María Isabel Yeannes

Physical and Chemical Changes in Anchovy (Engraulis anchoita) Flesh During Marination

ABSTRACT In this work the physical and chemical changes promoted by the marinating process in anchovy fillet during brining and marinating stages were studied. During the marinating stage a diffusion of acetic acid and sodium chloride takes place into the tissue of fish flesh until a balanced concentration is reached. Most changes in the components of the fillet occurred in the first 24 hours being called by the authors “variable grade period” in contrast with “constant grade period” that occurred at the end of the marinating process. The sensorial score of full marinating was reached at nine days, when the structural changes had concluded.

Development of Quality Index Method for anchovy (Engraulis anchoita) stored in ice: Assessment of its shelf-life by chemical and sensory methods

The objective of this study was to develop a quality index method for Engraulis anchoita stored in ice and to determine its shelf-life based on this quality index method and chemical indices such as total volatile bases and thiobarbituric acid-reactive substances. Besides, the chemical composition with emphasis on the polyunsaturated fatty acids content was determined. The results indicate that E. anchoita is a valuable protein source and lipid with important content of n-3 polyunsaturated fatty acids. The developed quality index method scheme was composed of 28 demerit points, divided into 4 parameters and 10 attributes. All attributes showed correlation with time of storage (R > 0.90). The quality index (QI) presented a linear relationship with storage (QI = 2.55x days in ice + 1.76; R2 = 0.98). In the shelf-life assessment-based quality index method, the rejection sensory point was observed after 7 days of storage due to the presence of unpleasant odours and deteriorated appearance. The total volatile basic nitrogen value remained below the upper limit of acceptability during the 10 days of ice storage. The evolution of thiobarbituric acid-reactive substances indicates lipids oxidation during the storage of anchovies. According to the results, the quality index method scheme developed for the E. anchoita stored in ice could be considered adequate to evaluate their freshness and to estimate its shelf-life.

Ripening of salted anchovy (Engraulis anchoita): development of lipid oxidation, colour and other sensorial characteristics

BACKGROUND Changes in lipids are in general associated with quality deterioration, though earlier studies in anchovy indicate that the volatile compounds of importance to the characteristic flavour could be generated by lipid oxidation. The aim of the present paper was to study the changes in the fatty acid composition and the lipid oxidation of Engraulis anchoita during ripening and their relationship with the development of the typical sensorial characteristics. RESULTS As a result of ripening, polyunsaturated fatty acids decrease from 4.27 to 2.42 and 2.00 g kg(-1) fatty acids in gutted fish and fillet, respectively. The most affected class of fatty acids was the n-3 fatty acids, especially docosahexaenoic acid. Moreover, saturated fatty acids were the most stable to the process. 2-Thiobarbituric acid reactive substances (TBARS) increased throughout ripening, and the use of fillets instead of gutted fish reduced this value. The a value was the parameter most modified, showing a marked increase which correlates with the acquisition of a uniform pink colour. Sensory analysis did not show development of off-odour or undesirable changes in colour during ripening. CONCLUSION As a result of ripening, the fatty acid profile was modified and an increment of TBARS was observed. However, these changes did not lead to deterioration in the quality of the product.

Modifications in the chemical compounds and sensorial attributes of Engraulis anchoita fillet during marinating process

Marinated fish are fish products preserved by the combined action of salt and organic acids. The objective of this work was to analyze the variations in the chemical compounds of anchovy fillets that give them sensorial characteristics during the marinating process of Engraulis anchoita. The protein content decreased slightly and the TVB-N level decreased significantly in both the brining and marinating stages. In the marinating stage an increase in the total free aminoacids was observed. The NBV level in the brining and marinating solutions increased during these stages due to the solubilization of the non-protein nitrogenous compounds and the degradation of some protein compounds.The decrease of the contents of protein and TVB-N, and the increase of the acidity and the free aminoacids content during the marinating process give the marinated fillets the characteristic texture and aroma.

Typical Microorganisms in Cold Marinated Anchovies (Engraulis anchoita) Filled with Corn Oil and Spices

Abstract The aim of this work was to study the influence of microbiological load of spices in the microflora of anchovy marinades. Microorganisms were not detected in anchovy at the end of the marinating stage, previous to packaging the marinated fillet. In the spices used, the microorganisms found were Lactobacillus paracasei paracasei 1, Bacillus mycoides, and Monilia spp. in black pepper; L. cellobiosus and B. mycoides in bay leaves; L. acidophilus and B. mycoides in paprika; and L. acidophilus, B. mycoides and Micrococcus varians in milled red pep per. After three months of storage of marinated anchovy at 4°C and 18°C only L. paracasei paracasei 1, L. acidophilus 1, M. varias and B. mycoides were found. Several of these bacteria were from spices and were considered typical of marinades, since the homeostatic mechanisms were adaptable in the medium.

