Irradiance and Temperature Influence the Bactericidal Effect of 460-Nanometer Light-Emitting Diodes on Salmonella in Orange Juice

2016 ◽  
Vol 79 (4) ◽  
pp. 553-560 ◽  
Author(s):  
VINAYAK GHATE ◽  
AMIT KUMAR ◽  
WEIBIAO ZHOU ◽  
HYUN-GYUN YUK
Keyword(s):  
Orange Juice ◽  
Pathogenic Bacteria ◽  
Light Emitting Diodes ◽  
Antibacterial Effect ◽  
Weibull Model ◽  
Bactericidal Effect ◽  
Inactivation Kinetics ◽  
Light Emitting ◽  
Color Changes ◽  
D Values

ABSTRACT Blue light-emitting diodes (LEDs) have been known to produce an antibacterial effect on various pathogenic bacteria. To extend this application to foods, blue 460-nm LEDs were evaluated for their antibacterial effect on Salmonella in orange juice. A cocktail of Salmonella enterica serovars Gaminara, Montevideo, Newport, Typhimurium, and Saintpaul was inoculated into pasteurized orange juice and illuminated with 460-nm LEDs at irradiances of 92, 147.7, and 254.7 mW/cm2 and temperatures of 4, 12, and 20°C. Subsequently, linear, Weibull, and Gompertz models were fitted to the resultant survival curves. The color of the orange juice during illumination was also monitored. It was observed that irradiance and temperature both influenced the inactivation of Salmonella, which ranged from 2 to 5 log CFU/ml. The inactivation kinetics was best described by the Weibull model. An irradiance of 92 mW/cm2 and temperatures of 12 and 20°C were the most bactericidal combinations, with D-values of 1,580 and 2,013 J/cm2, respectively. Significant color changes were also observed after illumination; these changes could be minimized by choosing appropriate irradiance and temperature. These results demonstrate the potential of 460-nm LEDs for the preservation of fruit juices in the retail markets and their utility in minimizing the risk of salmonellosis.

Thermal Inactivation of Human Norovirus Surrogates in Spinach and Measurement of Its Uncertainty

2014 ◽  
Vol 77 (2) ◽  
pp. 276-283 ◽  
Author(s):  
HAYRIYE BOZKURT ◽  
DORIS H. D'SOUZA ◽  
P. MICHAEL DAVIDSON
Keyword(s):  
Thermal Inactivation ◽  
Weibull Model ◽  
Inactivation Kinetics ◽  
Murine Norovirus ◽  
Order Model ◽  
Human Norovirus ◽  
Test Volume ◽  
Total Uncertainty ◽  
First Order ◽  
D Values

Leafy greens, including spinach, have potential for human norovirus transmission through improper handling and/or contact with contaminated water. Inactivation of norovirus prior to consumption is essential to protect public health. Because of the inability to propagate human noroviruses in vitro, murine norovirus (MNV-1) and feline calicivirus (FCV-F9) have been used as surrogates to model human norovirus behavior under laboratory conditions. The objectives of this study were to determine thermal inactivation kinetics of MNV-1 and FCV-F9 in spinach, compare first-order and Weibull models, and measure the uncertainty associated with the process. D-values were determined for viruses at 50, 56, 60, 65, and 72°C in 2-ml vials. The D-values calculated from the first-order model (50 to 72°C) ranged from 0.16 to 14.57 min for MNV-1 and 0.15 to 17.39 min for FCV-9. Using the Weibull model, the tD for MNV-1 and FCV-F9 to destroy 1 log (D = 1) at the same temperatures ranged from 0.22 to 15.26 and 0.27 to 20.71 min, respectively. The z-values determined for MNV-1 were 11.66 ± 0.42°C using the Weibull model and 10.98 ± 0.58°C for the first-order model and for FCV-F9 were 10.85 ± 0.67°C and 9.89 ± 0.79°C, respectively. There was no difference in D- or z-value using the two models (P >0.05). Relative uncertainty for dilution factor, personal counting, and test volume were 0.005, 0.0004, and ca. 0.84%, respectively. The major contribution to total uncertainty was from the model selected. Total uncertainties for FCV-F9 for the Weibull and first-order models were 3.53 to 7.56% and 11.99 to 21.01%, respectively, and for MNV-1, 3.10 to 7.01% and 13.14 to 16.94%, respectively. Novel and precise information on thermal inactivation of human norovirus surrogates in spinach was generated, enabling more reliable thermal process calculations to control noroviruses. The results of this study may be useful to the frozen food industry in designing blanching processes for spinach to inactivate or control noroviruses.

