Postharvest Quality of `Thompson Seedless' Grapes after Insecticidal Controlled Atmosphere Treatments

Abstract

Nonfumigated `Thompson Seedless' table grapes were stored in air or one of four atmospheres: 0.5% O2 and 35% CO2; 0.5% O2 and 45% CO2; 0.5% O2 and 55% CO2; and 100% CO2. Grapes were stored at 5C and 20C for 6 and 4.5 days, respectively. The fruit were evaluated for weight loss, berry firmness, soluble solids, titratable acidity, berry shattering, rachis browning, berry browning, and volatiles (acetaldehyde and ethanol). Fruit quality was not affected at 5C; however, at 20C, controlled atmosphere (CA) treatments had a detrimental effect on rachis browning and soluble solids. CA at both temperatures induced the production of high levels of acetaldehyde and ethanol. After treatment at 5C, volatile concentrations were two-thirds lower than at 20C. A consumer taste panel evaluated fruit 3 days after removal from CA. Consumer preference was negatively affected by the CA treatments at 20C; however at 5C, consumer preferencewas not affected by the treatments. Preliminary data for mortality of Omnivorous Leafroller pupae (Platynota stultana), Western Flower Thrips adults (Frankliniella occidentalis), and Pacific Spider Mite adults (Tetranychus pacificus) indicate that many of these treatments would provide quarantine security.