Drying of bacterial cellulose gel by heat-press treatment at various temperatures and its property evaluation

Bacterial cellulose (BC) is a natural biopolymer with significant characteristics and is extensively used in various study fields or industries such as cosmetics, food, and pharmaceuticals. Despite its widespread use, the high water content and thickness pose challenges for versatile applications and efficient handling. Therefore, this study aimed to evaluate BC’s heat-pressing (HP) process derived from commercial nata de coco at 30 kg/cm² (2.9 MPa) and temperatures of 125, 150, 175, and 200 °C for 60 min as drying methods. A microwave (MW) heat treatment at 300 watts for 10 min was also used for comparison analysis. The gel was vacuum-filtrated during the experiment to eliminate excess water and decrease heating time. After being heat-pressed, the BC was thoroughly characterized for its structural and physical properties using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The results demonstrated that heat-pressed treatment resulted in a thin, flat, and dry BC sheet. The HP treatments did not change morphological or chemical structure. However, tensile strength and crystallinity increased as temperature increased, while elongation at break declined. Nano-dimension BC fibre did not differ for all heated treatments and was found lower than 70 nm.