Developing aggregative soil sampling methods to improve preharvest produce safety
Wu, Jiaying
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Permalink
https://hdl.handle.net/2142/127370
Description
Title
Developing aggregative soil sampling methods to improve preharvest produce safety
Author(s)
Wu, Jiaying
Issue Date
2024-12-02
Director of Research (if dissertation) or Advisor (if thesis)
Stasiewicz, Matthew
Doctoral Committee Chair(s)
Banerjee, Pratik
Committee Member(s)
Miller , Michael
Margenot, Andrew
Department of Study
Food Science & Human Nutrition
Discipline
Food Science & Human Nutrition
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Environmental sampling
Microbiome
Produce safety
Quality indicator
Safety indicator
Abstract
Practical and representative soil sampling methods can improve microbial quality and safety in produce production. Aggregative sampling methods, such as drags and booties, have been studied in both animal and produce production but have not yet been fully optimized for produce. This research aimed to enhance produce safety by advancing soil sampling methods using drags and booties.
The objectives of this research were to (i) evaluate the effectiveness of the aggregative sampling method, booties, as an alternative sampling technique by collecting soil samples from commercial romaine lettuce fields using booties, composite grabs, and high-resolution grabs, and (ii) test various wetting agents, skim milk powder, tryptic soy broth, buffered peptone water, phosphate buffered saline, and deionized water, for hydrating drags and booties in different agricultural soils.
To achieve the first objective, soil samples were collected from commercial romaine lettuce fields spanning 5060 m² using booties (n = 28; worn while walking along the path), composite grabs (n = 28; consisting of 60 grabs of 3–5 g each), and high-resolution grabs (n = 72; one sample per stratum). The study tested whether soil collected using bootie reflected the quality and safety indicator organisms and community diversity found in grab samples.
To achieve the second objective, soil samples were collected from fields with untreated swine manure applied by liquid injection and dairy manure applied by dry spreading using drags (n = 220; gauze sponge dragged along the path), booties (n = 220; worn while walking along the path), and grabs (n = 44; consisting of 6 grabs of 20–66 g each) along defined 100 m paths. The study evaluated if drags and booties hydrated with different wetting agents performed similarly in recovering quality and safety indicator organisms.
In conclusion, aggregative soil sampling methods were found to be comparable to grab sampling for recovering quality and safety indicator organisms. Differences between wetting agents were limited and biologically insignificant, although wetting agents with nutritional properties sometimes outperformed those without. This data will assist in developing modern soil sampling protocols using more feasible wetting agents for more representative aggregative soil sampling methods. The study justifies future work on testing aggregative soil sampling for foodborne pathogen detection.
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