Superabsorbent bacterial cellulose film produced from industrial residue of cashew apple juice processing.

The industrial residue of cashew apple juice processing (MRC) was evaluated as an alternative medium for bacterial cellulose (BC) production by Komagataeibacter xylinus ATCC 53582 and Komagataeibacter xylinus ARS B42. The synthetic Hestrin-Schramm medium (MHS) was used as a control for growing and BC production. First, BC production was assessed after 4, 6, 8, 10, and 12 days under static culture. After 12 days of cultivation, K. xylinus ATCC 53582 produced the highest BC titer in MHS (3.1 g·L-1) and MRC (3 g·L-1), while significant productivity was attained at 6 days of fermentation. To understand the effect of culture medium and fermentation time on the properties of the obtained films, BC produced at 4, 6, or 8 days were submitted to infrared spectroscopy with Fourier transform, thermogravimetry, mechanical tests, water absorption capacity, scanning electron microscopy, degree of polymerization and X-ray diffraction. The properties of BC synthesized in MRC were identical to those of BC from MHS, according to structural, physical, and thermal studies. MRC, on the other hand, allows the production of BC with a high water absorption capacity when compared to MHS. Despite the lower titer (0.88 g·L-1) achieved in MRC, the BC from K. xylinus ARS B42 presented a high thermal resistance and a remarkable absorption capacity (14664 %), suggesting that it might be used as a superabsorbent biomaterial.

Films from cashew byproducts: cashew gum and bacterial cellulose from cashew apple juice.

ABSTRACT: Cashew is a major crop in several tropical countries. Its cultivation is mostly aimed to the production of cashew nuts, whereas its byproducts (including cashew tree gum and cashew apples) are underutilized. In this study, cashew tree gum (CG) has been combined to nanofibrillated bacterial cellulose (NFBC) produced from cashew apple juice, at different ratios (from CG-only to NFBC-only), to produce edible films. While the CG-only dispersion (at 1 wt%) behaved as a quasi-Newtonian fluid, the addition of NFBC provided a shear-thinning behavior, making the dispersions easier to process, especially to cast. Moreover, the films containing increasing NFBC contents exhibited better physico-mechanical performance. When compared to the CG-only film, the films containing at least 25% NFBC presented remarkably higher strength and modulus (even similar to some conventional petroleum-derived polymers), lower water vapor permeability (WVP), and lower water solubility, although at the expense of lower elongation and higher opacity values. The combined use of both polysaccharides was demonstrated to be useful to overcome the limitations of both CG-only films (very low viscosity, poor tensile properties and very high WVP) and NFBC-only films (very high viscosity, making the dispersions difficult to mix and spread). Moreover, the use of different NFBC/CG ratios allow properties to be tuned to meet specific demands for different food packaging or coating purposes.