Circular dichroism. Collagen furan and pristine collagen samples were dissolved in deionized water at a concentration of 0.02 % (w/v) and monitored using a quartz cell of 0.1 cm path length in a JASCO J-1500 spectrometer (JASCO Corporation, Tokyo, Japan). Spectra were measured from 190 to 260 nm at 25 °C and with a scan rate of 1 nm/s. The samples were corrected against a baseline obtained by measuring deionized water.