Abstract
Lychee fruit (Litchi chinensis Sonn.) have a brilliant red pericarp upon harvest that turns brown during shipping and storage. 'Hong Huay' and 'Juckapat' lychee fruit were harvested at the commercial stage (90% to 100% red pericarp) in Thailand. In five separate experiments, fruit with pedicels were dipped for 30 seconds in various treatment solutions, including no dip and water as controls, ascorbic acid, citric acid, acetic acid, chitosan, HCl, and two Semperfresh products, in an effort to retard browning of the percarp. Fruit were air-dried, and stored at 2 or 10 C with 90% relative humidity for 1 to 3 weeks. Total soluble solids (TSS), titratable acidity (TA), weight loss, total ascorbic acid (TAA), and color (hue angle and chroma) were measured over the storage period. During storage, TSS generally increased while TA and TAA generally decreased (except for those treatments that were treated with ascorbate). Most treatments reduced weight loss compared to untreated fruit. Treatment of lychee fruit with acidified coatings including Semperfresh, acidified Semperfresh (with 2% citric acid), Semperfresh lychee treatment power (LTP) citric acid and chitosan + HCl sometimes resulted in brighter, redder color than control fruit, as evidenced by lower hue angle or higher chroma values.
