Change of volatile compounds in fresh fish meat during ice storage

Abstract: The change of volatile compounds in fresh fish meat during 3‐ to 4‐d ice storage was investigated for several fishes using an electronic nose system and a gas chromatography‐mass spectrometer (GC/MS) with headspace solid‐phase micro‐extraction (SPME). Principal component analyses for samples using the electronic nose system revealed that the increase of some volatile compounds during storage was rapid in sardine (Sardinops melanostictus), jack mackerel (Trachurus japonicus), and chub mackerel (Scomber japonicus); moderate in yellowtail (Seriola quinqueradiata), skipjack (Katsuwonus pelamis), and young oriental bluefin tuna (Thunnus thynnus). In contrast to these fishes, the change was little in “white meat” fishes such as red seabream (Chrysophrys major), Japanese seabass (Lateolabrax japonicus), flatfish (Paralichthys olivaceus), puffer (Lagocephalus wheeleri), and bartail flathead (Platycephalus indicus). SPME‐GC/MS analysis showed that some aldehydes and alcohols such as 1‐heptanol, (E)‐2‐octenal, (E)‐2‐hexenal, 1‐pentanol, (E,E)‐2,4‐heptadienal,2,4‐hexadienal, 1‐hexanol, 4‐heptenal, and so forth increased rapidly in jack mackerel and chub mackerel, slowly in skipjack, and a little in red seabream and puffer during the storage. The increase of these compounds was considered to have an effect on the change of electronic nose response. Hexanal was a dominant compound increased from the beginning of the storage in jack mackerel. The increase of volatile compounds was little in red seabream and puffer. The increase of these aldehydes and alcohols was thought to be an appropriate marker for monitoring the freshness of “fresh” fish except for white meat fish. Practical Application: The results of this study are ready to apply for preventing fishy off‐flavor of fisheries products. Lipid oxidative derivatives other than trimethylamine contributed to fresh fish flavor; therefore, to prevent lipid oxidation seemed important.     

Shelf life of several marine fish species of Bangladesh during ice storage

Organoleptic, biochemical and bacteriological aspects of five tropical marine fish such as silver jewfish, Bombay duck, big-eye tuna, Chinese pomfret and ribbon fish stored in ice were studied. Organoleptically all fish were found acceptable for 10–13 days before becoming inedible. Proximate analysis showed that moisture content increased slightly; protein and lipid content decreased gradually and ash had little or no significant change. pH, TVB-N, peroxide and aerobic plate count values increased with increasing storage period but the values were within acceptable range up to 10 days of storage. Changes in myofibrillar ATPase activity and solubility of these fishes showed that Ca²⁺ ATPase in the presence of both 0.1  m and 0.5  m KCl decreased gradually whereas no marked changes were observed in the Mg⁺² ATPase activities in the presence/absence of Ca⁺². Myofibrillar protein solubility of all fish samples also decreased considerably during ice storage. The decrement in Ca²⁺ ATPase activity and solubility indicates denaturation of myofibrillar protein of fish samples during ice storage.     

On-board handling and quality changes during storage of fish predominant in Mexican shrimp by-catch

An important factor in the realization of the potential of shrimp by-catch relates to how it can be easily and economically retrieved. This study deals with this problem and proposes a system of handling and storage of by-catch fish at sea. Some fish representative of by-catch from the Gulf of California were investigated for their storage qualities when held in crushed ice and chilled seawater (CSW). It was determined, using various chemical and physical parameters, that high quality was retained for fish held in ice and CSW for up to 14 and 10 days, respectively. Such storage periods are compatible with the average duration of shrimper voyages. Use of CSW appears a more appropriate method since storage and off-loading would be less labour intensive than with iced storage and ice usage would be reduced. Incorporation of CSW tanks, taking into account existing shrimp boat designs, is proposed which would not affect present iced/frozen storage capacities.     

Spoilage changes in the deep water fish, smooth oreo dory during storage in ice

Smooth oreo dory ( Pseudocyttus maculatus ), a deep water fish, was monitored for changes during storage in ice. Based on the sensory evaluation of the cooked flesh the storage life was 8 days for acceptable quality fish.
Bacterial counts of flesh and surface, the loss of inosine monophosphate (IMP) and the K value showed significant changes during the storage life. Therefore these were found to be useful for monitoring loss of freshness and development of spoilage. After 13 days there were off flavours in the cooked fish, dephosphorylation of IMP had levelled off, and the K value had reached 70%.
The changes that occurred during storage of this deep water species in ice were similar to those changes commonly observed in demersal species from shallow temperate coastal waters.     

