EFFECTS OF SALT AND SUCROSE ADDITION ON THERMAL DENATURATION AND AGGREGATION OF WATER-LEACHED FISH MUSCLE1

Heat-induced denaturation of water-leached fish muscle proteins, as affected by addition of sucrose and/or salt, were investigated by differential scanning calorimetry (DSC). Net enthalpic changes for these muscle proteins were always endothermic in nature, and of a greater magnitude at faster heating rates. This was interpreted to infer that aggregation at lower heating rates led to formation of a gel structure in which potential bondings were more completely accomplished; that is, a more energetically favorable structure was attained with slow heating. The stabilization of proteins by sucrose, and destablization of proteins by salt, were revealed by shifts in transition peaks and activation energies, the latter determined by two methods of kinetic analysis.     

Brining Procedures to Produce Uniform Salt Content in Fish

Inhibition of outgrowth and toxin production by Clostridium botulinum type E in smoked fish homogenates has been demonstrated at 3% water phase salt. Having the required salt content on a product that would not be too salty requires a uniform salt distribution throughout the fish. A two-stage brining procedure was developed that resulted in minimal differences in water phase salt contents between the thin and thick sections of a fish. The first stage involved soaking in 10% NaCl for 15 hr, using a fish to brine ratio of approximately 1 lb to IL. A second stage soak in 2% NaCl for 24–48 hr depending on the size of the fish leached out excessive salt in the thin sections of the fish while leaving the salt iinside the thick sections. Analysis of samples from four different areas on the smoked fish brined using the two stage procedure revealed a uniform salt content.     

Seasonal effects on the physicochemical characteristics of fish sauce made from capelin (Mallotus villosus)

Fresh capelin (Mallotus villosus) was harvested from the North Atlantic during both summer and winter fishing seasons. Reaction conditions for fish sauce processing were optimized with respect to temperature, salt concentration and reaction time, using a response surface methodology (RSM) experimental design. Whole capelin was minced and samples were ground with increasing salt concentrations. RSM optimizations were conducted, ranging from 5% to 30% salt, and incubating at 5° intervals from 0 to 65 °C. Autolytic activity was estimated by extracting the liquid formed by the mixture with trichloroacetic acid and estimating protein content by the Lowry method. Samples for fish sauce production were then prepared under optimized conditions by mixing ground capelin with 10% salt and incubating at 50 °C for up to 270 days for the summer capelin and up to 360 days for the winter capelin. Samples were collected at regular intervals and analyzed for liquid yield, moisture, protein, soluble solids, specific gravity, pH, colour and amino acid content. Kjeldahl protein content in the fish sauce from summer capelin was 2.03% after 250 days of fermentation and twice as high as that in winter capelin fish sauce. Moisture content and pH were lower in the summer capelin fish sauce, but Brix and density were higher than those in fish sauce from winter capelin. Brown colour formation was very rapid in the summer capelin fish sauce but slow in the winter capelin fish sauce. Summer capelin may be successfully utilized for the production of fish sauce without added enzymes.     

湿腌时盐质量浓度对草鱼肌肉组织结构和品质的影响

为探究湿腌时盐质量浓度对草鱼肌肉组织结构及其品质变化的影响,本实验以草鱼为原料,利用离心损失率、硫代巴比妥酸反应物(thiobarbituric acid reactive substances,TBARS)值、十二烷基硫酸钠-聚丙烯酰胺凝胶电泳、扫描电镜(scanning electron microscopy,SE...     

盐含量对草鱼片冰温腌干特性的影响

腌干能够显著延长水产品的储藏期,盐含量与水产品腌干特性密切相关。本实验通过添加不同含量的盐探究其对草鱼片冰温(-0.5±0.4) ℃腌干特性及4 ℃常规冷链储藏品质的影响。结果表明:草鱼片盐含量越高腌制过程中含水率下降速度越快,腌制平衡后含水率越低。同时盐含量影响草鱼片干燥时间、复水率、挥发性盐基氮的生成等。盐含量增加干燥时间延长、复水率增大、有效抑制挥发性盐基氮生成。综合各种指标变化草鱼片冰温腌干4 ℃储藏加盐量9%较为适宜。     

Characteristics of Fish Sauce Made from Pacific Whiting and Surimi By-products During Fermentation Stage

ABSTRACT: The fermentation condition for producing Pacific whiting fish sauce was static atmospheric fermentation with 25% salt at 50 °C. The effective enzymes in fermentation were heat stable and salt tolerant. Fermentation at 50 °C gave higher yields than at 35 °C. Total nitrogen content of whole fish fermented at 50 °C reached the equivalent level of commercial fish sauce before 15 d, supporting the strong degradation effects of Pacific whiting enzymes at earlier stages. Soluble solid and relative gravity also reached commercial level at 60 d. However, color value of unripened fish sauce was far from commercial fish sauce, indicating that ripening may be necessary to develop proper color. Staphylococcus, Bacillus , and Micrococcus were found as predominant microorganisms during fermentation.     

