Evaluating the food safety of culinary herbs cultivated in peat-free growing media

Primary supervisor: Professor Dawn Arnold, [email protected] and Dr. Lynn McIntyre

Non-academic partner: Royal Horticultural Society. Professor Alistair Griffiths and Dr. Raghavendra Prasad

Project Title: ‘Evaluating the food safety of culinary herbs cultivated in peat-free growing media’

Project description:

Peat has been a major ingredient as a horticulture growing medium component, owing to its physical, chemical and biological properties, and low economic cost. Peat extraction for horticulture use removes stable, sequestered carbon and releases it into the active carbon cycle, exacerbating climate change. Environmental actions on peat are increasingly being addressed through developing legislation in the UK and EU nations, hence phasing out the use of peat in horticulture by the transition towards economically viable and environmentally sustainable peat-free alternatives will be of great significance.

Culinary herbs (e.g. Basil, Coriander and Thyme) are a few of the ready-to-eat fresh food produce commonly consumed as part of a healthy diet. Herbs are often consumed raw and do not require additional processing before consumption like washing, thawing, or reheating and therefore have to satisfy high microbiological quality standards. 

As the UK and international horticulture industry are preparing for the transition to peat-free production/cultivation, a food-safety concern when using various peat alternatives and peat-free mixes (e.g. coir, word fibre, bark, green compost etc.) in culinary herbs production might carry the risk of human pathogens. Human pathogens such as Escherichia coli O157:H7, Salmonella spp. and Listeria monocytogenes present in a growing media ingredients including peat-based and/or peat-free alternatives/substrates could pose a potential risk of foodborne illness, resulting from the consumption of fresh produce contaminated with the above-mentioned human pathogens.

The potential presence, uptake and persistence of human pathogens from the growing media into the edible parts of consumed fresh produce by either physical contamination/internalisation will become an important issue to address from both peat-free culinary cultivation and food safety aspects. The proposed PhD study will assess the potential reason for the presence of the human pathogen in peat-alternatives/peat-free growing media and the role of agronomic/horticultural interventions that can inhibit the presence/physical spread/internalisation of human pathogens from various peat-free growing media into edible parts of culinary herbs.

Person specification: 

Candidates must hold a minimum of an upper second class (2:1) honours degree, or equivalent in an appropriate subject area (e.g. microbiology, agricultural science, biological science or a related subject) / high grade point average bachelor’s degree for international applicants or a 2.2 alongside a suitable Master’s Degree. Potential for research based on alternative qualifications/experience as judged acceptable by the university, will be considered on a case by case basis. 

The expected start date for the studentship is October 2024 but could be earlier. The student will be registered for a PhD at Harper Adams University and based at Harper Adams University, Edgmond, Shropshire, UK. With timely visits to RHS Wisley for trials and other research/training purposes. The studentship will cover the current tuition fee rate plus a yearly stipend set at the UKRI figure – £19,237 per year (2024/23 academic year). Should an earlier state date be selected the stipend will be £18,622 (2023/4 academic year).