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- Microstructural, physicochemical and sensorial effects of pears (cv. Rocha) stored under controlled atmosphere conditionsPublication . Galvis-Sánchez, Andrea C.; Teixeira, Claudia; Fonseca, Susana C.; Malcata, F. Xavier
- Effect of different levels of CO2 on the antioxidant content and the polyphenol oxidase activity of ‘Rocha’ pears during cold storagePublication . Galvis-Sánchez, Andrea C.; Fonseca, Susana C.; Gil-Izquierdo, Ángel; Gil, María I.; Malcata, F. XavierAbstract: Pears (Pyrus communis L. cv. ‘Rocha’) were exposed to air or controlled atmosphere (CA) containing various concentrations of CO2: 0, 0.5 and 5 kPa, all with 2 kPa O2. After 4months of storage at 2 ◦C, the fruits were transferred to air at room temperature, and assessed in terms of soluble solids, titratable acidity, pH, incidence of brown heart and flesh browning, phenolic content, vitamin C content and polyphenol oxidase activity. By 4months of storage, soluble solids and pH increased, and acidity decreased relative to harvest, but no differences were detected between pears stored under air or any of the CA tested. Higher contents of hydroxycinnamic derivatives and flavan-3-ols in the peel than in the flesh were recorded. However, the content of arbutin was higher in the flesh than in the peel, whereas flavonols were only detected in the peel. In general, hydroxycinnamic derivatives and flavonols were stable throughout storage, but flavan-3-ols decreased in concentration under air or CA. Arbutin was the only phenolic compound that increased in concentration as time elapsed. No clear relation was found between the storage conditions tested and the phenolic concentration in pears. Regarding ascorbic acid (AA) and dehydroascorbic acid (DHA), their concentrations were higher in the peel than in the flesh. Furthermore, AA and DHA were strongly affected by storage: the former decreased, whereas the latter increased in content. A decrease in PPO activity was apparent after harvest and during storage, particularly under higher levels of CO2. The combination 2 kPa O2 + 5kPa CO2 increased the incidence of internal disorders (viz. brown heart and flesh browning) after storage.
- Microstructural analysis of fresh-cut red bell pepper (Capsicum annuum L.) for postharvest quality optimizationPublication . Fonseca, Susana C.; Silva, Cristina L. M.; Malcata, F. XavierThe main objective of this work was to evaluate the microstructure of fresh-cut red bell pepper (Capsicum annuum L.) after cutting, when maintained (for 0,4 and 7 d) under refrigerated storage (2°C). In order to assess the microstructure of the product, scanning electron microscopy (SEM) was applied; however, to improve this technique, preparation procedures and quantitative image analysis were specifically developed. Since sample preparation affects deeply image quality, three sample preparation procedures (viz. freezing by immersion in liquid nitrogen and subsequent storage at -80°C, freezing by storage at -80 °C and subsequent freeze-drying, and freezing by immersion in liquid nitrogen and subsequent freezedrying) were tested. One could also test (with success) a methodology of quantitative image analysis via a panel – a large number of people (N=25) rated the degree of cellular destruction, using a continuous scale (from 1- no cellular destruction to 9-extreme cellular destruction). Statistical analysis of the experimental data revealed that frozen samples exhibited higher cellular destruction than via the other two procedures; no statistically significant differences were observed between these two other procedures. Red bell pepper samples stored for 4 and 7 d presented (as expected) higher degree of cellular destruction than initial day samples. This work allowed one to develop appropriate preparation procedures of sample and quantitative image analysis – that will permit the application of this microscopy technique in future work in this area.
- Relationship between instrumental and sensory quality parameters of various pear varietiesPublication . Galvis-Sánchez, Andrea C.; Teixeira, Claudia; Fonseca, Susana C.; Malcata, F. Xavier
- Microstructural analysis of fresh-cut red bell pepper (Capsicum annuumL.) aiming at postharvest quality optimizationPublication . Fonseca, Susana C.; Silva, Cristina L. M.; Malcata, F. Xavier
- Application of controlled and modified atmospheres for the preservation of postharvest quality in fresh fruits and vegetablesPublication . Fonseca, Susana C.; Malcata, F. XavierUses of preservation technologies for fruits and vegetables based on alteration of the overhead atmosphere have been increasing in the latest decades, as consumers demand fewer and less extensive treatments (of chemical nature or otherwise) of food items. This paper provides a specific review of available technologies which share as common core the deliberate formulation of the overhead atmosphere, with the goal of extending the useful life of fresh fruits and vegetables. Classical and novel technologies pertaining to controlled and modified atmospheres are duly presented and discussed, in terms of principles, advantages, limitations and applications. Finally, updated recommendations encompassing controlled and modified atmospheres are listed.
