Packaging and storage of porphyridium cruentum: metallised polyethylene terephthalate/polyethylene (PETmet/PE) versus polyethylene (PE)

The effect of the storage conditions of light (presence; absence) and relative humidity (50%; 75% RH) on the water content and colour of Porphyridium cruentum microalga powder was studied, then two packaging materials, low-density polyethylene (PE-LD) and metallised polyethylene terephthalate with polyethylene (PETmet/PE), were used to study their effect on the water content, colour, total carotenoids and chlorophylls contents, total phenolic content (TPC), and antioxidant activity (ABTS, DPPH, ORAC) of P. cruentum during storage at 23 °C and 50% RH. An atmosphere with 50% RH is recommended to minimise the water vapour absorption and lightness loss. In addition to the expected light protection, PETmet/PE material protected P. cruentum powder also against water absorption, contrary to PE material. There were no relevant colour changes of the microalga during storage in PETmet/PE. Regarding the total content of carotenoids and the antioxidant activity of the microalga, no significant differences were found between the biomasses stored in either packaging material. The TPC and DPPH values were practically constant during two months of storage, while ABTS and ORAC decreased more than 50% and 20%, respectively, during this time.