Mass transfer kinetics during osmotic dehydration of bananas (Musa sapientum,shum.)

Osmotic dehydration is used widely to partially remove water from plant tissues by immersion in a hypertonic solution. In this work, the influence of temperature (25–55 °C), sugar concentration (30–60%) and salt concentration (0–10%) of the osmotic solution was investigated during osmotic dehydration of banana (Musa sapientum, shum.). Mass transfer kinetics were modelled according to Peleg’s equation. Kinetic parameters were evaluated using response surface methodology. Peleg’s equation showed to be suitable for modelling the water removal and solute uptake. Initial rate of water loss and water concentration at equilibrium were influenced by linear factors of the three independent variables. Initial rate of sucrose uptake and sucrose uptake at equilibrium were affected by all factors and interactions. Initial rate of salt uptake and salt concentration at equilibrium showed a positive correlation with temperature and NaCl concentration and a negative correlation with sucrose concentration.     

Evaluation of water, sucrose and NaCl effective diffusivities during osmotic dehydration of banana (Musa sapientum, shum.)

Osmotic dehydration of banana (Musa sapientum, shum.) was optimized with respect to temperature (25-55 °C), salt (0-10 g/100 g) and sucrose (30-60 g/100 g) concentrations through response surface methodology. The solution of Fick’s law for unsteady-state mass transfer in a cylindrical configuration was used to calculate the effective diffusivities of water, sucrose and NaCl. Analyses were conducted in triplicate for moisture, sugar and salt contents. Peleg’s model was used to predict the equilibrium condition, which was shown to be appropriate for water loss and solute uptake. For the above conditions of osmotic dehydration, the effective diffusivity of water was found to be in the range of 5.19-6.47 × 10⁻¹⁰ m² s⁻¹, the sucrose effective diffusivity between 4.27-6.01 × 10⁻¹⁰ m² s⁻¹ and that of NaCl between 4.32-5.42 × 10⁻¹⁰ m² s⁻¹. The working conditions that simultaneously optimize these 3 variables were the temperature of 25 °C with a solution composed of 30 g/100 g of sucrose and 10 g/100 g of sodium chloride. This condition provided values of 4.80 × 10⁻¹⁰ m² s⁻¹ for effective diffusivity of water, of 3.21 × 10⁻¹⁰ m² s⁻¹ for effective diffusivity of sucrose and 4.49 × 10⁻¹⁰ m² s⁻¹ for effective diffusivity of sodium chloride.     

Quality of minimally processed red chicory (Cichorium intybus L.) evaluated by anthocyanin content,radical scavenging activity,sensory descriptors and microbial indices

Changes in the quality of minimally processed red chicory (Cichorium intybus L.) were studied during storage in a polyvinyl chloride (PVC) film and in a mono‐oriented polypropylene (OPP) film at 4 °C. The maximum limit of 5 × 10⁷ CFU g^?1 for mesophilic aerobic bacterial count was attained after 4 days using the PVC film and after 4.5 days using the OPP film. The loss of fruity aroma occurred after 3 days in the products stored in PVC but not in those stored in OPP. In spite of microbial growth, no off‐odour was perceived by trained panellists. Storage in PVC slightly decreased the contents of cyanidin 3‐O‐malonyl glucoside, total phenolics and antioxidant activity, whereas these parameters increased upon storage in OPP. When red chicory heads subjected to mild stress in the field were minimally processed, OPP packaging decreased the microbial growth with respect to PVC, but antioxidants were degraded in both conditions.     

Aroma composition and sensory quality of fruit juices processed from cultivars of elderberry (<Emphasis Type="Italic">Sambucus nigra</Emphasis> L.)

The experiment included identification and quantification of 25 aroma compounds and determination of the sensory quality of fruit juices processed from 32 cultivars of black elder using enzymation. It was concluded that disappearance of 15 esters and the increases of four alcohols, six terpenoids, six carbonyls, six aldehydes, three ketones, eight alcohols, trans-rose oxide, nerol oxide, and dihydroedulan primarily might be due to enzymatic conversion of esters of fatty acids and enzymatic hydrolysis of glucosides as found by processing of juices from other fruits. Juices processed from the elderberry cultivars significantly differed with respect to aroma compound composition and sensory characteristics. Factor analysis of the combined data from measurement of aroma composition and sensory evaluation resulted in extraction of four factors with factor scores that could be used for selection of cultivars with different promising sensory properties and varying concentrations of phenolic acids and flavonoids that may be useful for processing of functional elderberry juices with health promoting properties.