Thermal Inactivation of Salmonella Enteritidis PT 30 in Almond Kernels as Influenced by Water Activity

Villa-Rojas, Rossana; Tang, Juming; Wang, Shaojin; Gao, Mengxiang; Kang, Dong‐Hyun; Mah, Jae-Hyung; Gray, Peter; Sosa‐Morales, María Elena; López‐Malo, Aurelio

doi:10.4315/0362-028x.jfp-11-509

Cited by 138 publications

(66 citation statements)

References 38 publications

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“…The sample core temperatures reached the set-point quickly, resulting in the similar come-up times of 20 s for three temperatures and providing close to ideal isothermal conditions. This come-up time was similar to that of mashed potato in a capillary tube (Chung et al, 2008), but shorter than those of mashed potato in glass tubes and of almond kernels in the same cell (Villa-Rojas et al, 2013) caused by poor heat conduction in solid materials. After short coming up times, the initial reduction of E. coli was negligible based on small intercepts of the linear regression equations.…”

Section: Heat Resistance Of E Coli At Three Temperaturesmentioning

confidence: 54%

“…This test cell is designed for rapid heating of dry samples in water baths and allows easy loading and unloading of samples in a hermetically sealed cavity to evaluate the thermal resistance of vegetative cells and spores. This test cell has been successfully used to determine the D-and z-values of Salmonella, E. coli K12, and Clostridium sporogenes PA 3679 spores in liquid eggs, almonds, phosphate buffer and mashed potato (Chung et al, 2008;Jin et al, 2008;Villa-Rojas et al, 2013 …”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Thermo-tolerance and heat shock protein of Escherichia coli ATCC 25922 under thermal stress using test cell method

Ya-ge

Ling

et al. 2017

Emir. J. Food Agric

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Section: Heat Resistance Of E Coli At Three Temperaturesmentioning

confidence: 54%

Section: Introductionmentioning

confidence: 99%

Thermo-tolerance and heat shock protein of Escherichia coli ATCC 25922 under thermal stress using test cell method

Ya-ge

Ling

et al. 2017

Emir. J. Food Agric

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“…Tolerance of Salmonella Enteritidis to heat and hypochlorite stress has been reported as higher for cells grown at reduced a w (e.g., a w~0 .94) (25). Increased process times and/or elevated temperatures are necessary to kill Salmonella in a variety of low-a w products, including almond kernels, rawhide, and alfalfa seeds (5,8,42). Future studies should consider crossprotection, the physiological state of the pathogen cells, and inoculation methods when designing validation studies to assure inactivation of the most resistant Salmonella strains.…”

Section: Discussionmentioning

confidence: 99%

Inoculation Preparation Affects Survival of Salmonella enterica on Whole Black Peppercorns and Cumin Seeds Stored at Low Water Activity

Bowman

Waterman

Williams

et al. 2015

Journal of Food Protection

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Salmonellosis has been increasingly associated with contaminated spices. Identifying inoculation and stabilization methods for Salmonella on whole spices is important for development of validated inactivation processes. The objective of this study was to examine the effects of inoculation preparation on the recoverability of Salmonella enterica from dried whole peppercorns and cumin seeds. Whole black peppercorns and cumin seeds were inoculated with S. enterica using one dry transfer method and various wet inoculation methods: immersion of spice seeds in tryptic soy broth (TSB) plus Salmonella for 24 h (likely leading to inclusion of Salmonella in native microbiota biofilms formed around the seeds), application of cells grown in TSB, and/or application of cells scraped from tryptic soy agar (TSA). Postinoculation seeds were dried to a water activity of 0.3 within 24 h and held for 28 days. Seeds were sampled after drying (time 0) and periodically during the 28 days of storage. Salmonella cells were enumerated by serial dilution and plated onto xylose lysine Tergitol (XLT4) agar and TSA. Recovery of Salmonella was high after 28 days of storage but was dependent on inoculation method, with 4.05 to 6.22 and 3.75 to 8.38 log CFU/g recovered from peppercorns and cumin seeds, respectively, on XLT4 agar. The changes in surviving Salmonella (log CFU per gram) from initial inoculation levels after 28 days were significantly smaller for the biofilm inclusion method (z0.142 pepper , z0.186 cumin ) than for the other inoculation methods (20.425 pepper , 22.029 cumin for cells grown on TSA; 20.641 pepper , 20.718 cumin for dry transfer; 21.998 pepper for cells grown in TSB). In most cases, trends for reductions of total aerobic bacteria were similar to those of Salmonella. The inoculation method influenced the recoverability of Salmonella from whole peppercorns and cumin seeds after drying. The most stable inoculum strategies were dry transfer, 24-h incubation of Salmonella and spices in TSB (i.e., potential inclusion of Salmonella within native microbiota biofilms), and inoculation of Salmonella cells grown on TSA subsequent to drying. However, with the dry transfer method it was difficult to obtain the large amount of inoculum needed for inactivation studies.

