Abstract The aim of this study was to determine the effect of storage temperature on the kinetics of color change of chub mackerel dehydrated in a ternary solution (water, glycerol and salt) and vacuum packaged in films. The color of processed fish can change because of lipids and protein oxidation during storage. Samples were stored at 7, 25 and 35 °C for seven months and kinetic models of 0, 1 and 2 order were applied to describe the color changes. It was observed that an increase in the storage temperature improved the changes in the CIE color values (L*, a* and b*). First-order reaction had the best statistical parameters for a* at the three temperatures tested. The temperature dependence of parameter a* indicated an Arrhenius relationship and the activation energy (Ea) was 44.33 kJ/mol. The parameter b* fitted to the proposed models only in samples stored at 35 °C. The L* value decreased during storage at 25 and 35 °C (pale to dark). Storage at refrigeration temperature (7 °C) minimized the color changes.

Mass transfer kinetics in osmotic dehydration is usually modeled by Fick's law, empirical models and probabilistic models. The aim of this study was to determine the applicability of Peleg model to investigate the mass transfer during osmotic dehydration of mackerel (Scomber japonicus) slices at different temperatures. Osmotic dehydration was performed on mackerel slices by cooking-infusion in solutions with glycerol and salt (a w = 0.64) at different temperatures: 50, 70, and 90 ºC. Peleg rate constant (K1) (h(g/gdm)-1) varied with temperature variation from 0.761 to 0.396 for water loss, from 5.260 to 2.947 for salt gain, and from 0.854 to 0.566 for glycerol intake. In all cases, it followed the Arrhenius relationship (R²>0.86). The Ea (kJ / mol) values obtained were 16.14; 14.21, and 10.12 for water, salt, and glycerol, respectively. The statistical parameters that qualify the goodness of fit (R²>0.91 and RMSE<0.086) indicate promising applicability of Peleg model.

Os objetivos desta pesquisa foram determinar o efeito de diferentes condições na etapa de marinado para absorção de ácido e sal, tempo e características sensoriais da anchoita (Engraulis anchoita) marinada. As proporções utilizadas de solução:pescado foram: 0,77:1, 3:1 e 10:1 (com e sem agitação). O aumento da proporção permitiu uma velocidade maior de penetração do ácido e sal. O produto obtido na proporção 10:1 apresentou textura seca e fibrosa e leve gosto salgado. A concentração de sal foi significativamente menor (p < 0,01) nas amostras com agitação. A absorção do ácido não foi influenciada pela agitação; foi detectado ranço nos produtos produzidos com agitação. A proporção 3:1 diminui o tempo de marinação sem danificar os atributos sensoriais e pode ser usada para processar os marinados.

The aims of this research were to determine the effect of different conditions of the marination stage on the salt and acid uptake, immersion time, and sensorial characteristics during the marinating process of anchovy (Engraulis anchoita). Different solution:fish ratios and the agitation effect during this stage were analyzed. The ratios used were: 0.77:1, 3:1 and 10:1 (with and without agitation). An increase of marinating solution:fish ratio causes a higher speed of acid and salt penetration The product obtained with the 10:1 ratio had a dry and fibrous texture and a slightly salty taste. Salt concentration was statistically significantly lower (p < 0.01) in the samples with agitation. Agitation did not influence the acid uptake, and the salt penetration speed decreased, but rancidity was detected in this product. The ratio 3:1 decreases the marinating time without damaging sensory attributes and can be used in the fish marinating process.

