Citral-thymol based synergistic shellac coatings enhanced shelf life of Kinnow fruit stored under low temperature conditions

Abstract

Microbial spoilage incurs the main cause of reduced shelf life of Kinnow during storage and transportation. This study aimed to evaluate the postharvest application of plant-derived citral and thymol-based shellac wax coatings on ‘Kinnow’ mandarin under controlled conditions (5–7 °C, 90–95 % relative humidity (RH)) over a 75-day storage period. The fruit were coated with shellac wax (SH) supplemented with citral (1.0 %, CSH), thymol (1.0 %, TSH) and citral-thymol combined formulation (1.0 %, CTSH (1:1)). Rheology studies revealed that the Herschel–Bulkley model was the best fit for all coating solutions, ensuring desirable spreadability and adhesion. The CTSH-coating outperformed all other treatments by reducing mean spoilage to 0.46% as compared to commercial shellac (6.71%) over a period of 75 days under cold store conditions. The treated fruit could control the physiological weight loss to 5.73 % as compared to commercial SH coatings (7.62 %) for 60 days. The study concluded that CTSH-coated Kinnow fruit can be stored up to 60 days under cold store conditions at 5–7 °C and 90–95 % RH with acceptable fruit quality (sensory score 7.83). The activities of cell wall degrading enzymes such as Pectin methylesterase (PME) and cellulase were also found to be retarded, contributing to prolonged shelf life. Therefore, these coatings may offer a green substitute to the synthetic analogues, with no health side effects for extending the postharvest shelf life of Kinnow up to 60 days under cold store conditions.