Preparation of Highly Clarified Anthocyanin-Enriched Purple Sweet Potato Juices by Membrane Filtration and Optimization of Their Sensorial Properties.

The aim of this work was to prepare clarified anthocyanin-enriched juices from purple sweet potatoes (PSP) and to evaluate their sensorial properties, with promising prospect for antioxidant molecules. Four PSP juice samples were prepared and annotated as (1) crude PSP extract, (2) PSP extract followed by microfiltration, (3) by ultrafiltration and (4) by nanofiltration (4). Although anthocyanins retention was observed during the filtration process, PSP microfiltrated juices generated better permeate with compromising between appearance transparency and anthocyanin content. Juice sensory properties (color, flavor, mouthfeel and clarity) were optimized by an L9(34) orthogonal design using PSP extract concentrations, white sugar concentrations and citric acid concentrations as factors. An optimal sensory evaluation score was achieved when these three factors were 90, 24 and 0.05%, respectively. Results of this work will contribute to large-scale production of high quality PSP juice. Practical Applications Over the last years, a growing interest has been shown in the production of anthocyanin-enriched juices with high quality. Therefore, the potential of several techniques to produce this kind of juices is being explored. For instance, membrane technologies have been proposed and investigated for juice clarification and high sensory quality drink production. Thus, this technique could be an interesting tool to clarify sweet potato juices, rich in anthocyanins, and to obtain products with high sensory quality. [ABSTRACT FROM AUTHOR]