Browsing by Author "Pereira, M. J."
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- Bioactive compounds in ready-to-eat rocket leaves as affected by oxygen partial pressure and storage time: a kinetic modellingPublication . Pereira, M. J.; Amaro, A. L.; Oliveira, A.; Pintado, M.Storage techniques, such as low temperature and modified atmosphere packaging, are efficient in keeping visual quality of ready-to-eat (RTE) products such as processed leafy vegetables throughout the supply chain, but studies on appearance often neglect the effect of different storage conditions on their nutritional properties. The effects of initial O2 partial pressure (20, 10, 5 and 2.5 kPa O2) in packages and storage time (14 d) on RTE rocket leaves on the bioactive compounds, phenolics, ascorbic acid, and antioxidant activity were determined. Kinetic models were applied to allow the assessment and prediction of the influence of initial partial pressure on nutritional composition. The results show that lowering package initial O2 partial pressure from 20 kPa to 5–10 kPa reduced the respiration rate by 53 and 38%, respectively. However, antioxidant activity and ascorbic acid content showed most effects with an initial O2 of 5 kPa. The kinetic parameters are relevant to help predict phytochemical changes during storage under different package O2 partial pressures. To obtain an overall quality, the application of intermediate atmospheres would be beneficial.
- Comparison of spray drying, freeze drying and convective hot air drying for the production of a probiotic orange powderPublication . Barbosa, J.; Borges, S.; Amorim, M.; Pereira, M. J.; Oliveira, A.; Pintado, M. E.; Teixeira, P.Survival of two LAB in orange powders obtained by spray-(SD), freeze-(FD) and convective hot air drying (CD) was investigated during drying and subsequent storage. Colour and vitamin C content of the powders were also evaluated. There was no decrease in the cell number during SD and FD, but a reduction of ~2 log cycles was obtained in CD. During storage at 4 °C no significant differences (p > 0.05) in the survival of Lactobacillus plantarum 299v were observed for the orange powder obtained by the different techniques. However, during storage at room temperature, its survival was better in orange powders prepared by CD. For Pediococcus acidilactici HA-6111-2, reductions during storage were minimal for most of the conditions investigated. Considering the initial cell number obtained after each drying process, SD and FD allowed survival of an increased number of cells after storage period. The best colour retention was obtained by FD, with no maltodextrin, and the higher total vitamin C retention was achieved in SD and FD powders. By the high production costs and long drying times of FD, it can be concluded that SD could be a good method to produce a new functional non-dairy product, such as a probiotic orange juice powder
- Impact of minimal processing and storage on strawberry functional and nutritional qualityPublication . Amaro, Ana L.; Pereira, M. J.; Colelli, G.; Pintado, M. E.Strawberry (Fragaria spp.) is a widely consumed fruit valued not only for its attractive color, aroma and taste but also as a good source of biologically active compounds, such as vitamin C, flavonoids, namely anthocyanins, and other polyphenols. The consumption of strawberries has been associated to human health benefits due to their antioxidant, anticancer, Anti-Inflammatory and Anti-Neurodegenerative properties. Strawberries are presented in the market as fresh whole fruits or processed, as Readyto-Eat Fresh-Cut fruit or incorporated in processed foods and beverages. Lifestyles of modern consumers, along with the demand for natural, fresh, flavorful, convenient and high quality products, with health benefits, have raised the production and consumption of processed strawberry. Processed strawberries represent a convenient alternative to supply the dietary needs of fresh food, but Processing-Induced wounding can enhance quality loss, changes in bioactive compounds contents and consequently in antioxidant capacity. Processing and storage factors affecting strawberry physiological and nutritional quality may result in the ingestion of nutritionally altered fruit. The knowledge and control of minimal processing and storage conditions of strawberries allows modulation of their nutritional and functional quality. This chapter surveys the postharvest minimal processing factors and storage conditions that affect strawberry phytochemical and functional quality, with focus on biologically active compounds, and emphasizes how processing technologies impact these compounds.
