Resumen
- Introduction. Cashew apple is often regarded as a by-product of the cashew nut industry, and remains under-developed. Among the various possible technological options for the clarification of the pulpy fruit juices, cross-flow microfiltration on mineral membranes is a particularly promising process. Thus, the objective of our work was to evaluate the advantages of this process for the production of clarified cashew apple juice. Materials and methods. Filtration assays were conducted at 30 ºC in a laboratory-scale pilot equipment with several tubular aluminium membranes. Four membranes were tested, differentiated by the average diameter of their pores [(0.1; 0.2; 0.8 and 1.4) µm]. The performances (permeate flux) and the composition (condensed tannins, acidity, ascorbic acid, pH, turbidity, color and soluble dry extract) of the clarified juice obtained were compared for each one of these membranes. The use of an enzymatic liquefaction pre-treatment added to the microfiltration was evaluated. Results and discussion. The permeate flux obtained ranged from (36 to 79) L·h–1·m–2. The best results for the study conditions were obtained with the membranes with an average pore diameter of (0.1 and 0.2) µm. Microfiltration coupled with an enzymatic liquefaction pre-treatment improved the filtration yield by (30 to 60)%. All the membranes used made it possible to obtain a completely clarified juice in which the ascorbic acid content was very close to that of the fresh juice. On the other hand, the phenolic compounds present in great quantity in the raw apple cashew juice were almost completely eliminated during the process, thus making it possible to considerably decrease the juice astringency. Conclusion. Our work checked the potential of the cross-flow microfiltration process for the production of clarified cashew apple juice. Nevertheless, before considering a future industrial application, the treatment conditions will have to be optimized and the nutritional and sensory qualities of clarified cashew apple juice will have to be better characterized