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- 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.
- 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.
- 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.
- Quality of grated carrot (var. Nantes) packed under vacuumPublication . Rocha, Ada MCN; Ferreira, João FFC; Silva, Ângelo MM; Almeida, Gonçalo N.; Morais, Alcina M. M. B.The quality of grated carrot (variety Nantes) was evaluated throughout 10 days of storage in two different atmospheres: air and vacuum at 2 ◦C. The parameters of quality were microbiological and physico-chemical. Sensory evaluation of vacuum-packed grated carrots was performed after the microbiology study. The objective was to study the use of a vacuum for preservation of this type of product. The use of a vacuum was sufficiently promising with respect to the capacity to extend the shelf life of grated carrot by reducing microbial load and by minimising physico-chemical changes. The shelf life of grated carrot under vacuum was extended to 8 days at 2 ◦C.
- Effects of vacuum packaging on the physical quality of minimally processed potatoesPublication . Rocha, Ada M. C. N.; Coulon, Emilie C.; Morais, Alcina M. M. B.In recent years, consumers have become more health conscious in their food choices but they also have less time to prepare healthy meals. As a result, minimally processed (MP) products have become an important sector of the food industry because of their ‘fresh-like’ qualities, convenience and speed of meal preparation. In this study, the physical qualities of MP potatoes (‘Désirée’ variety) stored for 7 days in vacuum packaging were evaluated. The shelf life of MP potatoes was effectively extended to nearly 1 week under refrigerated storage by using vacuum packaging systems. The main quality parameters were constant during storage.
- Quality of ‘Royal Gala’ cut apple during osmotic dehydrationPublication . Pieters, Bert; Assis, Fernanda Rosa; Morais, Rui Manuel Santos Costa; Morais, Alcina Maria Miranda BernardoThe present work aimed to evaluate quality parameters of ‘Royal Gala’ apple cubes during osmotic dehydration (OD). We investigated the following OD conditions: osmotic agent, pressure, and temperature. The osmotic agent, being lower after OD with sorbitol than sucrose solutions, mainly influenced the water activity of the product. The color changes increased with increased temperature and were higher in vacuum experiments than at atmospheric pressure. In general, we recommend OD at 25 °C and atmospheric pressure for the preservation of the total phenolic content (TPC) and antioxidant activity (AA) of apple cubes during the process. Peleg’s model was found to provide the best fit of TPC and AA data.
- Mathematical modelling of the osmotic dehydration of physalisPublication . Assis, Fernanda Rosa; Morais, Rui Manuel Santos Costa de; Morais, Alcina Maria Miranda Bernardo dePhysalis was osmotically dehydrated with 60 °Bx sucrose or sorbitol solutions at 60 °C and with a mass ratio of sample to solution of 1:4, at atmospheric pressure or under vacuum at 150 mbar. The Crank’s, Peleg’s and Page’s models were tested to describe the mass transfer kinetics for water loss (WL) and solids gain (SG). The effective diffusivities of both water and solute were around 10-11 m2 s-1 under all conditions. Peleg’s model presented the best fit. The use of sorbitol as the osmotic agent resulted in an increase in the WL rate. In experiments with sucrose solutions, a higher WL was obtained under vacuum than at atmospheric pressure. The SG was particularly low during osmotic dehydration. Thus, the use of sorbitol as the osmotic agent was shown to be a promising alternative to sucrose.