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- Effect of conventional heat and thermosonication treatments on broccoli (brassica oleracea L.) total phenolic contentPublication . Gonçalves, Elsa M.; Alegria, C.; Abreu, Marta; Brandão, Teresa R. S.; Silva, Cristina L. M.
- Colour and texture evaluation of whole tomatoes (Lycopersicum esculentum L.) at different ripening stagesPublication . Pinheiro, Joaquina; Alegria, C.; Abreu, Marta; Gonçalves, Elsa M.; Silva, Cristina L. M.
- Effect of postharvest treatment (hot water and thermosonication) on tomatoes (Lycopersicum esculentum L.) physical-chemical and nutritional quality during storagePublication . Pinheiro, Joaquina; Alegria, C.; Abreu, Marta; Gonçalves, Elsa M.; Silva, Cristina L. M.
- Evaluation of alternative preservation treatments (water heat treatment, ultrasounds, thermosonication and UV-C radiation) to improve safety and quality of whole tomatoPublication . Pinheiro, Joaquina; Alegria, Carla; Abreu, Marta; Gonçalves, Elsa M.; Silva, Cristina L. M.Previously optimised postharvest treatments were compared to conventional chlorinated water treatment in terms of their effects on the overall quality of tomato (‘Zinac’) during storage at 10 °C. The treatments in question were water heat treatment (WHT = 40 °C, 30 min), ultrasounds (US = 45 kHz, 80 %, 30 min), thermosonication (TS =40 °C, 30 min, 45 kHz, 80 %) and ultraviolet irradiation (UV-C: 0.97 kJ m−2). The quality factors evaluated were colour, texture, sensorial analysis, mass loss, antioxidant capacity, total phenolic content, peroxidase and pectin methylesterase enzymatic activities, and microbial load reduction. The results demonstrate that all treatments tested preserve tomato quality to some extent during storage at 10 °C. WHT, TS and UV-C proved to be more efficient on minimising colour and texture changes with the additional advantage of microbial load reduction, leading to a shelf life extension when compared to control trials. However, at the end of storage, with exception of WHT samples, the antioxidant activity and phenolic content of treated samples was lower than for control samples. Moreover, sensorial results were well correlated with instrumental colour experimental data. This study presents alternative postharvest technologies that improve tomato (Zinac) quality during shelf life period and minimise the negative impact of conventional chlorinated water on human safety, health and environment.
- Modelización del cambio de color y firmeza de tomates (Lycopersicum esculentum L.) a diferentes condiciones del almacenamientoPublication . Pinheiro, Joaquina; Alegria, C.; Abreu, Marta; Gonçalves, Elsa M.; Silva, Cristina L. M.The effect of temperature and storage time on tomatoes (Lycopersicum esculentum L.) colour (a* and ºh) and firmness (maximum force) were analysed at 2º, 5º, 10º, 15º and 20 ºC. The development of these quality attributes followed a fractional kinetic model. The regression coefficient (R2) for the generated models were high, 0.94 for both colour parameters (a* and ºh) and 0.84 for firmness. A significant (p<0.05) increase and decrease for a* and maximum force, respectively, were observed during storage. This study can contribute for the understanding of the real effect of temperature and storage time on two important quality attributes of tomatoes, such as colour and firmness.
- Postharvest quality of refrigerated tomato fruit (Solanum lycopersicum, cv. Zinac) at two maturity stages following heat treatmentPublication . Pinheiro, Joaquina; Alegria, C.; Abreu, Marta; Sol, Manuela; Gonçalves, Elsa M.; Silva, Cristina L. M.
