A preliminary study of phytochemical quantification and thermal characterization of Faloak (Sterculia quadrifida R. Br) leaf powder

Native to East Nusa Tenggara, Indonesia, the faloak plant is used in traditional medicine, concentrating on its bark. Faloak leaves, on the other hand, are a plentiful and promising natural resource complete with phytochemical components that are worth investigating for both food and medical uses. Thus, this work aims to determine the phytochemical quantification, represented by total phenolic and flavonoid content, and the thermal properties of faloak leaf powder originating from East Nusa Tenggara. The result revealed that the faloak leaf powder has a high total phenolic and flavonoid content of 89.26 mg GAE/g DW and 9.57 mg QE/g DW, respectively. Faloak leaf powder has a particle size distribution of 0.145 to 110.467 µm, with a d50 of 10.072 µm. Also, it has a negative surface charge, with a value of-19.1 mV, based on the zeta potential analysis. The presence of phenolic and flavonoid compounds in faloak leaf powder was confirmed by the fingerprint chemical bounds of those compounds in Fourier transform infrared (FTIR) spectra. Furthermore, thermogravimetric analysis (TGA) and differential thermal analysis (DTA) demonstrated that the faloak leaf powder revealed good stability at moderate temperatures. As a result, faloak leaf powder has the potential and promise to be used as a functional ingredient in developing innovative functional food products or applications in other fields, such as pharmaceuticals.