Abstract Fishing products are characterized for being highly perishable; therefore, preservation methods are used to retain freshness, quality and extend shelf life. One of the factors that influences most on the loss of freshness, quality and shelf life, is storage temperature. This study evaluated the effect of storage temperature (0 °C and 5 °C) on the quality and shelf life of tilapia (Oreochromis niloticus) muscle during 20 days of storage. Adenosine 5’-triphosphate (ATP) and related compounds, K-value, pH, color, texture, water holding capacity (WHC), total volatile bases (TVB-N), and total count of mesophilic microorganisms were monitored. The results indicated that time and storage temperature had a significant effect (P < 0.05) on K-value, TVB-N, and total count of mesophilic microorganisms. The present study concludes that, by storing tilapia muscle at a lower temperature, a longer shelf life is produced, which implies that the product can be kept with good quality for a longer period of time. Likewise, the edible quality of tilapia muscle was affected by storage temperature, observing a shelf life of 16 days at 0 °C and 8 days at 5 °C.

Resumen Los productos pesqueros se caracterizan por ser altamente perecederos; por lo tanto, se utilizan métodos para conservar la frescura, la calidad y extender la vida útil. Uno de los factores que más influye en la pérdida de frescura, calidad y vida útil es la temperatura de almacenamiento. Este estudio evaluó el efecto de la temperatura de almacenamiento (0 °C y 5 °C) sobre la calidad y vida útil del músculo de tilapia (Ore ochromis niloticus) durante 20 días de almacenamiento. Se monitorearon el ATP (adenosina-5’-trifosfato) y compuestos relacionados, el indice K, el pH, el color, la textura, la capacidad de retención de agua (CRA), las bases volátiles totales (TVB-N) y el recuento total de microorganismos mesófilos. Los resultados indicaron que el tiempo y la temperatura de almacenamiento tuvieron un efecto significativo (P < 0.05) sobre el indice K, TVB-N y el recuento total de microorganismos mesófilos. En el presente estudio se concluye que al almacenar el músculo de tilapia a menor temperatura se produce una mayor vida útil, lo que implica que el producto se puede conservar con buena calidad por más tiempo. Asimismo, la calidad comestible del músculo de tilapia se vio afectada por la temperatura de almacenamiento, observándose una vida útil de 16 días a 0 °C y 8 días a 5 °C.

Abstract The study aims to investigate the effects of mixing on the protein solubility and secondary structure in corn dough during processing for tortilla production. To evaluate how mixing affects dough rheology, the storage moduli (G´), loss moduli (G´´) and tangent of the phase angle (Tan δ) dependent on frequency and texture profile analysis (TPA) were determined. HPLC-SEC showed an increased proportion of soluble polymeric proteins (soluble high molecular weight species). FT-IR results revealed that mixing promotes an increase of the β-sheet structure and a reduction of α-helix proportion, which suggests protein aggregation. Rheological data showed that the elastic prevailed over the viscous behavior (G´ > G´´) in the corn dough, with a soft solid material and an ordered and stable structure. Mixing, an intermediate step for dough production had important effects in protein structure and dough rheological properties. The increased Tan δ ( G´´/ G´) is consistent with an increased viscous character and polymers aggregation that was demonstrated in this case for proteins.

Resumen El estudio tiene como objetivo investigar los efectos del mezclado sobre la solubilidad de las proteínas del maiz y su estructura secundaria, en masas de maíz durante el procesamiento para la producción de tortillas. Para evaluar cómo el mezclado afecta la reología de la masa, se determinaron los módulos de almacenamiento (G´), los módulos de pérdida (G´´) y el ángulo de fase (Tan δ) dependientes de la frecuencia y el perfil de textura (TPA). Los análisis cromatográficos (HPLC-SEC) mostraron una mayor proporción de proteínas poliméricas solubles (especies solubles de peso molecular alto). Los resultados de FT-IR revelaron que la mezcla promueve el aumento de la estructura de la hoja β y la reducción de la proporción de la hélice α, lo que sugiere la agregación de las proteínas. Los datos reológicos mostraron que en las masas de maíz prevaleció el comportamiento elástico sobre el viscoso (G´ > G´´), un material sólido, blando con una estructura ordenada y estable. El mezclado, un paso intermedio para la producción de masa, tuvo efectos importantes en la estructura de la proteína y las propiedades reológicas de la masa, el aumento de Tan δ es consistente con un mayor carácter viscoso y agregación de polímeros que se demostró en este caso para las proteínas.

