Frontiers in Sustainable Food Systems (Nov 2023)

Microbiological quality of microgreen seeds purchased from online vendors and evaluating seed decontamination techniques available online

  • Thalia Guadalupe Ocho Bernal,
  • Thalia Guadalupe Ocho Bernal,
  • Nathan Lyttle,
  • Yangjin Jung

DOI
https://doi.org/10.3389/fsufs.2023.1264472
Journal volume & issue
Vol. 7

Abstract

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This study aimed to assess the microbiological quality of microgreen seeds purchased online, including the levels of total aerobic plate counts (APC), Escherichia coli/coliforms, mold & yeast, and the presence of Salmonella spp. and Listeria monocytogenes. Additionally, seed decontamination practices commonly found online were evaluated, involving soaking in water only (SDW), 3% hydrogen peroxide (H), and a “poor man's solution” (HV; a mixture of 3% hydrogen peroxide and 5% acidity white vinegar with water), with or without heat treatment at 50 and 60°C for 20 and 40 h. The effectiveness of these treatments was evaluated using Amaranth (AM), Borage (BO), and Carrot (CA) seeds in reducing Enterobacteriaceae, coliforms, and mold & yeast, along with examining the germination rate. A total of 102 samples composed of 14 species were purchased from online vendors, and the microbial levels tested were significantly different among the seed species (p < 0.05). Among the species, BO, CA, and Onion (ON) seeds exhibited the highest APC levels (4.99–5.37 log CFU/g), which was significantly higher than the APC of Arugula, Cabbage, Mustard, Kale, and Pea seeds (p < 0.05). The coliform population of BO (3.77 ± 0.68 log CFU/g) was significantly higher than in other species. The 10-min soaking of AM, BO, and CA in H significantly reduced the microbial levels (p < 0.05), and the subsequent heat treatment at 60°C for 20 h further enhanced microbial reduction (total 1.2–3.4 log reduction by heat and soaking). The germination rates were not significantly affected by the different treatment combinations (p > 0.05). This study provides scientifically-validated data for small-scale and home growers to ensure the safety and improve the quality of microgreens.

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