Brendan Anthony Niemira

Salmonella spp. is a pathogenic microorganism linked to eggs and egg products. In-shell eggs are not required to be pasteurized in any country before they reach the consumer. The use of an emerging technology known as radio frequency has been successfully used to inactivate this pathogen inside in-shell eggs and claim pasteurization standards (5 - log reduction). The objective of this manuscript was to conduct the engineering cost of egg processing using a radio frequency pasteurizer and compare the processing cost to conventional thermal pasteurization for in-shell eggs. The ARS-patented radio frequency pasteurizer was used (40.68 MHz, 35 W) to pasteurize eggs in 24.5 min. The conventional thermal pasteurization (56.7 °C) required 60 min for the same level of inactivation. The techno-economic analysis (TEA) included information from stakeholders, egg processors and equipment manufacturers and was used together with energy balances and some key assumptions. Calculations for the engineering cost were made based on the required energy for each system, showing that the radio frequency required a third of the total cost of electricity to pasteurize eggs in a year compared with thermal, based on utilities costs in PA. Other utilities such as water and steam were also minor for radio frequency pasteurization. After two years of operation, the projected additional cost of processing is ~USD 0.19 per egg for the radio frequency system, compared with USD 0.22 per egg for conventional thermal treatment, largely due to volume-based amortization of capital costs and lower annual operating costs for the RF process. Radio frequency thus could be an option to pasteurize eggs in farms from PA and potentially in other states, using the system developed by our research team, while reducing energy consumption and increasing return on investment.

Salmonella spp. represent a food safety risk in the production chain because of their potential for biofilm development. This study examined the biofilm formation of eight Salmonella serotypes from diverse foodborne outbreaks on three food-contact surfaces, stainless steel, silicone, and nylon, at 10 °C and 37 °C. The effect of temperature was observed in slower biofilm formation at 10 °C with about 5-log (cfu/cm²) after 24 h, contrasting with 7-log (cfu/cm²) at 37 °C. The material also influenced biofilm formation, with the strongest biofilms on stainless steel at 10 °C and silicone at 37 °C. The serotypes producing the strongest biofilms were S. Enteritidis, S. Saint Paul, and S. Montevideo. The weakest serotypes were S. Senftenberg, S. Anatum, and the avirulent S. Typhimurium. The production of extra-polymeric substances was evident with S. Enteritidis. The biofilm index showed the highest value for low temperature, nylon, and silicone, and for S. Montevideo, S. Enteritidis, and S. Saint Paul. The whole-genome sequencing of each serovar suggested that single nucleotide polymorphisms in the curli (csg) genes may have contributed to the strong biofilm-forming ability of S. Montevideo and S. Saint Paul and the weaker ability of S. Senftenberg. These results can help with the correct development of sanitizing interventions based on the Salmonella strain of concern.

Salmonella enterica serovar Enteritidis is the main pathogen of concern in eggs and egg products, although other serotypes have been reported worldwide. Egg processing guidelines and regulations vary widely from country to country; some are ambiguous, incomplete, or obsolete. However, foodborne outbreaks linked to Salmonella spp. and eggs continue to be reported worldwide and are constantly increasing, with many illnesses, deaths, and significant economic impact. This review aims to conduct a comprehensive investigation in egg processing regulations and Salmonella foodborne outbreaks in several countries of six continents in the last 50 years. The manuscript presents and contrasts the lack of surveillance programs, regulations, adequate testing, and traceability in some countries but also the creation of new regulations to reduce the incidence of Salmonella in eggs. One of the newest trends in the egg industry is related to farmers markets and backyard egg producers, which might represent a food safety gap in the production chain if these are not regulated. The review also discusses some interventions and approaches to control the growth and presence of Salmonella in fresh eggs, such as refrigeration. Though regulations in many countries do not require eggs to be under refrigeration and some other countries do not have enough access to them, jeopardizing the food safety of the product.

