UV-C inactivation of microorganisms in a highly opaque model fluid using a pilot scale ultra-thin film annular reactor: Validation of delivered dose

Inactivation of deposited bioaerosols on food contact surfaces with UV-C light emitting diode devices

The airborne transmission of infectious diseases and bioaerosol-induced cross-contamination pose significant challenges in the food, dairy, and pharma industries. This study evaluated the effectiveness of 279 nm UV-C LED irradiation for decontaminating bioaerosols, specifically containing microorganisms such as Escherichia coli (C3040- Kanamycin resistant), Salmonella Enteritidis (ATCC 4931), and Pseudomonas fragi (ATCC 4973), on food contact surfaces. Borosilicate glass, silicon rubber, and stainless steel (316L) surfaces were selected for experimentation for their usage in the food industry. A 50 µL cell suspension was aerosolized at 25 psi pressure using a 4-jet BLAM Nebulizer within a customized glass chamber and then deposited onto the surface of the coupons. The serial dilution approach was used for the microbial enumeration, followed by duplicate plating. With a low Root Mean Square Error (RMSE) and high R2 values, the biphasic kinetic model for UV-C inactivation curves of all three pathogens demonstrated the excellent goodness of fit parameters. At a UV-C dose of 6 mJ cm-2, glass surfaces showed the maximum microbial inactivation (i.e., 2.80, 3.81, and 3.56 log CFU/mL for E. coli, Salmonella, and P. fragi, respectively). Stainless steel and silicon rubber surfaces showed significant microbial inactivation, but log10 reductions observed were consistently lower than glass surface. Our research indicates that UV-C LEDs (279 nm) can effectively disinfect bioaerosols on food contact surfaces.IMPORTANCEFood safety is a major public health concern, with contaminated food causing serious illnesses. UV-C light, used for germicidal action, is effective in disinfecting surfaces and is not subject to the same strict legal restrictions as chemical disinfectants, simplifying compliance with food safety regulations. In this study, we evaluated the efficacy of UV-C (279 nm) LED systems for inactivation of surface-deposited bioaerosols of kanamycin-resistant Escherichia coli (C3040), Salmonella Enteritidis (ATCC 4931), and Pseudomonas fragi (ATCC 4973). The research outcomes can be used to develop UV-based surface disinfection systems to minimize the risk of foodborne illnesses and enhance safety in high-traffic food preparation areas.

UV-C Light: A Promising Preservation Technology for Vegetable-Based Nonsolid Food Products

A variety of bioactive substances present in fruit- and vegetable-processed products have health-promoting properties. The consumption of nutrient-rich plant-based products is essential to address undernutrition and micronutrient deficiencies. Preservation is paramount in manufacturing plant-based nonsolid foods such as juices, purees, and sauces. Thermal processing has been widely used to preserve fruit- and vegetable-based products by reducing enzymatic and microbial activities, thereby ensuring safety and prolonged shelf life. However, the nutritional value of products is compromised due to the deleterious effects of thermal treatments on essential nutrients and bioactive compounds. To prevent the loss of nutrients associated with thermal treatment, alternative technologies are being researched extensively. In studies conducted on nonsolid food, UV-C treatment has been proven to preserve quality and minimize nutrient degradation. This review compiles information on the use of UV-C technology in preserving the nutritional attributes of nonsolid foods derived from fruit and vegetables. The legislation, market potential, consumer acceptance, and limitations of UV-C are reviewed.

Non-thermal Processing Technologies for Dairy Products: Their Effect on Safety and Quality Characteristics

Thermal treatment has always been the processing method of choice for food treatment in order to make it safe for consumption and to extend its shelf life. Over the past years non-thermal processing technologies are gaining momentum and they have been utilized especially as technological advancements have made upscaling and continuous treatment possible. Additionally, non-thermal treatments are usually environmentally friendly and energy-efficient, hence sustainable. On the other hand, challenges exist; initial cost of some non-thermal processes is high, the microbial inactivation needs to be continuously assessed and verified, application to both to solid and liquid foods is not always available, some organoleptic characteristics might be affected. The combination of thermal and non-thermal processing methods that will produce safe foods with minimal effect on nutrients and quality characteristics, while improving the environmental/energy fingerprint might be more plausible.

Modeling and validation of delivered fluence of a continuous Dean flow pilot scale UV system: monitoring fluence by biodosimetry approach

The inactivation of pathogenic microorganisms in water and high transmittance liquid foods has been studied extensively. The efficiency of the process is relatively low for treating opaque liquid foods using traditional UV systems. This study evaluated the ability of UV-C light to inactivate foodborne pathogens in a simulated opaque fluid (6.5 to 17 cm^-1) at commercial relevant flow rates (31.70, 63.40, 95.10 gph) using a pilot-scale Dean Flow UV system. In this study, a mathematical model for the prediction of delivered fluence was developed by the biodosimetry method. The results revealed that increased Reduction equivalent fluence (REF) rates were observed with increased flow rates due to additional turbulence. The experimental and calculated REF were well correlated with the UV-C absorption coefficient range of 6.5 to 17 cm^-1 indicating efficient mixing in the reactor. REF scaled up linearly at experimental conditions as an inverse function of flow rate and absorption coefficient, and a linear mathematical model (R² > 0.99, p < 0.05) to predict delivered REF was developed. The model was tested and validated against independent experiments using Salmonella Typhimurium and Bacillus cereus endospores. The predicted and experimental REF values were in close agreement (p > 0.05). It is demonstrated that the developed model can predict the REF, thus microbial inactivation of microbial suspensions in simulated fluid with the absorption coefficient of 6.5-17 cm^-1 and flow rates of 31.70-95.10 gph. The pilot system will be field-tested against microorganisms in highly absorbing and scattering fluids.