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- MakaleYalnız künye2026An insight of oil protection theory: Survival, structural and metabolic adaptation of Salmonella enterica Enteritidis Phage Type 30 in three triglycerides
Zhao, Huan; Sun, Rui; Cao, Shidi; Ozturk, Samet; Erdogdu, Ferruh; Liu, Xingyi; Liu, Shuxiang
Oil protection theory posits that oil enhances microbial survival and heat resistance in low-moisture foods, yet the role of triglyceride composition remains poorly defined. This study investigates how Salmonella enterica Enteritidis PT 30 adapts during desiccation in peanut oil (mixed triglycerides, aw,25 degrees C = 0.30) and two representative components, namely, trilinolein and glyceryl trioleate. The lipid-specific structural and metabolic adaptations were analyzed through confocal microscopy and transcriptomics. S. Enteritidis exhibited the lowest persistence (3.43-log reduction over 180 days) and weakest heat resistance (2.5 h at 80 degrees C to achieve 3.5-log reduction) in peanut oil. The survival of S. Enteritidis in triglycerides could be correlated with its metabolic dormancy via suppression of ribosomal and oxidative phosphorylation pathways. Trilinolein enhanced S. Enteritidis' heat resistance (30 h at 80 degrees C for 3.5-log reduction) and moderate storage mortality (1.64-log reduction at 180 d), driven by stress hyperactivity. Glyceryl trioleate balanced heat tolerance (8 h) with optimal storage survival (1.19-log reduction), mediated by partial metabolic suppression. Peanut oil preserved S. Enteritidis transient motility in water-rich microenvironments, while pure triglycerides formed compact, dehydrated aggregates. Transcriptomics identified divergent strategies. Peanut oil induced dormancy at the expense of stress resilience, whereas homogeneous lipids imposed distinct constraints; that is, trilinolein amplified oxidative stress, and glyceryl trioleate intensified desiccation. These findings refine oil protection theory, demonstrating that lipid heterogeneity-not just low water activity-shapes microbial outcomes. The mixed components of peanut oil buffer stress but limit protective efficacy, while its purified constituents reveal how specific triglycerides modulate survival. This mechanistic understanding advances theoretical models of pathogen persistence in oily matrices and guides targeted strategies to mitigate risks in low-moisture oil-rich food systems.
- MakaleYalnız künye2026Radio frequency heating of whole peanuts for microbial safety and quality preservation using interlayer displacement under stationary and moving conditions: Effects of salt coating and natural skin on heating behavior
Kahraman, Kubra; Tasci, Caner; Cakir, Elif Nida; Liu, Shuxiang; Soncu, Eda Demirok; Erdogdu, Ferruh; Ozturk, Samet
This study aimed to improve the efficiency of a radio frequency (RF) heating system for pasteurizing whole peanuts while maintaining quality attributes using a stationary position or continuous movement. Heating efficiency was evaluated using commercially available roasted whole peanuts: salt-coated skin-on, unsalted skin-on, and unsalted peeled peanuts. To improve heating uniformity and ensure sufficient microbial inactivation of Salmonella enterica serovar Enteritidis PT30, a single interlayer-displacement strategy was applied in both stationary and continuous modes. Quality attributes including protein structure and fatty-acid profiles were assessed under the selected RF processing conditions. The RF system equipped with a conveyor belt was used to process peeled, unsalted peanuts inoculated with S. Enteritidis PT30 at approximately 7.9–8.5 log CFU/g. The three commercial peanut types exhibited differences in RF temperature distribution and heating uniformity, with salt-coated skin-on peanuts showing higher average temperature than unsalted peeled samples under the evaluated conditions. Continuous movement increased average temperature by approximately 10 °C but resulted in poorer heating uniformity, with a 3 °C higher standard deviation (SD). A single interlayer-displacement (overturning) step improved heating uniformity. This step increased Salmonella reductions from 3.41 to 4.77 log CFU/g under stationary processing and from 2.92 to 4.22 log CFU/g under continuous processing after 60 min of RF heating. The evaluated protein and lipid quality characteristics of unsalted peeled peanuts remained largely unchanged following RF processing. Overall, these findings demonstrated the potential of RF heating combined with interlayer displacement for microbial decontamination of unsalted peeled whole peanuts while maintaining the quality attributes evaluated in this study.
