Survival and thermal resistance among four Salmonella serovars inoculated onto flaxseeds

• Published in: Food microbiology Vol. 91; p. 103516
• Main Authors: Malekmohammadi, Sahar, Shah, Manoj K., Townsend Ramsett, Megan K., Bergholz, Teresa M.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.10.2020
• Subjects: Colony Count, Microbial; Flax - chemistry; Flax - microbiology; Flaxseed; Food Microbiology; Food Storage; Hot Temperature; Microbial Viability; Pasteurization; Salmonella; Salmonella - classification; Salmonella - physiology; Serogroup; Species Specificity; Steam; Thermal inactivation; Thermotolerance; Vacuum; Vacuum steam pasteurization; Water - analysis; Salmonella; Flaxseed; Vacuum steam pasteurization; Thermal inactivation
• ISSN: 0740-0020; 1095-9998
• DOI: 10.1016/j.fm.2020.103516

Thermal resistance among Salmonella serovars has been shown to vary, however, such data are minimal for Salmonella inoculated onto low moisture foods. We evaluated survival and subsequent thermal resistance for 32 strains of Salmonella from four serovars (Agona, Enteritidis, Montevideo, and Tennessee) on flaxseed over 24 weeks. After inoculation, flaxseeds were adjusted to aw = 0.5 and stored at 22 °C. After 24 weeks at 22 °C, strains of serovar Agona had a significantly slower rate of reduction compared to those of Enteritidis and Montevideo (adj. p < 0.05). Inoculated flaxseeds were processed at 71 °C with vacuum steam pasteurization at 4 time points during storage. Average initial D71°C values ranging from 1.0 to 1.5 min were similar across serovars. Over 24 weeks, D71°C varied in a serovar-dependent manner. D71°C at 8, 16, and 24 weeks did not change significantly for Enteritidis and Montevideo but did for Tennessee and Agona. While significant, the differences in D71°C over time were less than 1 min, indicating that storage time prior to heat treatment would have a minimal effect on the processing time required to inactivate Salmonella on flaxseed. •Salmonella survival rates on flaxseed at 22 °C over 24 weeks were serovar dependent.•D71°C for serovars Enteritidis and Tennessee on flaxseeds were similar over time.•D71°C for Agona were significantly higher than Enteritidis after 24 weeks storage.