Cold plasma processing of cranberry juice for the retention of bioactive compounds and physicochemical properties

The study examined the impact of dielectric barrier discharge (DBD) cold plasma on the bioactive compounds, physicochemical properties, microbial inactivation, and antioxidant activity of undiluted cranberry juice. The juice was recirculated through an atmospheric-pressure DBD reactor operated with an argon–oxygen (98:2, v /v) working gas at a peak-to-peak voltage of 10 kV and a driving frequency of 20 kHz, at a flow rate of 100 mL min −1 . Treatment times of 0, 5, 10, 15, and 20 min were applied to the cranberry juice; where treatment time zero represented untreated juice. The results showed that the application of a cold plasma treatment on cranberry juice reduced microbial loads significantly, with the 15 min treatment giving the largest reduction of 1.88 log CFU/mL, while its effect on nutritional, bioactive and physicochemical properties were dependent on the treatment duration. Indeed, the 5 and 10-min treatments (DBD-5 and DBD-10) resulted in significant decreases in the total anthocyanins, phenolic content (TPC), and antioxidant activity while the total carotenoids increased with the DBD-10 treatment, likely due to plasma-induced membrane breakdown hence improving bioactive compounds extraction. The 15-min (DBD-15) cold plasma treated sample had a better results outcome as there was limited reduction in macro-minerals (Ca, K, Mg), maintained color stability and A-type procyanidins retention, with high antimicrobial efficiency. Direct assessment of the reactive species delivered to the liquid showed dissolved ozone at 2.78 ± 0.01 mg/L in every treated sample and none in the untreated control, with no difference between treatment times ( p = 0.144), together with an eight-to ten-fold rise in hydrogen peroxide and a progressive strengthening of the water hydrogen-bond network, while no nitrogen-containing products were detected, as expected for a nitrogen-free working gas. The study observed that the use of cold plasma treatment can promote microbial safety and maintain cranberry juice's bioactive compounds quality.