Enzymatic activity during frozen storage of Atlantic horse mackerel (Trachurus trachurus) pre-treated by high-pressure processing

The assessment of enzymatic activity on Atlantic horse mackerel (Trachurus trachurus) during frozen storage was carried out in samples pre-treated by high-pressure processing (HPP) combinations of 150, 300 and 450 MPa with 0-, 2.5- and 5-min holding time (untreated samples were used as controls). The activities of four enzymes (acid phosphatase, cathepsins B and D, and lipase) in fish muscle were quantified during accelerated storage conditions (up to 3 months at −10 °C). The experimental data were fitted to second-order polynomial models to determine the effect of pressure level, holding time and frozen storage time on these enzyme activities and to identify conditions of maximum/minimal enzyme inactivation. Acid phosphatase and cathepsin (B and D) activities were significantly (p<0.05) influenced by HPP, showing behaviours during frozen storage different from control samples. Acid phosphatase and cathepsin B activities decreased (p<0.05) with HPP treatments, being this effect more intense for cathepsin B, particularly at 450 MPa. Regarding cathepsin D, the activity increased (p<0.05) at intermediate pressure (300MPa) and decreased (p<0.05) at higher pressure (450 MPa). During frozen storage, cathepsin D enzymatic activity tended to increase over time indicating activity recovery of these enzymes. Although a predictive model for its activity was not acceptable, the increase in lipase activity during storage was the most pronounced trend observed

Obtención de gas de síntesis por tratamiento térmico en microondas de biomasa y biogás

En este trabajo se estudia la pirólisis, tanto en microondas como en horno eléctrico, de un residuo procedente de la industria del café, con objeto de comparar la influencia del calentamiento en las características de las fracciones resultantes. La alta proporción de gas de síntesis (H2 + CO) obtenida con el microondas (hasta del 73%) es debida al hecho que la auto-gasificación del carbonizado con el CO2 liberado y que la descomposición catalítica de CH4 se ven favorecidas por este tipo de calentamiento.Así, los experimentos de estas dos últimas reacciones llevadas a cabo de manera individual, con ambos sistemas de calentamiento, demuestran que se dan mayores conversiones en el microondas. En el caso de la descomposición de CH4, la conversión, que inicialmente alcanza valores próximos al 100%, experimentaun descenso importante al cabo de pocos minutos como consecuencia de la formación de depósitos de carbono que bloquean los centros activos de la superficie del catalizador. Sin embargo, una combinación de ambas reacciones, i.e. reformado de CH4 con CO2, mejora el proceso de conversión de CH4 a H2, debido a que el CO2 gasifica los depósitos de carbono generados, permitiendo una regeneración “in situ” del catalizador. Estos resultados han servido como punto de partida para el desarrollo de un nuevo procedimiento que permitiría convertir biogás en gas de síntesis

Medición de la calidad de vida en niños y adolescentes: comprobación preliminar de la validez y fiabilidad de la versión española del cuestionario KINDL

