延迟加冰对冰藏大黄鱼品质变化的影响

通过微生物、化学和感官指标,以立即加冰为对照研究在25℃环境中延迟4h 和8h 后加冰对养殖大黄鱼(Pseudosciaena crocea)冰藏期间品质变化和货架期的影响。结果表明在延迟加冰阶段菌落总数(TVC)、嗜冷菌数、假单胞菌数、产硫化氢细菌数和总挥发性盐基氮(TVB-N)显著增加;感官品质显著降低;三甲胺氮(TMA-N)变化不明显。延迟加冰可显著增加大黄鱼冰藏期间各种微生物的数量,加快TMA-N 和TVB-N 的产生速率,显著缩短冰藏大黄鱼的货架期和产生异味的时间。感官评价显示立即加冰和延迟4h 与8h 加冰大黄鱼的货架期分别为648、550h 和408h,立即加冰比延迟加冰货架期分别延长98h 和240h,鲜鱼捕获后立即进行加冰处理是相当必要的。     

PCR-DGGE结合生理生化鉴定分析冷藏金枪鱼细菌菌相变化

以感官、色差、质构、挥发性盐基氮(TVB-N)、K值以及菌落总数、嗜冷菌总数为鲜度指标,研究4℃冷藏金枪鱼贮藏期间品质变化;并结合生理生化鉴定和16S rDNA,应用变性梯度凝胶电泳(DGGE)指纹图谱技术,分析冷藏金枪鱼主要微生物的菌相演替变化规律。结果表明:冷藏期间,金枪鱼感官品质劣变明显,亮度值L*、红度值a*和咀嚼性、硬度均呈下降趋势;贮藏第4天,菌落总数自3.60 lg (CFU/g)升至4.66 lg (CFU/g),而嗜冷菌数与菌落总数之间的差异减小;贮藏第6天,TVB-N值与K值分别由初始值9.62 mg/100 g和3.22%上升至25.00 mg/100 g和23.00%;不同冷藏时期的金枪鱼中微生物群落结构具有相似性,样品初始菌相中主要优势菌为噬氢菌、不动杆菌、假单胞菌、解糖假苍白杆菌、Boseaeneae、鞘氨醇单胞菌和油短波单胞菌。随着贮藏时间的延长,微生物多样性降低,至货架期终点第6天,红游动菌、约氏不动杆菌、假单胞菌、解糖假苍白杆菌成为主要优势腐败菌。     

基于电子鼻技术对真空包装三文鱼片的新鲜度评价

采用电子鼻对(4±1)℃条件下真空包装三文鱼片的挥发性物质进行检测并进行主成分分析(PCA)、线性判别分析(LDA)、负荷加载分析(LA),同时研究了鱼片在冷藏期间的感官、挥发性盐基氮值(TVB-N)、质构、色差值的变化规律。结果表明,三文鱼片冷藏期间的感官评分逐渐下降,TVB-N值明显增加,12 d时达到28. 768 mg/100g,已超出淡水鱼TVB-N值小于20. 00 mg/100g的规定范围;鱼片硬度值变化先增加后下降,弹性值缓慢下降;色差L*、a*、b*值变化波动不大,ΔE值前期变化较小,第4天开始迅速上升,第8天ΔE值达到24. 37,与初始鱼片颜色差异显著;电子鼻PCA及LDA分析均对不同冷藏时间的三文鱼片区分度良好,LA分析发现其中主要挥发性物质为氮氧化合物、芳香物质、乙醇及无机硫化物,电子鼻分析结果与感官、TVB-N值、质构及色差分析结果基本一致,表明电子鼻技术可作为真空包装三文鱼片新鲜度的快速评价方法。     

银杏叶提取液与竹醋液流化冰对鲳鱼冰藏期间品质变化的影响

研究银杏叶提取液流化冰与竹醋液流化冰对鲳鱼冰藏期间品质变化的影响。将新鲜鲳鱼运至实验室,清洗后随机分组,分别用体积分数1%银杏叶提取液与体积分数1%竹醋液制得的流化冰进行冰藏处理,以普通流化冰处理后的样品为对照组。贮藏期间,分别于第0、5、9、12、15、18天进行各组样品的感官、理化(质构、电导率、pH值、K值、硫代巴比妥酸值、挥发性盐基氮(total volatile basis nitrogen,TVB-N)含量)与微生物(菌落总数、假单胞菌总数和希瓦氏菌总数)指标分析,并结合低场核磁共振技术对冰藏鲳鱼品质变化的影响进行综合评价。结果得出:与对照组相比,银杏叶提取液和竹醋液流化冰处理组均能较好保持样品的感官品质与质构特性,延缓其电导率值、pH值、K值、TVB-N含量与微生物指标的上升,减慢鱼肉的氧化速率。银杏叶提取液与竹醋液流化冰处理能使鲳鱼的冰藏期从9~12 d分别延长至15~16 d和17~18 d。     

