Salmonella and Campylobacter are major foodborne pathogens that cause outbreaks associated with contaminated chicken liver. Proper cooking is necessary to avoid the risk of illness to consumers. This study tested the thermal inactivation of a 4-strain Salmonella cocktail and a 3-strain Campylobacter cocktail in chicken livers separately at temperatures ranging from 55.0 to 62.5°C. Inoculated livers were sealed in aluminum cells and immersed in a water bath. The decimal reduction time (D-values) of Salmonella in chicken livers were 9.01, 2.36, 0.82, and 0.23 min at 55.0, 57.5, 60.0, and 62.5°C, respectively. The D-values of Campylobacter ranged from 2.22 min at 55.0°C to 0.19 min at 60.0°C. Salmonella and Campylobacter had similar z-values in chicken livers of 4.8 and 4.6°C, respectively. Chicken livers can be heated to internal temperatures of 70.0 to 73.9°C for at least 1.6 to 0.2 s to achieve a 7-log reduction of Salmonella. Validation tests demonstrated that heating chicken livers to internal temperatures of 70.0 to 73.9°C for 2 to 0 s resulted in a reduction of Salmonella exceeding 7 logs. Collectively, these data show that Salmonella exhibits higher heat resistance than Campylobacter in chicken livers. Therefore, Salmonella could be considered as the target pathogen when designing thermal treatments or cooking instructions for liver products. These findings will aid in designing effective thermal processing for both industrial and home cooking to eliminate Salmonella and Campylobacter, ensuring consumer safety when consuming chicken liver products.

The objective of this study was to identify a suitable surrogate for E. coli O157:H7 strain 19685/91 and O113:H21 strain TS18/08, by assessing their thermal resistance at temperatures of 60 °C, 65 °C, and 72 °C in strawberry nectar. The influence of the matrix and the research methodology on the decimal reduction time (D-value) was investigated. Thermal kinetics and safety assessment demonstrated that E. coli ATCC 8739 is a suitable surrogate. The study demonstrated that the presence of fruit particles in the nectar increased thermal resistance of the tested strains. Variations in D-values were observed depending on the research method employed, with D-values in glass capillaries were up to 6.6 times lower compared to larger sample volumes. Encapsulation of E. coli ATCC 8739 exhibited high efficiency of 90.25 ± 0.26% and maintained stable viable counts after 26 days of storage in strawberry nectar at 4 °C. There were no significant differences in thermal resistance between surrogates directly inoculated into strawberry nectar and those encapsulated in alginate beads. Additionally, the encapsulated strains did not migrate outside the beads. Therefore, encapsulated E. coli ATCC 8739 in alginate beads can be effectively utilized in industrial settings to validate thermal treatments as a reliable and safe method.

Far-ultraviolet C (UVC) light has demonstrated its ability to inactivate microbes on surfaces. However, the factors influencing the efficacy of far-UVC surface disinfection remain unclear. This study aimed to explore the effects of material properties on far-UVC disinfection of bioaerosols (represented by Escherichia coli (E. coli)) deposited on surfaces. The susceptibility constants (Z-values) of E. coli on 14 common materials were measured and analyzed. Additionally, five possible influencing factors (roughness, pores, electrostatic charge, wetness, and temperature) related to surface properties were investigated by control experiments. The results show that far-UVC light effectively disinfected E. coli on the 14 materials, with disinfection efficiencies ranging from 69.1% to 98.9% under a dose of 100.8 J/m2. Surface roughness and electrostatic charges had negligible influence on far-UVC disinfection of E. coli on surfaces. However, for porous materials, pore sizes larger than the E. coli size resulted in lower Z-values. Higher surface wetness decreased both the Z-value and natural decay rate. Meanwhile, a higher surface temperature of 40 °C resulted in a higher Z-value and natural decay rate. The results can improve our understanding of far-UVC disinfection of microbes on surfaces, and the database can be used for numerical models.