Salmonella spp. are pathogenic microorganisms linked to foodborne outbreaks associated with eggs and egg products. Salmonella can resist sanitation of egg processing equipment and form biofilms on food-contact surfaces. A major challenge for controlling Salmonella is the ability to detect the cells during the early stages of attachment to indicate that interventions are needed to sanitize the surface. This research investigated the use of long-read sequencing to identify Salmonella during the early stages (0–5 h) of cell attachment to three common food-contact surfaces—stainless steel, silicone, and nylon—and compared it with traditional microbiological methods. Results of the conventional plate counts showed that the detection of Salmonella began after three hours of incubation, with less than 1 log CFU/cm² of growth. Silicone had the highest number of Salmonella attached (0.87 log CFU/cm²), followed by stainless steel (0.70 log CFU/cm²). Long-read whole genome sequencing identified attached Salmonella on stainless steel, silicone, and nylon after only one hour of incubation. The results of this study suggest that long-read sequencing could be a very useful method for detecting Salmonella at low concentrations in the processing environment during the early stages of cell attachment to food-contact surfaces, allowing for correct sanitation intervention.

During conventional pasteurization, eggs are submerged for 60 min at 56.7 °C, a lengthy and costly process that affects egg quality. Radio frequency (RF), a means to pasteurize eggs without affecting quality, is a novel option based on fast volumetric heating; however, there is scarce information about the quality of such treated food. This research consisted in a comprehensive quality study on eggs treated with RF. The RF system was operated at 40.68 MHz, 40 W and 16 W (8 min total), and 42 rpm. The quality assessment included the determination of Haugh unit, yolk index, compression strength, albumen turbidity, albumen and yolk pH, and yolk color. Additional analyses were conducted to quantify the mineral composition of the eggshell (40.68 MHz, 40 W, 42 rpm, 5.5, 8.5, and 10 min); these samples were observed by SEM. The results showed that RF did not significantly (p > 0.05) change any quality parameters. The mineral composition remained constant in processed eggs. The SEM images of RF-treated eggs showed some smooth spots; however, these areas could exist due to the high variability of the eggshells. RF is an option to process intact eggs, maintaining their fresh quality and keeping the integrity of the eggshell to ensure the food safety of the internal egg components.

Fresh blueberries are delicate, hand-picked, packaged, and refrigerated fruits vulnerable to spoilage and contamination. Cold atmospheric plasma (CAP) is a promising antimicrobial technology; therefore, this study evaluated the CAP treatment effect on acid-tolerant Listeria innocua and Listeria monocytogenes and evaluated changes in the quality of the treated fruit. Samples were spot-inoculated with pH 5.5 and 6.0 acid-adapted Listeria species. Samples were treated with gliding arc CAP for 15, 30, 45, and 60 s and evaluated after 0, 1, 4, 7, and 11 days of storage at 4 °C and 90% humidity for the following quality parameters: total aerobic counts, yeast and molds, texture, color, soluble solids, pH, and titratable acidity. CAP treatments of 30 s and over demonstrated significant reductions in pathogens under both the resistant strain and pH conditions. Sixty-second CAP achieved a 0.54 Log CFU g⁻¹ reduction in L. monocytogenes (pH 5.5) and 0.28 Log CFU g⁻¹ for L. monocytogenes (pH 6.0). Yeast and mold counts on day 0 showed statistically significant reductions after 30, 45, and 60 s CAP with an average 2.34 Log CFU g⁻¹ reduction when compared to non-CAP treated samples. Quality parameters did not show major significant differences among CAP treatments during shelf life. CAP is an effective antimicrobial treatment that does not significantly affect fruit quality.

Meat is a nutritious food with a short shelf life, making it challenging to ensure safety, quality, and nutritional value. Foodborne pathogens and oxidation are the main concerns that lead to health risks and economic losses. Conventional approaches like hot water, steam pasteurization, and chemical washes for meat decontamination improve safety but cause nutritional and quality issues. Plasma‐activated water (PAW) is a potential alternative to thermal treatment that can reduce oxidation and microbial growth, an essential factor in ensuring safety, quality, and nutritional value. This review explores the different types of PAW and their physiochemical properties. It also outlines the reaction pathways involved in the generation of short‐lived and long‐lived reactive nitrogen and oxygen species (RONS) in PAW, which contribute to its antimicrobial abilities. The review also highlights current studies on PAW inactivation against various planktonic bacteria, as well as critical processing parameters that can improve PAW inactivation efficacy. Promising applications of PAW for meat curing, thawing, and decontamination are discussed, with emphasis on the need to understand how RONS in PAW affect meat quality. Recent reports on combining PAW with ultrasound, mild heating, and non‐thermal plasma to improve inactivation efficacy are also presented. Finally, the need to develop energy‐efficient systems for the production and scalability of PAW is discussed for its use as a potential meat disinfectant without compromising meat quality.