THE POTENTIAL USE OF SULFUR DIOXIDE PACKAGING SHEETS TO RETAIN ‘MAURITIUS’ LITCHI FRUIT RED PERICARP COLOUR

  • Harold Kgetja Malahlela
  • Tieho Paulus Mafeo
  • Nhlanhla Mathaba

Abstract

After harvesting litchi fruit, the red pericarp colour is rapidly lost resulting in discolouration and browning during storage and marketing. Therefore, the objective of this study was to investigate the potential of sulfur dioxide packaging sheets to retain ‘Mauritius’ litchi fruit red pericarp colour. A factorial combination of two packaging materials (plastic punnets and bags), six SO2 treatments (control, SO2 fumigation and four SO2 sheets viz. Uva-Uno-29% Na2S2O5, Dual-Release-Blue-35.85% Na2S2O5, Slow-Release-36.5% Na2S2O5 and Dual-Release-Green-37.55% Na2S2O5) and four storage periods (day 0, 1,2 and 5) in a completely randomised design with 3 replicates was used. Treated ‘Mauritius’ fruit were stored at 4°C for 10 days, thereafter evaluated for pericarp browning index (BI), hue angle (h°), chroma (C*), and lightness (L*). All SO2 treatments effectively minimised the loss of ‘Mauritius’ fruit red pericarp colour when compared with control. In addition, Uva-Uno and Slow-Release + plastic-bags resulted in reduced pericarp browning of ‘Mauritius’ fruit than control in either packaging. Fumigation (SO2) treatment bleached ‘Mauritius’ fruit pericarp in both packaging materials. Moreover, treatment with SO2 fumigation in plastic-punnets was superior over other SO2 treatments and control in either packaging. It was noticed that ‘Mauritius’ fruit in all treatments were spoiled after 5 days of shelf-life, except for SO2 fumigated fruit in plastic-punnets. Due to restrictions in the use of chemicals, Uva-Uno and Slow-Release sheet in either packaging material could be recommended as a safe postharvest treatment for ‘Mauritius’ fruit pericarp colour retention.
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