Green solid-liquid extraction of cactus (Opuntia ficus-indica) cladode dietary fibers. I- optimization, pilot-scale production, and characterization

In this research work, an optimization of an environment friendly extraction method of cactus (Opuntia ficus indica) cladode dietary fibers was conducted. For this purpose, a central composite experimental design with two factors (temperature and time) and five levels was established. The basic objective of this optimization was to maximize fiber yield using hot water as an extraction eco-solvent. The optimum extraction time (330 min) and temperature (100 degrees C) were determined with a constant medium agitation rate. Additionally, this study also aimed at establishing the validation of the statistical model to carry out the extrapolation of the extraction process at the pilot scale. The fibers extracted at the pilot scale showed yields (45.2 +/- 0.01%) in agreement with those obtained through the optimization and validation lab-scale steps (44.97 +/- 0.02). Fourier Transform Infrared (FTIR) spectroscopy, X-ray Diffraction (XRD) and Scanning electron microscopy (SEM) analysis were conducted to investigate the structure and microstructure of pilot scale-produced fibers. FTIR spectrum and XRD pattern were typical to lignocellulosic fibers results. Sharp and thin peaks characteristic of cellulose were detected. Pure and crystallized phases were recorded with a 45% crystallinity index. SEM analysis presented elongated and organized cells with a uniform structure comparable to cellulosic fibers microstructure.

Automated summary

In this study, an optimization of the extraction method of cactus cladode dietary fibers was conducted. The optimal extraction time and temperature were determined using a central composite experimental design. The pilot scale extraction process validated the results obtained at the lab-scale. Analysis of the pilot scale-produced fibers confirmed their lignocellulosic structure and microstructure.