Modification of the cell wall polysaccharides and phytochemicals of okra pods by cold plasma treatment

Abstract

The effect of different processing times of cold plasma (CP) treatment on the cell wall polysaccharides and phytochemical properties of okra pods was investigated. The Fourier-transform infrared spectroscopy (FT-IR) spectra of water-soluble pectin (WSP), chelator-soluble pectin (CSP), and diluted alkali-soluble pectin (DASP) fractions isolated from okra pods subjected to different CP treatment times were analyzed by principal component analysis (PCA) and the results highlighted significant differences among different pectin fractions. The CP treatment caused a decrease in the contents of lycopene and chlorophyll alpha. However, the CP treatment with 30 s (CP30) resulted in a slight increase (4%) in the content of chlorophyll beta and led to the smallest color change of okra pods. The CP5, CP15, and CP30 slightly decreased the total phenolics (TP) content of okra pods by 5, 13, and 20%, respectively. The total flavonoids (TF) content of okra pods was not significantly affected by the CP. The short CP treatment, i.e. CP5, was found to be beneficial to the antioxidant potential of okra pods determined by the FRAP, DPPH, and ABTS assays. The antioxidant potentials of CP-treated okra pods determined by the FRAP, DPPH, and ABTS assays were positively correlated with TP contents (r = 0.53, r = 0.97, and r = 0.82, respectively) and TF contents (r = 0.92, r = 0.76, and r = 0.87, respectively). The results of this study provide a deep understanding and insight into non-thermal CP treatment and its influence on the properties of agro-food products and are useful for designing and optimizing non-thermal unit operations.