Effect of freezing and freeze-drying on bioactive compounds and antioxidant activity of carnauba pulp (Copernicia prunifera (Mill.) H.E. Moore)

Abstract

Carnauba (Copernicia prunifera (Mill.) H.E. Moore) is a fruit of the Brazilian Caatinga and Cerrado regions. It has good nutritional characteristics, bioactive compounds, and antioxidant activity. However, some processing techniques can affect its chemical characteristics. This study aims at evaluating the effect of freezing and freeze-drying on the bioactive compounds and antioxidant activity of carnauba pulp. The carnauba pulp was submitted to three different treatments: slow freezing (-18 °C/24h), fast freezing (-92 °C/60s) and freeze-drying. Then the bioactive compounds of fresh samples were analyzed - vitamin C, phenolics, flavonoids, anthocyanins, carotenoids - along with the antioxidant activity (DPPH), immediately after processing and after 180 days of freezing storage. It was observed that the process influences the behavior of bioactive compounds and antioxidants, with significant losses of vitamin C, anthocyanins, and carotenoids in all treatments soon after processing, while total phenolic compounds, flavonoids and antioxidant activity increased significantly. At the end of 180 days a reduction of all bioactive compounds and antioxidant activity was observed although the freeze-dried samples presented a better stability of the compounds. Thus, quick freezing and freeze-drying could be representing the more promising technological processes for the maintenance of bioactive compounds and antioxidant activity of carnauba pulp.