冻藏期间温度波动对三文鱼品质的影响

长期储存期间(3个月),测定三文鱼在冻藏条件为(-18±2)℃、(-18±1)℃、(-18±0.5)℃贮存温度下(温度规律性上下波动)的pH值、色差、挥发性盐基氮(total volatile base nitrogen,TVB-N)值、质构特性以及K值、持水力(water holding capacity,WHC)、感官品质等指标,与-18℃恒温组对比分析,探究温度波动对于三文鱼品质变化的影响,为开发低温度波动冷库提供理论支持。试验表明,在冻藏条件-18℃环境下,温度波动对三文鱼样品的pH值未见规律性影响,而对样品的质构特性、K值、TVB-N值以及色差值、WHC影响显著(P0.05)。即温度波动越小,样品的品质变化越缓慢。     

冷藏三文鱼片特定腐败菌致腐能力测定与分析

以接种三文鱼片特定腐败菌(荧光假单胞菌)的无菌三文鱼片和灭菌三文鱼汁为研究对象,通过定期测定其在0℃冷藏过程中腐败菌数、腐败代谢产物及感官的变化情况,并以其产生腐败臭味时的TVB-N产量因子(YTVBN/CFU)作为其腐败能力的定量指标,探究三文鱼片特定腐败菌荧光假单胞菌的致腐能力。结果表明:接种荧光假单胞菌的无菌鱼片和灭菌鱼汁的货架期分别为216 h和144 h,此时假单胞菌的菌落数分别为7.54 lg cfu/g和7.03 lg cfu/m L;TVB-N的含量分别为30.82 mg/100 g和29.76 mg/100 m L;产量因子YTVB-N/CFU分别为6.36×10-9 mg TVB-N/CFU和0.22×10-9mg TVB-N/CFU。该研究可为靶向抑制三文鱼腐败优势菌的生长,提高三文鱼的品质及延长其货架期提供一定的参考。     

大菱鲆冷藏过程中的鲜度变化与货架期

以感官、化学和微生物为指标,对大菱鲆(Scophthalmus maximus)在0(冰藏)、3、7℃和10℃贮藏过程中的鲜度变化和货架期进行研究,并探讨菌落总数、嗜冷菌、假单胞菌、产H2S 菌、TVB-N、TMA-N 与感官评价的一致性。结果表明,在0 、3 、7 、10℃贮藏过程中,大菱鲆较好品质期分别为433、197、93h 和68h, 货架期分别为602、362、165h 和116h。各温度较好品质期终点和货架期终点时菌落总数分别为(5.74 ± 0.31)、(6.99 ± 0.39)lg(CFU/g),假单胞菌数分别为(5.48 ± 0.24)、(6.26 ± 0.71)lg(CFU/g),TVB-N 均值分别为(15.66 ± 1.93)、(31.81 ± 1.94)mg/100g,TMA-N 均值分别为(2.73 ± 0.12)、(10.71 ± 0.81)mg/100g,各温度下较好品质期终点和货架期终点时各指标均值均无显著差异(P ＞ 0.05),表明菌落总数、假单胞菌、TVB-N 和TMA-N 作为大菱鲆低温贮藏的鲜度指标与感官评价有较好的一致性。     

臭氧冰与电解水冰处理延长鲳鱼的冷藏货架期

为了研究臭氧冰与电解水冰对东海白鲳的保鲜效果,本文采用浓度为0.89mg/kg的臭氧冰与电解水冰(p H:2.49±0.01、ORP=(1115.0±0.5)mv、ACC=(28±1)mg/kg)处理鲳鱼后贮藏于1℃环境中,以普通冰处理作为对照。通过感官评定、菌落总数(APC)、挥发性盐基氮(TVB-N)值、p H、三甲胺氮(TMA-N)值、硫代巴比妥酸(TBA)、K值等指标对鲳鱼进行品质评价。实验结果表明:在贮藏前6d,臭氧冰和电解水冰对TMA-N影响并不显著(p>0.05);贮藏后期,普通冰组、臭氧冰组的TVB-N值、p H、TMA-N值急剧上升,感官质量显著下降(p<0.05)。综合菌落总数、K值、感官指标、TVB-N、TMA-N等指标得出普通冰对鲳鱼的保鲜期为10d,相比于普通冰,浓度为0.89mg/kg的臭氧冰能够延长东海白鲳货架期1~2d,而电解水冰能够延长东海白鲳货架期至19d。且电解水冰能够显著抑制菌落总数、延缓TVB-N值、K值等的增长,但对脂肪氧化有不利影响。臭氧冰和电解水冰能够有效抑制微生物的生长繁殖,显著保持鲳鱼品质,延长鲳鱼货架期。研究结果为鲳鱼品质保鲜提供理论参考。     

