冷藏和微冻条件下鲤鱼品质变化的研究

为了了解淡水养殖鲤鱼在冷藏和微冻贮藏条件下的品质变化情况,本研究将经前处理后的鲜活鲤鱼分别贮藏于4℃和-3℃冰箱中,测定了菌落总数(TVC)、挥发性盐基氮(TVB-N)、硫代巴比妥酸值(TBA)以及K值等指标的变化。结果显示:冷藏第12天鲤鱼的菌落总数为5.67 logcfu/g,微冻第40天为5.72 logcfu/g;冷藏第8天时TVB-N值为10.55 mg/100 g,微冻第30天TVB-N值为18.85 mg/100 g;冷藏条件下TBA值在贮藏的第14天为0.52 mg/kg,微冻第40天为1.06 mg/kg,均未超过2.00 mg/kg;冷藏第8天K值为55.96%,微冻第30天K值为53.99%。综合各指标变化,4℃和-3℃贮藏鲤鱼的贮藏期分别为8 d和30d,-3℃的微冻贮藏较4℃贮藏鲤鱼贮藏期延长了2.75倍。     

复合生物保鲜剂结合冰温贮藏对红鳍东方鲀的保鲜效果

为了延长红鳍东方鲀鱼块的货架期,利用响应面Box-Behnken原理设计柠檬酸、百里酚和海藻酸钠3因素3水平响应面分析实验,建立以菌落总数为响应值的二次多项式回归模型。并通过pH、汁液流失率、挥发性盐基氮(TVB-N)、硫代巴比妥酸(TBA)、菌落总数及优势腐败菌假单胞菌等指标测定,对最佳配比的复合生物保鲜剂的保鲜效果进行了验证。结果显示,冰温下,柠檬酸、百里酚、海藻酸钠的最优配比分别为0.68%、1.45%、1.94%,贮藏30 d时菌落总数为最低值5.50 lg (CFU/g),并且3种保鲜剂两两间均存在极显著的交互作用。经验证,该复合生物保鲜剂可以显著抑制微生物的增长,有效降低贮藏过程中的TVB-N含量、TBA含量,显著减缓了鱼块的腐败变质发生,货架期较对照组的15 d延长至30 d。     

三种生物保鲜剂结合冷藏对菊黄东方鲀的保鲜效果

为了研究生物保鲜剂对菊黄东方鲀品质的影响,以菌落总数、挥发性盐基氮及汁液流失率为指标,探讨在4℃贮藏条件下,不同生物保鲜剂(茶多酚、乳酸链球菌素以及溶菌酶)处理对菊黄东方鲀品质的影响。结果表明,在贮藏10 d时,0.5%浓度茶多酚组的菌落总数为4.71 lg(CFU/g),TVB-N值为12.82 mg/100 g,汁液流失率为6.12%。在贮藏15 d时,0.2%浓度乳酸链球菌菌落总数仅为4.44 lg(CFU/g),TVB-N值为13.16 mg/100 g,汁液流失率为6.91%。在贮藏10 d时,0.3%浓度溶菌酶组的菌落总数为4.68 lg(CFU/g),TVB-N值为13.25 mg/100 g,汁液流失率为4.47%。空白组在贮藏10 d时的菌落总数达到5.52 lg(CFU/g),显著高于其他保鲜剂处理组(P0.05)。空白组汁液流失率显著低于保鲜剂组。结论:0.5%茶多酚、0.2%乳酸链球菌素及0.3%溶菌酶对菊黄东方鲀的保鲜效果均最佳。     

