Gamma Radiation Applied in Euterpe oleraceae Pulps

Aims: The aim of this work was to evaluate the optimal radiation dose to maintain the antioxidant capacity of conventional and organic acaí freeze-dried pulps.

Study Design: All analyses were conducted in sextuplicate for each experiment.

Place and Duration of Study: Were conducted at the LATAIA and the irradiation processes at the Laboratory of Nuclear Instrumentation, UFRJ, Rio de Janeiro, Brazil. The study was carried out from July, 2018 to March, 2020.

Methodology: Frozen acaí pulps from two commercial brands, one of them organic and other conventional were used and purchased in the city of Rio de Janeiro, packed in plastic bags containing 1 kg. For each brand, frozen pulps (5 kg) were thawed at 4ºC, opened and homogenized. Samples were subdivided into aliquots ranging from 20 to 300 g for the assays and frozen inside the plastic bags until analyses. A Cobalt 60, Gammacell irradiator was used and doses of 1.25. 2.5. 3.75 and 5 kGy were applied in the in natura pulps. Antioxidant capacity was performed by the ORAC and DPPH methods and, phenolic compounds by Folin Ciocalteau method and, total anthocyanins and majority anthocyanidins by HPLC.

Results: Anthocyanins increases at irradiaton dose up to 3.75 kGy in organic açaí but it was not significant in conventional acaí irradiated at low doses (1.25 to 3.75 kGy). Our results suggested that irradiation doses up to 5 kGy do not decrease total phenolic or anthocyanin contents nor the pulp antioxidant activity compared with non-irradiated pulps. The results showed irradiation did not reduce these analytes, and even increased in the organic acaí.

Conclusion: The study evidenced that gamma irradiation can be an alternative safe process for fruit pulps preservation. We conclude that irradiation doses up to 5 kGy can be used in acaí without harming its antioxidant properties.