Innovative Non-thermal Processing Technologies for Enhancing Pet Food Safety and Quality: A Comprehensive Review of Publications, Patents, and Market Trends

Abstract

Non-thermal processing technologies have emerged as promising alternatives to traditional heat treatments in the pet food industry. To date, no prior review has systematically integrated peer-reviewed publications, patents, and commercial product launches on non-thermal technologies in the pet food sector during 2014–2024. This integrative approach fills an important gap by linking scientific evidence with innovation activity and market adoption. Unlike conventional thermal methods, which often degrade heat-sensitive nutrients and alter the sensory qualities of pet food, these innovative techniques leverage physical principles to inactivate pathogens while preserving the product’s nutritional and sensory integrity. This review explores the application of key non-thermal technologies, including high-pressure processing (HPP), plasma treatment, irradiation, and pulsed light, in enhancing the safety and quality of pet food. Analyses were conducted on scientific publications, patent trends, and market trends. High-pressure processing has demonstrated exceptional efficacy in microbial reduction with minimal impact on nutrient content. Plasma treatment offers versatility for surface sterilization applications, while ionizing radiation effectively extends shelf life by significantly reducing microbial loads. Pulsed light provides rapid and efficient pathogen inactivation, particularly on smooth surfaces. Additionally, this review examines the advantages of these technologies, such as decreased reliance on chemical preservatives and improved sustainability. It also highlights recent advancements, regulatory considerations, and the challenges associated with scaling up these technologies for industrial application in the pet food sector.

1. Introduction

In recent years, shifts in household structure and the growing humanization of pets have accelerated pet adoption, making the pet food market increasingly attractive. − The global pet care market is experiencing consistent growth, driven by the pet humanization trend. In 2023, the global pet food market was estimated at USD 120.87 billion and is expected to expand, reaching approximately USD 127 billion in 2024 and USD 194 billion by 2032. There is a rise in demand for premium, functional pet foods that prioritize high-quality and safe ingredients, digestive health, and tailored nutrition, , including alternative protein foods. Traditional thermal treatments are a crucial process for extending the shelf-life of pet food and reducing the risk of pathogenic microorganisms. But it can also negatively influence the final product’s nutritional quality and sensory attributes. Thermal pasteurization of animal-derived protein ingredients in dog food negatively impacts organoleptic properties and protein digestibility, ultimately reducing nutritional value. These adverse effects are primarily caused by Maillard reactions, protein denaturation, and aggregation. , This has prompted food professionals to explore alternative processing methods, such as non-thermal treatments.

Novel non-thermal processing techniques are innovative methods used to achieve microbial inactivation in food without causing any adverse effect of heating. , However, it should be noted that certain “non-thermal” technologies may still involve incidental heating (e.g., adiabatic temperature rise during HPP or localized surface heating under pulsed light), and thus their effects must be carefully considered. Non-thermal technologies in food processing such as high-pressure processing (HPP), irradiation, pulsed light, plasma, and ozone treatment have emerged as effective alternatives to traditional thermal methods by preserving food quality while ensuring microbial safety as shown in Figure .

1.

Mechanisms of non-thermal processing: high-pressure processing (HPP), irradiation, pulsed light treatment, plasma, and ozone processing.

Non-thermal pasteurization and sterilization methods aimed at preservation, decontamination, and control of pathogens and spoilage microorganisms have generated growing interest in raw ingredients used for pet food. This review is organized as follows: Section discusses current research status, Sections – examine each major non-thermal technology (HPP, irradiation, pulsed light, plasma, ozone), and Section addresses patents, market trends, regulations, and future perspectives. Salmonella is a major biological hazard in raw meat and poultry used in pet food and treats, posing potential health risks to both pets and humans. HPP has shown to inactivate pathogenic bacteria in a wide variety of animal proteins used in pet food such as Salmonella in ground chicken meat at low pressure level (i.e., 250–350 MPa), extraintestinal pathogenic Escherichia coli in ground chicken meat at 600 MPa for 3 min. Atmospheric cold plasma treatment was observed for its effectiveness in inactivating Campylobacter jejuni on chicken skin and breast fillets of 2 log CFU^.cm^–2 reductions after 120 s treatment time. Gamma irradiation at 1 kGy successfully reduced 2.2 logs of Salmonella Typhimurium and 1.6 logs of Staphylococcus aureus. Ozone treatment is effective at reducing Aspergillus flavus contamination in extruded dry dog food. Additionally, both batch and spray ozone sanitation systems can reduce foodborne pathogens on vegetables used in raw meat-based pet diets.