大黄鱼冷藏过程肌肉蛋白质生化特性与新鲜度的相关性

为研究大黄鱼冷藏期间肌肉蛋白质变化与鲜度品质的相关性,以色差值、质构、挥发性盐基氮(TVB-N)以及感官评分等鲜度指标判断鱼肉品质,并结合肌肉蛋白质中盐溶性和水溶性蛋白质含量、总巯基含量、羰基含量、蛋白质分子量以及粒径分布等蛋白质生化特性指标,分析大黄鱼4 ℃冷藏10天肌肉蛋白质变化与鲜度品质的相关性。结果表明：冷藏期间大黄鱼鱼肉的L*,a*和w值下降,b*值上升;鱼肉咀嚼性、黏着性和硬度下降;TVB-N由(4.42±0.21)mg/100 g增至(38.46±0.87)mg/100 g,并于第8天达二级鲜度标准,感官评分第8天不可接受。冷藏期间大黄鱼盐溶性和水溶性蛋白质含量、总巯基含量、羰基含量变化趋势相似。盐溶性蛋白质含量呈先小幅上升后下降变化趋势,由(159.36±6.51)mg/g降至(91.99±13.82)mg/g,质量分数下降了42.27%,水溶性蛋白质含量由(33.68±2.13)mg/g降至(17.57±0.70)mg/g,质量分数下降了47.77%;盐溶性蛋白质的巯基含量和羰基含量分别由(3.95±0.04)mol/105 g pro降至(1.08±0.13)mol/105 g pro、(1.08±0.04)nmol/mg升至(3.94±0.43)nmol/mg,水溶性蛋白质巯基含量和羰基含量分别由(4.74±0.17)mol/105 g pro降至(2.66±0.15)mol/105 g pro、(0.21±0.14)nmol/mg升至(2.67±0.25)nmol/mg;盐溶性蛋白质粒径在冷藏第0～8天,由(203.32±5.44)nm增大至(425.40±8.63)nm,8天后降至(317.03±1.20)nm,水溶性蛋白质粒径从(190.80±0.30)nm降至(144.23±1.32)nm;SDS-PAGE电泳证明30 ku左右产生新的蛋白质条带且蛋白质量有一定程度减少。结果表明盐溶性和水溶性蛋白质生化特性与新鲜度有良好相关性,其中水溶性蛋白质相关性更好。     

琼胶寡糖及EGCG对冰藏花鲈鱼片新鲜度与蛋白质生化特性的影响

花鲈贮运期间易受微生物与内源酶的联合作用,导致新鲜度及蛋白质生化特性改变,影响其食用价值。因此,采用适当的保鲜方式对花鲈贮运流通过程中的品质变化加以调控,以保证其品质安全显得尤为重要。为探究表没食子儿茶素没食子酸酯(EGCG)及琼胶寡糖(AO)对冰藏花鲈鱼片的保鲜效果,对硬度值、色差及新鲜度指标(硫代巴比妥酸值、K值、挥发性盐基氮、菌落总数、感官评分)进行测定,并对蛋白质生化特性(肌原纤维蛋白含量、二级结构、巯基、羰基含量)进行分析。结果显示,对照组在第16天时感官得分低于8,且菌落总数和K值已分别高达(6.78±0.15) lg(CFU/g)与67.37%±1.75%,不可食用,而EGCG组(EG)、琼胶寡糖组(AO)及复合组的样品仍具有较好的硬度、色泽及新鲜度。贮藏至20 d时对照组的TBA值高达(0.81±0.03) mg/kg,而EG组、AO组及复合组的TBA值在贮藏期间均未出现大幅度增加,且始终低于对照组。另外,贮藏至12 d时对照组的羰基含量已显著高于其他保鲜处理组,对照组在贮藏末期的羰基含量上升至(1.63±0.04)nmol/mg,而EG组、 AO组及复合组的羰基含量仅为(1.14±0.03)、(1.28±0.08)与(0.99±0.09) nmol/mg。贮藏末期复合组的蛋白含量、α螺旋、巯基均高于对照组和单一保鲜组。研究表明,EGCG及琼胶寡糖均能较好地维持鱼片的新鲜度,能显著抑制蛋白质变性与氧化,且二者复合后的保鲜效果优于单一保鲜剂,延长鱼片保质期至20 d以上。该研究为EGCG及琼胶寡糖的保鲜机理提供了理论基础,为开发高效的新型生物保鲜剂提供参考。     

