Effects of Various Polymeric Films on the Pericarp Microstructure and Storability of Longan (cv. Shixia) Fruit Treated with Propyl Disulfide Essential Oil from the Neem (Azadirachta indica) Plant.

Muhammad Rafiullah Khan,Hongxia Su,Ihsan Mabood Qazi,Taufiq Nawaz,Abdullah Khan,Rafi Ullah,Chongxing Huang,Liu Ren,Hakim Ullah,Muhammad Adnan

doi:10.3390/polym14030536

Muhammad Rafiullah Khan, Hongxia Su + Show 8 more

Open Access

https://doi.org/10.3390/polym14030536

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Abstract

Plant extracts represent a rich repository of metabolites with antioxidant and antimicrobial properties. Neem (Azadirachta indica) is a medicinal plant considered the tree of the 21st century. In this study, we investigated the antioxidant and antimicrobial effects of propyl disulfide (PD), a major volatile compound in neem seed, against the pericarp browning (BI), microbial decay incidence (DI), and water loss of longan fruit. Fresh longan cv. Shixia samples were packaged in oriented polypropylene (OPP) and polyethene (PE) packages of different thicknesses (20, 40, and 60 µm). Sterile gauze was fixed inside the packages and 500 uL of PD was placed on them to avoid the direct contact of PD with fruit samples. Packages were sealed immediately to minimize vaporization and stored at 12 ± 1 °C for 18 days. Fruit samples packaged in open net packages served as controls. The results showed that fruit treated with PD in OPP and PE packages significantly prevented losses of water, DI, and BI compared to control treatment. PD also maintained the color, TSS values, TA values, pH values, high peel firmness, high TPC content, and high TFC content, and reduced the activity levels of PPO and POD. Scanning electron microscope (SEM) analysis indicated that the exocarp, mesocarp, and endocarp of longan peel were smooth, uniform, and compact with no free space compared to control, where crakes, a damaged and loose structure, and a lot of fungal mycelia were found. The shortest shelf life of 9 days was observed in control as compared to 18 days in OPP-20 and OPP-40; 15 days in OPP-60, PE-20, and PE-40; and 12 days in PE-60 packaging films. Therefore, PD as a natural antioxidant and antimicrobial agent, in combination with OPP-20 and OPP-40 polymeric films, could successfully be applied commercially to extend the postharvest shelf life of longan.

Highlights

This article is an open access articleLongan (Dimocarpus longan L.) is an attractive subtropical fruit of the evergreen tree of the Sapindaceae family
Microbial decay, and water loss are the major concerns in longan fruit; in this study, we focused on the antioxidant and antimicrobial activity levels of propyl disulfide from neem
Statistics within the storage intervals showed that weight loss increased significantly on each quality test day in each treatment; oriented polypropylene (OPP)-20 comparatively prevented the loss in weight more than other treatments (Figure 2)

Summary

Introduction

This article is an open access articleLongan (Dimocarpus longan L.) is an attractive subtropical fruit of the evergreen tree of the Sapindaceae family. The fruit has high nutritional value and is best when eaten fresh. Longan is non-climacteric; the fruit is harvested at optimum maturity and does not continue to ripen once harvested. The fruit matures in high temperature and distributed under the terms and conditions of the Creative Commons. Humidity, meaning it deteriorates rapidly once harvested due to pericarp browning and microbial rot. Due to the unique pericarp structure of longan fruit, the dehydration and microbial invasion expedite the senescence and browning, shortening its postharvest life [1]. The continuous use of synthetic compounds needs to be eliminated to ensure the availability of safe and fresh fruits for longer periods of time

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