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.     

Endogenous proteinases in true sardine (Sardinops melanostictus)

Characterisation of the autolytic profile of true sardine (Sardinops melanostictus) indicated the involvement of heat-activated proteinases, active at both acidic and alkaline pH values. Autolytic activity decreased with increasing NaCl concentration (0–30%). When crude proteolytic activity in true sardine was studied, two activity peaks were observed, at pH 3.5 and 9.0. Crude proteinase extracts exhibited the highest activity at 55 °C and 60 °C when assayed at pH 3.5 and 9.0, respectively. The pH 3.5 peak activity was effectively inhibited by pepstatin A, while the pH 9.0 peak activity was mostly inhibited by soybean trypsin inhibitor, PMSF and TLCK, suggesting that the various proteinases were present in true sardine. The enzymes were stable for up to 8 h at 55 °C. The activities were also stable at a pH range of 2.0–4.0 and still retained high activity toward hemoglobin after incubation at pH 3.5 for 8 h. Activities of the crude extract continuously decreased as NaCl concentration increased. ATP showed no effect on enzyme activity, while CaCl₂ and MgCl₂ activated the proteinase activity. The results implied that pepsin is a predominant enzyme responsible for autolysis in true sardine during fish sauce fermentation.     

Effects of rice koji inoculated with Aspergillus luchuensis on the biochemical and sensory properties of a sailfin sandfish (Arctoscopus japonicus) fish sauce

The effects of rice koji inoculated with Aspergillus luchuensis on the biochemical and sensory properties of fish sauce produced from sailfin sandfish (Arctoscopus japonicus) with different salt concentrations (10% and 20%) were investigated over 10 months. Fish sauces prepared from sailfin sandfish with rice koji and a low salt concentration had higher total nitrogen, amino nitrogen and total free amino acid than did those without rice koji or with a high salt concentration. Sensory evaluation of fish sauces prepared with rice koji and a low salt concentration found better taste, flavour and overall acceptance than those prepared without rice koji during fermentation (P < 0.05). The use of rice koji increased the total nitrogen, amino nitrogen and free amino acid and also enhanced the sensory qualities during fermentation. These results suggest that the use of rice koji can result in a low‐salt fish sauce with better flavour.     

Effects of low concentration of salt and sucrose on the quality of bighead carp (Aristichthys nobilis) fillets stored at 4 °C

The effect of low concentration of salt and sucrose on the quality of bighead carp (Aristichthys nobilis) fillets was evaluated over a 16-day storage at refrigerated temperature (4 °C). Fish samples were brined with 1.1% salt (T1) and 1.1% salt + 0.9% sucrose (T2). The control and the treated fish samples were analysed periodically for physicochemical (pH, total volatile base nitrogen (TVB-N), water loss, electrical conductivity (EC), color), microbial (total viable counts) and sensory characteristics. No significant differences were observed between T1 and T2 for sensory score and EC (p > 0.05). Brining treatments predominantly decreased chemical changes, reflected in TVB-N and pH, retarded water loss and discoloration, inhibited bacterial growth and increased the overall sensory quality of fish, compared to untreated fillets. The results indicated that brining treatments improved the quality and safety of bighead carp fillet, which can be exploited by fish processors.     

Novel starter cultures to inhibit biogenic amines accumulation during fish sauce fermentation

Bacteria with amine oxidase activity have become a particular interest to reduce biogenic amines concentration in food products such as meat and fish sausages. However, little information is available regarding the application of these bacteria in fish sauce. Hence, our study was aimed to investigate the effect of such starter cultures in reducing biogenic amines accumulation during fish sauce fermentation. Staphylococcus carnosus FS19 and Bacillus amyloliquefaciens FS05 isolated from fish sauce which possess amine oxidase activity were used as starter cultures in this study. Fermentation was held for 120 days at 35 °C. The pH value increased in all samples, while salt concentration remained constant throughout fermentation. Aerobic bacteria count was significantly lower (p < 0.05) in the control than in inoculated samples as a result of starter cultures addition. However, it decreased during fermentation due to the growth inhibition by high salt concentration. Proteolytic bacterial count decreased during fermentation with no significant difference (p > 0.05) among samples. These bacteria hydrolyzed protein in anchovy to produce free amino acid precursors for amines formation by decarboxylase bacteria. The presence of biogenic amines producing bacteria in this study was considered to be indigenous from raw material or contamination during fermentation, since our cultures were negative histamine producers. Amino acid histidine, arginine, lysine and tyrosine concentration decreased at different rates during fermentation as they were converted into their respective amines. In general, biogenic amines concentration namely histamine, putrescine, cadaverine and tyramine increased throughout fermentation. However, their concentrations were markedly higher (p < 0.05) in the control (without starter cultures) as compared to the samples treated with starter cultures. Histamine concentration was reduced by 27.7% and 15.4% by Staphylococcus carnosus FS19 and Bacillus amyloliquefaciens FS05, respectively. Both cultures could also reduce other amines during fermentation. After 120 days of fermentation, the overall biogenic amines concentration was 15.9% and 12.5% less in samples inoculated with Staphylococcus carnosus FS19 and Bacillus amyloliquefaciens FS05, respectively, as compared to control samples. These findings emphasized that application of starter cultures with amines oxidase activity in fish sauce fermentation was found to be effective in reducing biogenic amines accumulation.     