真空包装结合食盐水处理对海鲈鱼冷藏保鲜品质的影响

海鲈鱼采用浓度为10%和25%的食盐水溶液处理(24 h),放置于-1℃内冷藏,通过感官评价、菌落总数(TVC)、挥发性盐基氮(TVB-N)和pH值等指标来综合评价海鲈鱼贮藏品质。研究发现,不同浓度食盐水溶液处理具有减菌作用,冷藏过程中可以明显抑制细菌的生长,同时延缓微生物产生TVB-N的能力。通过Pearson相关分析,海鲈鱼冷藏过程中感官评分与TVC、TVB-N具有极显著相关性,而与pH值无显著相关性。海鲈鱼冷藏保鲜期需要结合3个指标进行综合评价;综合评估得出10%与25%食盐水溶液处理可以延长海鲈鱼达到优级品品质的冷藏期分别为4 d、8 d;达到合格品品质的冷藏期分别为8 d、12 d。     

冷藏和微冻条件下长丰鲢鱼片品质变化规律的研究

通过测定长丰鲢（ Changfeng silver carp ）鱼片在冷藏（4℃）和微冻（-3℃）条件下的感官品质、菌落总数（ TAC）、汁液流失率、 pH、电导率（ EC）、挥发性盐基氮（ TVB-N）以及K值等指标的变化,评价两种贮藏条件对长丰鲢鱼片品质的影响。结果表明：长丰鲢鱼片分别在4℃贮藏至第8天和-3℃贮藏至第25天时失去感官食用价值。4℃贮藏第6天菌落总数为6.75 lg cfu/g,-3℃贮藏第20天为5.89 lg cfu/g。 TVB-N值在4℃贮藏至第8天为29.1 mg/100 g,-3℃贮藏至第25天为21.1 mg/100 g。与冷藏相比,微冻贮藏下长丰鲢有较高的汁液流失率。综合各项指标变化,冷藏和微冻贮藏条件下长丰鲢鱼片的货架期分别为6 d和20 d,微冻贮藏较冷藏长丰鲢鱼片贮藏期延长了2.3倍。     

冰温保鲜条件下牙鲆的鲜度及质构变化

研究牙鲆在冰温贮藏条件下鱼肉的鲜度指标(pH值、K值、TVB-N、细菌总数)和质构特征参数(感官评定、组织构造、破断强度等)的变化,并与冷藏样品的相应变化进行了比较分析.结果表明,随着贮藏时间的延长,菌落总数、K值和TVB-N上升,pH值则先下降后上升,冷藏后期样品pH值上升较快且很高;至货架期终点时破断强度呈减小趋势,组织结构逐渐劣化.与冷藏样品相比,冰温贮藏条件能更有效地抑制牙鲆鱼体内微生物的作用,延长牙鲆的贮藏期.     

不同贮藏温度下大菱鲆品质变化及货架期预测模型的建立

为探究大菱鲆(Scophthalmus maximus)在不同贮藏温度下品质特性与货架期的关系,将大菱鲆贮藏在-3℃、0℃、4℃、10℃和15℃温度下,测定其感官品质、挥发性盐基总氮(TVB-N)、菌落总数、硫代巴比妥酸值(TBA)、电导率的变化,并且观测肌肉的微观结构;采用低场核磁共振技术(Low-field nuclear magnetic resonance, LF-NMR)分析鱼肉中水分迁移状况,并且建立了TVB-N及菌落总数与贮藏时间和温度的动力学模型。研究发现,随着贮藏时间的延长,5种不同贮藏温度下鱼肉中不易流动水均减少,货架期终点各贮藏温度下的样品相对于新鲜鱼肉,其肌纤维结构均由紧密变得疏松;TVB-N和菌落总数变化预测模型中的活化能和指前因子分别为79.50、75.07 kJ/mol和1.3×10^14、7.62×10^12。选用10℃进行验证性试验,结果显示实测值与预测值相对误差在10%以内。因此,可根据TVB-N值及菌落总数对大菱鲆贮藏在-3℃~15℃的货架期进行实时预测。     

