Chemical dips and edible coatings to retard softening and browning of fresh-cut banana

The effects of chemical dips and edible coatings on firmness and colour of fresh-cut banana (cv. Cavendish) from Madeira Island were investigated. Two calcium salts, calcium chloride and calcium lactate, were first investigated for the effects on firmness during four days of storage at 5°C. Firmness and colour were evaluated after a three-minute chemical dipping or chemical dipping followed by coating and during five days of storage at 5°C. The coatings tested consisted of pectin, alginate, carboxymethylcelullose, carrageenan or chitosan solution. Dip with 1% (w/v) calcium chloride, 0.50% (w/v) ascorbic acid and 0.75% (w/v) cysteine was the most efficient treatment in retarding softening and browning of banana slices. This dip also inhibited yeast growth. According to sensory analysis, the edible shelf life of banana slices dipped in such solution was the longest: five days at 5°C. Carrageenan solution was the significantly (p < 0.05) best coating among the ones studied, in preserving firmness and colour of fresh-cut banana during five days at 5°C.info:eu-repo/semantics/publishedVersio

Polyphenol oxidase activity and colour changes of ‘Starking’ Apple cubes coated with alginate and dehydrated with air

The objective was to study the effect of alginate coating on polyphenol oxidase (PPO) activity and colour of ‘Starking’ apple cubes during dehydration with hot air. Apple cubes were dehydrated at 20°C, 35°C or 40°C, with a parallel air-flow. Analysis of PPO activity, colour (L*, a*, b*) and dry matter were performed along the dehydration process at each temperature. All samples presented a peak in relative PPO activity in the beginning of the drying. Exponential models fitted well the experimental data after the peak. Cubes without coating presented lower PPO activity, suggesting lower browning than coated samples throughout the dehydration process, for all temperatures. Better results for coated samples were obtained with a perpendicular airflow drying at 40°C, after dipping the whole apple in water at 60°C for 10 minutes. In order to prevent coated samples from browning, drying by perpendicular airflow preceded by a thermal treatment of the whole apple is required.info:eu-repo/semantics/publishedVersio

Microalgae for the prevention of cardiovascular disease and stroke

This review focuses on and discusses the primary phytochemicals present in microalgal biomass - carotenoids, phenolic compounds, antioxidant vitamins, sterols, and polyunsaturated fatty acids - and also on the exopolysaccharides, which are produced by some types of microalgae and may play a significant role in the prevention of cardiovascular diseases(CVD) and strokes. We have listed several preclinical trials and clinical studies supporting the health benefits that most of these compounds may provide. Microalgae are very easy to grow and are not vulnerable to contaminants when grown under controlled conditions. Proper handling and growth conditions may improve the production of phytochemicals. Therefore, they may represent an excellent source of nutraceuticals and food supplements once their safety as a food supplement has been confirmed.info:eu-repo/semantics/publishedVersio

Carotenoids from Marine Microalgae: A Valuable Natural Source for the Prevention of Chronic Diseases

Epidemiological studies have shown a relation between antioxidants and the prevention of several chronic diseases. Microalgae are a potential novel source of bioactive molecules, including a wide range of different carotenoids that can be used as nutraceuticals, food supplements and novel food products. The objective of this review is (i) to update the research that has been carried out on the most known carotenoids produced by marine microalgae, including reporting on their high potentialities to produce other less known important compounds; (ii) to compile the work that has been done in order to establish some relationship between carotenoids and oxidative protection and treatment; (iii) to summarize the association of oxidative stress and the various reactive species including free radicals with several human diseases; and (iv) to provide evidence of the potential of carotenoids from marine microalgae to be used as therapeutics to treat or prevent these oxidative stress-related diseases

Influence of sulphate on the composition and antibacterial and antiviral properties of the exopolysaccharide from Porphyridium cruentum

Aims: 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.info:eu-repo/semantics/publishedVersio

Osmotic dehydration combined with freeze-drying of apple cubes and comparison with microwave drying and hot air drying

The effects of the pre-osmotic treatment on the mass transfer kinetics of the freeze-drying (FD) and on the water activity (aw) and the quality – colour, total phenolic content, antioxidant activity – of apple cubes were studied. The fit of the moisture content was carried out using several mathematical models. The comparison among FD, microwave drying (MWD) and hot air drying (HAD) of osmotically treated apple cubes was also performed according to the drying rate and the aw. The apple cubes were osmotically treated with 60ºBrix sucrose or sorbitol solutions at 60ºC, then frozen and freeze-dried. The FD reduced significantly the moisture content from 6.259, 1.086 and 1.031 to 0.138, 0.099 and 0.074 kgwater.kgdry matter-1 for the control and the samples osmotically pre-treated with sucrose and sorbitol, respectively. The modified Page’s model presented the highest precision of parameter estimates. The FD of samples osmotically pre-treated with the sucrose solution resulted in a higher drying rate than the others samples. The highest reduction in aw was observed in the fresh samples. After FD, the total phenolic content and the antioxidant activity of the osmotically pre-treated samples decreased around 80%, in comparison with the fresh apple, this reduction being due to the osmotic pre-treatment. The freeze-dried control samples achieved a lower aw in comparison with HAD and MWD. However, FD presented a lower drying rate.info:eu-repo/semantics/publishedVersio

Mathematical modelling of the osmotic dehydration of physalis

Abstract Physalis 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

Lactobacillus plantarum survival during the osmotic dehydration and storage of probiotic cut apple

The feasibility to incorporate Lactobacillus plantarum in apple cubes during the osmotic dehydration (OD) was investigated. The effects of 40 and 60 °Brix osmotic solutions of sucrose or sorbitol on the viability of L. plantarum during the OD at 37 °C and 1013 or 150 mbar was evaluated. The storage at 4 °C and a quick simulation (2 h) of the digestion of probiotic apple cubes through the gastro-intestinal tract were also performed and the viability of the probiotic evaluated. Lactobacillus plantarum got incorporated in the osmotically apple cubes (107–108 cfu/g) with preference for 40 °Brix solutions and it maintained the viability of 107 cfu/g during a 6 day-storage at 4 °C. L. plantarum also survived (107 cfu/g) during the simulation of the digestion. Colour changes of the probiotic apple cubes occurred after OD and storage. Therefore, osmotically dehydrated apple cubes incorporated with L. plantarum could be a new probiotic food.info:eu-repo/semantics/publishedVersio

Equipment’s role on the drying process of chestnut (Castanea sativa Mill.) fruits

In the present work, drying of chestnut (Castanea sativa Mill.) fruits was performed at different air temperatures in three equipments - convection oven, parallel flow tray dryer and fluidised bed dryer, at temperatures between 40 and 100°C. Newton diffusion approach and two-term models were found to be adequate in describing the moisture ratio and drying rates along time. For the same temperature, the dehydration processes that involved higher air velocities were > 1.6 times faster. On the other hand, for the same equipment the highest temperature (100°C) induced a drying rate ten times faster than the lowest temperature (40°C), reducing drying time. Apparent diffusivity ranged between 7.03 × 10−11 m2 s−1 (40°C, convection oven) and 1.06 × 10−9 m2 s−1 (100°C, fluidised bed dryer). In convection oven experiments, the diffusivity in function of temperature was well described by an Arrhenius type function, with an activation energy of 4.08 × 104 J mol−1.info:eu-repo/semantics/submittedVersio