大黄鱼卵鱼露的发酵工艺

以大黄鱼鱼卵发酵鱼露为研究对象,分析其在发酵过程中接曲量、加盐量、温度等条件对鱼露pH、总酸、氨基酸态氮、挥发性盐基氮、脂肪、硫代巴比妥酸等理化指标的影响,并分析了发酵第30 d时氨基酸的含量.结果表明:在大黄鱼鱼卵鱼露发酵过程中,pH整体上呈波动现象,且总酸含量的变化与其一致;氨基酸态氮含量在发酵过程中呈上升趋势,且...     

Seasonal variation in the fatty acid composition of three Mediterranean fish – sardine (Sardina pilchardus), anchovy (Engraulis encrasicholus) and picarel (Spicara smaris)

The total fat contents and the fatty acid compositions of three common Mediterranean fish, namely sardine (Sardina pilchardus), anchovy (Engraulis encrasicholus) and picarel (Spicara smaris) were determined at bimonthly intervals for a one-year period. The purpose of this work was to study the seasonal variation of the fatty acids in the three fish that are some of the best sources of n − 3 fatty acids. The fat and fatty acid content of the investigated fish species show a significant seasonal dependency. Two of the fish (anchovy and picarel) have the highest fat content during the late winter – spring period. On the other hand, sardine shows the highest fat concentrations during the spring-early summer period. The fish that showed the highest variation in fatty acid composition was the anchovy. The sardine was found to be the best source of n − 3 fatty acids during the one-year period (35.35 g/100 g fatty acids). Finally the picarel had the highest oleic acid content (on average, 13.89/100 g fatty acids).     

Chemical, microbiological and sensory changes associated with fish sauce processing

The production of sardine fermented fish sauce was replicated in the laboratory in order to study the chemical, microbiological and sensory changes associated with the process. Fish sauce were produced by incubating mixtures of sardine (Sardina pilchardus) at different concentrations of sodium chloride and glucose at 37 °C for 57 days. Changes in chemical composition (moisture, protein, fat contents), pH, total volatile basic nitrogen (TVB-N, mg N/100 g fish flesh), trimethylamine (TMA-N, mg/100 g fish flesh), thiobarbituric acid (TBA, mg malonaldehyde/kg fish flesh), water activity (aw), color measurement, total viable count, lactic acid bacteria count, yeast and moulds counts and sensory analyses were observed. The fish sauces with spices were determined lower bacteria counts than fish sauces without spices. The addition of glucose to the fish sauces caused a significant increasing in the bacterial counts. Staphylococcus aureus and yeast-mould counts were not detected during fermentation period. The use of spices in fermentation of sardine enhanced good color, aroma and taste.     

Changes of lipids in sardine (Sardinella gibbosa) muscle during iced storage

Changes in lipids of sardine (Sardinella gibbosa) muscle during 15 days of iced storage were investigated. Lipid deterioration, lipolysis and lipid oxidation, occurred throughout the storage. The progressive peroxide formation was monitored by the increase in the absorbance band at 3600–3200 cm⁻¹ in Fourier transform infrared (FTIR) spectra and increased peroxide values were observed in sardine muscle up to 6 days of iced storage, followed by a continuous decrease from then for 9 days (P < 0.05). The increase in thiobarbituric acid reactive substances (TBARS) was noticeable throughout the iced storage (P < 0.05). However, no difference in conjugated diene (CD) of sardine muscle was found within the first 12 days of iced storage (P > 0.05). Marked decreases in unsaturated fatty acids, especially eicosapentaenoic acid (EPA; C20:5(n − 3)) and docosahexaenoic acid (DHA; C22:6(n − 3)) were observed as the storage time increased. Those changes indicated that lipid oxidation occurred in sardine muscle. A gradual increase in free fatty acid formation, with decreases in triglyceride and phospholipid contents, was found during iced storage (P < 0.05), suggesting hydrolysis induced by lipases and phospholipases.     