冰温结合保鲜剂贮藏对牙鲆鲜度和质构的影响

研究了冰温结合复合配方保鲜剂贮藏技术对褐牙鲆(Paralichthys olivaceus)鲜度和质构特征参数变化的影响,同时与单一冰温贮藏样品的相应变化进行了比较和分析.结果表明:冰温结合保鲜剂贮藏方法能够显著延缓牙鲆鱼肉样品细菌总数、K值、TVB-N和pH值等的增加速度;随着贮藏时间的延长,样品组织结构、破断强度和感官指标等的变化均呈现减缓趋势;与单一冰温贮藏条件的样品相比,冰温结合保鲜剂样品的货架期能有效延长10 d左右,达到最佳保鲜效果.     

Combined Effect of Ozonized Water Pretreatment and Ozonized Flake Ice on Maintaining Quality of Japanese Sea Bass (Lateolabrax japonicus)

The effect of the combined application of ozonized water pretreatment and ozonized flake ice (O+OIce) as compared with traditional flake ice (CK), ozonized flake ice (OIce), and ozonized water pretreatment and traditional flake ice (O) was investigated for the storage of Japanese sea bass. Microbiological, chemical, and sensory analysis and moisture content were carried out throughout a storage period of 18 days. A slower increase of total viable mesophilic count (TVC), total volatile base nitrogen (TVB-N), and thiobarbituric acid reactive substances (TBARS) was observed for O+OIce as compared with OIce, O, and CK. Treatment of O+OIce also allowed a better control of pH as compared with OIce, O, and CK. None of the treatments resulted in a significant difference in myofibrillar protein extractability and moisture content. The shelf life of Japanese sea bass treated with CK, OIce, O, and O+OIce, determined by sensory evaluation, was 9, 15, 12, and more than 18 days, respectively. Principal component analysis results showed that the treatments significantly affected the fish quality during storage, and the sensory attributes had a significant correlation with TVB-N, TVC, and TBARS. In conclusion, the combined application of ozonized water and ozonized flake ice had the best effect on fish quality maintenance.     

鲤鱼冷藏中的鲜度变化与货架期

以感官、化学和微生物为指标,研究了养殖鲤鱼在0℃(冰藏)、5℃、10℃和15℃贮藏过程中的鲜度变化和货架期,并对菌落总数、嗜冷菌、假单胞菌、挥发性盐基氮与感官评价的一致性程度进行了探讨。结果表明,在0℃、5℃、10℃、15℃的贮藏过程中,鲤鱼的高品质期分别为426 h、189 h、95 h和58 h,货架期分别为713 h、382 h、146 h和87 h。各温度高品质期终点和货架期终点时菌落总数分别为6.63±0.45 lg cfu/g、7.18±0.29 lg cfu/g,假单胞菌数分别为5.69±0.75 lg cfu/g、6.50±0.33 lg cfu/g,挥发性盐基氮均值分别为9.90±0.52 mg/100 g、20.52±0.34 mg/100 g。各温度下高品质期终点和货架期终点时各指标均值均无显著差异(P0.05),表明菌落总数、假单胞菌和挥发性盐基氮作为鲤鱼低温贮藏的鲜度指标与感官鲜度评价有较好的一致性。     

Effect of electrical stunning at slaughter on the carcass, flesh and eating quality of farmed sea bass (Dicentrarchus labrax)

Food quality aspects of farmed sea bass (Dicentrarchus labrax) were compared following two methods of slaughter: the normal commercial method of killing, by immersion in an ice slurry, or by first electrically stunning the fish, before immersion in an ice slurry. Quality was assessed for up to 10 days of storage on ice after slaughter. No differences were found between the slaughter methods in terms of an overall sensory evaluation of cooked fillets, or in terms of overall carcass quality: overall appearance, internal and external haemorrhage, fin damage, burst gall bladder, staining of the body cavity by leakage from the gut or damage to the spine. Using objective measurements of colour, no differences between fish from either treatment were found in terms of external colour or colour of the fillets. A chemical analysis of flesh nucleotide breakdown products as well as the freshness indicator K_i value did not differentiate the two treatments nor did the industry standard freshness scoring technique (QIM, quality index method), over 10 days of storage on ice. Flesh pH was marginally lower in electrically stunned fish at 4 h post mortem (6.42 cf 6.56) but by 24 h, pH in fish from both treatments had decreased to a similar level (6.22). Humane electrical stunning of sea bass at slaughter neither measurably improved nor decreased product quality for between 1 and 10 days of storage on ice. Electrical stunning accelerated the pattern of onset and resolution of rigor mortis. If electrical stunning were to be widely adopted, re‐education of buyers would be necessary as rigor mortis is currently used by buyers as a proxy measure of fish freshness.     

