Bioaccessibility, antioxidant activity and colour of carotenoids in ultrafrozen orange juices: Influence of thawing conditions

- We assayed different thawing conditions in ultrafrozen orange juices.
- Colour, carotenoids, antioxidant activity and bioaccesibility were studied.
- Microwave thawing reduced the provitamin A and the macular carotenoids content.
- Ambient and refrigeration temperatures decreased the bioaccesibility of carotenoids.
- Microwave defrosting increased the bioaccesibility of bioactive carotenoids.

Ultrafrozen orange juices are produced to preserve the nutritional and sensory quality of the fresh juices. However the effects of the thawing conditions on the nutritional quality have been scarcely studied. To gain insight into this subject we have assessed the impact of different thawing conditions (microwave, room and refrigeration temperature) on the carotenoids levels and bioaccessibility in ultrafrozen orange juices. Other related properties, such as colour, and antioxidant activity were also evaluated. The results demonstrated that the bioactive carotenoid content and the antioxidant activity were significantly affected by the microwave thawing. These juices showed the highest values for the % of relative bioaccessibility of provitamin A carotenoids, when compared to the other thawing conditions. On the other hand, thawing at room or refrigeration temperatures did not have a negative impact neither on the colour, provitamin A and macular carotenoid compounds nor in the antioxidant activity.