EFFECT OF CHITOSAN COMBINED WITH CITRIC ACID AND TEMPERATURE ON SHELF LIFE OF 'CHOM PHU' LONGAN

The effects of chitosan coating combined with citric acid in extending shelf life of longan fruits and maintaining their quality were investigated. The fruits were treated with aqueous solution of 0, 0.5 and 1.0% chitosan, combined with citric acid solution of 0, 3.0 and 4.0%, respectively and then stored of 4°C with 90% relative humidity. Physical and chemical properties and sensory characteristics were evaluated. The result indicated that the lightness (L* value) of pericarp and flesh were decreased. The firmness of pericarp and flesh, total chlorophyll, total soluble solids, pH, and vitamin C were decreased. On the other hand, total percentage of weight loss, anthocyanin, citric, malic, and tartaric acid were increased. The longan treated with 0.5% chitosan, combined with 3.0% citric acid solution and stored at 4°C can be kept 19 days.