Effects of Oil-in-Water Nanoemulsion Based on Sunflower Oil on the Quality of Farmed Sea Bass and Gilthead Sea Bream Stored at Chilled Temperature (2 ± 2°C)

The influence of oil-in-water nanoemulsion on the sensory, chemical, and microbiological qualities of sea bream and sea bass fillets stored at 2 ± 2°C was investigated. The results showed that the use of nanoemulsion extended the shelf life of fish one or two days when compared with the control. Treatment with nanoemulsion significantly (p < 0.05) decreased the values of chemical parameters throughout the storage period. Bacterial growth was inhibited by the use of nanoemulsion. Nanoemulsion had an inhibitory effect on protein denaturation during refrigerated storage and microwave cooking. Based on the results, it can be concluded that sunflower oil-based nanoemulsion extended the shelf life and improved the quality of both sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax) fillets during storage.     

养殖大黄鱼加工和冰藏过程中鲜度和细菌类型的变化

通过对养殖海水以及捕获、加工、流通和冰藏等整个供应链过程养殖大黄鱼的温度履历、感官、化学、微生物的品质监测,评估养殖海水、碎冰和加工过程中大黄鱼细菌卫生状况,分析其在整个过程鲜度和细菌相变化。结果表明,养殖海水和碎冰的菌落总数分别为4.99±0.41 lg cfu/g和3.90±0.32 lg cfu/g,大肠菌群数分别为30~450 MNP/100 g和低于30 MNP/100 g;新捕获养殖大黄鱼的菌落总数为3.82±0.38 lg cfu/g,假单胞菌数为3.13±0.58 lg cfu/g,嗜冷菌数为2.82±0.60 lg cfu/g,大肠菌群数为低于30 MPN/100 g;冰藏第18天时TVBN含量为28.62±0.51 mg/100 g,菌落总数、假单胞菌数、嗜冷菌数和大肠菌群数分别为6.24±0.06lg cfu/g、6.01±0.25 lg cfu/g、5.68±0.21 lg cfu/g和30 MPN/100 g。养殖海水和新捕获鱼中细菌种类繁多,革兰氏阴性菌分别占其总菌株数的64.9%和56.8%;革兰氏阳性菌分别占其总菌株数的27.0%和42.0%;优势菌群为黏性威克斯菌、腐败希瓦氏菌和假单胞菌属。加工结束后,假单胞菌(34.9%)、玫瑰小球菌(32.6%)和缺陷短波单胞菌(14.0%)成为主要菌群。冰藏第4天时仅分离出4种不同类型的细菌,腐败希瓦氏菌比例上升明显,冰藏第10天和第18天时,所占比例分别为63.5%和69.1%,是冷却链养殖大黄鱼产品的优势腐败菌。     

Effects of Lactic Acid Bacteria and Citrus Essential Oil on the Quality of Vacuum-Packed Sea Bass (Dicentrarchus labrax) Fillets During Refrigerated Storage

The preservative effect of refrigerated and vacuum-packed sea bass (Dicentrarchus labrax) fillets inoculated with four mixtures of lactic acid bacteria (LAB) (Lactococcus lactis, Lactobacillus plantarum, and Carnobacterium piscicola) and incorporated with citrus essential oil (CEO) was evaluated on the basis of microbiological and biochemical analysis.