Changes in baseline levels of nucleotides during ice storage of fish and crustaceans from the Portuguese coast

Adenine nucleotides and related compounds were measured in North Atlantic hake, monkfish, rockfish, Norway lobster, and red shrimp from the South of Portugal immediately after catch and after a 72-hours ice storage period. To preserve the samples until analysis, a freezing technique with liquid nitrogen was developed and data compared with those from immediate extraction. The use of plastic vials in liquid nitrogen freezing gave similar data as when immediate post mortem extraction was done. Inosine monophosphate (IMP) was the main nucleotide present in the fish species, whereas adenosine monophosphate (AMP) was the major component of crustaceans. During ice storage of fish, adenine nucleotides were almost completely converted to IMP. Rockfish showed a significant catabolism of IMP with conversion to hypoxanthine (Hx). Red shrimp and, especially, Norway lobster presented an important transformation of AMP into IMP. In general, Hx was either not detected (crustaceans) or was present in very low amounts, the highest levels being detected in rockfish after ice storage. This species presented also after 72 h the highest K value (58%), whereas in the other cases the values ranged between 7% and 11%. Trigonelline (Trigo), a UV-absorbing betaine, was also present in both crustacean species together with adenosine triphosphate (ATP) and related compounds.     

Occurrence of biogenic amine-forming lactic acid bacteria in wine and cider

A collection of 810 lactic acid bacteria (LAB) strains isolated from wine and cider was screened for potential biogenic amine (BA) producers by combining molecular and phenotypic approaches. A newly developed multiplex PCR method allowed for the simultaneous detection of four genes involved in the production of histamine (histidine decarboxylase, hdc), tyramine (tyrosine decarboxylase, tyrdc) and putrescine (via either ornithine decarboxylase, odc, or agmatine deiminase, agdi) while TLC and HPLC analysis allowed for BA-production determination. One hundred and fifty-eight LAB strains were monitored by the molecular/phenotypic double approach and revealed a good correlation between genotypic and phenotypic data. Eighteen per cent of the tested strains were positive for at least one BA target gene with up to three detected simultaneously, in particular amongst Lactobacillus brevis and Lactobacillus hilgardii isolates for the tyrdc and agdi genes. The most frequent gene corresponded to the agdi gene detected in 112 strains (14% of all LAB strains) of 10 different LAB species. The tyrdc gene was detected in 67 strains represented by 7 different LAB species (8% overall), especially those isolated from wine. Lower levels of hdc⁺ (2% of strains) and especially odc⁺ (0.5% of strains) strains were observed. Interestingly, species that have never been described to carry BA-producing pathway genes were identified in this study. Furthermore, only one cadaverine-producer was detected and corresponded to Lactobacillus 30a, a collection strain not found in fermented beverages, although cadaverine is commonly detected in wines.     

海鲈鱼腌制过程中产胺菌的分离筛选与生物学特性研究

为探明海鲈腌制加工过程生物胺产生菌的菌相,通过生物胺对培养基进行初筛,采用高效液相色谱进行分析以,并通过VITEK 2菌种鉴定系统,对海鲈腌制加工过程中的产胺菌进行分离鉴定,研究了温度、p H和Na Cl浓度对产胺量较高的菌株生长和产胺能力的影响。结果表明,海鲈腌制加工过程中不仅存在假单胞菌(Pseudomonas)、弧菌(Vibrio)以及葡萄球菌(Staphylococcus)等常见的产胺菌,而且还分离到新的产胺菌——麻疹孪生球菌(Gemella morbillorum)、琼氏不动杆菌(Acinetobacter junii)、皮氏罗尔斯顿菌(Ralstonia pickettii)和格氏乳球菌(Lactococcus garvieae)。这些生物胺产生菌生长和产胺的最适温度是30℃,p H值对其影响不大,具有较高的耐盐性,100~200 g/L的食盐质量浓度可以抑制产胺菌的生长,100 g/L的食盐质量浓度下可以抑制组胺的产生,但200 g/L的食盐才可以抑制腐胺、尸胺和酪胺的形成。     

Recrystallization of ice in ice cream during controlled accelerated storage

Accelerated ice recrystallization in a thin film of vanilla ice cream was studied on a cold stage microscope, housed in a refrigerated glove box. Sample temperature was held constant (within ±0.01 °C) or sinusoidally oscillated for 5 days. Changes in ice crystal size distribution were monitored using an image analysis technique. Several recrystallization mechanisms were observed. Melt-refreeze recrystallization was important for oscillating-temperature conditions, while rounding was particularly apparent at a constant temperature. Accretion was evident for all conditions studied, but migratory recrystallization was observed only rarely.Mean ice crystal size increased as a function of approximately time^−0.33. Recrystallization rates increased with mean storage temperature (−20 to −5 °C) and amplitude of temperature fluctuations (0.01 to 2 °C). However, recrystallization still occurred at very low amplitudes (±0.01 °C), with a recrystallization rate about half as large as for recrystallization with temperature fluctuations of ± 1 °C. Slower temperature fluctuations (2 h cycle) resulted in an initial lag in recrystallization rate that was not observed for more rapid fluctuations (10-min cycle).     