苹果多酚处理后冰鲜大黄鱼贮藏期间品质与水分迁移的变化

为研究苹果多酚(apple polyphenols,AP)处理对大黄鱼冰藏期间综合品质变化影响。试验分别选用0. 25 g/L(AP1)、0. 50 g/L(AP2)与1. 00 g/L(AP3)苹果多酚液处理样品,以无菌水处理为对照组(CK)。分析其贮藏期间的p H值、色差、硫代巴比妥酸(TBA)、总挥发性盐基氮(TVB-N)、总巯基含量、菌落总数(TVC)、嗜冷菌数(PBC)与感官变化,并结合持水率、低场核磁共振(LF-NMR)与核磁成像(MRI)技术综合评价其水分迁移。结果得出,CK组样品的TBA值在冰藏12 d后增至(1. 94±0. 236) mg MDA/kg,AP3组样品在冰藏期内未超过1. 5mg MDA/kg。大黄鱼经苹果多酚液处理后,其p H、TVB-N、TVC与PBC值上升受抑,总巯基含量降幅减缓,鱼肉中自由水的流速下降,同时能延缓样品色泽改变,改善其保水性与感官性状。综上所述,1. 00 g/L苹果多酚液能使大黄鱼冰藏期延长2～4 d,该研究结果可为苹果多酚用于水产品贮运保鲜提供理论参考。     

酸性电解水预处理结合不同冰藏方式对大黄鱼保鲜效果的影响

为探究大黄鱼冰鲜贮藏期间理化指标(K值、色泽、质构)、微生物指标、水分迁移特性、微观结构、感官特性的变化,该实验设置酸性电解水预处理结合流化冰、酸性电解水冰、碎冰的处理组,可横向对比同种冰藏方式下预处理对品质的影响、纵向对比不同冰藏方式间的差异.结果表明,酸性电解水预处理的减菌作用能将初始菌落总数3.84 lgCFU/...     

Evaluation of Sensory and Microbiological Changes and Identification of Proteolytic Bacteria during the Iced Storage of Farmed Turbot (Psetta maxima)

ABSTRACT Sensory and quantitative microbiological analyses were performed in farmed turbot ( Psetta maxima ) during iced storage. Sensory analyses revealed a shelf life of 19 d for farmed turbot. The production of total volatile base nitrogen (TVB-N) and trimethylamine-nitrogen (TMA-N) was low and reached levels close to 40 mg TVB-N/ 100 g muscle and 3.5 mg /TMA-N/100 g muscle, even after 40 d of refrigerated storage. The pH value of turbot muscle increased from an initial value of 6.3 to close to 7.0 after 29 d of iced storage. Microbial growth was slow in iced turbot: total aerobic counts reached levels below 7 log colony forming units/g units even after 40 d of storage. Lactic acid bacteria—mainly Lactobacillus delbrueckii subsp. delbrueckii and Lactococcus lactis subsp. lactis strains—were predominant among the proteolytic strains isolated from iced turbot. Proteolytic strains of L. lactis subsp. lactis, Brochothrix thermosphacta, Plesiomonas shigelloides, Proteus vulgaris , and Pantoea species were also isolated from temperature-abused turbot, such proteolytic strains being predominant with respect to nonpro-teolytic microorganisms, suggesting a preferential role of such proteolytic bacteria in the spoilage of turbot. The slow bacterial growth, together with the relative predominance of lactic acid bacteria over Gram-negative microorganisms, may be related to the extraordinary maintenance of the quality and extended shelf life of farmed turbot.     

