Optimization of condition for demineralization Baltic cod (Gadus morhua) backbone

Fish offal, among others, backbones, separated during mechanical processing of raw material can serve as an additional source of proteins, especially of collagen. To obtain native collagen previous deprotenization and demineralization of backbones is necessary. Therefore, the aim of this work was to determine optimal parameters for demineralization of Baltic cod backbones with HCl solutions, as well as by complexing metal ions with ethylenediamineteraacetic acid (EDTA). The best demineralization effect was achieved in 1.0 M HCl solution. After 24 h of extraction repeated three times, 99% of mineral substances were solubilized. Simultaneously, the smallest loss of collagen, up to 3%, was observed in these conditions. The process conducted in EDTA solution was less effective than that with HCl solution. After four times repeated 24 h extraction in 0.1 M EDTA solution only about 58% of mineral compounds were removed. Somewhat better efficiency was reached with 0.5 M EDTA solution. The yield of the process amounted to about 72%. Demineralization with EDTA did not cause loss of collagen.