ObjetivosObtener una versión española del cuestionario KINDL transculturalmente equivalente a la versión original alemana, y evaluar sus propiedades psicométricas en una muestra de padres y de niños/adolescentes sanos de 8–16 añosDiseñoEstudio transversalEmplazamientoDos colegios públicos de EGB y ESO de la cuenca minera central de Asturias de similares condiciones sociodemográficasParticipantesUn total de 243 niños de 8-16 años y 153 padresMediciones principalesCalidad de vida relacionada con la salud (CVRS) valorada mediante la versión adaptada del cuestionario alemán KINDL. Adicionalmente, se realizó una valoración externa de la CVRS infantil a través de un grupo de padres de los alumnos. También se comprobaron las propiedades psicométricas de la versión española adaptadaResultadosSólo 6 ítems (6/24) necesitaron sucesivas traducciones y discusión conceptual durante la fase de adaptación idiomática. El análisis factorial confirmó la validez de construcción de las escalas, excepto en la dimensión “Escuela” de la versión 13–16 años. La consistencia interna, medida mediante el coeficiente α de Cronbach, fue buena para el total del cuestionario (> 0,70) y aceptable en la mayoría de las escalas (> 0,50). El sexo femenino y la mayor edad de los niños se correspondieron con peores puntuaciones de CVRS en la mayoría de las dimensiones investigadas (p < 0,01)ConclusionesLa versión española del KINDL presentó coeficientes de fiabilidad y validez aceptables. Se encontraron insuficiencias puntuales en este primer paso de la investigación en la escala “Escuela” entre adolescentes. Los resultados constituyen un importante punto de partida para disponer de un instrumento de medida de la CVRS infantil, en lengua españolaObjectivesTo obtain a first Spanish version of the KINDL questionnaire idiomatic and culturally equivalent to the German original version, and then to evaluate its psychometric properties in a sample of healthy children/adolescents 8-16 years old, and their parentsDesignCross-sectional studySetting2 public schools of Asturias of similar sociodemographic conditionsParticipants243 children 8–16 year-old, and 153 parents were investigatedMain measurementsHRQoL evaluated through the generic questionnaire KINDL. An external assessment through the parents was made as well. The psychometric properties of the Spanish version of the questionnaire were investigated and results on HRQoL are presented for different ages and gender in the Spanish sampleResults6 ítems (6/24) needed successive translations and conceptual discussion during the phase of idiomatic adaptation. The factorial analysis confirmed the validity of construction of the instrument for most scales. The internal consistency, measured by αCronbach coefficent, was good for the total of the questionnaire (>0.70) and acceptable in most of the scales (>0.50). Only the school scale for adolescents shows very poor reliability. Females and children with higher age scored lower in most of the investigated dimensions (P<.01)ConclusionsThe first Spanish version of the Kindl showed acceptable reliability and validity. In spite of the punctual inadequacies found in this first step of the investigation, the results constitute an important starting point to work futher on the KINDL as an HRQoL instrument -in Spanish language-, to measure subjective well-being in childre

Effect of high-pressure processing of Atlantic mackerel (Scomber scombrus) on biochemical changes during commercial frozen storage

This research focuses on biochemical changes related to quality losses observed in Atlantic mackerel (Scomber scombrus) muscle stored under commercial frozen storage conditions (9 months, −18 °C) when subjected to highhydrostatic pressure (HHP) treatments (125, 150, 175, and 200 MPa for 0 min) before freezing. After freezing, free fatty acid (FFA) formation (lipid hydrolysis assessment) showed a marked inhibition in HHP-treated fish and during frozen storage of samples treated at 175 MPa. Fluorescence ratio (FR) assessment of tertiary lipid oxidation showed a partial inhibitory effect during the 0–9-month period for samples treated at 175 and 200 MPa. After a 3-month storage of samples treated at these pressure levels, one-dimensional SDS-PAGE analysis of the sarcoplasmic protein fraction revealed the disappearance of a band; additionally, samples treated at 150 MPa showed the same effect at month 9. After gel excision, trypsin digestion, tandem mass spectrometry (MS/MS), and sequence database analysis, the band was identified as phosphoglycerate mutase 2 (28.7 kDa). On the other hand, HHP processing did not show a significant effect on trimethylamine (TMA) values, primary and secondary lipid oxidation, PUFA levels, 1-D myofibril protein pattern, and the activity of acid phosphatase and cathepsins B and D. Biochemical quality indices such as FFA, TMA, and FR and the activity of acid phosphatase and cathepsin B showed a progressive increase throughout the frozen storage of all samples

Lipid and protein changes related to quality loss in frozen sardine (Sardina pilchardus) previously processed under high-pressure conditions

This research focuses on biochemical changes related to quality loss in frozen (−18 °C for 9 months) sardine (Sardina pilchardus) previously subjected to high-pressure (HP) processing (125–200 MPa). The inhibition (p < 0.05) of lipid hydrolysis development (lower free fatty acid formation and lipase activity), observed in frozen sardine as a result of the previous HP treatment, increased with the pressure level applied. Several parameters including peroxide value, thiobarbituric acid index, fluorescent compounds, and polyenes showed that the applied HP conditions prior to sardine freezing did not increase lipid oxidation. Also, HP did not induce a substantial modification of acid phosphatase and cathepsins B and D activities, and the electrophoretic patterns of sarcoplasmic and myofibrillar protein fractions did not change. However, HP processing led to a decrease in myofibrillar protein content in frozen pressure-treated fish, an effect that was higher in 175- and 200-MPa treated samples. In conclusion, this research showed that pressure treatments in the 125–200- MPa range with holding time of 0 min cause only minor modifications in biochemical indicators of deterioration throughout the subsequent frozen storage of samples for up to 9 months. This study shows the need to optimize HP conditions, particularly in the case of applications combining HP treatments, frozen storage, and thawing to obtain products with high quality and commercial viability

