The aim of this study was to analyze the influence of the drying process by combined methods. Osmotic dehydration was performed using glucose or sorbitol solutions at different concentrations (40 or 60°Brix), temperatures (25 or 40C) and two fruit-to-syrup ratios (1:4 or 1:10). Hot air drying was performed at different temperatures (60, 70 or 80C). Dried plums were evaluated in terms of color, texture, rehydration ability, phenolic compounds (total phenols, flavonoids) and water activity. The color was analyzed through two methods: colorimeter and image analysis. The evaluations showed a decrease in luminosity and an increase of reddening due to browning originated during the drying process. The image analysis was the most appropriate to evaluate the changes in color. Firmness of plums increased in relation to fresh fruit and was more evident at higher drying temperature. High drying temperatures provoked a collapse of the plum structure, which hindered water absorption in the rehydration process. The phenolic compounds in plums were conditioned by the drying temperature; the content of phenols and flavonoids was higher when they were dried at 70C. Plums osmodehydrated in sorbitol 60% w/w, with a fruit/syrup ratio of 1/10, at 25C and air dried at 70C obtained a high degree of dehydration and best maintained quality attributes. PRACTICAL APPLICATIONSPlums, natural or processed, can be considered as a functional food, since it provides nutrients and contains additional features that benefit the health of consumers. Hence, the importance to keep them with minimal changes to their nutritional value. The combined process by means of the osmotic dehydration and the hot air drying helps to preserve the desirable quality attributes of the fruit, as well as reduce the water content to obtain products stable against microbiological agents and reaction chemical. This information may help any industry of drying fruit to optimize the process conditions and reduce costs of processing and packaging. TEMPERATURE IS 60, 70 OR 80C, RESPECTIVELY Osmotic agent = g, glucose; s, sorbitol.Concentration of the osmotic agent = 40%; 60%. Fruit/syrup ratio = r1/4 = ratio 1-4; r1/10 = ratio 1-10. Temperature osmotic solution = 25C; 40C. Drying temperature = 60C; 70C; 80C.

The objective was to determine the adequate conditions for the microwave-assisted extraction of antioxidant compounds from the seed hull of sunflower hybrids. The existence of genetic and environmental variability in the phenolic content obtained under the selected extraction conditions was also analyzed. The extractions were carried out at 70 °C-20 and 90 °C-10 min, using water as solvent and a power of 600 W. The total phenol, flavonoid and antioxidant activity were evaluated. The microwave extraction process at 90 °C-10 min gave significantly higher values of total phenol (407.13 ± 6.11-512.71 ± 23.54 mg gallic acid⋅100 g −1 hull), flavonoids (210.09 ± 6.15-297.64 ± 5.68 mg catechin⋅100 g −1 hull) and antioxidant activity (76.73 ± 4.40-110.80 ± 3.51 μmol TE⋅g −1 hull) than those obtained at 70 °C-20 min. The cultivation environment also significantly affected the antioxidant yield, with total phenol and flavonoid contents being significantly higher for the hybrids grown in Balcarce than for those from Tandil. A significant interaction between hybrids and cultivation environmental was also observed for the antioxidant activity, indicating that the environmental effects were not similar among hybrids. The results of this study provide valuable information related to giving added value to a residue of the oil industry.

The influence of osmotic pretreatment on nectarines with solutions of glucose syrup and sorbitol and subsequent dehydration at different temperatures (60°C, 70°C, or 80°C) was evaluated. The kinetics of moisture loss during drying was obtained and mathematical models were adjusted to estimate the kinetic parameters. Effective diffusion coefficients were calculated using Fick's second law. All drying kinetics exhibited only a falling-rate period during hot-air drying owing to moisture loss in the osmotic pretreatment. Moisture loss was favoured by the use of sorbitol, whereas the diffusivity of water increased when glucose was used as an osmotic agent. Logarithmic and Midilli et al. models best described the changes in moisture over time, whereas Fick's second law estimated water diffusion coefficient values between 4.96 Â 10 −9 and 2.43 Â 10 −8 m 2 s −1 . These models may be employed to predict the optimum conditions for osmo-dehydrating nectarines under hot-air drying at the industrial level.

The objective of this work was to analyze the relevant process conditions on osmotic dehydration of plums and to determine the diffusion coefficients related to this process. The influence of solution (type and concentration of solute, temperature, fruit/solution ratio) and process time on water loss, water content and solutes gain were studied. Process analysis was performed experimentally by means of a set of 16 duplicate tests and numerically by mathematical modeling of the unsteady-state mass transfer phenomena. Experiments were carried out with glucose and sorbitol solutions (40–60 % w/w), dehydrating plum pieces during 2 h at temperatures of 25 and 40ºC, with fruit/solution ratios of 1/4 and 1/10. For calculating effective diffusion coefficients, a novelty inverse-method was applied, the approximate shape of food-pieces was considered using Finite Elements Method. Calculated diffusion coefficients ranged from 1.13 × 10−09to 4.71 × 10−09m2s−1and 0.44 × 10−09to 3.46 × 10−09m2s−1, for water and solutes, respectively.

Nectarines, plums and peaches were dehydrated with osmotic solutions (glucose at 60°Brix or sorbitol at 60°Brix) at temperature of 35ºC for scheduled periods (0.5, 1, 2, 4, 6, 8 h). Thermal properties of fresh and osmotically dehydrated fruits were measured by DSC where samples were heated from -40ºC to 40ºC at a rate of 2ºC min -1 . In this work, we obtained experimental data on the variation of water content and soluble solids during the osmotic dehydration of nectarines, peaches and plums in solutions of glucose or sorbitol; experimental data for enthalpy of fresh and osmotically dehydrated nectarines, plums and peaches as a function of temperature and type of osmotic solute; correlations for initial freezing temperature of osmotically dehydrated stone fruits as a function of water content and type of dehydrating solute and correlations between heat capacity or enthalpy and temperature for some fresh and osmotically dehydrated stone fruits.