Transportation management, postharvest quality and shelf-life extension of lettuce.
Jordan, J. L.; Prussia, S. E.; Shewfelt, R. L.; Thai, C. N.; Mongelli, R.;
Research Bulletin - University of Georgia, College of Agriculture, Experiment Stations Year: 1990 Issue: No. 386 Pages: 48pp. Ref: 32 ref.
1990
บทคัดย่อ
Changes are predicted in the shelf life of lettuce caused by the management of temperature and ethylene during transport from the western USA to Georgia. Results indicate that optimal economic returns are derived when the arrival temperature of a head of lettuce is below 42 deg F. Problem areas for temperature management were found to be primarily on the floor of the trailer. Investments in transport equipment better to control temperature on the trailer floor would be economically feasible. Also explored were the differences in lettuce arrival temperatures between dense-packed loads and airflow stacking, using a proxy for airflow temperatures. The economic impact of management techniques (stacking patterns) to control temperature and increase shelf life was determined, and returns were estimated. The study found no practical differences in shelf life (for properly pre-cooled lettuce) between the two stacking patterns, except when transit time is five days. Finally, when shipping perishable commodities, handlers often prefer shipments that consist of multiple commodities. Such shipments should combine only those commodities that are compatible with respect to a number of factors, including physiologically active gases like ethylene. In looking at the changes in shelf life due to ethylene management during the shipping of lettuce from Arizona and its marketing in Georgia, the lettuce samples were treated with three levels of ethylene, representing no ethylene, the equivalent of one pallet of apples in a full lettuce load, and the equivalent of two pallets of apples. The study found that even these small additions of an ethylene-generating commodity into a full load of lettuce produced significant reductions in shelf life. The economic cost in terms of lettuce quality far outweighs the benefit of the savings in transport services.