- MakaleAçık Erişim2026Designing an industrial-scale radio frequency decontamination process for peanut butter
Coskun, Eda; Ozturk, Samet; Tasci, Caner; Kahraman, Kubra; Liu, Shuxiang; Li, Rui; Wang, Shaojin; Mert, Behic; Marra, Francesco; Erdogdu, Ferruh
Centers for Disease Control and Prevention (CDC) has reported outbreaks of Salmonella, particularly associated with low-moisture foods including peanut butter. Even though roasting is included along the processing line, the presence of these safety issues indicates the requirement of process following the packaging of the samples. Because of the lower thermal diffusivity of the peanut butter, a conventional thermal process is expected to be challenging with expected temperature non-uniformities. Therefore, radio frequency (RF) heating was considered in this study for thermal processing of peanut butter samples. For this purpose, a computational model was developed to determine the temperature change of peanut butter samples. Experimental studies for model validation were completed in a 10 kW - 27.12 MHz RF system at 3300 and 4000 V electrode potentials. Following the model validation, a comparison to the conventional thermal processing was presented, and industrial scale thermal processing studies were applied where up to 30 packaged samples were placed within the RF cavity. Process efficiency was determined with the process time decrease, temperature uniformity and decontamination effects. Science4Impact: This study demonstrated RF processing for an efficient thermal decontamination with uniform temperature distribution attained within the samples in an industrial scale process.
- MakaleAçık Erişim2024Improving radio frequency heating uniformity in peanuts: Effects of packaging geometry, electrode gap, particle size and interlayer displacement process
Tasci, Caner; Liu, Shuxiang; Erdogdu, Ferruh; Ozturk, Samet
This study aimed to assess the impact of various processing parameters including electrode gap, packaging geometry, and particle size on the heating efficiency of radio frequency (RF) processing for peanut thermal decontamination. In addition, interlayer displacements were presented to evaluate the effect of the mixing on heating uniformity. Experimental studies were carried out using 3D-printed polylactic acid (PLA) containers (square, rectangular, and cylindrical) to place the peanut samples with particle sizes ranging from 0.71 to 2.00 mm at 100–140 mm electrode gaps. Temperature changes within the samples were monitored using fiber optic sensors and surface temperature distributions were determined with an infrared camera. Heating uniformity index (λ) was then calculated to assess the effects of RF processing conditions on RF heating uniformity. Results showed that the cylindrical container exhibited a more consistent and uniform heating profile (λ = 0.12) with 1.58 °C min−1 heating rate compared to other containers, and a single interlayer displacement between top and bottom layers further improved temperature distribution uniformity. Smaller particle sizes also led to faster heating rates from 1.71 to 1.55 °C min−1 with more uniform heating due to the reduced porosity within the particles with increased thermal conduction and electromagnetic energy absorption. This study presented valuable insights for developing an effective RF process as an alternative to conventional thermal treatments for decontamination of low-moisture, high-fat particulate foods. Industrial significance: This research presented an innovative approach applying RF heating for a possible decontamination process for peanut samples. The research tackled the growing worldwide consumer demand for food products to satisfy food safety regulations while peanuts were selected to demonstrate the process effect due to the recent food safety issues in peanut butter considering that a pre-process for decontamination would lead to a decrease in the resulting safety issues.
- BildiriYalnız künye2024RADIO FREQUENCY PROCESSING OF PEANUT BUTTER: COMPUTATIONAL MODEL DEVELOPMENT AND PROCESS DESIGN
Coskun, Eda; Ozturk, Samet; Tasci, Caner; Polat, Kubra; Liu, Shuxiang; Li, Rui; Wang, Shaojin; Mert, Behic; Marra, Francesco; Erdogdu, Ferruh
Within the last decade, Centers for Disease Control and Prevention (CDC) has reported outbreaks of Salmonella, particularly associated with low -moisture foods including peanut butter. In this study, radio frequency (RF) application was carried out for thermal processing of peanut butter samples. For this purpose, a computational model was developed to determine the temperature change of peanut samples using Comsol Multiphysics v6.0 (Comsol AB, Stockholm, Sweden), and experimental studies for model validation were completed in a 10 kW 27.12 MHz RF system at 3300 and 4000 V electrode potentials Following the model validation, industrial scale thermal processing studies were done with up to 30 samples located within the RF cavity. This study demonstrated the feasibility of the RF application for an efficient processing with rather uniform temperature distribution attained within the samples.