Comparison of physicochemical and sensory changes in fresh and frozen herring (Clupea harrengus L.) during marinating

BACKGROUND: The influence of freezing on the changes during ripening is better described for salted fish than marinades. Therefore in the present study the effect of preliminary freezing of raw material on the ripening of carcasses and fillets marinated during 18 days at a temperature of 10 °C, in brine with 6% salt and 5% acetic acid was examined. RESULTS: In both cases the marinating of thawed frozen material resulted in larger mass losses and decrease of the value of meat colour parameters. The semi‐marinades from raw herring were characterised by higher values of total estimation based on sensory analysis. The statistical analysis showed weak correlation between the discriminants of sensory assessment and the studied physicochemical parameters of semi‐marinades. CONCLUSIONS: These results suggest that the semi‐marinades from raw fish are characterised by higher sensory quality, better colour parameters and higher yield than those from frozen thawed fish. Copyright © 2010 Society of Chemical Industry     

腊鱼加工中的乳酸菌及其特性

以白鲢为原料,对腊鱼加工过程的乳酸菌进行分离鉴定,并分析了其特性,为腊鱼加工及其品质控制提供实验数据。结果表明,腊鱼加工中存在植物乳杆菌、弯曲乳杆菌、食品乳杆菌、乳酸片球菌、戊糖片球菌,且不同加工阶段乳酸菌菌种分布不同。原料鱼、腌制结束时鱼体和成品中杆菌分别占乳酸菌的88%、56%和94%,是腊鱼加工中的优势乳酸菌。所有分离的乳酸菌都具有一定的耐盐、耐低温能力和蛋白酶活性,其中弯曲乳杆菌、乳酸片球菌的耐盐和耐低温能力较高;乳酸片球菌的蛋白酶活性最高。     

A Factorial Approach to Modeling aw of a Multicomponent Food in the High Moisture Range (aw 0.90–1.00)

Water activity (a_w) depression in a multicomponent food such as fish sausage was investigated using a 4x3x3 factorial design on combinations of NaCl, nonfat dry milk (NFDM) and lard added to a fixed amount of minced fish. The effects of NaCl, NFDM, lard and the interaction NaCl x NFDM, were significant. The responses across levels of the above factors were linear. From the magnitude of effect of each factor, two extended models for predicting a_w were derived in terms of molal salt concentration and two empirical parameters called water activity depressing capacity, d_i, and water binding capacity, WBC, respectively. Both were demonstrated to predict accurately a_w of newly formulated fish sausage.     

Salt and moisture content determination of fish by bioelectrical impedance and a needle-type multi-electrode array

The aim of this study was to test the applicability of bioelectrical measurements and a needle-type multi-electrode array in evaluating salt and moisture content of structurally heterogeneous food samples, such as fish. Impedance measurements were performed at different frequencies in order to find the most appropriate range, where impedance module and/or phase angle are the most sensitive to salt and moisture content. The salt, moisture, and water phase salt (WPS) of the salted rainbow trout samples were successfully evaluated by the impedance module measured at 50 kHz (AdR2 > 0.85). Due to rapid and non-destructive analysis coupled with low cost device design, this method for determination of salt and/or moisture has potential as the quality control technique for the fish industry.     

静磁场对发酵鱼露工艺的影响

为探究鱼露酿造的新工艺,以淡水鱼下脚料为原料,粉碎成鱼糜与80 g/L盐、沪酿3.042米曲霉制成的酱油曲混合后,在静磁场环境下培养发酵生产鱼露.在不同静磁场环境下40℃发酵30 d,通过测定鱼露发酵过程中氨基态氮、总氮、挥发性盐基氮、无盐固形物、总酸、pH值和非酶褐变的变化,分析静磁场环境对鱼露发酵工艺及其品质的影响...     