Effects of gutting and ungutting on microbiological, chemical, and sensory properties of aquacultured sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax) stored in ice

The effect of gutting and ungutting on microbiological, chemical, and sensory properties of aqua-cultured sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax) stored in ice were studied. The total viable mesophilic and psychrophilic bacterial counts increased throughout the storage period of gutted and ungutted sea bream and sea bass. The mesophilic counts reached 8.19 log cfu/g for ungutted sea bream and 7.93 log cfu/g for ungutted sea bass after 14 days of storage. The mesophilic counts reached 8.89 log cfu/g for gutted sea bream and 8.16 log cfu/g for gutted sea bass after 14 days of storage. On day 14 of storage the psychrophilic counts of ungutted sea bream and sea bass were 8.24 log cfu/g and 8.03 log cfu/g, respectively, and for gutted sea bream and sea bass were 8.93 and 8.22, respectively. At the end of the storage period of 14 days, TVB-N, TBA, and TMA-N values of ungutted sea bass were determined as 50.13 +/- 0.25 mg/100 g, 2.66 +/- 0.06 mg malonaldehit/kg, 9.86 +/- 0.01 mg/100 g respectively. TVB-N, TBA, and TMA-N values of ungutted sea bream reached 55.90 +/- 0.36 mg/100g, 2.51 +/- 0.21 mg malonaldehit/kg, 9.79 +/- 0.01 mg/100 g on day 14 respectively. And also at the end of the storage period of 14 days, TVB-N, TBA, and TMA-N values of gutted sea bass were determined as 48.00 +/- 0.26 mg/100 g, 2.48 +/- 0.03 mg malonaldehit/kg, 8.71 +/- 0.06 mg/100 g respectively. TVB-N, TBA, and TMA-N values of gutted sea bream reached 49.66 +/- 0.77 mg/100g, 2.64 +/- 0.07 mg malonaldehit/kg, 8.97 +/- 0.01 mg/100 g on day 14 respectively. The result of this study indicates that the shelf-life of whole ungutted sea bass and sea bream stored in ice as determined by the overal acceptibility sensory scores, chemical quality, and microbiological results show us that the fish were spoilt on day 14. Each chemical, sensory, and microbiological result for sea bream showed us that there was a correlation and similarity and on day 14 it was spoilt.     

Quality Assessment of Tiger Tooth Croaker (Otolithes ruber) During Ice Storage

Quality and shelf life of tiger tooth croaker (Otolithes ruber) during 19 days of iced storage were investigated in terms of sensory, chemical (total volatile basic nitrogen (TVB-N), thiobarbituric values (TBA), peroxide value (PV), free fatty acid (FFA), and pH) and microbiological (total viable count, TVC and total psychrotrophic count. TPC) aspects. Acceptability quality of Tiger tooth croaker determined by panelists was 15–17 days. Limiting factors for acceptability were eye, gills, peritoneum, smell of gills and abdominal cavity, internal organs and flesh. Bacterial loads in samples were higher than limiting level (3 × 10⁶ CFU g^?1) between 15–17 days of ice storage. Of the chemical indicators of spoilage, the initial value of pH was 6.71 and increased to 7.35 at the end of storage. TVB-N content was 15.31mg N/100g on day 0 and reached to 36.52 on day 19. The acceptability of tiger tooth croaker decreased as FFA, PV and TBA values increased (P < 0.05). The release of FFA increased from an initial value of 4.15 (expressed as % of oleic acid) to a final value of 12.75 during the storage period. The initial PV value was 11.69 meq/kg and it increased to 50.75 meq/kg on day 12 and then started to decrease to 35.82 meq/kg at the end of storage period. The initial and final values of TBA were 0.83 and 3.75, respectively.     

去头/内脏处理对秋刀鱼冷藏特性的影响

为了探究去头/内脏处理对秋刀鱼冷藏货架期和腐败特征的影响,分析了不同形态秋刀鱼在4 ℃贮藏过程中感官评分、总挥发性盐基氮（total volatile basic nitrogen,TVB-N）值、硫代巴比妥酸反应物（thiobarbituric acid-reactive substance,TBARS）值、微生物指标（细菌总数）以及气味组成的变化规律。结果显示,随着贮藏时间的延长,2 组秋刀鱼样品的感官评分都呈下降趋势,去头/内脏处理组的下降趋势更为明显;处理组的TVB-N值在第8天时接近30 mg/100 g,而对照组在第12天时才达到该界限值,略滞后于感官评分指示的货架期终点;去头/内脏处理加速了鱼肉脂质的氧化速度,但2 组样品在货架期终点时TBARS均未超过5 mg/kg的限值;处理组的细菌总数初始值显著高于对照组（P＜0.05）,在第8天时超过7.0（lg（CFU/g））,对照组样品在贮藏第10天时接近该界限值。完整态秋刀鱼4 ℃贮藏的货架期为10～12 d,去头/内脏处理组的货架期约为8 d。货架期终点时2 组样品对应的电子鼻气味组成有显著性差异,表明腐败进程明显不同。     

Effect of ungutting on microbiological, chemical and sensory properties of aquacultured sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax) stored in ice