- Influence of harvesting factors on sensory attributes and phenolic and aroma compounds composition of Cymbopogon citratus leaves infusionsPublication . Coelho, Marta; Rocha, C.; Cunha, L.M.; Cardoso, L.; Alves, L.; Lima, R.C.; Pereira, M. J.; Campos, Francisco M.; Pintado, M. E.Herbal infusions are receiving increasing attention for the number of physiological benefits that can bring to human health. Cymbopogon citratus is one the most used plants in traditionalmedicine besides its characteristics and unique aroma appreciated by the consumers; however, little is known about the effects of harvesting on functional and sensory properties of this plant. The present work aimed to assess the lemongrass infusions, which were harvested following a factorial plan according to the type of cut (manual and mechanical) and part of the plant (tips and 2nd half leaves). Total phenolic content, antioxidant capacity, aroma compounds composition (terpenoids) and sensory profiles and consumer perception of different samples were assessed. The quantitative descriptive analysis (QDA) and Check-All-That-Apply (CATA) methods were used to describe the lemongrass infusion, complemented with the overall liking evaluation, using a 9-point scale. Results showed that there were significant differences between type of cut and part of the plant concerning phenolic compounds: samples obtained by mechanical cut showed in general higher content of individual phenolic compounds (in particular for chlorogenic acid) and tips showed in general the highest contents for both types of cut. Consumers panel did not found significant differences between samples. Generally, consumers indicate a bitter taste in all infusions when the content of the phenolic compounds was higher, in particular for p-coumaric acid. Concerning the aroma compounds no significant differences were observed between type of cut and part of the plant, and citral was the terpenoid present in higher quantity. Regarding the sensory profile methods, it was found that QDA and CATA were both good methods to describe this infusion. Considering the role of consumers' evaluation throughout the value chain, the infusion preparedwith plant tips of lemongrass was selected as the premium herbal tea.
- Influence of storage conditions on polyphenolic, terpenoids and sensory profile from Cymbopogon citratus infusionsPublication . Coelho, M.; Rocha, C.; Pereira, M. J.; Cunha, L. M.; Cardoso, L.; Alves, L.; Lima, R. C.; Campos, F. M.; Pintado, M.
- Kinetics of quality changes in cantaloupe melon as affected by MAP and temperature conditionsPublication . Amaro, A. L.; Pereira, M. J.; Pintado, M.Introduction: Fresh-cut fruit quality and shelf-life are limited by minimal processing operations and storage conditions. Modified atmosphere packaging and refrigerated storage are frequently used to reduce the respiration rate without negatively affecting the physiology of the fruit and to enhance shelf life. The effects of the production process upon the nutritional and phytochemical composition of cantaloupe melon was determined in order to validate the results obtained in real conditions and identify the critical points involved in the deterioration of the functional quality. The aim of this work is determine the kinetics of quality changes of fresh-cut cantaloupe melon as a function of oxygen partial pressure and storage temperature. Conclusions: The integration of all these results contributes to the understanding of the effects of storage conditions on overall quality of fresh-cut cantaloupe melon and provide useful information for developing processes aimed at the prediction and modulation of nutritional quality and shelf-life. The best conditions found for the preservation of overall quality of fresh-cut cantaloupe melon are initial package atmosphere of 5 % oxygen and storage temperature of 5 ºC.
- Modeling the effect of oxygen pressure and temperature on respiration rate of ready-to-eat rocket leaves. A probabilistic study of the Michaelis-Menten modelPublication . Pereira, M. J.; Amaro, Ana L.; Pintado, M.; Poças, M. F.Effective and efficient design of modified atmosphere packaging (MAP) systems for ready-to-eat (RTE) products requires knowledge on produce respiration rate under various temperatures and oxygen levels. In order to model the respiratory behavior of RTE rocket leaves under different storage conditions, leaves respiration rate was measured during storage under four initial oxygen partial pressures (2.5; 5; 10 and 20 kPa O2) and three temperatures (0, 5 and 10 °C), for 10 days. The respiratory quotient was determined and found to range between 0.6 and 1.3. Temperature showed a significant impact on respiration rate and the effect of oxygen partial pressures was found to be temperature-dependent. The oxygen pressure effect on respiration rate was accurately described using Michaelis–Menten kinetics, without inhibition by carbon dioxide, and the effect of temperature was well modeled by exponential functions. Monte Carlo simulation allowed quantification of the relative impact of the reduction of oxygen pressure and temperature on the decrease in respiration rate and the potential shelf life increase of RTE rocket leaves. Temperature contributed to more than 80% of the Michaelis–Menten model variance while oxygen pressure contributed only with 13%. The model obtained is a useful tool for defining packaging and storage conditions for a shelf-life extension of rocket leaves.
- Otimização das condições da cadeia de distribuição: impacto da temperatura e da atmosfera modificada na conservação dos produtos IV gamaPublication . Pereira, M. J.; Amaro, A. L.; Pintado, M.; Poças, F.