Abstract The aim of this research was to evaluate the effect of storage temperature (0 and 5°C) on the main metabolites and related parameters to rigor mortis in muscle of tilapia (Oreochromis niloticus). The rigor index (IR), adenosine 5’-triphosphate (ATP), glycogen, lactic acid, pH and texture were evaluated. The IR analysis was performed during 266 hours of storage at the two temperatures, while the rest of the parameters were monitored at 0 and at 48 hours of storage at both temperatures. It was found that both temperature and storage time, had a significant effect on IR, being more pronounced at 5°C compared to 0°C.

Resumen El objetivo de la presente investigación fue evaluar el efecto de la temperatura de almacenamiento (0 y 5ºC) sobre los principales metabolitos y parámetros relacionados con el rigor mortis del músculo de tilapia (Oreochromis niloticus). Se evaluó el índice de rigor (IR), adenosina 5´-trifosfato (ATP), glucógeno, ácido láctico, pH y textura. El análisis del IR se realizó durante 266 h de almacenamiento a las dos temperaturas, mientras que el resto de los parámetros se monitorearon al tiempo 0 y a las 48 h de almacenamiento en ambas temperaturas. Se encontró que tanto la temperatura como el tiempo de almacenamiento presentaron un efecto significativo sobre el IR, siendo más pronunciado a 5°C en comparación al de 0°C.

Abstract Horticultural products disinfection with short wave ultraviolet light (UV-C) depends mainly on dose. This parameter is defined as the product between time and intensity radiation. In general, short doses cause beneficial or hormetic effects, such as decrease of microbial load and fruits and vegetables quality preservation. While UV-C light high doses or long exposure times generate changes in those products, such as enzymatic browning, loss of texture, among others, which cause a decrease in shelf life and functional properties. Therefore, this article presents the most cited techniques to determine doses in horticultural products, some experimental and others that employ microbiology and mathematical knowledge, radiochromic films and computational fluid dynamics (CFD). The review highlights that CFD allow the development of simulations in real environments, quickly and economically, including radiation models prone to experimental validation and help to improve the arrengement of horticultural products in the equipment to achieve a uniform irradiation.

Resumen La desinfección de productos hortofrutícolas con luz ultravioleta de onda corta (UV-C) depende principalmente de la dosis. Este parámetro se define como el producto entre el tiempo e intensidad de radiación. En general, las dosis cortas ocasionan efectos benéficos u horméticos, tales como la disminución de carga microbiana y preservación de la calidad de las frutas y hortalizas durante su vida útil. Mientras que las dosis altas o los largos tiempos de exposición a la luz UV-C generan cambios en dichos productos, tales como el oscurecimiento enzimático, pérdida de textura, entre otros, los cuales provocan una disminución de la vida útil y la pérdida de las propiedades funcionales. Por lo tanto, este artículo presenta las técnicas más citadas para determinar las dosis en productos hortofrutícolas, algunas de carácter experimental y otras que emplean conocimientos de microbiología y matemáticas, películas radiocrómicas y la dinámica de fluidos computacional (CFD). La revisión destaca que la CFD permite el desarrollo de simulaciones en entornos reales de forma rápida y económica, comprende modelos de radiación que pueden ser validados de forma experimental y ayuda a mejorar la disposición de los productos hortofrutícolas en el equipo para lograr una irradiación más uniforme.

Abstract The present research work determined the effect of the stable and oscillating seawater temperature at three different levels (21, 24 and 28°C), on the physiological condition of the lion’s paw scallop Nodipecten subnodosus. For this, we evaluated the following physiological indicators: adenosine triphosphate content (ATP), glycogen and total carbohydrates, as well as muscle yield index (MYI) and adenylated energy charge, which were determined in the abductor muscle of organisms, extracted directly from the lagoon and after the treatments application. It was found that in the experiment, concentrations of ATP, glycogen content, total carbohydrates, and MYI decreased significantly (P<0.05) after the application of treatments. No effect of temperature level and application form (oscillating and constant) on MYI and CEA was found, however, glycogen content showed a significant affect only from the temperature level, being organisms exposed to 28°C statistically different from those of 24 and 21°C. In conclusion, only the acclimatization temperature level affected the physiological condition of the lion’s paw scallop, being the organisms acclimatized to 28°C the most affected.

