Tannin Removal of Cashew Apple Juice by Powdered Gelatin Treatment and Its Utilization in Bacterial Cellulose Production.

In this study, cashew apple juice was treated with different levels of powdered gelatin (2%, 5%, and 10%) to remove tannins. The results showed that the addition of 5% gelatin removed 99.2% of condensed tannins while did not affect reducing sugars of juice. Subsequently, tannin-free cashew apple juice (CA) was aerobically fermented for 14 days with Komagataeibacter saccharivorans strain 1.1 (KS) and Gluconacetobacter entanii HWW100 (GE) in comparison with Hestrin-Schramm (HS) medium as control. The dry weight of bacterial cellulose (BC) obtained from the KS strain (2.12 and 1.48 g/L for CA and HS media, respectively) was higher than that from the GE strain (0.69 and 1.21 g/L for CA and HS media, respectively). Although GE showed low BC production yield, its viability in both media after 14-day fermentation was notable (6.06-7.21 log CFU/mL) compared to KS strain (1.90-3.30 log CFU/mL). In addition, the XRD and FT-IR analysis showed that there was no significant difference in the crystallinity and functional groups of BC films when cultured on CA and HS medium, while the morphology by SEM exhibited the phenolic molecules on the film surface. Cashew apple juice has been shown to be a viable and cost-effective medium for the BC production.