Encapsulation of polyethylene glycol as a phase change material using alginate microbeads to prevent temperature fluctuation- Case study: Fish packaging
Encapsulated PCM (phase change materials) has been developed to provide a thermal buffering system for food packaging. In this study, polyethylene glycol 400 (PEG) as a PCM was encapsulated in alginate in concentrations of 30, 40 and 50% (W/V) using calcium chloride (CaCl2) in concentrations of 0.5, 1, 1.5%. Crystallization temperature, melting temperature and melting enthalpy of PCM decreased after encapsulation. The optimum encapsulated PEG (50% of PEG and 0.5% CaCl2) had a diameter of 2.21 ± 0.54 μm. FTIR analysis of encapsulated microcapsules indicated characteristic peaks of alginate and pure PEG. TGA analysis showed more thermal stability for encapsulated PCM than pure PCM. After 100 thermal cyclic test microencapsulated beads showed some decrease in melting enthalpy, while other features of encapsulated PCM were almost intact. Encapsulated PCM was used for fish packaging to determine its effectiveness in controlling temperature fluctuation. When the packages were removed from the freezer, fish samples with the package containing encapsulated PCM and control package reached to 0 °C after 6500s and 3000s, 5 °C after 9030s and 4040s, 10 °C after 11520s and 5053s, and 25 °C after 19000s and 8200s, respectively. The data showed that using encapsulated PEG in fish packaging had a positive effect on preserving pH, water holding capacity, total volatile basic nitrogen, and thiobarbituric acid value. The results demonstrated that alginate could effectively encapsulate PEG, and the produced encapsulated PCM can be used for increasing of shelf life of perishable food during temperature fluctuations.