Halotolerant and halophilic histamine-forming bacteria isolated during the ripening of salted anchovies (Engraulis encrasicholus).

This study was performed to investigate halotolerant and halophilic histamine-producing bacteria isolated during the ripening of salted anchovies. Of the isolates obtained during the ripening of anchovies, 1.37% showed histamine-forming activity, most of them (70%) belonging to the Staphylococcus genus. S. epidermidis showed a powerful histamine-forming activity, producing more than 1,000 microg/ml in the presence of 3% and 10% NaCl. Another powerful histamine-producing bacterium isolated during the ripening of salted anchovies was S. capitis. It was able to produce about 400 microg/ml of histamine in 10% NaCl under experimental conditions. Most of these species might be expected to be found as a result of contamination of fish during capture and subsequent unhygienic handling. However, no increase in histamine content was found in any batches through the ripening process. Histamine content always was acceptable in accordance with the maximum allowable levels of histamine fixed by the Spanish and European Union regulations.     

Oxidative stability of brined anchovies (Engraulis encrasicholus) with plant extracts

The effect of brining with plant extracts on the oxidative stability of anchovies was investigated during storage. The brining process was done in 15 g 100 mL⁻¹ of sodium chloride solution with water, and with myrtle, rosemary and nettle extracts. Brined anchovies were stored at 4 ± 1  ° C for 28 days. Brining with plant extracts slowed down the lipid oxidation of anchovies. The highest antioxidant effect was observed in brined anchovies with rosemary and myrtle extracts during storage as indicated by peroxide value (POV), thiobarbituric acid reactive substance and oxidative rancidity (OR) scores. Furthermore, OR scores in brined anchovies were well correlated with thiobarbituric acid reactive substance ( r ² = 0.66, P  < 0.01) and POV ( r ² = 0.87; P  < 0.01). The fatty acid profiles were similar among the brined anchovies with plant extracts. These results suggest that brining with rosemary, myrtle and to a lesser extent, nettle extracts prevents development of oxidation in lipids of anchovies during storage.     

Increase on free fatty acids during ripening of anchovies (Engraulis anchoíta)

The changes of free fatty acids (FFA) during the ripening of salted anchovy was studied. In the course of the curing process, the content of free fatty acids (FFA) in the muscle increased fifteen-fold, mostly in the first 100 days of the process. Each sample was subjected to sensory evaluations. A high correlation between FFA contents and sensory scores was found. Therefore the determination of FFA is proposed as an objective index to assess the ripening of salted anchovies.     

Volatile and biogenic amines, microbiological counts, and bacterial amino acid decarboxylase activity throughout the salt-ripening process of anchovies (Engraulis encrasicholus)

Chemical and microbiological parameters were studied during the industrial production of salt-ripened anchovies (Engraulis encrasicholus). Gradual acidification and increases in the proteolysis index and in total volatile basic nitrogen were observed. At the end of the maturing process, the values reached pH 5.55 +/- 0.03, 21.33 +/- 5.82%, and 44.06 +/- 12.47 mg/ 100 g, respectively. In the three studied anchovy batches, the biogenic amines tyramine, histamine, putrescine, cadaverine, and agmatine increased during ripening. The highest values were found in the batch where initial microbial load was highest (batch 1), especially for enterobacteria and enterococci. Tyramine was the most abundant amine, reaching values from nondetectable to 90 mg/kg, whereas histamine did not surpass 20 mg/kg. Among the microorganisms isolated, Enterobacter cloacae, Aerococcus viridans, Kocuria varians, and Staphylococcus chromogenes were able to decarboxylate amino acids and produce biogenic amines in vitro. Most (70.59%) of the microorganisms identified were able to produce histamine, 23.53% were able to produce the diamines putrescine and cadaverine, and only 11.76% were able to produce tyramine, although this substance was the major biogenic amine found in anchovy samples.     

Autolytic degradation of belly tissue in anchovy (Engraulis encrasicholus)

Tissue degradation in anchovy was studied during storage under different conditions. Belly bursting seems to be caused by leakage of proteolytic enzymes from the pyloric caeca and intestine to the ventral muscle. These proteases have optimum pH in the alkaline range and they are very active in the neutral range. At pH 6.5, which is the post mortem pH of the tissue, the basic proteases play an important role in the degradation of myofibrillar protein and in the solubilization of connective tissue. The rate of tissue degradation during storage was considerably reduced if the fish was chilled by refrigerated or iced sea water to about 0°C, and the pH of the medium was reduced to 5 by addition of lactic or acetic acid.     