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“…There were also studies with capillary tubes using water bath for apple juice 12 , and glass vials with an oven-heated sand bath for crushed cocoa bean and hazelnut shells to determine the bacteria's thermo-tolerance 13 . Although these devices are common tools with water or oil bath for characterizing heat-resistant bacterial spores in foods, various thermo-tolerances of the same bacatria have been frequently reported from different heating methods 4,6,[14][15][16]18 developed a new apparatus to control sample surface temperatures during rapid heating and cooling cycles. This system used hot air and steam as the heating medium to provide a fast "dry" or "wet" heat treatment to a single food sample by setting a starting temperature, end temperature, heating time, hold time and cooling time by a user-friendly software…”

Section: Knowledge Of Bacteria's Heat Resistance Is Essential For Devmentioning

confidence: 99%

Performance of a heating block system designed for studying the heat resistance of bacteria in foods

Kou¹,

Li²,

Wang³

2016

2016 ASABE International Meeting

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Knowledge of bacteria's heat resistance is essential for developing effective thermal treatments.Choosing an appropriate test method is important to accurately determine bacteria's heat resistances. Although being a major factor to influence the thermo-tolerance of bacteria, the heating rate in samples cannot be controlled in water or oil bath methods due to main dependence on sample's thermal properties. A heating block system (HBS) was designed to regulate the heating rates in liquid, semi-solid and solid foods using a temperature controller. Distilled water, apple juice, mashed potato, almond powder and beef were selected to evaluate the HBS's performance by experiment and computer simulation. The results showed that the heating rates of 1, 5 and 10 °C/min with final set-point temperatures and holding times could be easily and precisely achieved in five selected food materials. A good agreement in sample central temperature profiles was obtained under various heating rates between experiment and simulation. The experimental and simulated results showed that the HBS could provide a sufficiently uniform heating environment in food samples. The effect of heating rate on bacterial thermal resistance was evaluated with the HBS. The system may hold potential applications for rapid and accurate assessments of bacteria's thermo-tolerances.Knowledge of bacteria's heat resistance is of great importance in developing effective food processing methods. Selection of appropriate heating parameters can effectively reduce the target microorganism populations while achieving minimal thermal impacts on food quality. In addition to growth temperatures, stages of growth, bacterial strains, sample compositions, and the pH of the heating medium, heat resistance of bacteria is mainly affected by final temperature, holding time and heating rate 1-3 . Thermal death time (TDT) test is a common method to determine the heat resistance of bacteria 1,[4][5][6][7] . The device used for those TDT tests needs to meet the basic requirements, such as precisely controlled sample temperatures, a short come-up time (CUT) to avoid thermal adaptation of bacteria, and isothermal conditions for uniform sample temperature distributions 5 . Therefore, choosing an appropriate test method is important to obtain accurate determination of bacteria's heat resistance.There have been many studies on TDT test devices in foods. Odlaug et al. 8 used aluminum tubes in a miniature retort system to study thermal destruction of Clostridium botulinum spores in tomato juice. Gaze et al. 9 placed samples of ground meat in 0.5-to 1-mm thick sterile bags, and then immerged them in a shaking water bath. Kotrola et al.10 placed turkey meat samples into a TDT sealed tube heated by a shaking oil bath. Chung et al.11 designed an aluminum test cell heated in oil bath for determining the heat resistance of Clostridium sporogenes in selected foods. There were also studies with capillary tubes using water bath for apple juice 12 , and glass vials with an oven-heated sand bat...

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Thermal Inactivation of Salmonella Enteritidis PT 30 in Almond Kernels as Influenced by Water Activity

Cited by 138 publications

References 38 publications

Thermo-tolerance and heat shock protein of Escherichia coli ATCC 25922 under thermal stress using test cell method

Thermo-tolerance and heat shock protein of Escherichia coli ATCC 25922 under thermal stress using test cell method

Inoculation Preparation Affects Survival of Salmonella enterica on Whole Black Peppercorns and Cumin Seeds Stored at Low Water Activity

Performance of a heating block system designed for studying the heat resistance of bacteria in foods

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