Development of Quality Index Method Scheme for Common Carp (Cyprinus carpio) Stored in Ice: Shelf-Life Assessment by Physicochemical, Microbiological, and Sensory Quality Indices

ABSTRACT Sensory methods are the most interesting methods to estimate fish quality. Among these, the recently developed quality index method (QIM) has gained popularity, as shown by the multiple publications of QIM schemes in the last years. The objective of this study was to create a new QIM scheme (QIM sensory table and corresponding point system) for the common carp (Cyprinus carpio), basing the definition of the rejection point on sensory, physicochemical (thiobarbituric acid reactive substances, total volatile basic nitrogen, pH, and color measurements), and microbiological criteria (counts of mesophiles, psychrotrophs, and Pseudomonas spp.). A new QIM scheme was developed and is proposed for use in the future; it will be useful for practical evaluations of carp freshness in all steps of the production chain, and it will contribute to a more effective use of the species as an alternative for human food supply.

Bacterial Contribution to Salted Anchovy (Engraulis anchoita Hubbs & Marinni, 1935) Ripening Process

The bacterial populations of the salted anchovy ripening process and its potential role on the development of the typical sensory characteristics of this product were studied. Salted anchovy samples were taken during the ripening process and submitted to microbiological analyses in order to monitor the evolution of bacterial groups. According to the results obtained, the ripening process was dominated by moderate halophilic bacteria. Moreover, many of the isolated strains showed proteolytic, lipolytic, and trimethylamine oxide (TMAO) reductase activities. These activities contribute to the development of the typical flavor of this product and to the increase of total volatile bases observed during ripening.

Influence of Water and Glycerol Contents on the aw of Fish Pastes

Abstract The influence of fish water content on the characteristics of water activity (aw) of reduced paste was studied. Two fish species were used: a fat species, mackerel (Scomber japonicus marplatensis), and a lean species, Brazilian sandperch (Pseudopercis semifasciata). Glycerol (from 15 to 50%) was used to decrease aw of the cooked fish paste.(54.12% and 77.89%) in mackerel, two relationships of aw versus percent added glycerol were obtained, and for Brazilian sandperch one relationship was obtained.

Quality Changes in Gamma Irradiated Marinades of Anchovy (Engraulis anchoita) During Refrigerated Storage

The effect of gamma irradiation (0, 1.8, and 3.3 kGy) on the microbiological, chemical, and color characteristics of marinated (7% acetic acid and 10% NaCl) and vacuum-packed anchovy fillets was analyzed during 20 months of refrigerated storage (4 ± 1°C). Acidity, pH, water activity (aw), total volatile basic nitrogen (TVBN), lipid oxidation, and color parameters were determined. Mesophilic and psychrotrophic bacteria, sulphite-reducing clostridia, total and fecal coliforms, Staphylococcus spp., yeasts, and molds were investigated. Gamma irradiation reduced the initial mesophilic bacterial counts and inhibited mesophils growth during 20 months. As a result, the production of TVBN during storage was lower in irradiated samples than in control. Also, lipid oxidation was lower in irradiated samples than in nonirradiated. The color of anchovy fillets was not affected by the irradiation treatment. Even if nonirradiated anchovy fillets presented a high stability in comparison with the traditional product (in flasks with vegetable oil and spices), gamma irradiation improved the microbiological and chemical quality of anchovy fillet marinades without inducing changes on its characteristic color for 20 months.

Determination of the moisture sorption behavior of osmotically dehydrated mackerel fillets by means of binary and ternary solutions.

In this study, the moisture sorption isotherm of osmotically dehydrated mackerel fillets (Scomber japonicus) was experimentally determined. The fillets were osmotically dehydrated with solutions of salt (NaCl) (120 and 180 g per liter of solution) or in combination with sugar (350 to 700 g per liter of solution). The sorption isotherms were determined using the static gravimetric methodology with six salts for the water activity range of 0.33–0.98 at 5 ℃ and 25 ℃. All the sorption curves were found to be type III. Temperature and the final tissue salt content had significant (p < 0.05) effects on the sorption isotherms. A regression program was used to fit the Halsey, Oswin and Smith moisture sorption isotherm models. Oswin equation gave the best fit for the whole range of water activity and temperatures. The Smith equation only presented valuable results for the mackerel fillets samples with the higher salt content.