Thermal Inactivation Kinetics of Sporolactobacillus nakayamae Spores, a Spoilage Bacterium Isolated from a Model Mashed Potato–Scallion Mixture

2016 ◽  
Vol 79 (9) ◽  
pp. 1482-1489
Author(s):  
HAYRIYE BOZKURT ◽  
JAIRUS R. D. DAVID ◽  
RYAN J. TALLEY ◽  
D. SCOTT LINEBACK ◽  
P. MICHAEL DAVIDSON
Keyword(s):  
Heat Resistance ◽  
Thermal Inactivation ◽  
Weibull Model ◽  
Inactivation Kinetics ◽  
Order Model ◽  
First Order ◽  
Different Temperatures ◽  
Spoilage Bacterium ◽  
D Values ◽  
Kinetics Of

ABSTRACT Sporolactobacillus species have been occasionally isolated from spoiled foods and environmental sources. Thus, food processors should be aware of their potential presence and characteristics. In this study, the heat resistance and influence of the growth and recovery media on apparent heat resistance of Sporolactobacillus nakayamae spores were studied and described mathematically. For each medium, survivor curves and thermal death curves were generated for different treatment times (0 to 25 min) at different temperatures (70, 75, and 80°C) and Weibull and first-order models were compared. Thermal inactivation data for S. nakayamae spores varied widely depending on the media formulations used, with glucose yeast peptone consistently yielding the highest D-values for the three temperatures tested. For this same medium, the D-values ranged from 25.24 ± 1.57 to 3.45 ± 0.27 min for the first-order model and from 24.18 ± 0.62 to 3.50 ± 0.24 min for the Weibull model at 70 and 80°C, respectively. The z-values determined for S. nakayamae spores were 11.91 ± 0.29°C for the Weibull model and 11.58 ± 0.43°C for the first-order model. The calculated activation energy was 200.5 ± 7.3 kJ/mol for the first-order model and 192.8 ± 22.1 kJ/mol for the Weibull model. The Weibull model consistently produced the best fit for all the survival curves. This study provides novel and precise information on thermal inactivation kinetics of S. nakayamae spores that will enable reliable thermal process calculations for eliminating this spoilage bacterium.

scholarly journals Alicyclobacillus acidoterrestris Strain Variability in the Inactivation Kinetics of Spores in Orange Juice by Temperature-Assisted High Hydrostatic Pressure

2020 ◽  
Vol 10 (21) ◽  
pp. 7542
Author(s):  
Patra Sourri ◽  
Anthoula A. Argyri ◽  
Efstathios Z. Panagou ◽  
George-John E. Nychas ◽  
Chrysoula C. Tassou
Keyword(s):  
High Pressure ◽  
Hydrostatic Pressure ◽  
Orange Juice ◽  
High Hydrostatic Pressure ◽  
Reference Strain ◽  
Wild Type Strain ◽  
Weibull Model ◽  
Inactivation Kinetics ◽  
High Pressure Level ◽  
Kinetics Of

In this work, the inactivation kinetics of Alicyclobacillus acidoterrestris spores by temperature-assisted high hydrostatic pressure was assessed by means of the Weibull model. Spores from two A. acidoterrestris strains (a wild-type strain and a reference strain) were inoculated in commercial orange juice and subjected to high pressure levels (500 and 600 MPa) combined with four temperature regimes (25, 45, 60 and 70 °C) for time up to 30 min. Results showed that for a given high-pressure level spore inactivation was higher as temperature progressively increased. Furthermore, the Weibull model consistently produced satisfactory fit to the inactivation data based on the values of the root mean squared error (RMSE < 0.54 log colony-forming units (CFU)/mL) and the coefficient of determination (R2 > 0.90 in most cases). The shape of inactivation curves was concave upward (p < 1) for all temperature/high pressure levels tested, indicating rapid inactivation of the sensitive cells of the bacterium whereas the remaining ones adapted to high hydrostatic pressure (HHP) treatment. The values of the shape (p) and scale (δ) parameters of the Weibull model were dependent on the applied temperature for a given high pressure level and they were further described in a secondary model using first-order fitting curves to provide predictions of the surviving spore population at 55 and 65 °C. Results revealed a systematic over-prediction for the wild-type strain regardless of temperature and high pressure applied, whereas for the reference strain under-prediction was evident after 3 log-cycles reduction of the surviving bacteria spores. Overall, the results obtained indicate that the effectiveness of high hydrostatic pressure against A. acidoterrestris spores is strain-dependent and also underline the need for temperature-assisted HPP for effective spore inactivation during orange juice processing.

