Effect of cold atmospheric pressure plasma pretreatment on the drying kinetics, physicochemical properties and selected bioactive compounds of okra pods subjected to hot air impingement drying

Abstract

This study aimed to evaluate the effect of cold atmospheric pressure plasma pretreatment (CP) on the drying kinetics, physicochemical properties, content of chlorophylls (alpha and beta), lycopene, phenolic compounds and antioxidant capacity of hot air impingement dried (HAID) okra pods. CP treatment significantly increased moisture diffusivity from 3.04 x 10⁻⁹ to 5.07 x 10⁻⁹ m²/s and decreased the HAID time by 38%, i.e., from 235 to 145 min. CP resulted in a reduction of alpha chlorophyll and lycopene contents, whereas the combination of CP and HAID allowed both chlorophylls to be preserved. The HPLC-MS/MS analysis revealed that CP-treated samples showed lower content of phenolic compounds, while combination of CP for 15 s and HAID provided excellent preservation of these compounds. The results show that the combination of the advanced CP treatment and HAID method was useful to obtain optimal results for both drying kinetics and the quality of okra pods.

Keywords:

• Okra pods
• cold atmospheric pressure plasma pretreatment
• hot air impingement drying
• microstructure
• chlorophylls
• phenolic compounds

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Additional information

Funding

The publication was written as a result of the author’s internship in Department of Biological and Agricultural Engineering, UC Davis (Davis, Ca, US) from 01 November 2022 to 31 January 2023, co-financed by the European Union under the European Social Fund (Operational Program Knowledge Education Development), carried out in the project Development Program at the University of Warmia and Mazury in Olsztyn (POWR.03.05. 00-00-Z310/17). Additionally, the research work conducted from 01 February 2023 to 18 August 2023 was partially supported by the University of Warmia and Mazury in Olsztyn, Poland.