Performance of multi-packaging for table grapes based on airflow, cooling rates and fruit quality

Abstract

The performance of three table grapes multi-scale designs, namely the 4.5kg box, 5kg open-top punnet and 5kg clamshell punnet, was studied. Results showed that vent-hole ratio of empty grape boxes had a significant influence on the resistance to airflow, where the 5kg punnet box with a vent-hole ratio of 6.13±0.04% had a lower pressure drop than the 4.5kg boxes with a lower vent-hole ratio of 3.80±1.74%. The addition of liner films and inner packages changed the pressure patterns, indicating that inner packaging had a great influence on airflow resistance and airflow patterns through multi-scale packages of grapes. Cooling rates of grapes in the 4.5kg multi-packaging was significantly (P<0.05) slower than that of grapes in 5kg punnet multi-packaging, where the 4.5kg box resulted in a seven-eighths cooling time of 30.30–46.14% and 12.69–25.00% more than that of open-top and clamshell punnet multi-packages, respectively. After 35days in cold storage at −0.5°C, grape bunches in the 5kg punnet box combination (open-top and clamshell) had a weight loss of 2.01–3.12%, while the bunches in the 4.5kg box combination had only 1.08% weight loss. The bunch stem dehydration rates were also higher in the 5kg punnet multi-package. These results were attributed to differences in vapour pressure deficit (VPD) measured between the three multi-scale packages, where the VPD inside the 4.5kg multi-packaging was 40.95Pa, while the VPD inside the 5kg open-top and clamshell punnet packaging were 92.97Pa and 100.71Pa, respectively.