Effects of ultraviolet-C light-emitting diodes at 275 nm on inactivation of Alicyclobacillusacidoterrestris vegetative cells and its spores as well as the quality attributes of orange juice

2020 ◽  
pp. 108201322095752 ◽  
Author(s):  
Yafei Zhai ◽  
Jiali Tian ◽  
Ruonan Ping ◽  
Hongxia Xiu ◽  
Qisen Xiang ◽  
...  
Keyword(s):  
Orange Juice ◽  
Light Emitting Diodes ◽  
Light Emitting Diode ◽  
Titratable Acidity ◽  
Quality Attributes ◽  
Soluble Solids ◽  
Total Phenolic ◽  
Vegetative Cells ◽  
Light Emitting ◽  
Ultraviolet C

Alicyclobacillus acidoterrestris is a thermoacidophilic, spore-forming bacillus. A. acidoterrestris and its spores can survive in pasteurized juices and cause microbial spoilage. In this work, the effects of ultraviolet-C light-emitting diodes at 275 nm on the inactivation of A. acidoterrestris vegetative cells and its spores in commercial pasteurized orange juice were studied. Meanwhile, the effects of ultraviolet-C light-emitting diodes on the quality attributes of the orange juice were also investigated. The quantities of A. acidoterrestris vegetative cells and its spores inoculated in orange juice were reduced by 6.04 and 2.49 log10 CFU/mL after ultraviolet-C light-emitting diode treatment at 220 mJ/cm2, respectively. The Weibull and Weibull plus tail models were satisfactorily fitted to estimate the reductions of A. acidoterrestris vegetative cells and its spores in orange juice, respectively. Physicochemical properties (pH, titratable acidity, total soluble solids, and clarity) of orange juice did not change significantly after exposure to ultraviolet-C light-emitting diodes. However, the total phenolic content of orange juice decreased with increasing fluence. In addition, ultraviolet-C light-emitting diode treatment at a higher fluence led to a noticeable color difference. These results indicate that ultraviolet-C light-emitting diode treatment has a potential application in the juice processing industry.

Inactivation Kinetics of Pathogens during Thermal Processing in Acidified Broth and Tomato Purée (pH 4.5)

2017 ◽  
Vol 80 (12) ◽  
pp. 2014-2021 ◽  
Author(s):  
Evann L. Dufort ◽  
Jonathan Sogin ◽  
Mark R. Etzel ◽  
Barbara H. Ingham
Keyword(s):  
Thermal Inactivation ◽  
Weibull Model ◽  
Inactivation Kinetics ◽  
E Coli ◽  
Log Reduction ◽  
Tomato Puree ◽  
Weibull Models ◽  
Canned Foods ◽  
D Values ◽  
Log Linear

ABSTRACT Thermal inactivation kinetics for single strains of Shiga toxin–producing Escherichia coli (STEC), Listeria monocytogenes, and Salmonella enterica were measured in acidified tryptic soy broth (TSB; pH 4.5) heated at 54°C. Inactivation curves also were measured for single-pathogen five-strain cocktails of E. coli O157:H7, L. monocytogenes, and S. enterica heated in tomato purée (pH 4.5) at 52, 54, 56, and 58°C. Inactivation curves were fit using log-linear and nonlinear (Weibull) models. The Weibull model yields the time for a 5-log reduction (t*) and a curve shape parameter (β). Decimal reduction times (D-values) and thermal resistance constants (z-values) from the two models were compared by defining t* = 5D* for the Weibull model. When the log-linear and Weibull models match at the 5-log reduction time, then t* = 5D* = 5D and D = D*. In 18 of 20 strains heated in acidified TSB, D and D* for the two models were not significantly different, although nonlinearity was observed in 35 of 60 trials. Similarly, in 51 of 52 trials for pathogen cocktails heated in tomato purée, D and D* were not significantly different, although nonlinearity was observed in 31% of trials. At a given temperature, D-values for S. enterica &lt;&lt; L. monocytogenes &lt; E. coli O157:H7 in tomato purée (pH 4.5). When using the two models, z-values calculated from the D-values were not significantly different for a given pathogen. Across all pathogens, z-values for E. coli O157:H7 and S. enterica were not different but were significantly lower than the z-values for L. monocytogenes. These results are useful for supporting process filings for tomato-based acidified food products with pH 4.5 and below and are relevant to small processors of tomato-based acidified canned foods who do not have the resources to conduct research on and validate pathogen lethality.

