Impact of packaging material and storage conditions on polyphenol stability, colour and sensory characteristics of freeze-dried sour cherry (prunus cerasus var. Marasca).

The aim of this study was to evaluate the influence of packaging materials and storage conditions on polyphenols stability, colour and sensory characteristics of freeze-dried sour cherry (Prunus cerasus var. Marasca). Freeze-dried sour cherries were packed in high barrier metalized polypropylene and aluminium packaging (PET/PPmet/PE and PET/Al/PE) for up to 12 months at 4, 20 and 37 °C. Characterisation of polyphenol compounds was done by HPLC UV/Vis PDA and in all samples individual anthocyanins (ANTs), flavonol-glycosides (FGs) and hydroxycinnamic acids (HCAs) were determined. Polyphenol content was not markedly affected by freeze-drying and decreases were amounted 1.5-5 %. Furthermore, obtained results indicated that minimal loss of polyphenol content in freeze dried sour cherries were achieved at 4 °C and 3 months of storage. Regardless of the type of packaging materials, samples stored at lower temperature during 12 months, retained the higher content of FGs (quercetin-3-glucoside, kaempferol-3-glucoside, kaempferol-3-rutinoside) and HCAs (neochlorogenic, chlorogenic, p-coumaric, caffeic and ferulic acid) than ANTs (cyanidin-3-glucosylrutinoside, cyanidin-3-rutinoside, cyanidin-3-glucoside, cyanidin-3-sophoroside). The same trend was confirmed with kinetic parameters, also. Sour cherry products packed in both type of laminate and stored at lower temperature retained characteristic dark red colour and sensory properties. This study showed that freeze-dried cherry products have pleasant sensory and very good nutritional properties, and storage in both type of laminates at 4 and 20 °C up to 6 months ensured good product quality.