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

The performance of three table grapes multi-scale designs, namely the 4.5 kg box, 5 kg open-top punnet and 5 kg 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 5 kg punnet box with a vent-hole ratio of 6.13 ± 0.04% had a lower pressure drop than the 4.5 kg 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 4.5 kg multi-packaging was significantly (P < 0.05) slower than that of grapes in 5 kg punnet multi-packaging, where the 4.5 kg 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 35 days in cold storage at −0.5 °C, grape bunches in the 5 kg punnet box combination (open-top and clamshell) had a weight loss of 2.01–3.12%, while the bunches in the 4.5 kg box combination had only 1.08% weight loss. The bunch stem dehydration rates were also higher in the 5 kg 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 4.5 kg multi-packaging was 40.95 Pa, while the VPD inside the 5 kg open-top and clamshell punnet packaging were 92.97 Pa and 100.71 Pa, respectively.