This review investigates the application of non-thermal processing technologies within the pet food industry, examines their underlying mechanisms, advantages, limitations, and potential for industry adoption. The focus is on understanding how these technologies effectively ensure the safety and quality of various pet food formats, including dry kibble, wet food, and semi-moist treats. Furthermore, the review explores recent advancements, regulatory considerations, and the future potential for integrating non-thermal processing methods within the pet food industry.

Previous reviews have examined non-thermal technologies primarily in the context of human foods or animal feed, focusing on microbial safety or nutrient retention. − ,, However, these works did not specifically address applications for pet foods, nor did they integrate evidence from patents and commercial product launches. To our knowledge, this is the first review to systematically compare five major non-thermal technologies (HPP, irradiation, pulsed light, plasma, and ozone) for pet food, while also synthesizing evidence across peer-reviewed publications (2014–2024), patent activity, and market data. By linking scientific, technological, and industrial perspectives, this review aims to provide a comprehensive resource for researchers, manufacturers, and regulators seeking to advance the safe and sustainable development of pet food products.

2. Current Status of Non-thermal Processing for Pet Food

Figure presents the number of Scopus-indexed publications from January 2014 to December 2024 related to pet food and four key non-thermal processing methods: high-pressure processing (HPP), irradiation, pulsed light, plasma, and ozone treatment. The present study revealed that plasma processing was the most frequently researched technology for pet food. This method demonstrated potential for maintaining nutritional value and sensory attributes. , Studies published between 2019 and 2020 demonstrated the successful application of plasma and pulsed light technologies for post-packaging decontamination of dry pet food surfaces. Plasma and pulsed light technologies have shown promise for improving product quality compared to thermal processing, although more data are needed to substantiate cost-effectiveness claims. However, their effectiveness can be limited by penetration into food products and treatment homogeneity. Ozone operates as a non-thermal technology, offering highly energy-efficient and residue-free technology. Ozone gas or aqueous ozone can also be used as an alternative to chemicals used for food preservation and managing food safety. ,

2.

Total number of English-language journal articles indexed in Scopus between 1 January 2014 and 31 December 2024 (N = 24) that include either “pet food”, “dog food”, or “cat food” in the title, abstract, or keywords (TITLE-ABS-KEY) fields, in combination with one of the following emerging food processing technologies: Irradiation, Plasma, HPP (High Pressure Processing), Pulsed light, or Ozone. Queries were restricted to the document type Article.

