Nano-hydroxyapatite (n-HAP) from Pangasius bone side streams and its application as a reinforcing agent in biodegradable food packaging films

Abstract

The bone side streams from catfish (Pangasianodon hypophthalmus) were used to produce nano-hydroxyapatite (n-HAP) by a calcination method. Bones were de-proteinized and calcined at 500, 700, and 900 °C at 2, 4, and 9 h, pulverized and cooled. Inductively coupled plasma (ICP-OES), Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and Transmission Electron Microscopy (TEM) were used to characterize the trace elements, functional groups, phase formation, and morphology of n-HAP, respectively. Using ICP-OES, an atomic ratio of 1.56 Ca/P was found in catfish bone calcined at 900 °C for 9 h. The FTIR spectra of the sample calcined to the same degree were matched with the standard hydroxyapatite FTIR spectrum. A high crystallinity of 99.5% was confirmed by XRD measurements as the calcination temperature and duration were increased. TEM analysis revealed that the n-HAP crystals have an average size of 71.38 nm. Cassava starch–n-HAP reinforced composite films were prepared with varying n-HAP concentrations which resulted in minor variations in the film thickness ranging from 0.05 to 0.16 mm. The control film exhibited a tensile strength (TS) value of 12.5 MPa while the maximum TS value of 16.10 MPa was exhibited by the sample with 0.8% n-HAP. The lowest elongation at break value was reported for the control film (1.55%) and the maximum (6.87%) was reported for the sample with 0.4% n-HAP. The film incorporating 0.8% n-HAP showed the highest seal strength while the water vapor transmission rate (WVTR) of the composite films reduced from 3.59 × 10⁻¹ g Pa⁻¹ m⁻¹ s⁻¹ to 1.67 × 10⁻¹ g Pa⁻¹ m⁻¹ s⁻¹ as n-HAP concentration increased. The film incorporating 0.4% n-HAP showed identical WVTR values to those of the film with 0.8% n-HAP. These results showed that the n-HAP-incorporating films exhibited better mechanical and barrier properties compared to the control film.