A model of postharvest moisture loss under air currents to reduce pericarp browning of litchi (Litchi chinensis Sonn.)

Abstract

Pericarp desiccation browning has long been established as a major cause of postharvest losses in fresh litchi (Litchi chinensis Sonn.). Air currents can greatly exacerbate postharvest moisture loss in fresh produce, but no quantitative research has been available on the effect of air currents on moisture loss in litchi fruit. The relationship between air current speed and moisture loss was explored by exposing fresh litchi fruit to various wind speeds and measuring loss of mass. A linear relationship was found between air speed and moisture loss over the range tested, from 0 to 1.55ms−1. A wind speed of 1.55ms−1 (5.6kh−1) increased moisture loss by a factor of 7. A water loss model was created using the air current relationship to explore implications for postharvest management of litchi fruit. The model incorporated information on the specific moisture loss (SML) of litchi, factors for air currents and previous moisture loss, and storage conditions. Critical points for moisture loss were identified, including harvest, pre-cooling, transport, and retail marketing. The model revealed the critical importance of cool storage and protection from air currents for maintaining the fresh, red colour so characteristic of the litchi fruit.