Effects of Modified Atmosphere Packaging and Irradiation on the Quality of Blueberries under Simulated Commercial Transportation and Retail Conditions

The phase-out of methyl bromide as a phytosanitary treatment for fresh fruit poses a challenge to the United States export commodity market. Irradiation has the potential to replace methyl bromide by controlling pests while maintaining fruit quality. Modified atmosphere packaging has been shown to enhance the shelf-life of various fruits, including blueberries.  The goal of this study was to determine the effect of the combination of irradiation treatment and modified atmosphere packaging on the shelf-life, overall quality, and consumer acceptance of southern highbush blueberries under simulated shipment and retail display conditions. Blueberry varieties Star, Jewel, and Snowchaser in 6 oz. clamshells, 12 clamshells in a tray, were packaged in nylon film designed to create modified atmosphere conditions and subjected to irradiation at a target dose of 400 Gy. The treatments included blueberries packaged in modified atmosphere film (MAP), treated with irradiation (I), combination of irradiation and modified atmosphere packaging (IMAP), and control.  After treatment, blueberries were stored for 1, 8, and 21 days at 0 to 4 °C to simulate refrigerated air, ground, and sea transportation, respectively, followed by a 3 day retail display simulation at 20 °C. Quality factors such as titratable acidity (TA), °Brix, texture, weight loss, gas concentration, and percentage of damage were evaluated periodically. Blueberries were also evaluated by 80–100 untrained consumers for appearance, flavor, texture, and overall acceptability and texture appropriateness. The attributes most significantly affected by treatment were texture, weight loss, and damage. After three weeks of storage, all three treatments retained firmness as compared to the control.  Weight loss and percentage of damage were lower in MAP and IMAP compared to control and irradiated samples across all three varieties. There were significant varietal differences in response to treatment.  Texture, TA and  °Brix were impacted for 'Star' and 'Jewel'  but not 'Snowchaser'. In 'Jewel' , MAP and IMAP had significantly (P < 0.05) higher values for liking of appearance, flavor, texture as well as overall liking during the three-week sea shipment simulation as compared to the untreated and irradiated blueberries. In 'Star', MAP also increased all sensory scores over time. In 'Snowchaser', however, average sensory scores for all three treatments were not significantly different. Overall, MAP and IMAP are suitable treatments in maintaining blueberry quality but it is important to test each variety for its tolerance to irradiation, modified atmosphere, and combination treatments.