according to the Z potential; it also improved the thermal stability and gelling according to the dynamic oscillatory measurements and differential scanning calorimetry. This information demonstrates that chitosan incorporation plays an important role in gel formation and improves the gelling capacity of squid proteins without affecting the brightness and whiteness, important parameters for this product.