Em produtos de pesca salgados e maturados são encontrados micro-organismos halotolerantes ou halofílicos (archaeobactéria) que não são afetados pelo sal. Eles podem ser bactérias halofílicas moderadas ou extremas. As bactérias halofílicas extremas requerem entre 15% e 30% de NaCl para o crescimento. As archaeobactérias halofílicas extremas podem ser seletivamente isoladas em diferentes meios. O objetivo deste trabalho foi determinar a efetividade do meio Sal-Ágar-Leite, um meio modificado em nosso laboratório com a adição de MgSO4 e KCl (nomeado SAMm), e seu efeito em crescimento bacteriano por meio da comparação com outros meios com e sem leite. Duas amostras de peixe salgado em fábricas de salgadura de peixe locais e duas cepas de laboratório foram usadas. As amostras de fábrica foram anchova maturada e filetes de anchova em óleo e as cepas de laboratório foram: Haloarcula spp. (proteolítico) (PC) e Halococcus spp (não proteolítico). Os seguintes meios foram usados alternativamente para o isolamento de bactérias halofílicas extremas: IRAM, Formulação de Gibbons e colaboradores, ágar de Bacalhau com Leite e SAMm. IRAM e Gibbons também foram usados enriquecidos com leite. Com o meio SAMm, os valores da recontagem foram semelhantes ou mais altos que com os meios tradicionais, a possibilidade de se obter resultados positivos dois ou três dias antes também acrescentam seus benefícios além da simplicidade de sua preparação. Por conseguinte, poderia ser considerada uma alternativa para os meios tradicionalmente usados para estudar bactérias halofílicas extremas.

Halotolerant or halophilic (Archaeabacteria) microorganisms can be found in salted and ripening fish products that are not affected by salt. They can be moderate or extremely halophilic bacteria. The extremely halophilic bacteria require between 15-30% of NaCl for growth. The extremely halophilic archaeobacteria may be selectively isolated in different media. The aim of this work was to determine the effectiveness of the Salt-Agar-Milk medium, a medium modified in our laboratory through the addition of MgSO4 and KCl - named SAMm, and its effect on the bacterial growth by means of comparison with other media, with and without milk, determining time of incubation and counting. Two samples of salted fish from local fish salting factories and two laboratory strains were used. The factory samples were matured anchovy and anchovy fillets in oil, and the laboratory strains were: Haloarcula spp. (proteolytic) and Halococcus spp. (non-proteolytic). The following media were alternatively used for the isolation of extremely halophilic bacteria: IRAM; Formulation of Gibbons and collaborators, Cod Milk agar, and SAMm. IRAM and Gibbons were also used enriched with milk. In the SAMm medium, there were obtained count values similar or higher than the ones of the traditional media; besides the simplicity of its elaboration, the possibility to obtain positive results two or three days earlier also added to its benefit. Consequently, it can be considered an alternative to the media traditionally used for the studied halophilic bacteria.

Foi estudada a difusão simultânea de cloreto de sódio e ácido acético em filés de anchoíta. Os resultados mostram que foram alcançadas condições de equilíbrio entre os filés e a solução de marinado, de acordo com os valores K obtidos para fechar a unidade. A solução de marinado precisou de agitação para evitar a formação de uma camada superficial diluída nos filés de pescado. Os tempos de equilíbrio para ácido e sal foram maiores para as amostras agitadas durante o marinado. O gasto de cloreto de sódio e ácido acético durante o marinado dos filés de anchoíta pode ser explicado pela lei de Fick. Os valores do coeficiente de difusão para ácido acético a 20 °C foram 3,39 × 10-6 e 3,49 × 10-6 cm²/segundos para marinado com e sem agitação, respectivamente. O valor do coeficiente de difusão de cloreto de sódio para marinado sem agitação foi de 2,39 × 10-7 cm²/segundos, contudo, para marinado com agitação, não pôde ser fixado.

Simultaneous diffusion of sodium chloride and acetic acid in anchovy fillets was studied. The results show that equilibrium conditions between the fillets and the marinating solution were reached according to the K values obtained close to unity. The marinating solution was stirred to prevent the formation of a diluted surface layer on the fish fillets. The equilibrium times for acid and salt were higher for the samples stirred during marinating. The sodium chloride and acetic acid uptake during marinating of anchovy fillets can be explained by Fick's law. The values of the diffusion coefficient for acetic acid at 20 °C were 3.39 × 10-6 and 3.49 × 10-6 cm²/seconds for marinating with and without agitation, respectively. The value of the diffusion coefficient for sodium chloride for marinating without agitation was 2.39 × 10-7 cm²/seconds, while it could not be obtained for marinating with agitation.