鳀鱼营养成分分析与评价

为了进一步了解鳀鱼的营养价值,提高鳀鱼的附加值,该研究对其主要营养成分、氨基酸、脂肪酸以及矿物元素含量进行了检测分析,并对其营养价值进行了评价.结果表明:鳀鱼水分、粗蛋白、粗脂肪和灰分质量分数分别为75.67％、16.38％、5.05％和2.31％.鳀鱼中共检测出17种氨基酸,必需氨基酸与氨基酸总量组成比例(EAA/T...     

Chymotrypsin and general proteolytic activities in muscle of Engraulis encrasicolus and Engraulis anchoita during the ripening process

 During fish ripening, biochemical changes occur that give rise to the organoleptic properties characteristic of the product. Enzymes play a key role in this ripening process, although it is not known exactly which enzymes are involved. We investigated the effects of the gutting method (nobbing only, or nobbing and butterflying) and addition of cathepsin C on general proteolytic activity, chymotrypsin activity, pH and organoleptic characteristics during brine ripening of fresh Engraulis encrasicolus. We also monitored these variables during brine ripening of frozen/thawed E. encrasicolus and E. anchoita. Butterflied fish ripened more rapidly than fish prepared by the traditional method (nobbing only). Inclusion of cathepsin C in the brine had a negative effect on texture (very firm, low juiciness) but a positive effect on flavour, which was more intense. Frozen/thawed fish were successfully ripened, giving a final product with fully acceptable organoleptic characteristics. In all batches except the E. anchoita batch both general proteolytic activity and chymotrypsin activity increased rapidly after immersion in brine, then dropped gradually over the ripening period. Received: 7 July 1999     

Inhibition of lipid oxidation in anchovy oil (Engraulis encrasicholus) enriched emulsions during refrigerated storage

The aim of this study was to produce a functional emulsion product enriched with anchovy (Engraulis encrasicholus) oil. Tomato and garlic extracts were added to perform oxidative stability. Tomato and garlic extracts were added to avoid oxidative degradation in such a product. The plant extracts delayed the formation of primary and secondary oxidation products. The value of conjugated diens (3.07 ± 0.15) was markedly low in the emulsions containing garlic extract at the end of the storage period. The p–Av values of the emulsions treated with the extracts were significantly (P < 0.01) lower than untreated samples. TBARS formation increased slightly, therewithal statistical difference was not observed in the samples treated with garlic extract during the storage. Strong odour and flavour of the garlic suppressed the odour of fish oil. The panellists preferred the flavour, odour and aroma characteristics of the samples treated with the extracts.     

Methods for phosphate addition in heavy salted cod (Gadus morhua L.)

Headed and gutted fresh or frozen and thawed cod (Gadus morhua L.) from the same net catch were hand filleted post rigor before carrying out small-scale salting trials. Fillets were heavy salted using three different methods introducing phosphate during injection, brining, or during pickle salting. For all salting methods, treatment with 0, 4.5, 9 or 18 g/L of the pyro and tri polyphosphate blend Carnal 2110 was carried out. Quality and chemical parameters were analyzed after 5 weeks and 6 ± 1 months of chilled storage of heavy salted fillets.     

不同解冻方式对鳀鱼鲜度及挥发性风味物质的影响

为了探究不同解冻方式(微波解冻、超声辅助解冻、盐水解冻、冷藏室解冻)对鳀鱼(Anchovy)鲜度及挥发性风味物质的影响,分析了样品不同解冻方式的解冻时间、持水力、菌落总数及挥发性盐基氮(TVB-N),同时进行了感官评价、电子鼻分析和挥发性风味物质的鉴定.结果表明:微波解冻耗时最短(22.4 min),微波解冻后鳀鱼持水...     