Preparation of eicosapentaenoic acid concentrates from sardine oil by Bacillus circulans lipase

An extracellular lipase derived from Bacillus circulans, isolated from marine macroalga, Turbinaraia conoides, was used to prepare n-3 polyunsaturated fatty acid (PUFA) concentrates from sardine oil triglycerides. The enzyme was purified 132-fold with specific activity of 386 LU/mg. The purified lipase was able to enrich sardine oil with 37.7 ± 1.98% 20:5n-3 and 5.11 ± 0.14% 18:3n-3 in the triglyceride fraction after 3 h of hydrolysis. Lower hydrophobic constants of n-3 fatty acids (18:3n-3_logP = 5.65; 20:5n-3_logP = 5.85, respectively) than n-6 (20:4n-6_logP = 6.16) resulted in higher hydrolytic resistance of the former toward lipase, leading to their enrichment in the triglyceride fraction. Lipase-catalysed hydrolysis of sardine oil for 3 h, followed by urea complexation, provided free fatty acids containing 51.3 ± 4.65% 20:5n-3. The purified methyl ester of 20:5n-3 (68.29 ± 2.15%) from the urea concentrate was attained by chromatography on argentated neutral alumina.     

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...     

Purification and identification of novel antioxidant peptides from enzymatic hydrolysates of sardinelle (Sardinellaaurita) by-products proteins

In order to utilise sardinelle (Sardinellaaurita) protein by-products, which is normally discarded as industrial waste in the process of fish manufacturing, heads and viscera proteins were hydrolysed by different proteases to obtain antioxidative peptides. All hydrolysates showed different degrees of hydrolysis and varying degrees of antioxidant activities. Hydrolysate generated with crude enzyme extract from sardine (Sardinapilchardus) displayed high antioxidant activity, and the higher DPPH radical-scavenging activity (87 ± 2.1% at 2 mg/ml) was obtained with a degree of hydrolysis of 6%. This hydrolysate was fractionated by size exclusion chromatography on a Sephadex G-25 into eight major fractions (P₁–P₈). Fraction P₄, which exhibited the highest DPPH scavenging activity, was then fractionated by reversed-phase high performance liquid chromatography (RP-HPLC). Seven antioxidant peptides were isolated. The molecular masses and amino acids sequences of the purified peptides were determined using ESI-MS and ESI-MS/MS, respectively. Their structures were identified as Leu-His-Tyr, Leu-Ala-Arg-Leu, Gly-Gly-Glu, Gly-Ala-His, Gly-Ala-Trp-Ala, Pro-His-Tyr-Leu and Gly-Ala-Leu-Ala-Ala-His. The first peptide displayed the highest DPPH radical-scavenging activity (63 ± 1.57%; at 150 μg/ml) among these peptides.     

Effect of fermentation by Aspergillus oryzae on the biochemical and sensory properties of anchovy (Engraulis japonicus) fish sauce

This study obtained an anchovy flavourful fish sauce by a bioprocess of aerobic fermentation with Aspergillus oryzae OAY1 in a period of time as short as 3 days. Amino nitrogen of the fish sauce increased to 7.35 mg mL^?1 by optimisation with response surface methodology (RSM). Results of chemical analysis showed that amino nitrogen, hydrolysis degree, reducing sugar and total amino acids all increased, along with the enhanced antioxidant activity. With regard to biogenic amines, most of the tested biogenic amines decreased after fermentation. Electronic nose test revealed that the odour of the fish sauce became more balanced and favourable after fermentation. In addition, volatile odorant analysis and sensory evaluation showed that no particularly unpleasant flavour ingredient was found in the anchovy fish sauce, and the taste was overall satisfactory. Meanwhile, consumer acceptance test showed that the anchovy fish sauce produced in this study using A. orzyae OAY1 had a high consumer acceptance similar to the commercial anchovy fish sauce. This aerobic fast‐fermentation process provided an efficient method for high‐quality fish sauce production.     

Characterization of Ca-activated cell-bound proteinase from Virgibacillus sp. SK37 isolated from fish sauce fermentation

Cell-bound proteinase from Virgibacillus sp. SK37 isolated from the first month of fish sauce fermentation was characterized. The enzyme showed the maximum activity at 65 °C, pH 7.0 and 9.5, using azocasein as a substrate. The enzyme required at least 10 mmol/l Ca²⁺ to effectively hydrolyze casein and the extent of casein degradation increased with Ca²⁺ concentration. Ethylenediaminetetraacetic acid (EDTA) and phenylmethanesulfonyl fluoride (PMSF) largely inhibited the activity, indicating a characteristic of Ca²⁺-activated serine proteinase. Among six synthetic substrates tested, the enzyme preferably hydrolyzed Suc-Ala-Ala-Pro-Phe-AMC, indicating a subtilisin-like proteinase. Although activity towards actomyosin at 20 g/100 ml NaCl decreased to 63% compared to at 5 g/100 ml, the enzyme showed high stability at 25 g/100 ml NaCl, 30 °C. This was the first study to report biochemical characteristics of cell-bound proteinase from a moderately halophilic bacterium isolated from fish sauce.     

