Ngcobo M.E.K., Delele M.A., Opara U.L., Meyer C.J.
Postharvest Technology Research Laboratory, Faculty of AgriSciences, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa; Department of Mechanical and Mechatronics Engineering, Faculty of Engineering, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa; Perishable Product Export Control Board, 45 Silwerboom Avenue, Plattekloof, Parow 7500, South Africa
Ngcobo, M.E.K., Postharvest Technology Research Laboratory, Faculty of AgriSciences, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa, Perishable Product Export Control Board, 45 Silwerboom Avenue, Plattekloof, Parow 7500, South Africa; Delele, M.A., Postharvest Technology Research Laboratory, Faculty of AgriSciences, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa; Opara, U.L., Postharvest Technology Research Laboratory, Faculty of AgriSciences, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa; Meyer, C.J., Department of Mechanical and Mechatronics Engineering, Faculty of Engineering, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
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. © 2013 Elsevier Ltd. All rights reserved.