Survival and thermal resistance of Salmonella in dry and hydrated nonfat dry milk and whole milk powder during extended storage

Sekhon, Amninder Singh; Singh, Arshdeep; Unger, Phoebe; Babb, Monipel; Yang, Yaeseol; Michael, Minto

doi:10.1016/j.ijfoodmicro.2020.108950

Cited by 25 publications

(11 citation statements)

References 26 publications

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“…For example, Sekhon et al. (2020) determined the thermal resistance of Salmonella cocktail (similar to this study) in nonfat dry milk and whole milk powder during the storage period of 6 months. Sekhon et al.…”

Section: Resultsmentioning

confidence: 66%

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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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Section: Resultsmentioning

confidence: 66%

“…Sekhon et al. (2020) reported that although the thermal resistance of Salmonella cocktail in whole milk powder (higher fat content) and nonfat dry milk was similar at the start of the storage, the thermal resistance of Salmonella increased during the storage period in whole milk powder but stayed similar in nonfat dry milk.…”

Section: Resultsmentioning

confidence: 99%

Validation of brownie baking step for controlling Salmonella and Listeria monocytogenes

Unger

Channaiah²,

Singh

et al. 2021

Food Science & Nutrition

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“…During these process conditions, Salmonella is able to induce cross-resistance and prolong its survival in the food production chain (Gruzdev et al, 2011). Previous research has emphasized that storage conditions of LMFs, including storage time (Blessington et al, 2013;Sekhon et al, 2021), ambient temperature (Sirsat et al, 2011), and humidity (Keller et al, 2013), also have a critical influence on the long-term survival of Salmonella. Moreover, divergent responses of Salmonella to desiccation storage have been shown in foods with different nutritional or component content.…”

Section: Open Accessmentioning

confidence: 99%

Metabolomics-based response of Salmonella to desiccation stress and skimmed milk powder storage

Chen²,

Zeng³

et al. 2023

Front. Microbiol.

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The strong survival ability of Salmonella in low-moisture foods (LMFs) has been of public concern, and is considered a threat to people’s health. Recently, the development of omics technology has promoted research on the molecular mechanisms of the desiccation stress response of pathogenic bacteria. However, multiple analytical aspects related to their physiological characteristics remain unclear. We explored the physiological metabolism changes of S. enterica Enteritidis exposed to a 24 h-desiccation treatment and a subsequent 3-month desiccation storage in skimmed milk powder (SMP) with an approach of gas chromatography–mass spectrometry (GC–MS) and ultra-performance liquid chromatography-Q Exactive-mass spectrometry (UPLC-QE-MS). A total of 8,292 peaks were extracted, of which 381 were detected by GC–MS and 7,911 peaks were identified by LC–MS/MS, respectively. Through analyses of differentially expressed metabolites (DEMs) and key pathways, a total of 58 DEMs emerged from the 24 h-desiccation treatment, which exhibited the highest relevance for five metabolic pathways, involving glycine, serine, and threonine metabolism, pyrimidine metabolism, purine metabolism, vitamin B6 metabolism, and pentose phosphate pathway. After 3-month SMP storage, 120 DEMs were identified, which were related to several regulatory pathways including arginine and proline metabolism, serine and threonine metabolism, β-alanine metabolism, glycerolipid metabolism, and glycolysis. The analyses of key enzyme activities of XOD, PK, and G6PDH and ATP content provided further evidence that supported the metabolic responses such as nucleic acid degradation, glycolysis, and ATP production played an important role in Salmonella’s adaptation to desiccation stress. This study enables a better understanding of metabolomics-based responses of Salmonella at the initial stage of desiccation stress and the following long-term adaptive stage. Meanwhile, the identified discriminative metabolic pathways may serve as potentially useful targets in developing strategies for the control and prevention of desiccation-adapted Salmonella in LMFs.

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“…However, there was no significant difference in the reduction in survival of the WT strain after storage in the three substrates (p > .05), suggesting that the survival of this strain was affected by food composition in the early stage of drying but not during storage. In this respect, a study compared the survival rate of Salmonella in nonfat and whole milk powder and found that food composition had no significant effect on survival during storage (Sekhon et al, 2021). In addition, the reduction in survival of both strains during drying was significantly higher than that during storage (p < .05), indicating that the stress resistance of S. Enteritidis during storage was stronger than that during drying, and its main stress resistance mechanism between the two periods may be different.…”

Section: Bacterial Survival In Low a W Food Substratesmentioning

confidence: 99%

Effect of rpoS on the survival and gene expression of Salmonella Enteritidis in low water activity foods

et al. 2023

Journal of Food Safety

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This study evaluated the effect of the transcriptional regulator RpoS on bacterial survival, tolerance to simulated gastrointestinal conditions, and the expression of stress resistance genes in wild‐type (WT) and rpoS‐deletion (ΔrpoS) Salmonella Enteritidis CICC 21482 in low water activity (Aw) foods at 24 hr of drying and 7 days of storage. The ΔrpoS strain was produced by allelic exchange using a suicide plasmid. Bacteria were inoculated into ginger powder, nonfat milk powder, and chocolate powder in the presence of simulated gastric and intestinal fluids, and survival was measured. Gene expression was measured using real‐time quantitative polymerase chain reaction. The ΔrpoS strain was less resistant to desiccation stress than the WT strain. The bacterial tolerance to gastrointestinal conditions varied depending on food composition, and high‐fat and protein content enhanced the survival of S. Enteritidis in the gastrointestinal conditions. In addition, under low Aw conditions, rpoS was weakly correlated with the expression of fadA but strongly correlated with the expression of grpE, otsA, otsB, dnaK, proV, rpoH, and sigDE in food substrates. This study elucidates the role of rpoS in desiccation stress and serves as the basis for preventing and controlling Salmonella contamination in low Aw foods.

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Survival and thermal resistance of Salmonella in dry and hydrated nonfat dry milk and whole milk powder during extended storage

Cited by 25 publications

References 26 publications

Validation of brownie baking step for controlling Salmonella and Listeria monocytogenes

Validation of brownie baking step for controlling Salmonella and Listeria monocytogenes

Metabolomics-based response of Salmonella to desiccation stress and skimmed milk powder storage

Effect of rpoS on the survival and gene expression of Salmonella Enteritidis in low water activity foods

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