Antioxidant activity of high-pressure processed tangerine juice

High-pressure processing is technology that has the potential to ensure microbiological safety of low pH fruit juices, while retaining freshness, increasing the stability of juice and retaining of all bioactive compounds. Investigation of HHP parameters on antioxidant activity of bioactive compounds from tangerine juice was conducted. Processing time and pressure parameters were chosen to ensure log5 inactivation of microorganisms. Pressures were 0 (fresh juice), 400, 500 and 600 MPa during 5 and 10 min. Antioxidant capacity (DPPH) and FRAP were measured and statistically analyzed using ANOVA and posthoc tests. Obtained results show that processing at lowest pressure leads to 13, 28 % decrease in antioxidant activity, compared to fresh juices. FRAP values slightly increase at 500 MPa (for 7, 29 %), as well as TOAC. The increase in pressure over 500 MPa did not lead to further changes in FRAP and TOAC values. Processing time had a positive influence, as there is an increase in both measured properties. Pressures over 400 MPa are excessive from an economic standpoint, and not necessary to achieve microbiological safety and juice stability, however, there is evidence that HHP influence on the cellular matrix, which results in the increased diffusion from the cells, which increases the antioxidant activity.