- Degradation kinetics of peroxidase enzyme, phenolic content, and physical and sensorial characteristics in broccoli (brassica oleracea L. ssp. Italica) during blanchingPublication . Gonçalves, Elsa M.; Pinheiro, Joaquina; Alegria, C.; Abreu, Marta; Brandão, Teresa R. S.; Silva, Cristina L.M.The effects of water blanching treatment on peroxidase inactivation, total phenolic content, color parameters [-a*/b* and hue (h *)], texture (maximum shear force), and sensory attributes (color and texture, evaluated by a trained panel) of broccoli (Brassica oleracea L. ssp. Italica) were studied at five temperatures (70, 75, 80, 85, and 90 C). Experimental results showed that all studied broccoli quality parameters suffered significative changes due to blanching treatments. The vegetal total phenolic content showed a marked decline. Degradation on objective color and texture measurements and alterations in sensorial attributes were detected. Correlations between sensory and instrumental measurements have been found. Under the conditions 70 C and 6.5 min or 90 C and 0.4 min, 90% of the initial peroxidase activity was reduced. At these conditions, no significant alterations were detected by panelists, and a small amount of phenolic content was lost (ca. 16 and 10%, respectively). The peroxidase inactivation and phenolic content degradation were found to follow first-order reaction models. The zero-order reaction model showed a good fit to the broccoli color (-a*/b* and h *), texture, and sensory parameters changes. The temperature effect was welldescribed by the Arrhenius law.
- Descontaminação em hortofrutícolas inteirosPublication . Pinheiro, Joaquina; Alegria, C.; Abreu, Marta; Gonçalves, Elsa M.; Moldão-Martins, Margarida; Silva, Cristina L. M.
- Influence of postharvest ultrasounds treatments on tomato (Solanum lycopersicum, cv. Zinac) quality and microbial load during storagePublication . Pinheiro, Joaquina; Alegria, Carla; Abreu, Marta; Gonçalves, Elsa M.; Silva, Cristina L. M.Whole tomato fruits were treated at ultrasonic power levels from 10% to 100%, and at a constant frequency of 45 kHz, for different times (1-19 min). A central composite rotatable design (CCRD) was applied to optimise ultrasonic treatments for tomato quality (colour, texture and total phenolic content (TPC)) maintenance. According to response surface analysis, the optimal treatment parameters were 55%_10 min, 80%_15 min and 100%_19 min. At these conditions, and especially at higher power levels, a maximum retention of colour and texture, as well as an increase of TPC and microbial reduction were obtained in comparison with untreated fruits during 15 storage days at 10 degrees C. The ultrasounds treatment was found to be effective in delaying colour development and texture losses, preserving sensorial quality of whole tomato, with increase of TPC and microbial load reduction. Moreover, this postharvest treatment can be used as an alternative for extending fresh fruits shelf-life.
- Impact of water heat treatment on physical-chemical, biochemical and microbiological quality of whole tomato (Solanum lycopersicum) fruitPublication . Pinheiro, Joaquina; Silva, Cristina L. M.; Alegria, Carla; Abreu, Marta; Sol, Manuela; Gonçalves, Elsa M.Water heat treatments (WHT) are applied to fresh fruits for disinfection purposes as well as to promote changes to the biochemical pathways involved in the ripening process, resulting in remarkable beneficial effects on postharvest quality maintenance and storage life extension. The objective of this study was to evaluate the overall effects of WHT on tomato (Solanum lycopersicum 'Zinac') quality and to determine an optimal WHT condition to extend its shelf-life. Fruits were immersed in hot water at different temperatures (from 40 to 60°C) and during different periods of time (2 to 60 min). WHT effects on fruit colour CIELab parameters (a* and °h), firmness (N), peroxidase (POD) and pectinmethylesterase (PME) enzyme activity, total phenolic content (TPC) and microbial load (mesophylic and yeasts & moulds counts (Y&M)) were evaluated. After WHT no observable color changes were denoted in all heat treated samples. At lower WHT, 40-50°C, maintenance in firmness was obtained when compared to untreated samples. Significant reductions on tomato firmness were observed in treatments with temperatures higher than 55°C. Both evaluated enzymatic activities were affected by the heat treatments. Regarding POD enzyme, an increase in its activity was found with intensive WHT, while PME activity decreased at all tested conditions with two exceptions (45 and 60°C). In fruits treated at 40°C/30 min the highest increase in TPC was found when compared to the control sample (ca. 27%). WHT at 50°C/2 min or 40°C/30 min promoted a reduction in mesophylic and Y&M load to undetectable levels, showing the effectiveness of these treatments to control microbial development in tomato fruits. Therefore, these treatments present an alternative postharvest process for tomato storage with beneficial effects to fruit quality as well as extension of shelf life.
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