Resumen El presente trabajo de investigación determinó el efecto de la temperatura estable y oscilante del agua de mar a tres diferentes niveles (21, 24 y 28°C), sobre la condición fisiológica de la almeja mano de león Nodipecten subnodosus. Para ello, se evaluaron los siguientes indicadores fisiológicos: contenido de adenosina trifosfato (ATP), glucógeno y carbohidratos totales, así como índice de rendimiento muscular (IRM) y carga energética adenilada (CEA), los cuales se determinaron en el músculo abductor de organismos extraídos directamente de la laguna y después de la aplicación de los tratamientos. Se encontró que, en el experimento, las concentraciones de ATP, contenido de glucógeno, carbohidratos totales, e IRM disminuyeron significantemente (P<0.05) después de la aplicación de los tratamientos. No se encontró un efecto del nivel de temperatura y la forma de aplicación (oscilante y constante) en el IRM y CEA, sin embargo, en el contenido de glucógeno se obtuvo un afecto significativo solo del nivel de temperatura, siendo los organismos sometidos a 28°C diferentes (P<0.05) a los de 24 y 21°C. Por lo tanto, se concluyó, que solo el nivel de temperatura de aclimatación afectó la condición fisiológica de la almeja mano de león, siendo los organismos aclimatados a 28°C los más afectados.

Abstract Microencapsulation was performed by complex coacervation of fig’s extracts in three stages of maturity, using two complexes: isolated soy protein with arabic gum (ISP / AG) and gelatin with arabic gum (G / AG) as wall material. The stability of the capsules was evaluated in terms of the presence of phenolic compounds, the antioxidant activity using the techniques by ABTS and hemolysis bioassay. In addition, we obtained the yield percentage and morphology of the microcapsules. The yield was higher in the G/AG complex, with values greater than 60 %. This complex also has a better pearl formation according to its morphology. Both complexes (G/ AG. ISP/AG and G/AG) have stability in terms of antioxidant capacity; therefore, the complex coacervation process is a technique capable to retain phenolic compounds present in fig.

Resumen Se realizó la microencapsulación por coacervación compleja de extractos de higo en tres etapas de madurez, utilizando dos complejos: Proteína de Soya Aislada con Goma Arábiga (SPI/GA) y Gelatina con Goma Arábiga (G/GA) como material de pared. La estabilidad de las cápsulas se evalúo en términos de la presencia de compuestos fenólicos, la actividad antioxidante mediante las técnicas de ABTS y bioensayo de hemólisis. El rendimiento fue mayor en el complejo de G/GA, con valores superiores al 60 %. Este complejo también logró una mejor formación de perlas de acuerdo a su morfología. Ambos complejos (SPI/GA y G/GA) mostraron estabilidad en términos de capacidad antioxidante, por lo tanto, el proceso de coacervación compleja es una técnica capaz de retener los compuestos fenólicos presentes en el higo.

Abstract The aim of this study was to evaluate the effects of chitosan-tomato plant extract (C-TPE) edible coating (EC) applications on the physicochemical, microbiological, sensory and antioxidant capacity of chicken during storage. Edible coatings prepared with chitosan 1%, acetic acid 1%, glycerol and TPE (0.1 and 0.3%) were tested. The slices were submerged for 1 minute in different treatments (T1: C 1%; T2: C 1% + TPE 0.1%; T3: C 1% + TPE 0.3%; T4: control) and stored at 4 °C. At the end of the storage period, the treatments exhibited the greatest physicochemical and microbiological effects in the slices, reducing the microbial population relative to the control. The T2 treatment exhibited the highest antioxidant capacity, total phenolic content and overall acceptance. The results demonstrate that the application of C with the addition of a natural extract, such as those from the tomato plant, can be an alternative method for preserving chicken meat.

Abstract Fish consumption has increased in recent years. However, fish meat is highly perishable, which demonstrates the need for technologies to preserve its quality. Edible coatings (EC) might provide an alternative to extend the shelf life of fish. The goal of this study was to evaluate the effect of EC of chitosan (C) in combination with carvacrol (CAR) on the physical and microbiological changes of tilapia fillets. Fillets were submerged for two minutes in different treatments (T1: control; T2: C 2%; T3: C 2% + 0.125% CAR; T 4: C 2% + 0.25% CAR). At the end of storage, T1 and T2 showed the lowest values of total volatile bases (TVB). The color parameters L*, a* and b* varied from each treatment. The texture decreased and the different treatments reduced the microbial population in relation to the control; T3 and T4 were the most effective. These results show that the use of C with CAR might be an alternative method to preserve the quality and safety of tilapia fillets.