Survival of bacteria during oxygen limitation

Regulatory mechanisms that enable bacteria associated with food, drinks and the human body to adapt to changes in the availability of oxygen are reviewed. Excess oxygen induces two adaptive responses to oxidative stress. Five or more control circuits enable enteric bacteria to generate energy and grow well in anaerobic environments. Two sets of enzymes catalyse both nitrate and nitrite reduction, and dual two-component regulatory systems sense and respond to the available nitrate and nitrite in the environment. The periplasmic nitrate reductase enables bacteria to scavenge low concentrations of nitrate: similar systems are found in food-borne and other pathogens.     

冷藏即食虾仁保藏期间品质变化

目的:制备一种高水分虾仁即食调理食品(水分含量>70%,水分活度>0.95),并对其冷藏保藏期间品质变化进行了研究。方法:活虾去虾头、壳及肠线后,100 ℃ 沸水浴预煮2 min,沥干水后进行真空包装,然后进行二次沸水浴100 ℃热处理10 min,最后微波(600 W)处理2 min。研究冷藏即食虾仁在保藏期间(4 ℃,7 d)水分含量、水分活度、残余内源酶活力、质构、风味物质、微生物等指标的变化。结果:产品在保藏期内水分含量和水分活度没有显著变化;质构方面,产品的回复性略有降低、粘性略有升高,弹性及硬度等没有显著性变化;残余内源酶活力在保藏期间变化幅度不超过1%;虽醇类、酯类和烷烃类等风味物质略有增加,但整体感官品质仍然可以接受,产品的微生物总数低于10⁴ CFU/g,且重金属含量均低于0.5 mg/kg。采用水煮、真空包装、微波处理、低温保藏相结合制备的虾仁即食调理食品,在预设货架期7 d内可以保持较高的水分活度和良好的感官品质。     

Synergistic antibacterial effect of nisin,ethylenediaminetetraacetic acid,and sulfite on native microflora of fresh white shrimp during ice storage

This study aims to investigate the effectiveness of using nisin, ethylenediaminetetraacetic acid (EDTA), and sulfite alone or in combination in reducing Vibrio parahaemolyticus, Salmonella enterica, and Pseudomonas fluorescens in broth and native microflora on raw Pacific white shrimp during ice storage. Nisin (50 ppm), EDTA (20 mM), alone or in combination were used to test on the growth of V. parahaemolyticus, S. enterica, and P. fluorescens in broth. Nisin (50 ppm), EDTA (20 mM), sodium metabisulfite (1.25 and 0.625%), ice; alone or in combination were used on shrimps during 1°C storage for 10 days. Microbial and chemical changes were analyzed during shrimp storage. First, the combination of nisin and EDTA exhibited antibacterial effects against V. parahaemolyticus, S. enterica, and P. fluorescens in broth. Second, in shrimp preservation, the combination of nisin, EDTA, and sulfite at a low dose of 0.625% exhibited higher antimicrobial activity than did a high dose of sulfite (1.25%). Based on aerobic bacteria counts, psychrotrophic bacteria, and TVB-N, shrimp treatment with combination of nisin, EDTA, and low-dose sulfite were still acceptable within 10 days of storage. Based on our findings, nisin and EDTA can be used to reduce uses of sulfite for shrimp preservation in the future.     

Effect of post-rigor fish storage on ice on physicochemical properties of actomyosin

Actomyosin was purified from post-rigor fish stored for various times on ice and was characterised by Mg²⁺-ATPase activity, ATP-sensitivity and SDS-polyacrylamide gel electrophoretic patterns. It had a similar reduced viscosity to that of the myofibrillar extract and the viscosity of both extracts fell in a similar manner as the time of storage of the whole fish on ice increased. No changes in the extractability, the Mg²⁺-ATPase activity or the electrophoretic pattern of actomyosin were detected when extracted from fish muscle held for up to 11 days in ice.     

