ABSTRACT
Although silver carp bones (SCB) are generated as waste, they are a natural source of calcium and have the potential to be a food ingredient. When the SCB had been soaked in hot sodium hydroxide (0.8%), autoclaved, and ground into SCB powder (SCBP), the total calcium content, analyzed by inductive coupled plasma-optical emission spectroscopy, was about 32%. X-ray absorption near-edge structure (XANES) spectroscopy specified hydroxyapatite as the major calcium component. The soluble calcium in SCBP was found to be 0.59% in de-ionized water. SCBP induced the cross-linking of proteins in minced fish after incubation at 40°C, as indicated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Fortification of SCBP at 0.0, 0.5, and 1.0% (w/w) in fish emulsion sausage resulted in a decrease of moisture content, while the fat and protein contents increased slightly. Total ash content in the sausage increased significantly, and total calcium content increased 15-fold in fortified SCBP. The hardness and gumminess values of sausage were improved with the addition of SCBP, while the microstructure was not altered by SCBP.
Acknowledgments
We also thank the Synchrotron Light Research Institute (Public Organization) for the XAS experiments at BL5.2: SUT-NANOTEC-SLRI Beamline.