Caracterização físico-química e sensorial de doces de pêssego com diferentes teores de açúcar

O presente estudo teve como objetivo desenvolver e caracterizar físico-química e sensorialmente doces de pêssego com diferentes teores de açúcar. Para tal, confecionaram-se oito doces de pêssego com diferentes concentrações de açúcar. Os resultados demonstraram que os oito doces de pêssego elaborados apresentaram diferenças significativas na cor, no que respeita à luminosidade (L*) e parâmetro b*. Concretamente, os doces com menores teores de açúcar foram os que apresentaram maiores valores de L* e de b* (maior luminosidade e cor amarela, respetivamente), indicativos de uma menor ocorrência de reações de escurecimento e de uma maior proporção de polpa com coloração amarela. Os doces também apresentaram diferentes valores de pH, acidez titulável e atividade da água. No entanto, como todos os doces apresentaram valores de pH e atividade da água inferiores a 4,5 e 0,93, respetivamente, os doces elaborados não demonstraram risco de produção de toxina botulínica e de crescimento da salmonela, Clostridium botulinum e de outras bactérias patogénicas. No que se refere à avaliação organolética, após análise sensorial de três doces por um painel de consumidores, foram detetadas diferenças significativas entre os doces face à doçura e apreciação global, tendo sido o doce com menor teor de açúcar (1:0,3, polpa:açúcar) o que teve maior aceitação por parte dos consumidores, tendo estes gostado moderadamente a muito.info:eu-repo/semantics/publishedVersio

High pressure and thermal pasteurization effects on sweet cherry juice microbiological stability and physicochemical properties

This study evaluated high pressure processing (P1 – 400 MPa/5 min; P2 – 550 MPa/2 min) and thermal pasteurization (TP – 70°C/30 s) effects on sweet cherry juice’s microbiological and physicochemical parameters, during four weeks of refrigerated storage. All treatments reduced the microbiological load to undetectable levels not affecting total soluble solids and titratable acidity. The pH increased with all treatments, however, it decreased during storage. Phenols were differently affected: TP increased them by 6%, P1 had no effect while P2 decreased them by 11%. During storage, phenols in control and TP samples decreased by 26% and 20%, P1 samples decreased them by 11% whereas P2 showed no variation. TP had no effect on anthocyanins, while pressure treatments increased them by 8%. Anthocyanins decreased during storage, particularly in the control and P1 (decreasing 41%). All treatments had no effect on antioxidant activity until the 14th day, thereafter high pressure processing samples showed the highest antioxidant activity

Shelf-life extension of watermelon juice preserved by hyperbaric storage at room temperature compared to refrigeration

This work reports Hyperbaric Storage (HS) preservation of raw watermelon juice at variable/uncontrolled room temperature (RT,z21 C) for 7 days at 100 MPa and compared it with refrigeration (RF). At the end of storage, there was an increase in microbial counts (total aerobic mesophiles, psychrophiles, and yeasts and moulds) to above 6 log10 CFU/mL for samples stored at atmospheric pressure (RF and RT), while juice stored under HS/RT showed maximum values of about 2 log10 CFU/mL for total aerobic mesophiles/ psychrophiles and below the detection limit for yeasts and moulds. HS/RT juice showed also physicochemical parameters at levels similar to the initial juice. Thus, HS/RT can not only be used to preserve foods with no refrigeration energetic costs (since it does not require temperature control), but additionally, has also a great potential to extend the shelf-life of food products, compared to RF. This is the first case in the literature showing this additional potential/advantage of HS/RT