Foaming capacity of fish minces during frozen storage

This work covers a year's study of the foaming capacity (FC) of minced muscle of three fish species—blue whiting (Micromesistius poutassou R). horse mackerel (Trachurus trachurus L), and mackerel (Scomber scombrus L)—caught in two different seasons (January and July) and stored at – 18°C. Periodic assays were performed to determine protein solubility, FC and dimethylamine formation. The results show that FC is initially inhibited by the presence of the species own lipids; however, during frozen storage this effect is attenuated and thus FC increases. The results corroborate the view that protein solubility is not an indispensible requisite for FC, and that mere dispersion of proteins is sufficient. However, FC is not diminished by changes in protein during frozen storage when this deficiency is offset by sufficient protein concentration. On the other hand, FC is clearly affected by the formaldehyde generated during frozen storage, so that beyond a certain level the aggregates formed as a result of formaldehyde formation are too large to disperse, and hence FC decreases drastically.     

冰藏期间鲶鱼理化性质变化的研究

目的 研究冰藏期间鲶鱼的理化性质变化。方法 通过测定在冰藏条件(0 ℃)下保存时间为0、1、3、7、14、21 d的鲶鱼的色泽、蛋白质含量、pH、汁液损失等指标及蛋白质降解程度变化规律, 分析随保存时间延长鲶鱼品质的变化。结果 冰藏期间鲶鱼肌肉pH呈“V”字型变化, 由6.38±0.08 (0 d)降低至6.25±0.06 (3 d)之后上升至6.47±0.08 (21 d); 水溶性蛋白含量在前3 d逐渐上升, 之后逐渐下降至4.62%; 鲶鱼明度及汁液流失随着冰藏时间的延长而逐渐升高, 其损失率增加至7.01%; 鲶鱼的蛋白质分子量因结构破坏而逐渐降低。结论 冰藏贮存作为一种保鲜技术能在一段时间保持鲶鱼良好的品质, 但冰藏贮存时间不宜超过7 d。     

不同气调包装对醉虾贮藏品质的影响

研究了40%CO2+60%N2和100%CO2的气调包装以及真空和空气包装4种包装方式对贮藏醉虾菌落总数、理化指标和感官指标的影响。结果表明:相对于真空和空气包装组,100%CO2或40%CO2+60%N2的气体包装,对醉虾的保鲜效果较好,其样品的菌落总数和挥发性盐基氮含量较低,质地和色泽变化较小,感官评分较高。但由于100%CO2包装随着贮藏时间的延长,气体收缩较明显导致产品包装外观不理想,40%CO2+60%N2的混合气体包装更适合于醉虾的贮藏。     

低盐虾酱在不同温度下贮藏的品质变化与货架期

对低盐虾酱在20℃、25℃、30℃、35℃下贮藏的品质变化与货架期进行了研究。通过检测贮藏期间菌落总数、副溶血性弧菌、挥发性盐基氮(TVB-N)的变化,并结合感官品质的变化,初步推测了在不同温度下贮藏产品的货架期,并对货架期终点的指标值进行了分析。结果表明:在20℃、25℃、30℃、35℃贮藏过程中,低盐虾酱货架期分别为100d、100d、80d、60d。各温度货架期终点时的菌落总数分别为3.8×104cfu/g、3.9×104cfu/g、4.1×104cfu/g、4.2×104cfu/g,TVB-N值分别为134.6mg/100g,146.8mg/100g,148.7mg/100g,153.6mg/100g,未检出副溶血性弧菌。在4种温度贮藏条件下,感官品质的变化主要是由微生物和化学变化导致的,其变化与菌落总数、TVB-N的变化趋势基本一致。     

鱼、虾饵料的加工技术(下)

详细介绍了鱼虾在不同生长期的生活习性和生理特性,阐述了各成长阶段鱼虾饵料的加工工艺与设备选择的要点,分析了影响鱼虾饵料质量的因素.     

Behaviour of the mechanically separated flesh of some common fish species of the Mexican shrimp by-catch during storage at −20°C

Deboned minces prepared from fish species predominant in the Mexican shrimp by-catch were examined with respect to their stability during storage for 10 months at –20°C. Reductions in the extractability of salt-soluble proteins occurred to varying levels in all samples, particularly in the initial storage phase. These changes were shown to influence the textural characteristics of the minces, albeit to a minimal extent. Considerable variability in the colour of minces from different species was observed and a washing procedure which effectively removes dark pigments is described. In general, the acceptability of the products was maintained throughout the storage period. It is thus concluded that deboning and the freezing of the resultant minces could offer a potential means of processing currently wasted by-catch fish into human food.