Concentration of lycopene from watermelon juice by membrane separation processes / Concentração de licopeno de suco de melancia através de processos de separação por membranas




Watermelon (Citrullus lanatus var lanatus) is a fruit originally from Africa which has been object of scientific interest due its high lycopene content. To increase your marketing potential the watermelon has to be processed either as a fresh single strength juice or as a concentrated or pasteurized juices or still dried in order to produce a stable powder. Membrane separation processes are conducted at low temperatures maintaining the quality of the final product. They have been suggested for the processing of fruit juices, for their preservation and concentration. The aim of this work was to study microfiltration and reverse osmosis processes to concentrate fresh watermelon juice evaluating its effect on lycopene content and consequently on the antioxidant capacity of the obtained juice. Microfiltration processes were conducted in a system with ceramic membrane of medium pore size of 0.1mm and effective filtration area of 0.22 m2. It was evaluated the influence of the process variables, temperature (T) and flow rate (F), on the permeate flux (J), lycopene content (L) and antioxidant capacity (AC) of the obtained juice. The experiments were carried out according to a complete factorial design 22, with triplicate at the central point. It was observed that flow rate and temperature resulted in significative effects on the permeate flux. Regarding the lycopene content and antioxidant capacity just the flow rate had significant effects. The reverse osmosis trials were carried out at 30C and 60 bar, with polyamide composite membranes, in plate and frame configuration module. The concentration processes presented an initial permeate flux of 44.3L.h-1.m- and an average permeate flux of 18.63 L.h-1.m-. The concentrated juice reached 30 Brix, corresponding to a concentration factor of 3.6. The lycopene content and antioxidant capacity increased, respectively, 3.2 and 2.4 folds in relation to the single strength juice. The juice obtained at the best condition of the microfiltration experimental design was microencapsulated by spray-drying with arabic gum and maltodextrin as encapsulating agents. The microencapsulated product increased in 216% its lycopene content and 192.5% its antioxidant capacity, but degradation processes happen during the storage period. Sensorial analysis shows no significant difference between the fresh juice and the concentrated by reverse osmosis and reconstituted, that means that the consumers did not perceive that the juice was submitted to RO process. The formulated milk beverage prepared from the retentate of reverse osmosis had a good acceptability regarding the color, flavor and taste attributes, with approval notes ranging from 70% to 83%. The results obtained in this work show that the microfiltration and reverse osmosis processes can be effective to watermelon juice processing concentrating the lycopene, preserving its physical and chemical properties and improving its antioxidant capacity maintaining its sensorial attributes.


melancia membranes. licopeno ciencia e tecnologia de alimentos membranas watermelon lycopene

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