Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 14, 1996
Publication Date: N/A
Interpretive Summary: The Mexican fruit fly is an internal feeding, quarantine pest in citrus and its presence limits where and how fruit can be marketed. Commodity treatments approved by the U.S. Department of Agriculture, Animal and Plant Health Inspection Service for grapefruit include methyl bromide fumigation, cold storage, vapor heat, and high temperature forced air. Methyl bromide fumigation, cold storage, and vapor heat treatments can damage the market quality of grapefruit. The objective of this research was to investigate whether a controlled atmosphere established inside a high temperature forced air chamber could enhance Mexican fruit fly mortality and thereby reduce the amount of time grapefruit infested with Mexican fruit fly need to be exposed to high temperature forced air. Results from this research suggest that establishing a controlled atmosphere during heating can reduce the amount of time fruit must be exposed to heat to provide quarantine security against Mexican fruit fly.
The potential for disinfesting grapefruit of Mexican fruit fly by heating the fruit in a controlled atmosphere was evaluated by comparing larval mortality and fruit quality after heat treatments with or without altered levels of oxygen and carbon dioxide. The mortality of third instar, Anastrepha ludens larvae was significantly higher when larvae were heated at 44 deg C in 1% oxygen for 2 hours than when larvae were heated for the same amount of time at the same temperature in air or in air enriched with 20% carbon dioxide. Reducing the concentration of oxygen to 1% from 21% (air) during a heat treatment resulted in a 30% shorter exposure time (3.5 hours versus 5 hours) to achieve 100% larval mortality. The concentration of oxygen and carbon dioxide inside the grapefruit during exposure to 46 deg C were signifi- cantly different when the fruit were exposed to low oxygen, air, or high carbon dioxide during heating. Inconsistent fruit quality results warrant further study to optimize controlled atmosphere conditions during heating.