Functional group, transversal optic and longitudinal optic analysis using kramer-kronig method of

Pleurotus ostreatus, known as the white oyster mushroom, has higher nutrients than other mushrooms. The purpose of this research is to analyze the result of FTIR spectrum mycelium and oyster mushroom based on the open time of baglog after incubation time. Based on FTIR result, function groups of molecules are C-O, C=O, C-H, and O-H in the mycelium and oyster mushrooms. The molecule C-O, C=O, and C-H indicate carbohydrates and O-H molecule suggests water. O-H molecule in the 40th day has low transmittance. It shows that water content in the 40th is more than the 35th days. The value of the absorption energy constant in oyster mushroom is higher than mycelium. The value of spring constant in oyster mushroom is higher than mycelium by the harmonic stretching principle and unharmonic. Based on FTIR spectral at wavenumber range 400–1200 cm-1, Transversal Optic (TO) and Longitudinal Optic (LO) values were obtained using the Kramer-Kronig method.