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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 künye2026Quality deterioration kinetics of roasted peanut matrices under fixed-time and estimated-lethality at various water activities
Islam, Shahriar; Li, Zhiwei; Wang, Xin; Tasci, Caner; Ozturk, Samet; Erdoǧdu, Ferruh; Zhang, Qing; Liu, Shuxiang
Water activity and particle size are critical determinants of quality stability and safety in low-moisture, lipid-rich foods. However, their combined effects during thermal processing of roasted peanut matrices remain insufficiently quantified. This study evaluated quality deterioration in roasted peanut matrices with different structural forms: crushed, flour, powder, and butter. Samples were equilibrated to water activity values of 0.11–0.92 at 25 °C and heated at 80 °C for 120 min. Colour, acid value, sensory score, and changes in relative fatty acid composition were measured. Kinetic experiments were also conducted at aw,25°C 0.32 using D-value-based thermal schedules at 85, 90, and 95 °C to relate microbial lethality to quality loss. Water activity strongly affected quality stability, with the predicted quality-favourable values varying slightly among responses. Therefore, aw,25°C (0.32) was selected as a practical condition for subsequent kinetic evaluation. Matrix performance differed between the fixed-time and D-value-based treatments. These findings describe quality deterioration under fixed-time and D-value-based thermal schedules.
- 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 Erişim2026Structure-Dependent Triglyceride Protection of Freeze-Dried Lactiplantibacillus plantarum: Storage Protection Window, Lipid Oxidation, and Stress Adaptation
Sun, Zheneng; Zhang, Nan; Wang, Xiaomai; Wei, Xinyao; Ozturk, Samet; Liu, Shuxiang
Lipid-rich matrices can protect probiotics by limiting direct exposure to moisture, oxygen, and gastrointestinal stressors. However, triglycerides are chemically dynamic during storage, and differences in fatty acid structure and oxidation susceptibility may determine whether they exert protective or detrimental effects. In this study, tricaprylin, triolein, and trilinolein were evaluated as post-drying lipid storage matrices for freeze-dried Lactiplantibacillus plantarum 124 during storage at 25 °C, and 37 °C was used to accelerate lipid oxidation. Survival during storage, fatty acid chain retention, oxidation-derived products, stress tolerance, qualitative confocal imaging of membrane-integrity patterns, and transcriptomic responses were analyzed. After 30 d at 25 °C, log reductions were 0.30, 0.24, and 0.24 log10 units in the tricaprylin, triolein, and trilinolein groups, respectively, compared with 0.60 log10 units in the oil-free control, defining a common protective window. Tricaprylin showed the highest fatty acid chain retention, whereas trilinolein exhibited the greatest loss and strongest oxidative change. GC–MS detected no representative oxidation-derived products in tricaprylin, while unsaturated triglycerides generated dimethyl azelate and methyl 9-oxononanoate. Cells recovered from the protective window showed improved acid and bile tolerance, with survival increasing from 30.48% to 53.43–55.65% and from 14.85% to 22.49–27.79%, respectively. Confocal imaging further showed better-preserved membrane-integrity patterns in the triglyceride-treated groups after acid exposure. Transcriptomics indicated enhanced transport, redox, DNA-related, and cell-envelope responses, accompanied by reduced translation and growth-associated metabolism. Within the experimental conditions tested, these results suggest that triglyceride-associated attenuation of viability loss varies among triglyceride systems and across storage stages, while excessive oxidation of unsaturated triglycerides may weaken probiotic stability.
- 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.
- Derleme MakaleYalnız künye2026Emerging thermal and non-thermal technologies addressing Salmonella contamination in low-moisture spices and herbs
Lian, Yi; Verma, Tushar; Chen, Long; Sun, Shengqian; Ozturk, Samet; Subbiah, Jeyamkondan; Liu, Shuxiang; Wei, Xinyao
Spices and herbs are vital flavoring agents in food. However, they are particularly vulnerable to microbial contamination primarily due to their open production environments and low water activity, which enhances microbial resistance to conventional pasteurization. In addition, traditional decontamination methods often struggle to balance microbial safety and product quality. This review aims to deliver valuable insights into innovative technologies designed for improving microbial safety and overall quality of spices and herbs while fostering advancements in the industry. This review comprehensively summarizes the principles, applications, and influencing factors of emerging thermal technologies (e.g., radio frequency heating, superheated steam, and vacuum steam) and non-thermal technologies (e.g., ethylene oxide, chlorine dioxide, cold plasma, and ionizing irradiation). Furthermore, it critically discusses the current limitations of these technologies and proposes strategies for future advancements. Novel decontamination technologies show promise in improving microbial safety and preserving the quality of spice and herb products. In particular, radio frequency and chlorine dioxide technologies emerge as promising options for spice decontamination due to their better ability to balance microbial control efficiency and quality retention. Further research should focus on optimizing parameters through models, developing combination technologies, and promoting pilot test verification to facilitate industrial application.
- 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 künye2023Increased heat tolerance and transcriptome analysis of Salmonella enterica Enteritidis PT 30 heat-shocked at 42 ℃
Qiu, Yan; Ozturk, Samet; Cui, Xinyao; Qin, Wen; Wu, Qingping; Liu, Shuxiang
In this study, we compared the heat tolerance parameter (D65℃) values of Salmonella enterica serovar Enteritidis PT 30 (S. Enteritidis ) heat adapted at different degrees (at 42 ℃ for 20–180 min) and cultivated using two methods. The treated group with the highest D65℃ value (LP-42 ℃-60 min) and the untreated groups (Control-TSB and Control-TSA) were subjected to transcriptome analysis. Heat-adaptation increased the D65℃ values of S. Enteritidis by 24.5–60.8%. The D65℃ values of the LP-42 ℃-60 min group (1.85 ± 0.13 min, 7.7% higher) was comparable to that of the Control-TSA. A total of 483 up- and 443 downregulated genes of S. enteritidis were identified in the LP-42 ℃-60 min group (log2fold change > 1, adjusted p-value < 0.05). Among these genes, 5 co-expressed and 15 differentially expressed genes in the LP-42 ℃-60 min and Control-TSA grops possibly contributed to the high D65℃ values of S. Enteritidis. The Rpo regulon was involved in the heat adaptation of S. Enteritidis, as evidenced by the significant upregulation of rpoS, rpoN, and rpoE. KEGG enrichment pathways, such as biosynthesis of secondary metabolites, tricarboxylic acid, and ribosomes were identified and mapped to reveal the molecular mechanisms of S. enteritidis during heat adaptation. This study quantified the enhanced heat tolerance of S. Enteritidis heat adapted at different degrees of heat-adaptation. The results of this study may serve as a basis for elucidating the molecular mechanisms underlying the enhanced heat tolerance at the transcriptome level.
- 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.