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- 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.
- Influence of sulphate on the composition and antibacterial and antiviral properties of the exopolysaccharide from Porphyridium cruentumPublication . Raposo, Maria Filomena de Jesus; Morais, Alcina Maria Miranda Bernardo de; Morais, Rui Manuel Santos Costa deAims: The influence of two culture media and three different concentrations of sulphate in the medium on the growth of two strains of Porphyridium cruentum and on the production, composition and viscoelastic characteristics, and antimicrobial properties of the sulphated exopolysaccharide (EPS) were studied. Mainmethods: A Bohlin C50 rheometerwas used to evaluate the viscosity and elasticity of the EPS solutions. HSV virus, types 1 and 2, Vaccinia virus and Vesicular stomatitis virus were used along with two Gram-negative (Escherichia coli and Salmonella enteritidis) and one Gram-positive (Staphylococcus aureus) bacteria, for testing the antimicrobial activity of EPS. Key-findings: The growth ofmicroalgae was higher in NTIP medium and the production of EPS was enhanced by sulphate 21 mM. The protein content of the EPS was enhanced by the addition of sulphate 52mMand 104mM; this concentration also induced an increase in sulphate content of the EPS. However, neither the contents of EPS in carbohydrates and uronic acidswere affected by the culturemediumsupplementation in sulphate. In general, the EPS from the Spanish strain presented a higher antiviral activity than the EPS from the Israeli strain. All EPS extracts revealed a strong activity against V. stomatitis virus, higher than the activity of all chemical compounds tested. The EPS from the Israeli strain also presented antibacterial activity against S. enteritidis. Significance: Enrichment of the culture mediumwith sulphate improved protein and sulphate content of EPS. EPS extracts presented a relevant activity against V. stomatitis virus and S. enteritidis bacterium.
- 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.
- A functional dried fruit matrix incorporated with probiotic strains: Lactobacillus Plantarum and Lactobacillus KefirPublication . Rêgo, A.; Freixo, R.; Silva, J.; Gibbs, P.; Morais, A. M. M. B.; Teixeira, P.The consumption of probiotic functional foods, i.e. processed foods enriched with microorganisms that confer health benefits to the host, shows a progressive increase in the last decade due to changes in habits and trends of consumers attracted by the benefits of these products. Currently, the development of fruits and vegetables with probiotic content is a topic of high interest for the probiotic-food consumers as these are a popular item perceived as healthy by consumers, and issues related with lactose intolerance are overcome. The aim of this research study was to develop a new healthy dry food that contains a source of probiotic strains providing some benefits to consumers. Apple was selected as an experimental food matrix and two different probiotic Lactobacillus species, L. plantarum and L. kefir, were tested separately. Samples were taken immediately before and after the drying process in order to determine the viability of bacteria adhered to the matrix. Dried apple cubes were stored in sterile closed glass containers or in sealed bags vacuum packed and normal atmosphere) at room temperature and at 4ºC. The bacterial viability in the dried product was tested at different storage times. For both probiotic strains, a decrease of approximately 2 log cycles in bacterial cell numbers was observed after drying. The bacterial number in apple cubes at the time of storage at room temperature and 4ºC was approximately 1x107 cfu/g. Both probiotic strains died after one month of storage at room temperature, while during storage at 4ºC the cells remained viable after 3 months, with bacterial number around 1x106 cfu/g.
- 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.