a FTIR spectrum of acorn polysaccharide dried with different drying methods: Before drying; AP-F: Freeze drying; AP-H 100 °C: Air drying 100 °C; AP-H 80 °C: Air drying 80 °C; AP-H 60 °C: Air drying 60 °C; AP-H room tempt: Air drying in room temperature; AP-V 40 °C: Vacuum drying 40 °C; AP-V 60 °C: Vacuum drying 60 °C. b. FTIR-ATR spectra of APP samples dried in different condition: A) Freeze dried, B) Air dried sample in 100 °C, C) Air dried sample in 80 °C, D) Air dried sample in 60 °C, E) Air dried sample in room temperature, F) Vacuum dried sample in 60 °C, G) Vacuum dried sample in 40 °C. Data have been offset for simplicity. c. Curve fit with band combination for the second-order FTIR spectra of freeze dried sample.