2.2.3. Near infrared (NIR) absorption spectrometry Each sample was analyzed using a Fourier transform near- infrared absorption spectrometer, an NIRFlex N-500 analyzer (Buchi Labortechnik AG, Switzerland), 10,000–4000 cm −1 measurement fre- quency, at 4 cm −1 intervals. Measurement conditions were an optical path of 1 nm at 25 ◦C.