Enhancing circular economy: eco-friendly starch extraction and modification using fungal crude enzymatic extract from cocoa shell waste

Starch extraction methods usually employ hazardous compounds. The development of enzyme-based green extraction methods is a necessity for a sustainable and healthier world, with no turning back. A crude multienzymatic extract (CME), obtained from the solid-state fermentation (SSF) of Theobroma cacao shells, was employed for extracting starch from ginger. A Doehlert design was employed to determine the optimal conditions, resulting in a maximum starch extraction efficiency of 14.72% using CME and a decantation time of 64 min. The enzymatic treatment led to a reduction of 15.4% in amylose content and a 29.2% decrease in lipids within the enzyme extracted starch. X-ray diffraction (XRD) analysis revealed that the starch exhibited type A crystallinity; in the starch extracted with water, peaks were observed at 2θ values of 15°, 17°, and 20°. In the enzyme-extracted starch, there was a shift in the peaks to 2θ values of 15.2°, 17.4°, and 23°. Fourier-transform infrared spectroscopy (FTIR) demonstrated changes in the starch monomer network within its structure, and an unusual presence of acetylated starch at 1744 cm⁻¹ was observed. Thermogravimetric analysis indicated a 3.4% reduction in thermal stability, and DSC analysis showed lower gelatinization enthalpy at 60 °C. Scanning electron microscopy (SEM) revealed no damage to the starch granules. These findings underscore the potential of CME produced through SSF for the extraction and acetylation of starch from ginger rhizomes. This paves the way for more environmentally friendly processes in the starch industry, with potential for innovative applications in food and beyond.