Impact of electron beam irradiation on the chlorophyll degradation and antioxidant capacity of mango fruit

Truc Trung Nguyen,Pongphen Jitareerat,Natta Laohakunjit,Masaya Kato,Apiradee Uthairatanakij,Varit Srilaong

doi:10.1186/s13765-021-00592-8

Abstract

At the present, the mechanism of chlorophyll degradation in response to ionizing irradiation in harvested fruits have not been examined. To understand the effect of electron beam (E-beam) irradiation on the chlorophyll degrading pathway in relation to chlorophyll degrading enzymes activity, reactive oxygen species (ROS) and antioxidant capacities of harvested mangoes stored at 13 °C for 16 days were studied. E-beam-treated fruit significantly suppressed the activities of chlorophyll degrading enzymes especially pheophytinase (PPH) and chlorophyll degrading peroxidase (Chl-POX) in the late stage of storage. This resulted in the chlorophyll content being maintained. However, E-beam irradiation did not affect the activities of chlorophyllase (Chlase) and magnesium de-chelatase (MD). The respiration rate, ethylene production, ROS accumulation (hydrogen peroxide [H2O2] and superoxide radical [O−.2]) immediately increased after E-beam treatment, following which they significantly decreased in comparison to the control. E-beam treatment enhanced the fruit’s antioxidant capacity by activating the activities of catalase (CAT) and ascorbate peroxidase (APX) and glutathione (GSH) content, and inactivated the activity of superoxide dismutase (SOD). Further, it did not affect the activity of glutathione reductase (GR) and glutathione disulfide (GSSG), vitamin C content, or total phenolic content. These results imply that E-beam treatment has the potential to delay chlorophyll degradation by suppressing the Chl-POX and PPH activities as well as reduce ROS production via CAT, APX, and SOD activities and GSH content.

Highlights

Mango (Mangifera indica L.) is a popular tropical fruit for its dietary fiber, vitamin C, and pigments and is an excellent source of antioxidants and phytochemicals [1,2,3]
Pheophorbide a oxygenase (PAO) converts pheophorbide a to red chlorophyll catabolites, which is followed by a reduction in the red chlorophyll catabolite induced by red chlorophyll catabolite reductase (RCCR), resulting in a colorless fluorescent product known as the primary fluorescent chlorophyll catabolite
Effect of E‐beam irradiation on chlorophyll content and chlorophyll‐degrading enzymes Chlorophyll is the green pigment that plays a role as an indicator of fresh and healthy fruit

Summary

Introduction

Mango (Mangifera indica L.) is a popular tropical fruit for its dietary fiber, vitamin C, and pigments and is an excellent source of antioxidants and phytochemicals [1,2,3]. After harvesting, it ripens within 4 days under ambient temperature [4]. One of the most visible changes during the postharvest ripening of mangoes is chlorophyll degradation [5], which further leads to the yellowing of its Chlorophyll is a naturally green pigment biosynthesized in higher plants. The late stage consists of the oxygenolytic cleavage of pheophorbide a, reduction of the red chlorophyll catabolite, and modification of the primary fluorescent chlorophyll catabolite. Chlorophyll is degraded by the oxidation of its phytyl chain, caused by reactive oxygen species (ROS) or oxy free radicals in higher plants such as Petroselinum sativum [15] and Posidonia oceanica [16]

Methods

Results

Conclusion