- Effect of CA-storage on the physical and sensorial quality of "Rocha" pearPublication . Galvis-Sanchez, Andrea C.; Fonseca, Susana C.; Morais, Alcina M. M. B.; Malcata, F. Xavier
- Influence of low oxygen and high carbon dioxide on shredded Galega kale quality for development of modified atmosphere packagesPublication . Fonseca, Susana C.; Oliveira, Fernanda A. R.; Brecht, Jeffrey K.; Chau, Khe V.Respiration rate, sensory attributes, colour alterations, and water, chlorophyll and ascorbic acid contents were monitored during storage of shredded Galega kale (Brassica oleracea var. acephala DC.) at 20 ◦C to define an adequate range of O2 and CO2 partial pressures for product preservation. Different low O2 and high CO2 atmospheres were tested. First, tolerance to low O2 partial pressures (1, 2, 3 or 21 kPa O2 with balance N2) was tested. Quality retention was improved as O2 partial pressure was reduced and there was no induction of anaerobic respiration. Then, tolerance to high CO2 partial pressures (0, 10, 15 or 20 kPa CO2 plus 21 kPa O2 and balance N2) was tested. The high CO2 partial pressures extended the shelf life of the shredded kale and no symptoms of CO2 injury were detected. Finally, combinations of low O2 and high CO2 (1 or 2 kPa O2 plus 15 or 20 kPa CO2, with balance N2, and an air control) were analysed. No differences were observed among the different gas combinations. An atmosphere of 1–2 kPa O2 plus 15–20 kPa CO2 and balance N2 extends the shelf life of shredded Galega kale to 4–5 days at 20◦C, compared with 2–3 days in air storage. Predictive models of chlorophyll a and b degradation as a function of time and gas composition were developed.
- Physicochemical and Sensory Evaluation of ‘Rocha’ Pear Following Controlled Atmosphere StoragePublication . Galvis-Sánchez, A. C.; Fonseca, S. C.; Morais, A. M. M. B.; Malcata, F. XavierThe effects of several processing factors (storage time, time in the open air at room temperature, and overhead concentrations of O2 and CO2) on color, firmness, polyphenol oxidase (PPO) activity, and sensory attributes of pears (cv. Rocha) grown in 2 locations were studied using a multiple linear regression model. Backward elimination (F ≥ 0.005) was used to assess the significant factors. Extended storage time, long-time exposure at room temperature, and high O2 concentration played major roles on color changes assessed instrumentally and further confirmed by a sensory panel. Firmness was strongly affected by storage time and by time in the open air at room temperature. Finally, PPO activity was dependent on the growing location.
- Microstructural changes of 'rocha' pear following storage under controlled atmospherePublication . Fonseca, S. C.; Malcata, F. X.; Galvis-Sánchez, A. C.This research effort was aimed at evaluating the influence of storage (for 4 mo at 2°C), under various controlled atmospheres (viz. 1.9 kPa O2 + 4.9 kPa CO2, 1.9 kPa O2 + 0.5 kPa CO2 and 1.9 kPa O2 + 0 kPa CO2), on the microstructure of ′Rocha′ pear. Toward this goal, the morphology of cellular disassembly, as well as the quantity of granules and intercellular space using scanning electron microscopy (SEM), were tentatively correlated with sensory and instrumental firmness, by 1, 6 and 8 d of exposure to air, at room temperature, after storage. A specific methodology, based on panel evaluation of SEM images, was developed and statistically validated. The degree of cellular disassembly increased throughout exposure time to air at room temperature. Pears stored under 1.9 kPa O2 + 0.5 kPa CO2 yielded a degree of cellular disassembly similar to that of the control.