The effect of storage conditions on the stability of chitosan-coated nanoliposomes containing phycocyanin

Increasing and improving the stability of colors in food during processing and also controlling the release until consumption is one of the most important issues and challenges in the use of natural colors in food. Hence, the objective of this study was to produce phytocyanin-containing nanoliposomes coated with chitosan by thin-layer ultrasonic hydration method to increase the stability of phycocyanin and to investigate its physical properties and encapsulation efficiency during storage. In this study, phycocyanin was coated with different concentrations of chitosan (0, 0.1, 0.2, 0.4, and 0.6 mg/mL) and stored at two temperatures (4 and 25° C) for 28 days. Then, to determine the best concentration of chitosan for coating the nanoliposomes, encapsulation efficiency, particle size, and zeta potential tests were performed. The results revealed that by increasing the concentration of chitosan to more than 0.2 mg/mL, no significant change in encapsulation efficiency was observed (p> 0.05). The sample without chitosan had the lowest particle size which was not a significant difference from samples containing 0.2 and 0.4 (p> 0.05). Increasing chitosan in the coating of nanoliposomes has led to increased zeta potential. Finally, a sample containing 0.2 mg/mL chitosan was selected as the best sample. Findings from analyses performed during the storage of nanoliposomes showed that nanoliposomes containing phycocyanin, which did not have any chitosan coating, had the highest encapsulation efficiency. On the other hand, it was found that with increasing storage temperature and storage time, the encapsulation efficiency decreased but the particle size increased. The lowest zeta potential of the samples was related to the phycocyanin-free nanoliposome sample which did not change significantly until the 21st day of storage at 4 °C. Scanning electron microscopy (SEM) images of the samples also confirmed the results of particle measurements.