Adequate surrogate identification is critical for validating in-plant thermal process controls for Salmonella inactivation in different food matrices. This study compared the thermal inactivation parameters (D- and z-values) and evaluated the heat resistance of Enterococcus faecium (8459) as a surrogate for a 5-serovar Salmonella cocktail in cornmeal. The cornmeal was spray inoculated with the respective bacteria to achieve ~9 log CFU/g population and set to the desired moisture contents (16, 22, and 28% w.b.). The inoculated cornmeal was then heat-treated at pre-determined temperatures (60, 64, and 68 °C) in sealed aluminum thermal-death-time disks in hot water baths for pre-determined time intervals. Injury-recovery media [brain heart infusion (BHI) agar overlaid with xylose lysine deoxycholate (XLD) agar for Salmonella or BHI agar overlaid m-enterococcus agar for E. faecium] were used for microbial enumeration to account for thermally injured bacterial cells. The D-values of Salmonella in cornmeal at 16, 22, and 28% moisture content were 37.5, 8.4, and 2.4 min at 60 °C, 19.9, 3.5, and 1.1 min at 64 °C, and 10.1, 1.4, and 0.5 min at 68 °C, respectively. The D-values of E. faecium in cornmeal at 16, 22, and 28% moisture content were 140.4, 18.9, and 3.3 min at 60 °C, 78.4, 7.1, and 1.6 min at 64 °C, and 37.3, 2.8, and 0.8 min at 68 °C, respectively. The z-values of E. faecium and Salmonella in cornmeal at 16, 22, and 28% moisture content were 13.9, 9.7, and 12.5 °C, and 14.0, 10.4, and 11.7 °C, respectively. These results indicated similar or higher thermal resistance (D-values) and equivalent thermal sensitivity (z-values) of E. faecium compared to Salmonella at different moisture contents and respective temperatures (P ≤ 0.05). Therefore, E. faecium could be used as a surrogate for Salmonella during thermal process validation of cornmeal processing.

Bacillus cereus, a foodborne pathogen, is capable of forming spores and biofilms as methods to withstand environmental stresses. These bacterial structures are an issue for food safety as they aid the bacteria survive heat sterilisation processes of foods and food contact surfaces. This study was conducted to investigate the role of the biofilm structure in providing an extra layer of protection to spores against heat treatments. For this, heat resistance of B. cereus spores in intact biofilms was compared to that of planktonic spores in vitro and in a Cheonggukjang jjigae food model. Using methods developed in this study to measure the wet and dry heat resistance of spores in intact biofilms, it was found that B. cereus spores have significantly higher heat resistances when present in biofilms rather than as planktonic spores, and that dry heat is less effective than wet heat at killing spores in biofilms. In further detail, for wet heat treatments, spores in biofilms of the strain isolated from Cheonggukjang (Korean fermented whole soybean), B. cereus CH3, had generally higher wet heat resistances than the reference strain, B. cereus ATCC 10987, both in vitro and in the Cheonggukjang jjigae food model. However, the spores in biofilms of the two strains showed similar heat resistance to dry heat, with some exceptions, when biofilms were formed in vitro or in Cheonggukjang jjigae broth. Meanwhile, B. cereus ATCC 10987 spores in biofilms had higher or similar wet heat resistances in vitro compared to in Cheonggukjang jjigae broth. Wet heat resistances of B. cereus CH3 spores in biofilms were all statistically similar regardless of biofilm formation media (brain heart infusion and Cheonggukjang jjigae broths). For dry heat, spores in biofilms of both B. cereus strains were more heat resistant when biofilms were formed in the Cheonggukjang jjigae food model rather than in vitro. Altogether, heat resistances of spores in biofilms formed in vitro and in the food environment were found to be different depending on the tested B. cereus strain, but higher than planktonic spores in any case. This is the first study examining the heat resistance of B. cereus spores in intact biofilms matrices attached to the surface, both in vitro and in a food model. Therefore, this research is valuable to understand the protective effects of biofilms formed in food environments and to reduce the food safety risks associated with B. cereus.

