Liquefaction of chicken sternal cartilage by steam explosion to isolate chondroitin sulfate.

Chondroitin sulfate (CS), together with peptide, was isolated from the liquid fraction of chicken sternal cartilage subjected to steam explosion (SE) by membrane separation. Cartilage was liquefied via the SE conditions, including various pressures (1.0-1.6 MPa) and times (60-140 s). The extraction procedure was optimized as follows: the amount of papain added, 0.11%; enzymolysis time, 10.5 h; and enzymolysis temperature, 56.5 °C, under which the highest recovery and total yield of CS were 92.15% and 18.55% at 1.4 MPa for120 s, and the counterparts of peptides were 87.35% (1.0 MPa, 140 s) and 63.07% (1.6 MPa, 140 s). The average molecular weight of CS samples ranged from 30 to 35 kDa. CS sample was confirmed using agarose-gel electrophoresis, and the structure was analysed Fourier transform infrared spectroscopy, chromatography and nuclear magnetic resonance. Taken together, SE can be an eco-friendly pretreatment method to liquefy cartilage for CS isolation.