Pressure-driven crossflow microfiltration coupled with centrifugation for tannin reduction and clarification of cashew apple juice: Modeling of permeate flux decline and optimization of process parameters

In this study, the process parameters such as rotational speed, time, membrane pore size (MPS) and transmembrane pressure were chosen for centrifugation and microfiltration, respectively. The artificial neural network-genetic algorithm technique was followed to achieve the optimized process parameters for centrifugation (7532 rpm rotational speed and 52.6 min time). Likewise, the optimum process conditions for microfiltration were obtained as 0.2 mu m MPS and 138 kPa TMP. At this optimum condition, 88% tannin content, 97% turbidity, and 95% color have been removed, and 87% ascorbic acid content and 97% TSS have been preserved in the clarified juice. Besides, a high steady-state permeate flux of 74.87 L/m(2).h was also achieved at this optimum condition. Furthermore, a resistance-in-series model was developed which can accurately represent the flux behavior of the microfiltration system. Hence, microfiltration coupled with centrifugation can be effectively utilized to remove tannin from cashew apple juice, the primary reason behind consumer acceptability. Novelty impact statement The novelty and significance of this work is the development of a nonthermal clarification technology with optimum process parameters for the reduction of tannin, turbidity, and retention of ascorbic acid content using centrifugation and microfiltration. The clarified juice at the optimum conditions had low astringency (tannin content: 15.31 mg tannic acid/100 ml) and haziness (turbidity: 1.89 NTU, color intensity:0.05 abs and clarity: 99.51 T), with maximum retention of ascorbic acid content (227 mg/100 ml). This study does not involve thermal treatment or addition of any preservatives/additives and hence could assist the food industries to commercially develop a turbid-free, astringent-less, and highly nutritious cashew apple juice.