Fresh blue shrimp (Litopenaeus stylirostris) muscle was stored with antioxidants under different conditions: ANTIOX 2%, packed in bilayer film of polyamide-low density polyethylene film (PA-LDPE) with 2% α-tocopherol; ANTIOX 4%, packed in PA-LDPE film with 4% α-tocopherol; and ANTIOX-GLAZED, samples stored glazed with 2% α-tocopherol. Shrimps packed in PA-LDPE without α-tocopherol were used as CONTROL. All samples were stored at –20 °C for 120 days. As compared to the CONTROL, the shrimp stored with the antioxidant showed lower lipid oxidation (0.10-0.14 vs 1.58 mgMA/kg of muscle), lost less firmness and astaxanthin content. ANTIOX 2% and ANTIOX-GLAZED showed the lowest concentrations of formaldehyde (0.081-0.083 μM/g). There were no significant differences in color and sensory properties, but differences in the integrity of the muscle fibers were observed. The treatments with α-tocopherol maintained the shrimp muscle quality during frozen storage. However, no significant differences were found between these treatments.

Rancidity development during frozen storage (–20 °C) of sierra fish (Scomberomorus sierra) was studied. Fillets were packed in low-density polyethylene films with and without butylated hydroxytoluene added (BHT-LDPE and LDPE respectively). Fillets stored with no package were used as control. Special attention was given to the effect of previous ice storage (0, 3, 6, 9 and 15 days) on the quality of the frozen fish. Physical (pH and texture) and chemical (peroxide value, PV and thiobarbituric acid index, TBA-i) analyses were carried out. Lipid oxidation increased with ice storage time in fish muscle without film packing, being greater than the film packed muscle (with and without antioxidant). An effect of previous ice storage time was observed on the frozen product (in all treatments). However, fish muscle with film packing containing antioxidant showed less lipid deterioration. Under the conditions applied in this study, the plastic films with antioxidant prevented the lipids oxidation during the cold handling of the sierra muscle.

A study was conducted to evaluate the effect of the photoperiod and biomass rate of shrimp:macroalgae over the total ammonia nitrogen (TAN) removal by the macroalgae Gracilaria vermiculophylla, in an integrated culture with shrimp Litopenaeus vannamei, with zero water exchange. Four photoperiods were evaluated: 12:12, 14:10, 16:08 and 24:00 h of light:darkness and two biomass ratios 1:4 and 1:8. The experimental design was a factorial of 4x2, with four replicates by treatment. The lowest concentrations TAN (0.55 ± 0.17 mg L-1), N-NO2 (0.145 ± 0.29 mg L-1) y N-NO3 (3.13 ± 0.73 mg L-1) were registered in the biomass rate of 1:8. The highest growth rates of the macroalgae (3.07 ± 1.44% day-1) were recorded with 24:00 h photoperiod and biomass ratio 1:8. The highest rate of N incorporation (0.31 ± 0.12 mg N L-1) of the macroalgae occurred under the same conditions. Shrimp growth was similar to data reported in traditional recirculation systems. The integration of G. vermiculophylla without water exchange system was able to maintain the TAN and N-NO2 under levels conditions for the growth of L. vannamei.

Se evaluó el efecto del fotoperiodo y la relación de biomasa camarón:macroalga en la remoción de nitrógeno amoniacal total (NAT), por la macroalga Gracilaria vermiculophylla, en cultivo con camarón Litopenaeus vannamei, sin recambio de agua. Se evaluaron cuatro fotoperiodos: 12:12, 14:10, 16:08 y 24:00 h de luz:oscuridad y dos relaciones de biomasa camarón:macroalga, 1:4 y 1:8. El diseño experimental fue factorial de 4x2 con cuatro réplicas por tratamiento. Las menores concentraciones de NAT (0,55 ± 0,17 mg L-1), N-NO² (0,145 ± 0,29 mg L-1) y N-NO3 (3,13 ± 0,73 mg L-1) se registraron en la relación 1:8. Las mayores tasas de crecimiento de la macroalga (3,07 ± 1,44% día-1) se obtuvieron con fotoperiodo de 24:00 h y relación de biomasa 1:8. La mayor tasa de incorporación de N en la macroalga (0,31 ± 0,12 mg N L-1 día-1) ocurrió en las mismas condiciones. El crecimiento del camarón fue similar al reportado en sistemas tradicionales de recirculación. La integración de G. vermiculophylla en el sistema sin recambio, fue capaz de mantener los niveles de compuestos nitrogenados tóxicos en niveles favorables para el crecimiento de L. vannamei.