- MakaleYalnız künye2023Microwave decontamination processing of tahini and process design considerations using a computational approach
Topcam, Huseyin; Coskun, Eda; Son, Ezgi; Kutuk, Dilay; Aytac, S. Aykut; Mert, Behic; Ozturk, Samet; Erdogdu, Ferruh
Tahini, as a low moisture food product, is linked to several outbreaks of Salmonella recently even though a high temperature roasting (of sesame seeds) through its production is involved. Therefore, a final decontamination approach might be required for safety. Considering its higher oil content and lower thermophysical properties, conventional approaches are not easy to apply while preserving the quality attributes. Therefore, microwave heating was used for decontamination purpose. For this purpose, a computational mathematical model was developed first to determine the temperature distribution of tahini during microwave heating, and microbial inactivation studies for Salmonella enteritidis (ATCC 13076) were carried out. Changes in color and peroxide values were evaluated, and the experimentally validated model was further used to design an industrial process to achieve a 5-log cycle reduction as an efficient decontamination processing. The target temperature over 80 °C within the sample was demonstrated to achieve such a process, and industrial scale process conditions were presented for 262 kg/h process capacity.
- MakaleYalnız künye2023Effect of oil exposure stages on the heat resistance of Salmonella enterica serovar Enteritidis phage type 30 in peanut flour
Liu, Shuxiang; Qiu, Yan; Ji, Kexin; Ozturk, Samet; Erdogdu, Ferruh; Qin, Wen; Yang, Ren; Wu, Qingping
The oil in low-moisture foods (LMFs) shows protective effects on bacteria during thermal processing. However, the circumstances under which this protective effect strengthens remain unclear. This study aimed to understand which step of the oil exposure to bacterial cells (inoculation, isothermal inactivation, or recovery and enumer-ation step) in LMFs can enhance their heat resistance. Peanut flour (PF) and defatted PF (DPF) were selected as the oil-rich and oil-free LMF models. Salmonella enterica Enteritidis Phage Type 30 (S. Enteritidis) was inoculated into four designated PF groups representing different oil exposure stages. It was isothermally treated to obtain heat resistance parameters. At a constant moisture content (aw,25 degrees C = 0.32 +/- 0.02) and controlled aw,85 degrees C (0.32 +/- 0.02), S. Enteritidis exhibited significantly high (p < 0.05) D values in oil-rich sample groups. For instance, the heat resistance values of S. Enteritidis in the PF-DPF and DPF-PF groups were D80 degrees C of 138.22 +/- 7.45 min and 101.89 +/- 7.82 min; however, the D80 degrees C in the DPF-DPF group was 34.54 +/- 2.07 min. The oil addition after the thermal treatment also helped injured bacterial recovery in the enumeration. For instance, the D80 degrees C, D85 degrees C, and D90 degrees C values in the DFF-DPF oil groups were 36.86 +/- 2.30, 20.65 +/- 1.23, and 7.91 +/- 0.52 min, respectively, which were higher than those in the DPF-DPF group at 34.54 +/- 2.07, 17.87 +/- 0.78, and 7.10 +/- 0.52 min. We confirmed that the oil protected S. Enteritidis in PF in all three stages: desiccation process, heat treatment, and recovery of bacterial cells in plates.
- MakaleAçık Erişim2022Continuous flow microwave processing of peanut butter: A (hypothetical) computational process design study with experimental validation
Coskun, Eda; Ozturk, Samet; Topcam, Huseyin; Karatas, Ozan; Li, Rui; Wang, Shaojin; Mert, Behic; Erdogdu, Ferruh
The increase in foodborne pathogen cases in low moisture foods has raised a significant food safety concern for food industry. One of the most significant outbreaks related with these food products was observed in 2008–2009 due to Salmonella problem in peanut butter. This issue was recently observed again for a multinational case. Challenges of conventional thermal processing due to the lower thermal conductivity – diffusivity value and higher viscosity, microwave (MW) heating might be an efficient processing while the non-uniform heating is a challenging drawback. Therefore, the objective of this study was to develop a mathematical model for MW processing of peanut butter and present industrial scale designs for continuous flow processing. For this purpose, the mathematical model was first experimentally validated using a lab-scale system and validated with experimental data. Following this, continuous flow MW process design studies were carried out with different holding tube configurations to obtain a temperature increase to enable decontamination and improve the temperature uniformity. These design simulations provided a better understanding to enhance the process efficiency of high viscosity low moisture peanut butter samples and for design and optimization of continuous flow MW processing.