Aichi virus (AiV) that results in gastroenteritis worldwide, is spread through contaminated shellfish and water. The resistance/tolerance of AiV to common inactivation processes along with the absence of commercially available vaccines makes it necessary to study its thermal inactivation kinetics. This research evaluated the heat inactivation of AiV in cell-culture media using 2-ml sterile glass vials by the linear and Weibull models. Heat treatments of AiV titers of 7 log plaque forming units (PFU)/ml were conducted thrice in a water-bath at 50, 54, and 58 °C for up to 90 min. Plaque assays for each dilution in duplicate were used to determine infectious virus titers. Linear model D-values for AiV at 50 ± 1 °C (± = standard error) (come-up time = 68 s), 54 ± 0.7 °C (130 s), and 58 ± 0.6°C (251 s) were 43.3 ± 4.23 (R2 = 0.40, RMSE = 0.56), 5.69 ± 0.28 (R2 = 0.80, RMSE = 0.43), and 1.20 ± 0.63 min (R2 = 0.69, RMSE = 0.39), respectively, and the linear model z-value was 5.14 ± 0.39°C (R2 = 0.99, RMSE = 0.08). For the same temperatures, the Weibull model td = 1 values were 20.98 ± 8.8 (R2 = 0.62, RMSE = 0.46, α (scale parameter) = 2.30, β (shape parameter) = 0.38), 3.84 ± 0.69 (R2 = 0.85, RMSE = 0.38, α = 1.08, β = 0.66), and 0.87 ± 0.10 min (R2 = 0.80, RMSE = 0.32, α = 0.22, β = 0.61), respectively and the z-value (using Td = 1 ) was 5.79 ± 0.22 °C (R2 = 1.0, RMSE = 0.03). A better fit was obtained with the Weibull model for log reductions versus time with higher R2 and lower RMSE values. Application of AiV inactivation parameters can help reduce the risk of AiV outbreaks.

The presence of Listeria monocytogenes in Mozzarella di Bufala Campana Protected Designation of Origin cheeses may depend on curd stretching conditions and post contaminations before packaging. To avoid cross-contamination, thermal treatment of water, brines and covering liquid may become necessary. The present study aimed to improve knowledge about L. monocytogenes thermal resistance focusing on the influence of some cheese making operations, namely curd stretching and heat treatment of fluids in contact with cheese after molding, in order to improve the safety of the cheese, optimize efficacy and sustainability of the processes. Moreover, the role that cheese curd stretching plays in L. monocytogenes inactivation was discussed. The 12 tested strains showed a very heterogeneous heat resistance that ranged from 7 to less than 1 Log10 Cfu/mL reduction after 8 min at 60°C. D-values (decimal reduction times) and z-values (thermal resistance constant) calculated for the most heat resistant strain among 60 and 70°C were highly affected by the matrix and, in particular, heat resistance noticeably increased in drained cheese curd. As cheese curd stretching is not an isothermal process, to simulate the overall lethal effect of an industrial process a secondary model was built. The lethal effect of the process was estimated around 4 Log10 reductions. The data provided may be useful for fresh pasta filata cheese producers in determining appropriate processing durations and temperatures for producing safe cheeses.

