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This work evaluated the production of dehydrated papayas (Carica papaya L.) with low sugar content. The product was obtained applying ultrasonic waves to enhance the loss of sugar from the fruit. To achieve this goal, this paper examined the influence of the ultrasonic pre-treatment before air-drying on dehydration of papaya. Ultrasonic pre-treatment for air-drying of fruits was studied and compared with osmotic dehydration. This study allowed estimate of the effective diffusivity water in the air-drying process for papayas submitted to ultrasonic pretreatment. Results show that the water effective diffusivity increases after application of ultrasound causing a reduction of about 16% in the drying time. During ultrasonic treatment the papayas lost sugar (13.8% in 30 min), so such a pre-treatment stage can be a practical process to produce dried fruits with lower sugar content.

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a b s t r a c tSugar esters are compounds with surfactant properties (biosurfactants), i.e., capable of reducing the surface tension and promote the emulsification of immiscible liquids. On the other hand, as with all emulsions, coconut milk is not physically stable and is prone to phase separation. Therefore, the aim of this work was to evaluate the synthesis of fructose, sucrose and lactose esters from the corresponding sugars using Candida antarctica type B lipase immobilized in two different supports, namely acrylic resin and chitosan, and evaluate its application in the stabilization of coconut milk emulsions. The enzyme immobilized on chitosan showed the highest yield of lactose ester production (84.1%). Additionally, the production of fructose ester was found to be higher for the enzyme immobilized on the acrylic resin support (74.3%) as compared with the one immobilized on chitosan (70.1%). The same trend was observed for the sucrose ester, although with lower percentage yields. Sugar esters were then added to samples of fresh coconut milk and characterized according to their surface tension, emulsification index and particle size distribution. Although the microscopic analysis showed similar results for all sugar esters, results indicated lactose ester as the best biosurfactant, with a surface tension of 38.0 N/m and an emulsification index of 54.1%, when used in a ratio of 1:10 (biosurfactant:coconut milk, v/v) for 48 h experiments.

This work has examined the influence of ultrasonic-assisted air-drying on the dehydration of apple (Malus domestica L. var Royal Gala) and its influence in the availability of vitamins A, B 1 , B 2 , B 3 , B 5 , B 6 , and E of the dried product. This study also has estimated the effective water diffusivity in air-drying process subjected to ultrasonic waves. The water effective diffusivity increased by up to 79 % by ultrasound application, which caused a reduction of about 35 % in the total drying time compared to the air-drying without sonication. The application of ultrasound increased the availability of vitamins B 1 , B 2 , B 3 , and B 6 in the dried product. A loss of vitamins B 5 and E were observed for all studied drying conditions.Keywords Malus domestica L. . Apple . Drying . Ultrasound . Vitamins Notations aHalf-length of the cubic sample (m) ABS Sample Sample (dried apple) absorbance ABS Reference Control (raw apple) absorbance D Effective diffusivity (m 2 /s) t Time (s) W Average moisture content of the fruit (g water /g dry solids ) W crit Critical moisture content (g water /g dry solids ) W eq Equilibrium moisture content (g water /g dry solids )