Tackling the cytotoxicity and genotoxicity of cellulose nanofibers from the banana rachis: A new food packaging alternative.

Cellulose nanofibrils from the banana rachis are a good alternative as packaging materials, food packaging, stabilizing agents, and functional food ingredients. To address the potential effects of ingested banana rachis cellulose nanofibrils (BR-CNFs), their toxicity in vitro and in vivo was evaluated using Caco-2 intestinal cells and mice, respectively. The results showed that BR-CNFs did not cause cytotoxic effects at the concentrations evaluated on Caco-2 cells. In addition to cytotoxicity tests, genotoxicity assays using comet assay indicated that Caco-2 cells showed no DNA damage at the concentrations of CNFs tested. Finally, acute in vivo cytotoxicity assays indicated that mice showed no sign of pathogenesis or lesions in the liver, kidney, or small intestine when treated with a single dose of BR-CNFs. Moreover, when the mice were treated daily for a month with BR-CNFs no hyperplasia or hypertrophy was observed in any of the organs evaluated. Additionally, biochemical parameters such as blood chemistry, creatinine, liver enzymes, and renal function showed that the BR-CNFs do not cause organ damage. Overall, this study shows that BR-CNFs are neither cytotoxic nor genotoxic. In conclusion, these studies are essential to guarantee the safety of this high value-added product in the food industry.

Use of Fourier Series in X-ray Diffraction (XRD) Analysis and Fourier-Transform Infrared Spectroscopy (FTIR) for Estimation of Crystallinity in Cellulose from Different Sources.

Cellulose crystallinity can be described according to the crystal size and the crystallinity index (CI). In this research, using Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) methods, we studied the crystallinity of three different types of cellulose: banana rachis (BR), commercial cellulose (CS), and bacterial cellulose (BC). For each type of cellulose, we analyzed three different crystallization grades. These variations were obtained using three milling conditions: 6.5 h, 10 min, and unmilled (films). We developed a code in MATLAB software to perform deconvolution of the XRD data to estimate CI and full width at half-maximum (FWHM). For deconvolution, crystalline peaks were represented with Voigt functions, and a Fourier series fitted to the amorphous profile was used as the amorphous contribution, which allowed the contribution of the amorphous profile to be more effectively modeled. Comparisons based on the FTIR spectra and XRD results showed there were no compositional differences between the amorphous samples. However, changes associated with crystallinity were observed when the milling time was 10 min. The obtained CI (%) values show agreement with values reported in the literature and confirm the effectiveness of the method used in this work in predicting the crystallization aspects of cellulose samples.

Influence of a Non-Ionic Surfactant in the Microstructure and Rheology of a Pickering Emulsion Stabilized by Cellulose Nanofibrils.

Emulsion stabilization is a broad and relevant field with applications in oil, polymer and food industries. In recent years, the use of solid particles to stabilize emulsions or Pickering emulsions have been studied for their kinetic and physical properties. Nanomaterials derived from natural sources are an interesting alternative for this application. Cellulose nanofibrils (CNFs) have been widely explored as a Pickering emulsifier with potential food applications, however, in some cases the presence of surfactants is unavoidable, and the literature is devoid of an evaluation of the effect of a non-ionic food-grade surfactant, such as polysorbate 80, in the stabilization of a vegetable oil by CNFs. To better assess the possible interactions between CNFs and this surfactant emulsions containing coconut oil, an emerging and broadly used oil, were processed with and without polysorbate 80 and evaluated in their qualitative stability, morphological and physical properties. Fluorescence microscopy, dynamic light scattering and rheology were used for this assessment. Results indicate in absence of the surfactant, emulsion stability increased at higher CNFs content, creaming was observed at 0.15 and 0.3 wt.% of CNFs, while it was not evidenced when 0.7 wt.% was used. After the addition of surfactant, the droplets are covered by the surfactant, resulting in particles with a smaller diameter, entrapped in the cellulosic structure. Rheology indicates a lower network stiffness after adding polysorbate 80.