Histamine contents of fermented fish products in Taiwan and isolation of histamine-forming bacteria

Twenty-seven imported fermented fish products from Southeast Asian countries and sold in the supermarkets in Taiwan, including fish sauce, fish paste and shrimp paste, were tested to determine the occurrence of histamine and histamine-forming bacteria. The levels of pH, salt content, total volatile basic nitrogen, trimethylamine, and aerobic plate count in all samples ranged from 4.8% to 6.5%, 16.2% to 45.3%, 51 to 275 mg/100 g, 5.4 to 53.9 mg/100 g and 1.0 to 4.2 log CFU/g, respectively. The average content for each of eight different biogenic amines in all samples was less than 90 ppm, except for histamine which has an average content of 394 ppm in fish sauce, 263 ppm in fish paste, and 382 ppm in shrimp paste. Most of the tested fermented fish products (92.6%) had histamine levels greater than the FDA guideline of 50 ppm, while seven of them (25.9%) contained >500 ppm of histamine. Although Bacillus coagulans and Bacillus megaterium were identified as the two histamine-producing bacteria capable of producing 13.7 and 8.1 ppm of histamine, respectively, in trypticase soy broth broth supplemented with 1.0% l-histidine, they were not determined to be the main contributors to histamine accumulation in these fermented fish products.     

Use of viscera extract from hybrid catfish (Clarias macrocephalus × Clarias gariepinus) for the production of protein hydrolysate from toothed ponyfish (Gazza minuta) muscle

Proteolytic activity of viscera extract from hybrid catfish (Clarias macrocephalus × Clarias gariepinus) was studied. The optimal pH and temperature were 9.0 and 50 °C, respectively, when toothed ponyfish (Gazza minuta) muscle was used as a substrate. When viscera extract from hybrid catfish was used for the production of protein hydrolysate from toothed ponyfish muscle, extract concentration, reaction time, and fish muscle/buffer ratio affected the hydrolysis and nitrogen recovery (NR) (p < 0.05). Optimum conditions for toothed ponyfish muscle hydrolysis were 3.5% hybrid catfish viscera extract, 15 min reaction time and fish muscle/buffer ratio of 1:3 (w/v). High correlation between the degree of hydrolysis (DH) and NR (R² = 0.974) was observed. Freeze-dried hydrolysate had a high protein content (89.02%, dry weight basis) and it was brownish yellow in colour (L^∗ = 63.67, a^∗ = 6.33, b^∗ = 22.41). The protein hydrolysate contained a high amount of essential amino acids (48.22%) and had arginine and lysine as the dominant amino acids.     

Biogenic Amines Formation in Fish Sauce Prepared from Fresh and Temperature-abused Indian Anchovy (Stolephorus indicus)

ABSTRACT: The formation of biogenic amines in fish sauce made from fresh and temperature-abused (left at 35°C for 8 and 16 h) Indian anchovy ( Stolephorus indicus ) was investigated. Histamine, cadaverine, putrescine, and tyramine were the predominant biogenic amines found in anchovy left at 35°C for 16 h and its fish sauce product. Changes of biogenic amines were subtle during the course of fermentation at room temperature (RT) and at 40°C, suggesting that the main source of biogenic amines was associated with raw material, rather than with the fermentation process. Soluble peptide and total nitrogen of fish sauce prepared from temperature-abused anchovy were higher at the initial stage of fermentation at RT and 40°C and became comparable to those prepared from fresh anchovy at the end of fermentation. Total free amino acid contents of samples fermented at RT for 52 wk (7208.3 to 8473.6 mg/100 mL) were higher than those fermented at 40°C for 13 wk (4560.9 to 5730.9 mg/100 mL). Fish sauce prepared from temperature-abused anchovy contained less free histidine and arginine. Fish sauce of a good quality was obtained using fresh anchovy fermented at RT. Besides total nitrogen content, biogenic amines should be considered as quality indicators of fish sauce.     

Interaction between fish myoglobin and myosin in vitro

Interaction between tuna myoglobin and myosins from tuna and sardine was investigated in a model system at 4 °C for up to 24 h. Both sardine and tuna myosins bound progressively with tuna myoglobin as the storage time increased (P < 0.05). The soret absorption peak was noticeable in the myoglobin–myosin mixture. The oxidation of oxymyoglobin in the presence of myosin was generally greater than that found in the absence of myosin (P < 0.05). Oxymyoglobin underwent oxidation to a greater extent in the presence of tuna myosin than sardine myosin (P < 0.05). The interaction between fish myoglobin and myosin also caused changes in reactive sulfhydryl content and altered the tryptophan fluorescent intensity. The loss in Ca²⁺-ATPase activity of myosin varied with fish species and was governed by the myoglobin added. Thus, the interaction between fish myoglobin and myosin most likely occurred as a function of time and was species-specific.     

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。