Effect of rhamnolipid-Aloe vera gel edible coating on post-harvest control of rot and quality parameters of ‘Agege Sweet’ orange

A local cultivar of sweet orange namely ‘Agege sweet’ constitutes a larger percentage among many citrus varieties planted in Nigeria, but there is a major setback in terms of extending its post-harvest shelf life. This work was designed to assess the effectiveness of a rhamnolipid coating to preserve the quality attributes of Agege sweet orange fruit during 8 wk ambient storage compared with that of Aloe vera gel. Petri plates were supplied with different treatments (volume per volume, v/v) of Aloe vera gel (0%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%) or rhamnolipid (0%, 0.25%, 0.5%, 1.0%, 1.5 %, 2.0%) and oranges were inoculated with a spore suspension of P. digitatum NSP01 spores. The solutions of rhamnolipid (2%) and Aloe vera gel (2%) were evaluated for their biocontrol activity on P. digitatum NSP01. The fruits were stored for 8 wk at 25ºC. The lesion area, firmness, and chemical composition were assessed. The oranges coated with Aloe vera gel and rhamnolipid significantly (p < 0.05) prevented loss in firmness, total soluble solids and titratable acidity and reduced the decay caused by P. digitatum NSP01. Therefore, the newly formulated rhamnolipid-Aloe vera edible coating could serve as a permanent substitute for chemical fungicides used in the management of diseases and pests affecting agricultural productivity

Prolonging the shelf life of ‘Agege Sweet’ orange with chitosan–rhamnolipid coating

This study evaluates the single and combined usage of chitosan (2% w/v) and rhamnolipid (2% w/v) as edible coatings to extend the shelf life of sweet oranges stored at 25 °C for 8 weeks. Physiochemical, microbial and sensory analysis of the oranges was conducted during ambient storage. The combined treatment of chitosan and rhamnolipid coating on oranges significantly delayed a loss in chlorophyll quality, malondialdehyde, weight loss, soluble solids content, titratable acidity, vitamin C content and delayed the loss of firmness during the 8 weeks of storage. The combined chitosan–rhamnolipid coating significantly increased the activities of superoxide dismutase, catalase, and peroxidase, as well as inhibited the generation of superoxide free radicals and the growth of mesophilic bacteria, yeast and mould