Initially, sea bass fillets showed high nutritional quality. During refrigerated storage, lipid contents did not show a significant decrease in any fish fillets; meanwhile, important proteolysis was observed in untreated control. In addition, results indicated that both CEO and LAB strains exhibited antimicrobial activity against spoilage, pathogenic, and fungi flora. Moreover, the total volatile bases (TVB-N) values were higher in control fillets, and the lowest TVB-N values were observed in Control CEO and C3 + CEO (30.47 ± 0.00 and 32.29 ± 1.12 mg TVB-N/100 g, respectively). Also, the levels of biogenic amines increased in all fillets without exceeding the upper limit of acceptability except for untreated control (sum of about 1396.63 ppm). Furthermore, this combined treatment ameliorated the muscle liquid-holding capacity, which improves technological properties.

Overall, this treatment may open new promising opportunities for the biopreservation of fish products by enhancing the period of storage of refrigerated and vacuum-packed sea bass fillets.     

Effect of Soluble CO2 Stabilization on the Quality of Fillets from Farmed Gilthead Sea Bream (Sparus aurata) and European Sea Bass (Dicentrarchus labrax)

ABSTRACT

Soluble gas stabilization (SGS) is a relatively recent methodology of active packaging that has been proposed to extend the shelf life of packaged fish. The aim of the present work was to study the effect of SGS applied at different extents (2 bars: 30 and 60 min) on the shelf life of sea bream and sea bass fillets packed in air during chilled storage. Quality changes were evaluated by sensory assessment, microbiological analysis (TVC), TBARs, pH value, TVB-N, and TMA-N. No significant extension of sensory shelf life was visible as a function of SGS treatment. The treatment of fillets in CO₂ at 2 bars during 60 min had a positive effect on the microbiological shelf life of both species. On the other hand, TMA-N and TVB-N showed similar changes during storage period and were not affected by the CO₂ treatment. Sea bream treated with SGS always presented higher TBARs than control samples. Nevertheless, oxidation of sea bream and in particular, of sea bass fillets, did not appear to be a significant problem during chilled storage.     

Preliminary results on quality and quality changes in reared meagre (Argyrosomus regius): body and fillet traits and freshness changes in refrigerated commercial-size fish

Meagre (Argyrosomus regius) intensively reared in tank by a Tuscany farm and fed commercial diets, were examined to study a) marketable and flesh nutritional traits in commercial-size fish and b) loss of freshness under refrigerated storage condition. Eighty fish, sampled in May, July and November (at 24, 26, 30 months of age) were submitted to linear measurements and weight of the most important body components. Whole fillets were analysed for moisture, lipid and fatty acid composition. Data were analysed by ANOVA (sampling date). A sub sample of fifty-four meagre (902–1840 g b.w.) was stored at 1 °C with ice cover and evaluated every 24 h after death until spoilage for the EU freshness classes, dielectric properties, rigor index, muscular and eye liquor pH, K₁% freshness index. Data were analysed by regression on time after death. A small sample of meagre (n = 6) and sea bass (Dicentrarchus labrax) (n = 6), reared in analogous rearing condition in the same farm were compared by ANCOVA on body weight (average b.w. 668 g). Meagre were characterised by 1.04 condition factor, 44% fillets, 6% viscera, negligible mesenteric fat (1%) and 94.5% dressing yield. The head incidence increased (P < 0.01) with b.w. increase. Moisture increased while lipid decreased (P < 0.01) in fillet from July to November (74.47 vs 75.96%; 2.93 vs 2.06%). An index of thrombogenicity calculated from the quantitative fatty acid composition was very low (0.10). In comparison with sea bass of the same body weight, meagre had greater length (41.2 vs 37.6 cm), head incidence (29.9 vs 20.7%) and dressing (94.8 vs 89.2%) and lower viscera (5.2 vs 10.9%), mesenteric fat (0.9 vs 7.9%) and intramuscular fat (2.24 vs 12.78%) incidences. Meagre had a 9-day shelf-life (E class from 1^st to 3^rdd and A class from 4^th to 7^thd). Rigor index and impedance remained higher than 90% and 66, respectively until the 3^rdd after death. The quality traits found for this species indicated meagre as a promising candidate for Mediterranean aquaculture.