Stability of bioactive components in smoothies within an extended period of one year

Abstract

The aim of the study was the colourimetric determination of polyphenols and antioxidative capacity in blueberry- and cranberry smoothies monthly over one year with high-throughput methods, i.e., total polyphenols (PPm) and total antioxidant capacity (TAC). The main interest was directed to the smoothie storability in terms of light and temperature effects to prevent the consumption of antioxidants and the degradation of polyphenols. In this respect, smoothies from the same batch were stored under four conditions, i.e., room temperature (22 °C ± 2 °C) and light, fridge temperature (4 ± 2 °C) and light, room temperature (22 °C ± 2 °C) in the dark (glass bottles encased with tin foil) and fridge temperature (4 ± 2 °C) in the dark. Results showed a significant temperature-dependent effect in favour of fridge temperature (4 ± 2 °C) compared to room temperature (22 °C ± 2 °C). Thus, optimal storage conditions for the shelf life of blueberry- and cranberry smoothies were observed at fridge temperature (4 ± 2 °C). At the same time, the exclusion of light had a minor impact in the case of antioxidants. Regarding polyphenols, the low temperature was also a key factor preventing degradation in contrast to dimming, which did not provide additional benefit. Health-promoting bioactive phytochemicals and antioxidants might be well preserved in smoothies for almost an entire year, superior at fridge temperature (4 ± 2 °C) and exclusion of light.