Postharvest supports and enhances the processes throughout the supply chain critical to ensuring that intrinsic product quality is maintained and that a quality product is available to the end-consumer in local and distant global markets. Postharvest covers producers, packhouses, marketing coordination, logistics and shipping, receivers/wholesalers and end-consumers. The postharvest research programme is structured into four themes, namely quality management, physiological defects, storage techniques and packaging and logistics. The research strategy for each theme is determined by a workgroup (one workgroup per theme) consisting of exporters, pre-and postharvest technical specialists, industry consultants and researchers. Additional workgroups are formed as and when needed.
When considering research strategy, the workgroups always keep in mind the objectives of the postharvest research programme, which are the following:
- To increase the marketable tons of fruit delivered per ton of fruit loaded.
- To present clients all along the postharvest value chain extending to the consumer with a safe product of reliable, good quality.
- To reduce wastage and losses from defects and pathogens (see the crop protection programme for postharvest pathology research).
- To increase efficiencies throughout the postharvest value chain.
- To increase the sustainability of postharvest practices.
- To reduce risk within the postharvest value chain.
Research needs relating to pre-harvest factors that affect postharvest quality and storability are addressed within the crop production programme.
Regular meetings and continuous discussion between the crop production, crop protection, and postharvest programme managers ensure that research between the three programmes is well integrated.
Dr Mariana Jooste
Current research addresses a number of themes; these include:
Quality management involves maintaining quality throughout the logistical chain until the product reaches the end consumer. Knowledge of preharvest factors, such as water deficits and fruit ripening patterns in the orchard, aids in making informed decisions regarding postharvest treatments, storage durations and regimes, and marketing strategies. The work conducted by Daniël Viljoen and his team at ExperiCo on deficit irrigation, as well as the ongoing research by Jason Ladegourdie on apple starch concentration and its rate of conversion in the orchard, addresses these industry needs and shows promising results. Shrivel, a major postharvest defect for both pome and stone fruit, remains a key research focus area. Due to logistical challenges between harvest and cooling, breaks in the cold chain, extended fruit storage periods, and growing concerns about plastic packaging, innovative projects and solutions to manage moisture loss in different cultivars will continue to be a priority for the postharvest research programme.
The main internal quality defects receiving research attention are heat damage in plums, superficial scald and internal browning in apples and pears. Research is aimed at understanding the underlying causative factors (both pre-and postharvest) and biochemistry of these defects to allow the development of technology to limit or prevent their occurrence. Other aims are to generate best practice guidelines for handling fruit both pre-and postharvest and to develop indicators to predict the risk of various defects in each season. Dr Ian Crouch and his team at ExperiCo are developing much needed photographic compendiums of pome and stone fruit disorders which are in the final stages of completion. They are also compiling a document containing the symptoms and causes as well as control measures of pome defects.
A key outcome of research in this area is the development of best practices and protocols to prevent or reduce the incidence of disorders and maintain fruit quality. The evaluation of storage technologies and protocols primarily focuses on non-chemical scald control and the prevention of internal browning.
Logistics projects focus on optimising the utilisation of shipping container space, while packaging projects aim to improve fruit cooling and optimising the maintenance of fruit pulp temperatures in transit. Additionally, they explore alternatives to non-recyclable, single-use plastics without compromising fruit quality or the structural integrity of the packaging.
When considering research strategy, the workgroups always keep in mind the objectives of the postharvest research programme, which are the following:
- To increase the marketable tons of fruit delivered per ton of fruit loaded;
- To present clients all along the post-harvest value chain extending up to the consumer with a safe product of reliable, good quality;
- To reduce wastage and losses from defects and pathogens (see the crop protection programme for post-harvest pathology research);
- To increase efficiencies throughout the post-harvest value chain;
- To increase the sustainability of post-harvest practices;
- To reduce risk within the post-harvest value chain.