- MakaleAçık Erişim2022Microwave decontamination process for hummus: A computational study with experimental validation
Son, Ezgi; Coskun, Eda; Ozturk, Samet; Bulduk, Kubra; Akpinar, Merve; Mert, Behic; Erdogdu, Ferruh
There has been an increasing demand for healthy snacks, and hummus is preferred as a plant-based product its rich protein content. Its increased consumption, on the other hand, has raised food safety issues with linkages to Listeria outbreak and a recent Salmonella related recall. These were observed in ready-to-eat hummus and indicated the requirement of further processing. Conventional thermal processes might require longer times with negative impact on the quality due to the high viscosity of hummus with its solid-like rheology. For an efficient process design, microwave (MW) processing might be considered with its volumetric heating feature. Therefore, the objective of this study was to present MW application for a decontamination process for hummus. For this purpose, a computational model was developed to determine the temperature change during the process. This model was validated using the experimentally obtained temperature data from samples processed in polystyrene petri dishes (60 g – 8.5 cm in diameter and 1.2 cm in height) in a lab-scale MW system. Color changes were determined, and changes in its viscosity were used to understand the variation in the rheological attributes. Hummus samples were also inoculated with Salmonella cocktail to ≈7–8 log10 CFU/g prior to the MW process, and 70 W MW processing for 5 min (to average temperature of 95.3 °C) resulted in >4 log cycle reduction. Changes in color and rheological attributes were not significant with rather limited mass losses, and these indicated the possible MW processing for hummus decontamination with the need of designing an industrial scale processing.
- MakaleYalnız künye2021Effect of far infrared heating process on surface decontamination and quality attributes of whole yellow and white onions
Coskun, Eda; Ozturk, Samet; Akpinar, Merve; Halkman, A. Kadir; Erdogdu, Ferruh
This study aimed to develop an effective decontamination process for whole yellow and white onions with maintained quality attributes. For this purpose, a far infrared radiation (FIR) process was evaluated to determine its effects on microbial safety and quality of the onions. Prior to the FIR process, samples were inoculated with Salmonella culture to about 7–8 log10 CFU/cm2 and stored for 1–48 h at room temperature. Inoculated samples were then processed up to 120 s at 400 °C infrared source temperature. Temperature chance of the onions was recorded by using T-type thermocouples, and surface temperature distribution was obtained with an infrared thermal camera. Quality attributes (color changes, mass losses and textural changes) were also evaluated following the FIR process. The results indicated that 3.3 and 2.4 log10 CFU/cm2 reductions in the Salmonella counts were obtained for the whole yellow and white onions, stored for 1 h at room temperature after 120 s FIR processing. The background microbial population on the outer skin of the onions was under the detection limit (<1 log10 CFU/g). It was observed that the effectiveness of FIR treatment on Salmonella decontamination decreased as the storage time increased from 1 to 48 h at room temperature. FIR process did not significantly affect the quality attributes of the onions, and the results confirmed the potential use of FIR process for surface decontamination of the onions. Further studies were suggested to design an effective FIR system for industrial scale applications.
- Kitap BölümüYalnız künye2020Process Uniformity During Electro-Thermal Applications and Modeling Approaches
Altin, Ozan; Ozturk, Samet; Topcam, Huseyin; Karatas, Ozan; Marra, Francesco; Erdogdu, Ferruh
This chapter brings a perspective to issues related to heating uniformity and modeling approaches of novel electrothermal technologies such as radio-frequency (RF) and microwave (MW) heating. Both RF (3 kHz–300 MHz) and MW (300 MHz–300 GHz) waves within the electromagnetic spectrum cause heat generation within foods as a result of molecular polarization and dipole rotation of existing water molecules (polar). RF and MW heating shows a great potential to achieve volumetric and rapid heat generation within food products, maintaining food quality and satisfying safety regulations in food industry compared with conventional heating systems.