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Use of low‐voltage direct current electricity treatment to increase phenolics content of postharvest okra: effects of some treatment parameters

Saetung, Thunyarat, Devahastin, Sakamon, Chiewchan, Naphaporn
International journal of food science & technology 2018 v.53 no.2 pp. 441-448
Abelmoschus esculentus, application timing, electrical treatment, electricity, electrolytes, okra, phenolic compounds, protein kinases, tap water
Low‐voltage direct current electricity was applied to increase phenolics content of postharvest okra (Abelmoschus esculentus L.) at different values of current (0.10–0.50 A) and application time (900–3600 s). Use of different electrolytes, namely tap water as well as 0.10‐ and 0.15‐mol L⁻¹ brine, was also investigated. Calcium‐dependent protein kinase was quantified to indicate responses of okra to the treatment. Free and bound phenolics contents were measured and the results used to confirm whether the increased phenolics was due to the applied electricity; initial contents of total, bound and free phenolics were noted to be 6.19, 1.73 and 4.46 g kg⁻¹, respectively. Total phenolics content (8.12–8.38 g kg⁻¹) significantly increased when using a current of 0.30 A, application time of 900–3600 s, with brine as the electrolytes. Use of current of 0.30 A and 0.10‐mol L⁻¹ brine for 900 s is suggested as the appropriate treatment condition.