Pg. 12-16 Effect of Reduced Sulphur Exposure and of Controlled Atmosphere Storage on the Post-storage Quality of Madras Litchi

Controlled atmosphere (CA) storage of litchi after harvest has been reported to extend shelf-life, enhance sensory quality, and reduce or prevent disease manifestation. Sulphur treatment prevents pericarp browning, and is fungicidal. However, it is associated with the development of off-flavours and reduced pericarp colouration after extended cold-storage, and its application is meeting with consumer resistance. The present study was carried out to assess the effect on the post-storage quality of Madras litchi fruits of controlled atmosphere storage in combination with reduced post-harvest SO₂ treatment duration.

The litchis stored under CA showed greater weight loss during cold-storage. As time progressed after cold-storage, the fruits were colonised by blue mould. Nine days after cold-storage, mould colonisation was least in the fruits exposed to SO2 for the shortest duration (500g SO₂ per MT for 15 minutes on the day of harvest), and in those having been placed under CA storage. Fourteen days after cold-storage, appreciably more fruits were healthy
following storage under CA or sulphur treatment for the shortest duration. Differences in TSS in relation to atmosphere storage were not apparent. There were slight differences in this regard relating to the duration of SO₂ treatment. Taste was most appealing in the fruits having been exposed to CA storage, and having received the shortest duration of SO₂ treatment.

The results clearly favour short-duration SO2 treatment and CA storage for Madras litchi. Fungicide treatment in addition to SO₂ treatment should be considered in view of the effect of sulphur treatment on the susceptibility of litchi fruits to blue mould colonisation.