The management of Heat Resistant Moulds (HRMs) is considered a great challenge for the juice fruit industry. Neosartorya, Byssochlamys and Talaromyces are three out of the main genera isolated from fruit juices that show great resistance to heat treatments. Several inactivation parameters can be found in the literature, however all of them were carried out in specific food matrices and using diverse inactivation methods. Thus, this meta-analysis study synthesizes the thermal resistance parameters of the three HRMs by adjusting extended Bigelow-based meta-regression models to data on inactivation experiments conducted in different liquid media. The meta-analytical data, extracted from publications between 1969 and 2017, was composed of decimal reduction time (D), inactivation method, temperature of inactivation, pH, °Brix, age of spores, and type of medium (model, juice, concentrates). Pooled D* values (D at 90 °C, pH 3.5 and 12° Brix) were estimated for B. fulva (1.95 min; 95% CI: 1.21-3.11 min), Talaromyces (4.03 min; 95% CI: 3.43-4.74 min), Neosartorya (0.5.35 min; 95% CI: 4.10-7.08 min), and B. nivea (10.32 min; 95% CI: 5.81-18.4 min). It was found that increasing the soluble solids in concentrates tends to cause a lower decrease in the heat resistance of Neosartorya and Talaromyces than increasing the soluble solids in model liquid or juices (p = 0.001; 0.012). In general, the screw-capped tubes and three neck round inactivation methods render higher D* values (p < 0.05) than the thermal death tubes, the polyethylene bag and the capillary methods. Spores of Talaromyces (overall zpH = 7.56; 95% CI: 5.13-13.5) and Neosartorya (overall zpH = 7.07; 95% CI: 5.04-10.8) appear to be more thermal sensitive to a decrease in medium pH than spores of Byssochlamys (overall zpH = 4.34; 95% CI: 3.20-6.73). The meta-regression models presented in this study can be valuable for estimating pooled inactivation kinetic parameters to be used by the fruit juice industry in the management of thermal processes and in the determination of shelf-life.

The present study aimed to determine the accuracy (Z-value) of non-invasive prenatal testing (NIPT) results for sex chromosome aneuploidy (SCA) in routine clinical practice.
Among a cohort of 12505 pregnant females, maternal plasma samples collected from our hospital were utilized for SCA analysis by NIPT detection. The positive samples were validated through an invasive procedure and karyotyping analysis. The predictive value from positive samples in sex chromosomes was compared to analyze the accuracy of the Z-value.
There were 65 females with sex chromosome abnormalities within 12,505 pregnant females in the NIPT detection, which was validated by karyotype analysis of amniotic fluid puncture through sequencing, as well as bioinformatics analysis, with 18 true-positive samples. The true-positive results with 45,X, 47,XXY, 47,XXX and 47,XYY karyotypes predicted by NIPT were 14.29%, 50.00%, 66.67% and 71.43%, respectively. Among sex chromosome cases, the findings indicated that positive NIPT results with Z ≥ 9 show a higher accuracy.
The findings of the present study demonstrate that the positive predictive value of NIPT for sex chromosome abnormalities is distinctive. The positive predictive value was highest for 47,XYY and lowest for 45,X. Additionally, the Z-value results are considered to be correlated with the accuracy of NIPT, although further studies need to be made.

This study was conducted to validate a simulated commercial baking process for plain muffins against E. coli O121 (isolated from the recent illness outbreak associated with flour), and compare the thermal inactivation parameters (D- and z-values) of cocktails of four isolates of E. coli O121 and three serovars of Salmonella (Newport, Typhimurium, and Senftenberg) in muffin batter. Flour samples were spray inoculated with the E. coli O121 or Salmonella cocktails, dried back to the pre-inoculation weight to achieve ~7 log10 CFU/g, and used to prepare muffin batter. For the muffin baking validation study using E. coli O121, muffin batter was baked at 375 °F (190.6 °C) oven temperature for 21 min followed by 30 min of ambient cooling. The E. coli O121 population decreased by >7 log10 CFU/g in muffins by 17 min of baking, and was completely eradicated after 21 min of baking and ambient cooling. The D-values of E. coli O121 and Salmonella cocktails in muffin batter at 60, 65 and 70 °C were 42.0 and 38.4, 7.5 and 7.2, and 0.4 and 0.5 min, respectively; whereas the z-values of E. coli O121 and Salmonella were 5.0 and 5.2 °C, respectively.