Nxumalo Kwanele Andy, Fawole Olaniyi Amos, Oluwafemi Oluwatobi Samuel
Postharvest Research Laboratory, Department of Botany and Plant Biotechnology, University of Johannesburg, Johannesburg, South Africa.
Department of Chemical Sciences (Formerly Applied Chemistry), University of Johannesburg, Johannesburg, South Africa.
Front Plant Sci. 2022 Jul 22;13:953861. doi: 10.3389/fpls.2022.953861. eCollection 2022.
Restricted postharvest application of synthetic fungicides in maintaining the quality of citrus fruits has led to a search for alternative postharvest treatments. This study evaluated the efficacy of gum arabic (GA) enriched with green synthesized zinc oxide nanoparticles (ZnO-NPs) in maintaining the postharvest quality of mandarin (cv. Kinnow). ZnO-NPs were synthesized using leaf extract and incorporated into GA (2% w/v) at 0, 0.25, 0.5, and 1% to form composite coatings: GA, GA + ZnO-NP 0.25%, GA + ZnO-NP 0.5% and GA + ZnO-NP 1%, respectively. Fruit were dipped for 3 min in the respective coatings, with untreated fruit used as control. Fruit were air-dried, packed in commercial cartons, and stored at 5 ± 1°C and 90 ± 5% relative humidity (RH) for 40 days and observed at 10 days intervals, plus 5 days at 20 ± 5°C and 65 ± 5% RH to determine the incidence of physiological disorders. GA + ZnO-NP showed promise as an alternative postharvest treatment for controlling postharvest physiological disorders associated with 'Kinnow' mandarin. For instance, GA + ZnO-NP 0.5% markedly minimized weight loss (9.2%), electrolyte leakage (43.8%) and chilling injury incidence (5.4%) compared to control (weight loss; 33.3%, electrolyte leakage; 90.3% and chilling injury incidence; 41.5%) at the end of the storage. GA + ZnO-NP 1% significantly alleviated rind pitting, with 13.2% incidence compared to 45.2% rind pitting incidence in the control fruit. This was due to significantly higher phytochemical and antioxidant capacity and reduced antioxidant enzyme degradation in coated fruit than in control. In conclusion, gum arabic coating enriched with ZnO-NPs at concentrations between 0.5 and 1% is recommended as a viable option to maintain the quality of 'Kinnow' mandarin fruit during cold storage.
合成杀菌剂在采后用于维持柑橘类水果品质方面受到限制，这促使人们寻找替代的采后处理方法。本研究评估了富含绿色合成氧化锌纳米颗粒（ZnO-NPs）的阿拉伯胶（GA）在维持金诺柑（品种为Kinnow）采后品质方面的效果。使用叶片提取物合成ZnO-NPs，并分别以0、0.25、0.5和1%的比例掺入GA（2% w/v）中，形成复合涂层：分别为GA、GA + ZnO-NP 0.25%、GA + ZnO-NP 0.5%和GA + ZnO-NP 1%。将果实分别在各自的涂层中浸泡3分钟，未处理的果实作为对照。果实风干后，装入商业纸箱，在5±1°C和90±5%相对湿度（RH）下储存40天，并每隔10天观察一次，再在20±5°C和65±5% RH下放置5天，以确定生理病害的发生率。GA + ZnO-NP有望作为一种替代采后处理方法，用于控制与金诺柑相关的采后生理病害。例如，与储存末期的对照（失重；33.3%、电解质渗漏；90.3%和冷害发生率；41.5%）相比，GA + ZnO-NP 0.5%显著降低了失重（9.2%）、电解质渗漏（43.8%）和冷害发生率（5.4%）。GA + ZnO-NP 1%显著减轻了果皮凹陷，发生率为13.2%，而对照果实的果皮凹陷发生率为45.2%。这是由于与对照相比，涂膜果实中具有显著更高的植物化学物质和抗氧化能力，且抗氧化酶降解减少。总之，建议使用浓度在0.5%至1%之间富含ZnO-NPs的阿拉伯胶涂层，作为在冷藏期间维持金诺柑果实品质的可行选择。