El agua de cola es un efluente complejo compuesto por una gran variedad de sólidos, los cuales deben ser removidos en su mayor parte para generar un efluente que pueda ser vertido directamente al mar. En el presente estudio el agua de cola se centrifugó y posteriormente se trató con quitosano a distintos valores de pH y concentraciones con la finalidad de remover sólidos presentes. Mediante la centrifugación se logró remover el 33,88% de los sólidos totales; 28,52% de proteína; 97,50% de grasa; 40% de ceniza y 20% de NNP, y disminuyeron la DBO5 y la DQO en un 42,2 y 63,3% respectivamente. El porcentaje de transmitancia aumentó de 14,6 a 18,4 siendo éste un cambio pequeño en relación al contenido de sólidos removido. La adición de quitosano al agua de cola centrifugada redujo en 25% el contenido de sólidos totales, 55% el de proteína, 40% el de grasa, 24% el de cenizas y 60% el de NNP. De igual forma, disminuyó la DBO5 y la DQO en un 48,4 y 31,2% respectivamente. Como resultado de la adición el porcentaje de transmitancia aumentó de 18,4 a 86,0; indicando que tal aumento se debió principalmente a la remoción de pigmentos y no de materia orgánica. Se logró una disminución importante en DBO5 y DQO; sin embargo, se requieren otras herramientas para reducir estos valores a concentraciones establecidas en la reglamentación sanitaria.

The stickwater is a complex effluent consisting of a variety of solids, most of which should be removed to produce a new effluent that can be directly poured into the sea. In this study, stickwater was centrifuged to remove solids and the resulting liquid was then treated with chitosan at different concentrations and pH to eliminate the solids left in it. Centrifugation extracted 33.88% of total solids, 28.52% protein, 97.50% fat, 40% ash and 20% NPN. It also decreased in 42.2 and 63.3% the BOD5 and COD, respectively. Transmittance percent increased from 14.6 to 18.4, a small change in relation to the content of solids removed. The addition of chitosan to centrifuged stickwater decreased 25% of the total solids content, 55% of protein, 40% fat, 24% ash and 60% NPN. Likewise, the addition of chitosan decreased the BOD5 and COD in 48.4 and 31.2%, respectively. As a consequence, transmittance increased from 18.4 to 86.0%, indicating that such increase was mainly due to the elimination of pigments rather than organic matter. A significant decrease was achieved in BOD5 and COD; nevertheless, other tools are required to reduce these figures to the levels established by the environmental health regulations.

O residuo liquido (stickwater) é un efluente complexo composto por uma grande variedade de sólidos, os quais deven ser removidos principalmente para gerar un efluente que possa ser vertido diretamente ao mar. No presente estudo o residuo líquido foi centrifugado e posteriormente tratado com quitosana a distintos valores de pH e concentrações com a finalidade de remover sólidos presentes. Mediante a centrifugación se conseguiu remover 33,88% dos sólidos totais; 28,52% de proteína; 97,50% de gordura; 40% de cinza e 20% de NNP, e diminuiram a DBO5 e a DQO em 42,2 e 63,3% respectivamente. A porcentagem de transmitância aumentou de 14,6 a 18,4 sendo esta uma mudança pequena em relação ao conteúdo de sólidos removido. A adição de quitosana no residuo líquido centrifugado reduziu em 25% o conteúdo de sólidos totais, 55% o de proteína, 40% o de gordura, 24% o de cinzas e 60% o de NNP. De igual forma, diminuiu a DBO e a DQO em 48,4 y 31,2% respectivamente. Como resultado da adição, a porcentagem de transmitância aumentou de 18,4 a 86,0; indicando que tal aumento foi devido principalmente à remoção de pigmentos e não de matéria orgânica. Alcançou-se uma diminuição importante em DBO5 e DQO; no entanto, são requeridas outras ferramentas para reduzir estes valores a concentrações estabelecidas na regulamentação sanitária.