Benchmarking quality in pot-grown herbs

Pot herbs have grown in popularity over the last few years as many consumers find the idea of keeping living herbs in their kitchen, and as a replacement seasoning and flavour enhancer in place of salt, an appealing prospect. However, herb quality and shelf life can be extremely variable and product wastage at store level and by consumers is high. There are some parallels between loss of post-production quality in cut fresh herbs and pot grown herbs as the same biotic and abiotic stress stimuli, such as Botrytis cinerea infection, drought, light depravation and high temperature, are challenges that the crop has to deal with (Cantwell and Reid, 1993). Cut fresh and pot grown herbs have quite different supply chains (SC): pot grown herbs are exclusively produced in the UK for UK consumers as soil makes overseas products unviable to transport. In the store the cut produce can be contained within a sealed bag, possibly with a modified atmosphere, and stored below ambient temperature, whereas pot grown herbs are minimally sleeved, and are sold at ambient temperature. The biology of drought response, senescence and pathogen attack are well characterised in other plant systems, but their role in herb quality is not yet known. Different genera have different stress tolerances, and there are genera where one trigger is the key driver of post-production quality e.g. the main issue with coriander is premature senescence (Jiang et al., 2002), whereas basil is sensitive to chilling in the SC. The aim of this project is to understand the biological events that result in loss of product quality to the extent that it becomes unsalable, and subsequently to recommend alternative handling procedures in order to reduce product wastage. Phase 1. Analysis of retailer statistics of product wastage A large amount of data is available from stores and depots that will enable the student to quantify seasonal variation in product quality of a range of lines. The researcher will also be able to statistically analyse which stores/depots linked to a particular retailer perform well or badly, thus informing our selection of lines, stores and depots for the next phase of the project. We will indentify three lines that represent high and low volume sales. We will follow these through different types of store owned by a single retailer, which are supplied by two depots. Phase 2. Store handling procedures We will track temperature and humidity of our chosen samples throughout the SC using data loggers. We anticipate that these may have to be removed before the product is placed on display in the store, but if this is the case we will then be able to take in-store measurements ourselves. We will also monitor light exposure levels and ethylene concentration throughout the SC. Together these datasets will help to identify risk points in typical handling procedures that could adversely affect crop quality. Phase 3. Biological measurements Postharvest measurements that are linked to crop quality will be measured on the chosen three lines throughout the different SC routes identified for the main project. We propose to measure rates of transpiration, respiration and photosynthesis, water loss, FW, sensory and flavour changes, Botrytis incidence and ethylene production. Data will be collected quarterly to assess seasonal variation. These data will enable us to pinpoint the key factors for each line that determine shelf life. Correlation with the data from phase 2 will enable us to identify particular risk points in the SC. Phase 4. Improvement of postharvest performance The form that this phase takes will be determined by our findings in phases 1-3, but it could involve implementing a change in practice of how different herbs are handled throughout the SC, or imposing a treatment before the plants leave Humber VHB so that they are better able to withstand the subsequent stresses of the supply chain. The project could be expanded to include cut herbs