Pg. 18-20 Maintaining market quality of fresh litchis during storage Part 2: Control of post-harvest decay

SO₂ fumigation gives acceptable decay-control of litchis when followed by refrigeration for 28 days. Prochloraz dip, at 250 ppm for 10 minutes also effectively controls decay. Wrapping materials such as Everfresh, Vitafilm and plastic significantly increase decay development. A hot Benomyl dip (500 ppm at 52 °C for two minutes) did not control decay effectively.

Summary:

• SO₂ fumigation followed by refrigeration for 28 days provides acceptable control of post-harvest decay in litchis cv Mauritius and Madras.
• Prochloraz dip at 250 ppm for 10 minutes is effective at controlling decay, while a hot Benomyl dip (500 ppm at 52°C) is not effective for long storage.
• Wrapping materials like Everfresh, Vitafilm, and plastic increase decay development, likely due to higher moisture content inside the packaging.
• Lower storage temperatures (around 1°C) result in better decay control without causing cold damage.
• SO₂ fumigation can produce undesirable sulfur taste in the fruit, negatively affecting organoleptic qualities.
• Decay is caused by fungi, with common pathogens including Penicillium spp, Pestalotia spp, Colletotrichum sp, Botryodiplodia sp, and various yeasts.
• Untreated and packaged fruit without SO₂ generally show much higher decay rates.
• Prochloraz and Benomyl treatments have been reported to cause some poor taste in litchis, likely due to high chemical concentrations.
• Future research should focus on optimizing SO₂ dosages, testing new packaging materials and fungicides, exploring new cultivars, and considering controlled atmosphere storage and biological controls.
• Maintaining a balance in moisture and decay control is critical to preserving litchi quality during extended storage and export by sea.