Development and certification of plum packaging formats for export of South African fruit to markets accepting irradiation in combination with insect barrier bags, as mitigation treatment

• Development of micro-perforated insect barrier bags and/or packaging formats that comply with APHIS specifications and give desired fruit quality maintenance for plums, for use as a mitigation measure in combination with irradiation.
• To evaluate the influence of irradiation and micro-perforated insect barrier bag packaging format, on the post-storage quality of plums.
• Certification of a plum-packaging format for irradiation and APHIS approval, using mini-pallets, to enable commencement of commercialisation.

A local company assisted in the development of bags which conformed to APHIS specifications. Songold, Laetitia and African Delight plums were packed in the newly developed insect barrier bags as well as in packaging representing commercial references, prior to irradiation at a commercial treatment facility. Post-storage quality was evaluated after commercial export protocols were simulated at the ExperiCo experimental cold storage facility.

When Songold plums were packed in insect barrier bags and irradiated at 400-900 Gy, the post storage quality was acceptable when fruit was pre-treated with SmartFresh^SM. Laetitia plums was acceptable with or without SmartFresh^SM pre-treatment. The internal quality of African Delight was acceptable with or without SmartFresh^SM pre-treatment. Irradiation did not affect the incidence of external browning on African Delight. The max to min irradiation dose ratios for the four packaging configurations tested in December 2013, were within 2.2 : 1, which is within the USDA limits