Effect of Plasma Exposure Time on the Polyphenolic Profile and Antioxidant Activity of Fresh-Cut Apples

Abstract

Cold atmospheric plasma (CAP) has shown good potentiality for the decontamination and stabilization of fresh fruit and vegetable products; however, information about its effect on nutritional quality is still scarce. The aim of this research was to evaluate the impact of a form of indirect treatment known as Dielectric Barrier Discharge (DBD) on apple slices—more specifically, the polyphenolic profile and antioxidant activity of fresh-cut Pink Lady apples. Atmospheric plasma was generated using air as feed gas, and directed to apple slices for up to 30 min. The effect of plasma treatment on physico-chemical parameters was mainly observed as a slight acidification of the tissue and reduction of browning after an extended period of exposure. The samples’ phenolic profile was significantly affected after 10 min of treatment, both in quantitative (an approximately 20% increase) and qualitative terms, while with increasing exposure time a progressive decrease of all polyphenol classes was observed. The antioxidant activity, evaluated by different in-vitro methods, followed a similar trend, increasing after 10 min of processing and then decreasing. Results highlighted how plasma exposure promotes a metabolic response of the fresh tissue, and the importance of carefully controlling the exposure time in order to minimize the loss of nutritional properties.

Influence of Atmospheric Cold Plasma Exposure on Naturally Present Fungal Spores and Physicochemical Characteristics of Sundried Tomatoes (Solanum lycopersicum L.)

“…As regards the antioxidant properties, no significant ( p > 0.05) variation of the reducing power and of the radical scavenging activity was highlighted after the ACP treatments. Similar results were also reported by [ 59 ] on kiwifruit treated by cold plasma at 15 kV for 20 min; conversely, other studies showed a positive influence of ACP on the antioxidant properties of plant products, ascribing this effect to the formation of phenolic compounds with higher antioxidant capacity [ 60 ], to the increase in the extractability of polyphenols and other antioxidants such as carotenoids and vitamin C [ 61 ], and to the accumulation of secondary metabolites that include phenolic compounds as defense responses to UV irradiation [ 62 , 63 ]. It is important to consider that the instrument used in our study did not produce UV radiation.…”

Impact of Atmospheric Pressure Microwave Plasma Treatment on Quality of Selected Spices

“…It is also worth emphasizing that similar findings were reported previously for other nonthermal processing methods such as a pulsed electric field [49]. The minimal effect of plasma treatment on phenolics content has been reported by Tappi et al [50] for fresh-cut apples. Other reports indicate that plasma radiation can increase the concentration of phenolic compounds.…”

Improvement of the Antioxidant Activity, Water Solubility, and Dispersion Stability of Prickly Pear Cactus Fruit Extracts Using Argon Cold Plasma Treatment

“…However, CPT has also been reported to increase antioxidant activities, likely through inducing the transformation of chemical compounds by CPT. The increase in the antioxidant activity of apple slices after CPT has been attributed to the oxidation of catechins, which causes the formation of procyanidins that possess a higher antioxidant activity than catechins (Tappi et al, 2018). In addition, suggested that the increased antioxidant activity of naringin after CPT could be due to the transformation of naringin to a chemical with a higher radical-scavenging activity.…”