2.1. High-Pressure Processing (HPP) Treatment for Pet Food

High-pressure processing (HPP) is a non-thermal food preservation technology where pressure is distributed instantaneously and uniformly throughout the food, with an associated adiabatic temperature increase of approximately 2–3 °C per 100 MPa. The magnitude of this temperature rise depends strongly on the food composition, particularly water and fat content. , HPP inactivates microorganisms primarily through the disruption of cellular membranes, denaturation of intracellular proteins, and interference with genetic materials. The high hydrostatic pressure compresses cellular structures, causing membrane permeability loss, protein unfolding, and enzyme inactivation. This leads to impaired metabolic function and cell death. Gram-negative bacteria are generally more sensitive to HPP than Gram-positive bacteria or bacterial spores due to their thinner peptidoglycan layers and more fragile outer membranes. HPP is being implemented in pet food production inactivate microorganisms through uniform pressure application (isostatic compression) during a few minutes while minimally impacting organoleptic and nutritional parameters. , The basic method involves placing food products in flexible packaging, loading them into carrier baskets within the vessel, and pressurizing them up to 600 MPa in a liquid of low compressibility, typically potable water. Unlike thermal processes, HPP does not rely on “penetration,” since pressure is transmitted instantaneously and uniformly throughout the product. However, bacterial spores are markedly more resistant to HPP, and complete sterilization often requires pressure-assisted thermal processing, which combines elevated pressure with moderate heat to achieve spore inactivation. Table presents the HPP treatment for raw meat and raw pet food over the last ten years. The inactivation of Salmonella spp. in raw pet food has been studied using various combinations of processing parameters and lactic acid concentrations. Serra-Castelló et al. reported that Salmonella reduction in chicken-based raw pet food for dogs ranged from 0.76 to >9 log units, depending on the pressure intensity (450–750 MPa), holding time (0–7 min) and lactic acid concentration (0–7.2 g/kg). In a related study, Serra-Castelló et al. also evaluated the effects of subsequent frozen storage following HPP. Their results indicated that Salmonella inactivation could be achieved either through lower pressures treatment combined with acidulation or higher pressures treatment without acidulation. Lactic acid and subsequent frozen storage also prevented the recovery of sub-lethally damaged microbial cells after HPP processing and contributed to the loss of viability of Salmonella. Moreover, HPP treatment slightly reduced redness (a* value) and increased yellowness (b* value), with a total color difference (ΔE) of approximately 1.1–1.3. The combined use of HPP and frozen storage successfully maintained a 5-log reduction of Salmonella and Shiga Toxin-producing E. coli in raw diet pet foods while Listeria monocytogenes was more HPP resistant. The most effective parameter to maintain microbial reduction obtained through HPP was 586 MPa for 3 min in beef and lamb and 4 min for chicken in pet food formulation. Only beef-based diets with protein and fat content of 13.88% and 13.20%, respectively, demonstrated a 5-log reduction of L. monocytogenes. The higher moisture content with lower protein and fat content in the raw-based diets contributed to higher inactivation of Salmonella spp. and Shiga toxin-producing Escherichia coli. The presence of high unsaturated fatty acids in pet food formulation enhances microbial inactivation, resulting in microorganisms remaining inactive during post-HPP storage. Recent studies indicate that the combination of HPP, lactic acid fermentation and frozen storage achieved a 5-log reduction of Salmonella spp., Shiga toxin-producing E. coli, and L. monocytogenes in raw pet foods. The addition of 1% lactic acid fermentation (LAF) combined with HPP treatment at 586 MPa for 4 min, followed by frozen storage (−10 to −16 °C) for up to 21 days, resulted in the most effective option for enhancing pathogen reduction in chicken-based raw pet food. The findings indicate that the effectiveness of HPP in inactivating pathogens is influenced by the applied pressure, holding time, type of ingredients, and stored condition with notable enhancement observed when lactic acid is incorporated into the raw pet food formulation. The addition of lactic acid for acidulation significantly enhanced microbiological inactivation at reduced pressures during HPP. The composition of food significantly influenced bacterial inactivation through HPP treatment, especially regarding moisture, fat, and protein levels. L. monocytogenes exhibited greater resistance to inactivation compared to Salmonella and E. coli.