Antimicrobial effect of UVC light-emitting diodes against Saccharomyces cerevisiae and its application in orange juice decontamination

2020 ◽  
Author(s):  
Liyuan Niu ◽  
Zihao Wu ◽  
Lanrui Yang ◽  
Yanqiu Wang ◽  
Qisen Xiang ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Radiation Dose ◽  
Orange Juice ◽  
Light Emitting Diodes ◽  
Membrane Damage ◽  
Antimicrobial Effect ◽  
Soluble Solids ◽  
Total Phenolic ◽  
Light Emitting ◽  
Spoilage Yeast

UVC light-emitting diodes (UVC-LEDs) is a novel eco-friendly alternative source of UV light. This study evaluated inactivation and membrane damage of spoilage yeast Saccharomyces cerevisiae by UVC-LEDs and its application in orange juice pasteurization. The results demonstrated that the antimicrobial effect of UVC-LED treatment against S. cerevisiae enhanced with the increase of radiation dose. When the dose of UVC-LED radiation was up to 1420 mJ/cm 2 , the population of S. cerevisiae in YPD broth was reduced by 4.86 log 10 CFU/mL. Through scanning electron microscope and fluorescent staining approaches, the structure and function of plasma membrane was observed severely damaged by UVC-LED treatment. The inactivation efficacy of UVC-LEDs against S. cerevisiae in orange juice also increased with increasing radiation dose. Radiation at dose of 1420 mJ/cm 2 highly reduced the number of S. cerevisiae in orange juice by 4.44 log 10 CFU/mL and did not induce remarkable changes in pH, total soluble solids, titratable acidity, and color parameters. However, total phenolic content in orange juice was found significantly decreased by UVC-LEDs. These findings contribute to a better comprehension of UVC-LED inactivation and provide theoretical support for its potential application in fruit and vegetable juices processing.

Determination of the Thermal Inactivation Kinetics of the Human Norovirus Surrogates, Murine Norovirus and Feline Calicivirus

2013 ◽  
Vol 76 (1) ◽  
pp. 79-84 ◽  
Author(s):  
HAYRIYE BOZKURT ◽  
DORIS H. D'SOUZA ◽  
P. MICHAEL DAVIDSON
Keyword(s):  
Thermal Inactivation ◽  
Weibull Model ◽  
Inactivation Kinetics ◽  
Feline Calicivirus ◽  
Murine Norovirus ◽  
Order Model ◽  
Human Norovirus ◽  
First Order ◽  
D Values ◽  
Kinetics Of

Studies are needed to bridge existing data gaps and determine appropriate parameters for thermal inactivation methods for human noroviruses. Cultivable surrogates, such as feline calicivirus (FCV-F9) and murine norovirus (MNV-1), have been used in the absence of human norovirus infectivity assays. This study aimed to characterize the thermal inactivation kinetics of MNV-1 and FCV-F9 at 50, 56, 60, 65, and 72°C for different treatment times (0 to 60 min). Thermal inactivation was performed using the capillary tube method with titers of 4.0 × 107 (MNV-1) and 5.8 × 108 (FCV-F9) PFU/ml in triplicate experiments, followed by standard plaque assays in duplicate for each experiment. Weibull and first-order models were compared to describe survival curve kinetics. Model fitness was investigated by comparing the regression coefficients (R2) and the chi-square (χ2) and root mean square error (RMSE) values. The D-values calculated from the first-order model (50 to 72°C) were 0.15 to 34.49 min for MNV-1 and 0.11 to 20.23 min for FCV-9. Using the Weibull model, the tD values needed to destroy 1 log PFU of MNV-1 and FCV-F9 at the same temperatures were 0.11 to 28.26 and 0.06 to 13.86 min, respectively. In terms of thermal resistance, MNV-1 was more sensitive than FCV-F9 up to 65°C. At 72°C, FCV-F9 was slightly more susceptible to heat inactivation. Results revealed that the Weibull model was more appropriate to represent the thermal inactivation behavior of both tested surrogates. The z-values were calculated using D-values for the first-order model and the tD values for the Weibull model. The z-values were 9.31 and 9.19°C for MNV-1 and 9.36 and 9.31°C for FCV-F9 for the first-order and Weibull models, respectively. This study provides more precise information than previous reports on the thermal inactivation kinetics of two norovirus surrogates for use in thermal process calculations.

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