Effect of different post-harvest treatments on overall quality retention in litchi fruit during low temperature storage

SummaryFreshly-harvested litchi (Litchi chinensis Sonn., L) fruit, of the cultivar ‘Mauritius’, were subjected to 5 min post-harvest dip treatments in aqueous solutions of: potassium metabisulphite, or Vapogard , or Chitosan or combined treatments of: potassium metabisulphite + Vapogard , or Chitosan + potassium metabisulphite, or Anolyte + Triton X-100 + Chitosan, or ammonia + Carnauba wax. Standard commercial sulphur dioxide fumigation was included as a comparative control. After treatment, fruit were held at 1°C, 95% RH for 21 d to simulate refrigerated sea shipment conditions, then held at 18°C, 80% RH for 2 d. Several parameters were used to evaluate fruit quality. Combined post-harvest dip treatment with potassium metabisulphite + Vapogard retained fruit marketability most effectively, preventing severe browning post-harvest diseases, and retaining fruit firmness. Potassium metabisulphite + Vapogard dip treatment also revealed superior eating quality, with a 19.5% soluble solids concentration, 0.2% titratable acidity and a decline in anthocyanin concentration. Fruit fumigated with sulphur dioxide showed increased weight loss with intensified micro-cracks on the pericarp. Chitosan was most effective in reducing the total microbial fructoplane population compared to other treatments. Penicillium expansum Link. and Cladosporium spp. were identified as the predominant fungi on litchi fruit used in this trial.