1. High Pressure Processing (HPP) Treatment for Pet Food during the Last Ten Years .

Food/Sample	Food format	Process condition	Packaging	Product testing	Microbial inactivation	Other major findings	Ref
Chicken-based raw diet pet food	Frozen raw pet food chubs	• Lactic acid fermented (LAF) at 0, 0.7% and 1.0%.	Whirl Pak bags (Nasco, Madison, WI)	• Microbiological test (L. monocytogenes, Salmonella spp., and E. coli STEC)	• HPP and LAF achieved a 5-log reduction in Salmonella spp., E. coli STEC, and L. monocytogenes.	• HPP led to a higher pH (6.01) without added LAF while 0.7% and 1.0% LAF reduced pH values of 5.64 and 5.43, respectively.
		HPP at 586 MPa, 4 °C, 2–4 min; come-up time 40 s; decompression NR.		• pH	• Adding 0.7% or 1.0% LAF prevented the recovery of Salmonella spp. under all HPP conditions and frozen storage.
					• At 1.0% LAF was the most effective in inactivating Salmonella spp., E. coli STEC, and L. monocytogenes.
Chicken, beef, and lamb-based raw pet food	Frozen ground meat or raw hamburger	• HPP at 586 MPa; 4 °C for chicken (2, 3, and 4 min), beef and lamb (1, 2, and 3 min)	Whirl Pak bags (Nasco, Madison, WI)	• Microbiological test (L. monocytogenes, Salmonella spp., and E. coli STEC)	• HPP for ≥2 min-maintained Salmonella inactivation in formulations (20–46% meat, 42–68% organs, 0.9–1.3% seeds, 10.7–11.1% fruits/vegetables/minor ingredients) during frozen storage.	• Formulations with higher moisture, lower protein, and fat showed greater of Salmonella spp. and E. coli STEC inactivation.
					• A 5-log reduction of E. coli was achieved from day 6 of frozen storage.
					• L. monocytogenes exhibited higher HPP resistance compared to Salmonella and E. coli STEC.
					• Optimal microbial reduction conditions are HPP: 586 MPa, 3 min (beef, lamb); 4 min (chicken)
Raw cat food from chicken, plant-based ingredients, salmon, and spices	Frozen raw cat food	• Lactic acid at 0–7.2 g/kg food.	Vacuum-packed in PA/PE plastic bags (Sistemvac, Estudi Graf S.A., Girona, Spain)	• Microbiological test for samples inoculated with Salmonella	• Greatest Salmonella reduction (9.08 log) with 3.6 g/kg of lactic acid at 750 MPa.	• HPP slightly reduced redness and increased yellowness.
		• HPP at 450–750 MPa; 0–7 min, 191 MPa/min come up; <5s decompression; initial 9 °C; compression ∼3 °C/100 MPa.		• Microbiological test for non-inoculated samples (total aerobic mesophilic bacteria, Enterobacteriaceae, Pseudomonas spp. and lactic acid bacteria (LAB))	• HPP reduced Enterobacteriaceae and Pseudomonas spp. below detection limit in non-inoculated pet food.	• HPP exhibited a slightly lighter attributed to myofibrillar denaturation
				• Pet food quality (a w , pH and color)	• Total aerobic mesophilic bacteria reduction of 0.92 to 2.73 log.
					• Above 600 MPa, LAB levels mostly below the quantification limit.
Raw dog food from chicken based	A block format of ca. 10 cm diameter and 1.5 cm-thick slices raw dog food	• Lactic acid at 71%.	Vacuum-packed in PA/PE plastic bags (Sistemvac, Estudi Graf S.A., Girona, Spain)	• Microbiological test for samples inoculated with Salmonella	• Increasing pressure intensity and holding time enhances Salmonella inactivation	• No significant pH differences before and after HPP (p > 0.05).
		• HPP at 450–750 MPa; 0–7 min; 200 MPa/min come-up; initial 9 °C; compression 3 °C/100 MPa.		• Pet food quality (a w and pH)	Maximum reduction of 9.33 log units at 750 MPa HPP.
					A 7-log reduction achieved with 600 MPa for ≥4.2 min in pet food with 7 g/kg lactic acid.
Dog food from chicken meat	Chicken meat	• HPP at 500 MPa; 1, 3, 5, and 7 min	Polyethylene vacuum packaging bag	• In vitro ileal disappearance (IVID)	-	• HPP did not affect vitro ileal disappearance of protein in chicken meat.
				• Dry matter and crude protein
Pet food from ground chicken	Ground chicken	• HPP at 300, 400, and 500 MPa (4 °C) up to 25 min	Whirl-Pak bags	• Microbiological (bacteria enumeration of uropathogenic E. coli (UPEC))	• Ground chicken required inactivate 1 log of UPEC, for 30.6, 8.37, and 4.43 min at 300, 400, and 500 MPa	-

^aPressure (MPa) and Temperature (°C).