The use of an 'electronic nose' device to monitor the ripening process of anchovies

Summary Qualitative changes in flavour profiles that are associated with the ripening of anchovies were investigated. Samples, either commercially processed or ripened on a laboratory scale, were analysed by a device known as an electronic nose, which is based on conductive polymers. Operational parameters were optimized by means of screening factorial designs using the discriminating power between samples as the objective function. Electronic nose measurements need no sample preparation and the results indicated that the ripening process of anchovies could be followed by using this technique. Several chemometric techniques (principal component analysis, k‐nearest neighbour, soft independent modelling of class analogy and multilayer feed forward artificial neural networks) were applied to model the ripening process and to classify samples into separate classes as a function of the ripening stage, and all produced satisfactory results. The ability and limitations of these predictive models are discussed, especially the influence that other factors have in affecting the raw material quality and characteristics in the developed models. These defined the conditions to be met in order to produce reliable predictions, thus establishing the real value of the electronic nose models in the monitoring of quality control of the anchovy maturation process and production.     

Influence of Raw Fish Quality on Some Physicochemical and Microbial Characteristics as Related to Ripening of Salted Anchovies (Engraulis encrasicholus L)

Influence of raw fish quality on the sensorial, physicochemical, and microbiological characteristics as related to ripening of salted anchovies has been studied. Raw fish remained iced for 4 d and samples were periodically taken for processing following traditional methods on d 0 (Extra: high quality fish), 2 (A: medium quality fish) and 4 (B: inedible as human food). The enzymatic activity is not suppressed when the ripening period is completed and alkaline proteinase activity dominates. No statistical differences were observed in the sensory assessment and in the majority of physicochemical and microbiological data obtained during the ripening process. However, differences are observed when raw material is of grade C (low quality fish), especially in the proteinase activity at pH 9.     

Survival of Staphylococcus aureus and Salmonella enteritidis on salted sardines (Sardina pilchardus) during ripening

The ripening period for salted sardines ranges from 4 to 6 months, depending on the season. Sometimes producing industries need to distribute the product earlier owing to market needs, and when this happens the product's safety needs to be assured. The purpose of this work was to study the survival of Staphylococcus aureus and Salmonella Enteritidis on salted sardines during a ripening period of 115 days. Salted sardines were inoculated with pure cultures of S. aureus and Salmonella Enteritidis (10(5) CFU/g of fish on day 0). After 5 days of ripening, the water activity value for the sardines decreased from 0.93 to 0.69. The survival of both pathogens and that of total viable cells were evaluated during the ripening process. Total viable counts decreased by 2 log units over the 115-day ripening period. Salmonella Enteritidis and S. aureus survived for 60 and 90 days, respectively. Therefore, the use of a 90-day ripening period could be effective in assuring the safety of the final product.     

Textural and biochemical changes during ripening of old-fashioned salted herrings

BACKGROUND: Understanding of the biochemical reactions taking place during ripening of salted herring is still rather limited. Therefore, salted herrings were traditionally produced and the impact of the brine composition was evaluated in relation to the development of the characteristic texture of salted herrings. The aim of this study was to measure the texture changes during ripening using two different methods and to correlate the texture changes with brine composition and with biochemical modifications at the molecular level. RESULTS: During ripening (up to 151 days), hardness was higher in salted herrings compared to raw herrings, irrespective of the brine composition. However, the increase in hardness of herring prepared with extra brine occurred later. After prolonged storage (371 days), hardness was found for both batches to decrease to the level of raw herring. The increase in hardness during the ripening period could be explained by free‐radical‐induced cross‐linking of myosin and the formation of aggregates. In addition, degradation of these aggregates correlated with the decrease in hardness observed at 371 days. CONCLUSIONS: Texture changes during ripening of salted herrings can be explained by oxidative reactions inducing myosin cross‐linking followed by subsequent degradation of these myosin aggregates. The brine composition might play a role in the development of herring texture but this need to be investigated in more details. Copyright © 2010 Society of Chemical Industry     

Influence of pre-cure freezing of Iberian ham on proteolytic changes throughout the ripening process

This work aimed to investigate the effect of pre-cure freezing Iberian hams on proteolysis phenomena throughout the ripening process. Non-protein nitrogen (NPN), peptide nitrogen (PN) and amino acid nitrogen (AN) as well as amino acid and dipeptide evolution followed the same trend in both refrigerated (R) and pre-cure frozen (F) Iberian hams during processing. At the different stages of ripening, there were no differences in the content of NPN and AN while F dry-cured hams had higher levels of PN than R hams at the final step. This seemed to be more related to the salt content (lower in F than in R hams) than to the pre-cure freezing treatment. Most amino acids and dipeptides detected showed higher concentrations in F than in R Iberian hams at the green stage, being rather similar at the intermediate phases. At the final stage, the effects of pre-cure freezing of Iberian hams were not well defined, higher levels of some amino acids and dipeptides were found in R than in F Iberian hams whereas other amino acids were lower in R than in F hams.     

