Stability of Listeria monocytogenes in wheat flour during extended storage and isothermal treatment

Taylor, Michael H.; Tsai, Hsieh-Chin; Rasco, Barbara; Tang, Juming; Zhu, Mei‐Jun

doi:10.1016/j.foodcont.2018.04.008

Cited by 50 publications

(22 citation statements)

References 34 publications

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“…The a w was recognized as a primary factor influencing bacterial thermal resistance in La w F. The thermal resistance of Salmonella in La w F is inversely related to a w (He et al, 2013;Villa-Rojas et al, 2013;Smith et al, 2016;Xu et al, 2019;Tsai et al, 2019a). The same is true for L. monocytogenes in wheat flour (Taylor et al, 2018), cocoa powder (Tsai et al, 2019b), milk powder (Ballom et al, 2020), and almond meal in the present study. The D 75 -value of L. monocytogenes in a w 0.25 almond meal was over two times of that in a w 0.45 almond meal.…”

Section: Impacts Of Water Activity On Thermal Resistance Of L Monocysupporting

confidence: 68%

“…The previous study showed that the desiccation stability of L. monocytogenes increased in wheat flour when a w decreased from 0.56 to 0.30 (Taylor et al, 2018). Concordantly, the stability of L. monocytogenes in almond meal stored at 22 • C increased as a w decreased, but the increment was much smaller than that in wheat flour.…”

Section: Storage Temperature and Water Activitymentioning

confidence: 74%

“…While a w is an important factor in determining thermal death-time curves, food matrices have a complex relationship with bacterial survival in La w F during thermal treatments. Previous studies showed that, in general, the thermal resistance of L. monocytogenes in NFDM (Ballom et al, 2020) were higher than that in wheat flour (Taylor et al, 2018) or cocoa powder (Tsai et al, 2019b) at their respective a w and inactivation temperatures. D 75 -and D 80 -values at a w 0.45 NFDM, wheat flour, and cocoa powder were 9.4/4.3, 7.7/3.1, and 3.4/1.8 min, respectively.…”

Section: Impacts Of Food Matrix On Thermal Resistance Of L Monocytogmentioning

confidence: 93%

“…All strains were maintained at −80 • C in trypticase soy broth [Becton, Dickinson and Company (BD), Sparks, MD, United States] supplied with 0.6% yeast extract (Fisher Scientific, Fair Lawn, NJ, United States) (TSBYE) and 20% (vol/vol) glycerol in a biosafety level 2 (BSL-2) microbiology laboratory. Lawn grown of each L. monocytogenes on trypticase soy agar with 0.6% yeast extract (TSAYE) plates was collected and mixed in equal proportions to prepare the three-strain cocktail (Taylor et al, 2018;Tsai et al, 2019b).…”

Section: Bacterial Strains and Bacterial Lawn Preparationmentioning

confidence: 99%

“…Raw almonds or almond meal can be stored for more than 1 year at room, refrigerated, or frozen temperatures (Lambertini et al, 2012). L. monocytogenes can survive for months or even years in various La w F (Kenney and Beuchat, 2004;Kimber et al, 2012;Brar et al, 2015;Koseki et al, 2015;Rachon et al, 2016;Taylor et al, 2018;Tsai et al, 2019b;Ballom et al, 2020), with their survival in La w F influenced by a w , storage temperature and food composition.…”

Section: Factors Influence Desiccation Stability Of L Monocytogenes mentioning

confidence: 99%

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Listeria monocytogenes in Almond Meal: Desiccation Stability and Isothermal Inactivation