Comparative Study on Organoleptic,Microbiological and Chemical Qualities of Dried Fish,Goldstripe Sardinella(Sardinella Gibbosa) with Low Salt Levels and Spices

Dried fish is very important component in Sri Lankan fishery productswhile current domestic production is estimated at around 40,000 tons per year. Generally, dried fish production in Sri Lanka is based on traditional methodology where 30% of salt is used averagely. Use of excess amount of salt can have negative health effects. Therefore production of dried fish with low salt is very important.Accordingly, partial substitution of salt with alternative substances can be done. Current study aimed at evaluating the effect of low levels of salt and combined effect of low salt and spices on quality of dried fish. The study was carried out using eviscerated and cleaned up GoldstripeSardinella with 0% (T1), 5% (T2), 10% (T3) salt levels and two different combinations of salt and spices (1%salt with 0.2%turmeric, 0.5%chlli, 0.5%pepper (T4) and 2%salt with 0.2%turmeric, 0.2%chlli, 0.2%pepper (T5)). Hot air dehydrator (65-70 °C) was used for fish drying. Chemical (moisture, water activity (a_w), Total volatile nitrogen (TVN), and sodium chloride), physical (texture and rehydration), microbiological (APC, mould and yeast count and coliform count) properties and sensory attributes of experimentally prepared dried fish were investigated. The chemical parameters for all treatments were significantly different (p<0.05) while physical parameters were not (p>0.05). T2 indicated the best chemical quality. The values for moisture, a_w, sodium chloride, TVN, texture and rehydration for T2, were 11.6584±0.03, 0.591±0.002, 12.43±0.15, 59.43 mg/100g±12.86, 1.54kg±0.14 and 12.70±3.54 respectively. T2 and T3 had least microbial counts while T1 and T5 had highest microbial count. But T5 had highest scores for all sensory attributes indicating consumer preference for low salt and spicy taste regardless of high TVN content and poor microbial quality.Therefore it is essential to improve the methodology to enhance the quality of low salt and spices added dried fish.     

低盐外加曲发酵潮汕鱼露的理化性质变化

以鳀鱼(Engraulis japonicus)为原料,在不同盐质量分数(10%,15%,20%,30%)和不同曲质量分数(0%,5%)条件下发酵30d,然后再增加盐量至30%后继续发酵180d,对整个发酵过程中的总可溶性氮(TSN)、氨基酸态氮(AA-N)、挥发性盐基氮(TVB-N)、pH值、非酶褐变指数、游离氨基酸组成、感官及色差变化进行分析。结果表明,低盐发酵及低盐外加曲发酵可加速潮汕鱼露发酵;与低盐发酵鱼露相比,低盐加曲发酵鱼露中TSN、氨基酸态氮以及主要氨基酸(谷氨酸、丙氨酸、赖氨酸)质量浓度有较大提高,其中加盐15%加曲5%工艺风味较好。     

Determination of iodide and iodate in edible salt by ion chromatography with integrated amperometric detection

Iodised salt compositions formulated with potassium iodate typically have iodate content of 20–40 ppm (μg/g) which translates to iodine content of 15–30 ppm. The technique of iodide estimation in brine by ion chromatography with amperometric detection was applied to iodate estimation in salt. The method involved reduction of iodate to iodide with excess sodium bisulphite followed by estimation of iodide. No other pre-treatment was necessary for iodate estimation in the concentration range of interest for iodised salt. Quantitative analysis was feasible for iodate concentrations ?5 ppm in salt. Iodised salt formulations containing iodide and iodate together were also analysed and the two constituents were quantified separately. Interferences from impurities normally present in salt were insignificant. An important advantage of the present method is that it eliminates the possibility of misleading results from potential adulterants which can impart positive iodometric test while, at the same time, keeping the analytical procedure simple.     

Study of the Differences Between Two Salt Qualities on Microbiology,Lipid and Water-Extractable Components of Momoni,a Ghanaian Fermented Fish Product

Lipid oxidation and low final product quality observed during processing and storage of a Ghanaian fermented fish product were investigated with respect to the quality of salts used in the curing procedures, namely crude solar salt and refined salt. On analysis of differences in composition, refined salt had a lower moisture and microbial load than crude salt. Differences after fermentation and storage of both refined-salted and crude-salted fish were as follows: decreases in water activity of fish during processing was slower with crude salt than with refined salt; volatile basic nitrogen and total microbiological counts were higher in crude-salted fish; the polyamine of highest concentration in crude-salted samples was histamine, whilst cadaverine concentration dominated in fish fermented with refined salt. TBARS and peroxide values of the extracted total lipids increased during processing. Free fatty acid and diglyceride concentrations were higher in the crude-salted fish than in the samples with refined salt. Poly-enoic fatty acid levels were higher in the samples fermented with refined salt, whilst the levels of total cholesterol oxides were higher in the crude-salted samples.     