Pectic polysaccharides during ripening of mango (Mangifera indica L)

The content of pectin decreased from 2.0 to 0.7% fresh weight (FW) and there was a concomitant increase in free galacturonic acid from 36 to 168 mg% FW during ripening of mango. Ion exchange chromatography on DEAE/cellulose resolved the pectic fraction into seven distinct peaks, with all of them showing a drastic decrease in pectin content and molecular weight as fruit ripening progressed, which indicated significant depolymerisation in vivo. Fraction I appeared to be an arabinogalactan‐type polymer, while fractions II and III were heterogalacturonans containing more than 60% galacturonic acid. Hydrolases implicated in pectin depolymerisation were polygalacturonase (PG), pectin methyl esterase (PME), galactanase, arabinanase and β ‐galactosidase. They all showed a climacteric peak in activity during ripening, except for PME which showed a continuous decrease in activity after an initial increase. These results are discussed in the light of fruit softening during ripening. Copyright © 2003 Society of Chemical Industry     

Occurrence of heavy metals (Hg, Cd, and Pb) and polychlorinated biphenyls in salted anchovies

The most popular brands of salted anchovies (Engraulis encrasicolus) from the Mediterranean Sea and Atlantic Ocean were purchased from several Italian supermarkets and grocery stores. Heavy metal (Hg, Cd, and Pb) and polychlorinated biphenyl (PCB) levels were determined and assessed by comparing the concentrations in these samples with the maximum permissible limits set by the European Union (Reg EC 629/2008 and Reg EC 1881/2006 [Off. J. Eur. Union L 173:3-9 and 364:5-24, respectively]). The Hg and Cd levels were higher than those of Pb in all samples examined. For Hg and Pb, the concentrations recorded in this study were below the authorized limits, while an appreciable percentage of samples from both locations (Mediterranean Sea, 35%, and Atlantic Ocean, 25%) showed Cd levels exceeding the threshold recommended for human consumption. Concerning PCBs, the results of principal component analysis showed that samples from the two different marine areas appeared to be discriminate, with Mediterranean anchovies more contaminated than the others, in spite of their lower lipid content. However, anchovy samples from both locations had dioxinlike-PCB levels (Mediterranean Sea, 0.011 pg World Health Organization toxic equivalency [WHO-TEQ] g(-1), wet weight, and Atlantic Ocean, 0.007 pg WHO-TEQ g(-1), wet weight) that were below the WHO-TEQ maximum concentration set by European regulation. The results of this study will help in generating data needed for the assessment of heavy metal and PCB intake from this food.     

Influences of rennet and container types on proteolysis of traditional Kurdish cheese during the ripening

The effect of rennet and container types was evaluated on proteolysis of traditional Kurdish cheese during 60 days ripening. The enzymes involved were commercial chymosin and traditional rennet from lamb abomasum. Goat skin (traditional container) and plastic containers were used as storage containers. The trend of proteolysis was determined by measuring the content of nitrogen (N) in compounds soluble in water, 12% trichloroacetic acid and 5% phosphotungstic acid along with the urea–polyacrylamide gel electrophoresis method. The results showed that the nitrogen in compounds soluble in water, 12% trichloroacetic acid and 5% phosphotungstic acid was higher in ripened cheeses into plastic containers; however, the containers had no significant effect on the breakdown of α‐ and β‐caseins (P < 0.05). Using commercial rennet caused the breakdown of α‐ and β‐caseins and the level of nitrogen in compounds soluble in water to increase. Finally, however, the amount of α‐ and β‐caseins breakdown was trivial, and α‐casein was decreased more than β‐casein in all samples.