et al. 2020

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Almond are among the most consumed tree nuts and used in a variety of food products. Recent almond butter recalls due to potential contamination of Listeria monocytogenes highlight the need to control L. monocytogenes in almond products. The objectives of this study were to examine the stability of L. monocytogenes in almond meal during extended storage and analyze thermal resistance of L. monocytogenes in almond meal of controlled moisture contents or water activity (a w) using thermal death time (TDT) cells and thermal water activity (TWA) cells, respectively. L. monocytogenes maintained a stable population in almond meal for 44-48 weeks at 4 • C regardless of a w ; however, we observed about 1.69 and 2.14 log 10 colony-forming units (CFU)/g reduction of L. monocytogenes in a w 0.25 and 0.45 almond meal over 44 to 48 weeks of storage at 22 • C. Under all test conditions using either TDT or TWA cells, the inactivation kinetics of L. monocytogenes in almond meal fitted the log-linear model well; thermal resistance of L. monocytogenes in almond meal was inversely related to the a w of samples. D 75-/D 80-values of L. monocytogenes in a w 0.25 and 0.45 almond meal obtained using TDT cells were 47.6/22.0 versus 17.2/11.0 min, respectively. D 80-, D 85-, and D 90-values of L. monocytogenes in a w 0.25 almond meal obtained using TWA cells were 59.5 ± 2.1, 27.7 ± 0.7, and 13.2 ± 1.1 min, respectively, in contrast to 22.0 ± 1.1, 10.6 ± 0.2, and 4.6 ± 0.4 min obtained using TDT cells. The z-value of L. monocytogenes in a w 0.25 almond meal was not affected by TWA and TDT cell type (15.4-15.5 • C), whereas zvalue of L. monocytogenes in a w 0.45 almond meal was 10 • C higher than that in a w 0.25 almond meal. This study contributes to our understanding of L. monocytogenes in nuts and impacts of a w on the development of thermal resistance in low-moisture foods.

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Section: Impacts Of Water Activity On Thermal Resistance Of L Monocysupporting

confidence: 68%

Section: Storage Temperature and Water Activitymentioning

confidence: 74%

Section: Impacts Of Food Matrix On Thermal Resistance Of L Monocytogmentioning

confidence: 93%

Section: Bacterial Strains and Bacterial Lawn Preparationmentioning

confidence: 99%

Section: Factors Influence Desiccation Stability Of L Monocytogenes mentioning

confidence: 99%

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Listeria monocytogenes in Almond Meal: Desiccation Stability and Isothermal Inactivation

et al. 2020

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Validation of brownie baking step for controlling Salmonella and Listeria monocytogenes

Unger

Channaiah²,

Singh

et al. 2021

Food Science & Nutrition

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Pathogens, such as Salmonella and Listeria monocytogenes, can survive under the dry environment of flour for extended periods of time and could multiply when flour is hydrated to prepare batter or dough. Therefore, inactivation of these pathogens during the cooking/baking step is vital to ensure the microbiological safety of bakery products such as brownies. The aim of this research was to validate a simulated commercial baking process as a kill‐step for controlling Salmonella and L. monocytogenes in brownies and to determine thermal inactivation parameters of these pathogens in brownie batter. Independent studies were conducted in a completely randomized design for each pathogen. All‐purpose flour was inoculated with a 5‐serovar Salmonella and 3‐strain L. monocytogenes cocktails. For baking validation, brownie batters were prepared from inoculated flour, and cooked in the oven set at 350°F (176.7°C) for 40 min followed by 15 min of ambient air cooling. For calculating D‐values, brownie batter was transferred into thermal‐death‐time disks, sealed, and placed in hot‐water baths. The samples were held for pre‐determined time intervals in hot‐water baths and immediately transferred to cold‐water baths. Microbial populations were enumerated using injury‐recovery media. At the end of baking, Salmonella and L. monocytogenes populations decreased by 6.3 and 5.9 log CFU/g, respectively. D‐values of Salmonella and L. monocytogenes cocktails were 53.4 and 37.5 min at 64°C; 27.2 and 16.9 min at 68°C; 10.7 and 9.1 min at 72°C; and 4.6 and 7.3 min at 76°C; respectively. The z‐values of Salmonella and L. monocytogenes cocktails were 11.1 and 16.4°C, respectively. This study can be used as a supporting document for the validation of similar brownie baking processes to control Salmonella and L. monocytogenes. The data from this study can also be employed for developing basic prediction models for the survival and thermal resistance of these pathogens during brownie baking step.

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Current understanding and perspectives on Listeria monocytogenes in low-moisture foods

Parreira

Farber

2019

Current Opinion in Food Science

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Stability of Listeria monocytogenes in wheat flour during extended storage and isothermal treatment

Cited by 50 publications

References 34 publications

Listeria monocytogenes in Almond Meal: Desiccation Stability and Isothermal Inactivation

Listeria monocytogenes in Almond Meal: Desiccation Stability and Isothermal Inactivation

Validation of brownie baking step for controlling Salmonella and Listeria monocytogenes

Current understanding and perspectives on Listeria monocytogenes in low-moisture foods

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