Abstract:Nano-sized fish bone emulsions were prepared from four types of freshwater fish (carp, grass carp, catfish, and tilapia) and two types of seawater fish (cod and shark), respectively. The properties of the emulsions were comparatively investigated in order to provide a theoretical foundation for the production and application of nano-sized fish bone products. The results showed that the highest crude protein content, collagen content, and degree of collagen cross-linking were found in shark bone, while the highest ash content was found in cod bone. During the initial 2 h of ball milling, the average fish bone particle size decreased drastically from 6.40~85.41 μm to 62.95~259.12 nm. The highest and lowest rates of decrease in fish bone particle size were found in cod bone and shark bone, respectively. With increasing milling time, the average particle size gradually stabilized (106.37~172.37 nm). The calcium release percentage, free amino acid content, trichloroacetic acid-soluble peptide content, and water-soluble protein content of the nano-sized fish bones increased steadily throughout the milling process (p <0.05). The results suggested that the mechanism of calcium release was associated with both the reduction of fish bone particle size and the formation of polypeptide/amino acid-chelated calcium. The shape of all six types of nano-sized fish bone particles was close to spherical. Among the six emulsions, the highest calcium release percentage was presented in grass carp bone, a relatively high whiteness was presented in in tilapia and cod bones, and a relatively high pH value was presented in cod and shark bones.