The effect of ungutting on microbiological, chemical and sensory properties of aquacultured sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax) stored in ice were studied. The total viable mesophilic and psychrophilic bacterial counts increased throughout the storage period of ungutted sea bream and sea bass. Mesophilic counts of ungutted sea bream and sea bass reached 7.39 log cfu/g and 7.26 log cfu/g after 9 days. At the end of the storage period of 14 days; TVB-N, TBA, TMA-N values of ungutted sea bream were determined as 37.5±0.51 mg/100 g, 3.82±0.03 mg MA/kg, 7.73±0.25 mg/100 g, respectively. TVB-N, TBA, TMA-N values of ungutted sea bass were reached 35.4±0.9 mg/100 g, 3.75±0.81 mg MA/kg, 6.94±0.08 mg/100 g on day 14th, respectively. Result of this study indicates that the shelf life of whole ungutted sea bream stored in ice as determined by the overall acceptability sensory scores, chemical quality and microbiological data is 12, 9 and 9 days, respectively. Each chemical, sensory and microbiological results for sea bream showed us that there was a correlation and similarity, and day 9 was the beginning of spoilage. Whole ungutted sea bass stored in ice as chemical results for sea bass showed us that day 7 was the beginning of spoilage and for sea bream day 9 was the beginning of spoilage.     

Quality and shelf life assessment of Pacific white shrimp (Litopenaeus vannamei) freshly harvested and stored on ice

Pacific white shrimps (Litopenaeus vannamei) are an important shrimp aquaculture species worldwide. To quantify the quality and shelf life of untreated shrimp is imperative prior to the application of preservative treatments. In this paper, the quality and shelf life of Pacific white shrimp freshly harvested from three different farms and stored on ice for up to 12 days was investigated. The titratable acidity (TA) of shrimp specimens exhibited significant decreases (P < 0.05) whereas the metric chroma (C), total colour difference (TCD), aerobic plate count (APC), trimethylamine (TMA-N) and total volatile basic – nitrogen (TVB-N), peroxide value (PV) and p-anisidine value (AnV) exhibited significant increases during iced storage (P < 0.05). The TMA-N and TVB-N were significantly correlated whereas temporal TMA-N/TVB-N ratio increased considerably (P < 0.05). While the PV and AnV significantly correlated (P < 0.05), the temporal PV/AnV ratio depicted how primary and secondary lipid oxidation of Pacific white shrimp could relate during iced storage of 12 days. The shelf life of ice stored Pacific white shrimps was determined to be 8 days. The information gained by this study could serve as baseline for preservative treatments applied to fresh shrimps.     

Quality Assessment of Farmed Rainbow Trout (Oncorhynchus mykiss) during Chilled Storage

ABSTRACT:  The quality changes of farmed rainbow trout ( Oncorhynchus mykiss ) stored in ice for a period of up to 20 (0, 4, 8, 12, 16, and 20) d were determined by chemical (total volatile basic nitrogen [TVB-N], free fatty acid (FFA), thiobarbituric acid (TBA), peroxide value (PV), heme iron), microbiological (total viable counts, TVC), and sensory methods. The TVB-N level showed fluctuations during storage, indicating that TVB-N could not be a good indicator of rainbow trout quality. The TBA values remained low and were found to fluctuate during storage. The PV values and the release of FFA increased ( P < 0.05), while heme iron content decreased during storage. The total viable counts of rainbow trout increased ( P < 0.05) from the initial value of 4.0 log CFU/g (day 0) to 7.04 log CFU/g (day 20) over the period of storage. This study showed that sensory analysis of rainbow trout correlated well with the microbiological analysis. The results of this study according to microbiological and sensorial data indicated that the shelf life of rainbow trout stored in ice was approximately 9 to 11 d.     

Effects of combining of smoking and marinating on the shelf life of anchovy stored at 4°C

The quality of smoked and marinated anchovy was investigated in terms of sensory, chemical [total volatile basic nitrogen (TVB-N), thiobarbituric acid (TBA), peroxide value (PV), fatty acids, free fatty acids (FFA), and pH] and microbiological parameters (total aerobic count (TVC), coliform, Escherichia coli, Salmonella, Staphylococcus aureus) during 7 months of storage. The results of sensory analyses showed that the total appearance, odor-taste, and texture scores decreased gradually during storage period. The results of the chemical analyses also correlated well with the sensory analyses apart from TVBN value. TBA significantly increased (p<0.05) from 1.9 to 4.25 MA/kg after the storage of 6 month. Peroxide value (POV) showed significant fluctuations (p<0.05) during the storage period. Initial TVC of 3.8 log CFU/g increased to 6.2 log CFU/g at the end of storage period. According to results obtained from sensory, chemical, and microbiological analyses, shelf life of this product was about 6 month.