Hot water treatments combined with cold storage as a tool for Ectomyelois ceratoniae mortality and maintenance of Deglet Noor palm date quality

Insect infestation caused by Ectomyelois ceratoniae or carob moth is one of the main postharvest disease pests of date fruit and causes serious economic losses during storage and export. Methyl bromide is the most widely used fumigant on stored dates in several countries although it will be withdrawn in 2015 in developing countries. Heat treatment technologies, such as hot water treatment (HWT) are currently a relatively simple, non-chemical alternative that can kill quarantine pests (insects and fungi) in perishable commodities. In this article, the proper HWT treatments (dose and time) that causes E. ceratoniae mortality while avoiding quality losses in Deglet Noor fruit when stored for 30 d at 2 degrees C followed by a retail period of 4 d at 23 degrees C was studied. The results show that the use of HWT of 50 degrees C for 10 min, 55 degrees C for 5 min and 60 degrees C for 3 min lead to E. ceratoniae mortality, also lowering the microbial growth (<1 log cfu g(-1), for mesophilic and <21og cfu g(-1) for yeasts and molds). HWT induced a slight reduction in skin color (luminosity and hue angle), antioxidant activity (10-15% in FRAP and 17-22% in DPPH) and total phenolic compounds (9-14%). Overall quality was slightly reduced using 60 degrees C for 3 min although all treatments remained above the limit of marketability as there was no heat damage. Storage time also reduced these parameters, as well as monosaccharides (glucose and fructose) and the concentrations of some amino acids such as alanine, aspartic acid and proline. HWT used as an alternative to chemical treatments to control carob moth yielded optimum-quality Deglet Noor date fruit that could be exported to developed countries. (C) 2015 Elsevier B.V. All rights reserved.