Loading...
80 results
Search Results
Now showing 1 - 10 of 80
- Possible influences of water loss and polyphenol oxidase activity on anthocyanin content and discoloration in fresh ripe strawberry (cv. Oso Grande) during storage at 1 degrees CPublication . Nunes, M. Cecília N.; Brecht, Jeffrey K.; Morais, Alcina M. M. B.; Sargent, Steve A.Fresh‘Oso Grande’strawberries wrapped in polyvinyl chloride stretch film lost 0.7% of their initial weight during storage for 8 d at 1 °C, whereas unwrapped fruit lost 11%. Greater water loss was associated with darker and less red fruit, lower concentrations of anthocyanins and other soluble phenolics, and higher polyphenol oxidase (PPO) activity. Anthocyanin degradation and oxidation of soluble phenolic compounds, caused possibly by increased PPO activity as a result of water loss, contributed to the development of strawberry surface browning during storage. Proper handling to reduce water loss during postharvest operations should be used to maintain acceptable color of strawberries during shipping and retailing.
- Physico-chemical qualities of minimally processed carrot stored under vacuumPublication . Rocha, Ada M. C. N.; Mota, Catarina C. A. R.; Morais, Alcina M. M. B.In the last decades, consumers have become more health conscious in their food choices, but they have also less time to prepare healthy meals. Increased consumer interest in fruits and vegetables as healthy foods in association with a modification of lifestyles has accelerated and increased efforts to find potential alternatives to the traditional consumption of fresh fruit and vegetables. This situation opens the possibility for new categories of products that are intended to be presented to foodservice operators conveniently peeled, cored or sliced in prepared packages, with fresh-like quality; they are called minimally processed (MP). The use of vacuum packaging presents a potential alternative to achieve an inhibition of the progress of deterioration of foodstuffs. In this study, the physical qualities of MP carrots (cv. Nantes) stored under refrigeration and in vacuum packaging were evaluated. The beneficial effect of vacuum packaging was noticeable only in the colour, sugar content and phenolic compounds of carrots.
- Revestimentos comestíveis para frutos de IV GamaPublication . Morais, Alcina M. M. B.
- Modified atmosphere package for apple ‘Bravo de Esmolfe’Publication . Rocha, A.M.C.N.; Barreiro, M.G.; Morais, Alcina M. M. B.Apple Bravo de Esmolfe original from the parish of Esmolfe is cultivated in specific regions of Portugal. This cultivar of medium to low production requires very low temperatures, but it is extremely sensitive to frost. The aim of this work was to evaluate the influence of modified atmosphere on the quality of apple (cv. Bravo de Esmolfe) during cold storage. Apples packed in modified atmosphere lost less weight, presented better colour, and preserved better firmness than fruits stored in air.
- Osmotic dehydration with sorbitol combined with hot air convective drying of apple cubesPublication . Assis, Fernanda R.; Morais, Rui M. S. C.; Morais, Alcina M. M. B.The aim of the present work was to study the effect of the osmotic dehydration (OD) pre-treatment on the mass transfer kinetics and water activity (aw) of apple cubes during hot air drying. The adequacy of different mathematical models to describe the moisture content of the product during this process was also evaluated. Apple cubes were osmotically dehydrated with sucrose or sorbitol solutions at 60 °C, and then dried by air at 25-80 °C. Overall, the OD and rise of the air temperature resulted in an increased water loss rate and a reduction of the aw. The osmotic agent used in the OD was not relevant to the air drying kinetics, but the pre-treatment with sorbitol solutions produced dried samples with lower aw. Newton's, Page's, modified Page's, Henderson and Pabis', Two-term, Two-term exponential, Logarithmic, Midilli et al.'s models could describe the moisture content well during the air drying process.
- Physicochemical changes during strawberry development in the field compared with those that occur in harvested fruit during storagePublication . Nunes, M. Cecilia N.; Brecht, Jeffrey K; Morais, Alcina M. M. B.; Sargent, Steven A‘Chandler’, ‘Oso Grande’ and ‘Sweet Charlie’ strawberry cultivars were harvested at four stages of color development ranging from color break to full red and stored in the dark for 8 days at 1 ◦C. Changes in the physical and chemical characteristics of fruit during storage were compared with those occurring during development in the field. Strawberry fruit harvested at the three-quarters colored and full red stages continued their development and ripening during storage. However, fruit harvested at the color break and half-colored stages did not develop like those ripened in the field. Strawberries harvested at the three-quarters colored stage developed the same pH, acidity, soluble solids, ascorbic acid and total phenolics content during storage as the at-harvest levels present in strawberries harvested at the full red stage. In addition, three-quarters colored strawberries were as firm and red after storage as the full red stage fruit were at the time of harvest. Thus, strawberries harvested at the three-quarters colored stage can be stored for a longer period than strawberries harvested full red while retaining better color and firmness.
- Microbiological and sensorial analysis of salicornia shoots preservedin controlled atmospherePublication . Raposo, M. F.J.; Silva, J.V. N.; Sousa, C. C.; Morais, Alcina M. M. B.; Morais, R. M.
- Effects of spray-drying and storage on astaxanthin content of Haematococcus pluvialis biomassPublication . Raposo, Maria Filomena J.; Morais, Alcina M. M. B.; Morais, Rui M. S. C.The main objective of this study was to evaluate the stability of astaxanthin after drying and storage at different conditions during a 9-week period. Recovery of astaxanthin was evaluated by extracting pigments from the dried powders and analysing extracts by HPLC. The powders obtained were stored under different conditions of temperature and oxygen level and the effects on the degradation of astaxanthin were examined. Under the experimental conditions conducted in this study, the drying temperature that yielded the highest content of astaxanthin was 220°C, as the inlet, and 120°C, as the outlet temperature of the drying chamber. The best results were obtained for biomass dried at 180/110°C and stored at −21°C under nitrogen, with astaxanthin degradation lower than 10% after 9 weeks of storage. A reasonable preservation of astaxanthin can be achieved by conditions 180/80°C, −21°C nitrogen, 180/110°C, 21°C nitrogen, and 220/80°C, 21°C vacuum: the ratio of astaxanthin degradation is equal or inferior to 40%. In order to prevent astaxanthin degradation of Haematococcus pluvialis biomass, it is recommended the storage of the spray dried carotenized cells (180/110ºC) under nitrogen and −21°C.
- Polyphenol oxidase activity and colour changes of peeled potato (cv. Monalisa) in vacuumPublication . Snoeck, Diedrik; Raposo, Maria Filomena de Jesus; Morais, Alcina M. M. B.Minimal processing of vegetables has some undesirable physiological consequences. The shelf life of peeled raw potatoes is limited by the onset of enzymatic browning at the cut surfaces. It is generally accepted that polyphenol oxidase (PPO) is the enzyme mainly responsible for this type of browning. This work aimed to study the effect of vacuum storage at 4°C on the colour, which is the main parameter limiting the shelf life of potato (cv. Monalisa). PPO activity was evaluated as well with the aim to investigate the relation with colour changes.
- Food safety and quality profile of Alheira de Vitela, Chouriço de Carne and Salpicão Serra D’Arga: traditional Portuguese sausages produced in the North of PortugalPublication . Noronha, Lúcia; Almeida, Ana Luísa; Freixo, Ricardo; Jácome, Samuel; Fonseca, Susana; Vaz-Velho, Manuela; Almeida, Gonçalo; Silva, Cristina L. M.; Morais, Alcina M. M. B.; Silva, Joana; Teixeira, Paula