Desalination of fish sauce by electrodialysis: effect on selected aroma compounds and amino acid compositions

Fish sauce is an ingredient that exhibits unique flavor and is widely used by people in Southeast Asia. Fish sauce, however, contains a significant amount of salt (sodium chloride). Recently, electrodialysis (ED) has been successfully applied to reduce salt in fish sauce; however, no information is available on the effect of ED on changes in compounds providing aroma and taste of ED-treated fish sauce. The selected aroma compounds, amino acids, and sensory quality of the ED-treated fish sauce with various salt concentrations were then analyzed. The amounts of trimethylamine, 2,6-dimethylpyrazine, phenols, and all carboxylic acids except for hexanoic acid significantly decreased, whereas benzaldehyde increased significantly when the salt removal level was higher. The amounts of all amino acids decreased with the increased salt removal level. Significant difference in flavor and saltiness intensity among ED-treated fish sauce with various salt concentrations, as assessed by a discriminative test, were observed. PRACTICAL APPLICATION: Information obtained in this work can serve as a guideline for optimization of a process to produce low-sodium fish sauce by ED. It also forms a basis for further in-depth sensory analysis of low-sodium fish sauce.     

Histamine Formation in Fish Sauce Production

ABSTRACT: The formation of histamine in fish sauce made from Stolephorus sp was studied. In the first experiment, fish were iced on board and mixed with salt at the factory, while in the second experiment fish were mixed with salt on board collection vessels. Eight batches were fermented for 12 mo. Histamine levels increased during fermentation to 22 to 159 and 589 to 686 ppm in the first and second experiments respectively. Good correlation between histamine levels in raw material and final products was found. It was concluded that histamine was formed both in the raw material and during fermentation. It was speculated that histidine decarboxylase enzymes formed prior to fermentation produced histamine during fermentation.     

Effects of the addition of spleen of skipjack tuna (Katsuwonus pelamis) on the liquefaction and characteristics of fish sauce made from sardine (Sardinella gibbosa)

The effects of the addition of spleen of skipjack tuna (Katsuwonus pelamis), at levels of 0%, 10% and 20%, on the liquefaction and characteristics of fish sauce produced from the sardine (Sardinella gibbosa) with different salt concentrations (15%, 20% and 25%) were monitored during fermentation for 180 days. Fish sauces prepared from sardine with spleen supplementation contained greater total nitrogen, amino nitrogen, formaldehyde nitrogen and ammonia nitrogen than did those without spleen addition throughout the fermentation. The rate of liquefaction was dependent on the amount of spleen added. Reduction of salt content accelerated the hydrolysis of fish protein during fermentation. The liquefaction rate of the lower salt-treated samples was generally faster than were those treated with higher salt content. Among all treatments, sardine with 25% spleen and 15% salt added exhibited the greatest protein hydrolysis, particularly at the early stages, suggesting the combined effects of autolysis and spleen proteinase. The greater liquefaction was coincidental with the development of browning as well as the increase in redness of liquid formed. An acceptability test revealed that the samples were different in colour, aroma, taste and overall acceptance (p < 0.05). Fish sauce samples containing 20% salt, without and with 10% spleen addition had similar acceptabilities to commercial fish sauce. Therefore, the addition of spleen, as well as salt reduction, can accelerate the liquefaction of sardine for fish sauce production.     

SOME PROPERTIES of FISH GELS MADE FROM SEVERAL NORTHWEST ATLANTIC SPECIES IN the PRESENCE of HIGH and LOW SALT

The relative effect of NaCl on true strain and stress at failure varied considerably among unfrozen fish species. Values of true strain were always greater in samples with 3% salt in the absence of cryoprotectants. the effect of NaCl on stress varied more widely than on true strain; in a couple of cases, stress at failure was higher for fish gels without 3% sodium chloride. Three of four fatty species (Atlantic mackerel, Atlantic menhaden and bluefish) were among the samples that had the lowest values of both true strain and stress. For red hake, seasonal effects of salt on gelation properties were observed. True strain and stress values of red hake were higher without added salt than they were with 3% added salt when cryoprotectants were added to the samples and the samples were stored for one week at -20C.     

真空辅助加压腌制对草鱼块品质的影响

以草鱼为原料,研究真空辅助加压腌制对草鱼块组织结构、感官和理化品质的影响。以常压腌制为对照,分别探讨常压、真空及真空辅助加压（0、2.3、4.6、6.9 kPa）腌制对草鱼块食盐质量分数、组织结构、总挥发性盐基氮（total volatile basic nitrogen,TVB-N）含量、水分质量分数、水分分布等的影响。结果表明,经腌制,食盐逐渐渗入鱼肉组织,真空腌制导致新鲜鱼肉产品得率下降,剪切力、硬度、回复性、黏性上升,硫代巴比妥酸反应物值下降,水分质量分数、离心损失率下降,细胞间隙增大。真空辅助加压腌制结束时食盐质量分数升高,产品得率下降,白度上升,当压强为6.9 kPa处理时,新鲜鱼肉的剪切力、硬度、内聚性、弹性、黏性最低,TVB-N含量无明显变化,汁液渗出率升高。结论：采用真空辅助加压腌制技术能够提升鱼块品质,并减缓鱼块腐败速率。