2.2. Irradiation Treatment for Pet Food

Irradiation treatment serves as a non-thermal processing technology that disrupts the genetic material of microorganisms, thereby inhibiting their reproduction and potential to cause illness, while also facilitating the breakdown of enzymes and proteins as shown. , Irradiation inactivates microorganisms primarily by inducing DNA damage through both direct ionization and the formation of reactive oxygen species and hydroxyl radicals generated by water radiolysis. At commonly used doses (≤10 kGy), enzyme and protein breakdown is minimal, preserving nutritional and sensory quality. It employs high-energy gamma rays, accelerated electron beams, and X-rays to reduce contamination and reduce microbial loads while managing oxidation (TBARS) and preserving acceptability when dose is optimized, especially in intermediate to low-moisture foods. Gamma irradiation can induce the radiolysis of water, leading to the formation of highly reactive free radicals. This process has shown potential for the decontamination of fungi and mycotoxins in low aw or dry pet foods. For the irradiation treatment of animal feed and pet food, FDA regulations specify a maximum absorbed dose. According to U.S. FDA, 21 CFR Part 579.22, the absorbed dose for bagged complete diets, packaged feeds, feed ingredients, bulk feeds, animal treats, and chews must not exceed 50 kGy. In addition, compliance with the Food Safety Modernization Act (FSMA) preventive controls for animal food requires adherence to 21 CFR Part 507, which mandates hazard analysis and risk-based preventive controls for facilities using irradiation or other non-thermal methods. Gamma irradiation has been shown to effectively reduce microbial load while enhancing quality, flavor, safety, and stability during storage in patties from ostrich and chicken meat, ground beef and smoked chicken breast. At commonly applied doses (≤5–10 kGy), irradiation has generally not produced notable effects on the sensory characteristics of meat; however, at higher doses (≥10–20 kGy), matrix-dependent changes such as increased TBARS values and flavor alterations have been observed. Table provides an update on irradiation treatment for pet food products over the past decade. The combination of irradiation with meat treated with cinnamaldehyde, alongside combinations of cinnamaldehyde with ascorbic acid or sodium pyrophosphate decahydrate, demonstrated enhanced antimicrobial efficacy. The combined treatment exhibited no influence on the physical and chemical properties of ground beef. The inactivation of Uropathogenic E. coli (UPEC) in ground chicken meat using gamma radiation was investigated by Sommers. The results showed that the D10 values (radiation dose required to reduce the microbial population by 90%) were 0.28 kGy at refrigeration (4 °C) and 0.36 kGy at frozen (−20 °C). In frozen conditions, microbial cells are more resistant to radiation due to reduced water mobility, which limits indirect DNA damage from radiolysis of water. Kim et al. showed that gamma irradiation treatment has no adverse effect on protein digestibility in vitro and preserving nutritional value of chicken meat for dog. In contrast, thermal processing significantly reduced nutritional values. Kakatkar et al. demonstrated that a dose of 2.5 kGy significantly reduced the number of bacteria and fungi in dried kibble and dried powder derived from fish waste, resulting in a shelf life of up to 65 days. This result demonstrates the potential efficacy of gamma irradiation as a food preservation method in the animal feed sector. Gamma irradiation doses below 5 kGy have shown only minor negative effects on protein digestion, lipid oxidation and overall composition of food products. However, higher doses (≥10 kGy) can cause lipid peroxidation, which may degrade product quality and indicate the need for innovative gamma irradiation in conjunction with other food preservation methods. For instance, at 20 kGy, TBARS values in dry pet food increased from 3.58 to 5.31 mg MDA/kg with electron-beam treatment and to 5.33 mg MDA/kg with X-ray treatment, indicating oxidative degradation. Gamma irradiation effectively reduces microbial contamination in pet food while preserving nutritional quality and sensory properties. However, higher doses (≥10 kGy) may cause lipid oxidation, and its effectiveness decreases in frozen conditions. Future research should focus on optimizing dose levels, combining irradiation with natural preservatives, and assessing long-term storage effects to enhance pet food safety and quality.

2. Irradiation Treatment for Pet Food Products during the Last Ten Years .

Food product	Food format	Process condition	Product testing	Microbial inactivation	Other major finding	Ref
Dog and cat kibble/powder	Dried kibble and dried powder	Pet foods were packed in polyethylene bags and irradiated at dose of 2.5 and 5.0 kGy (dose rate 8.71 kGy/h).	• Microbiological (total bacteria, mold, coliforms, Salmonella, S. aureus)	• 2.5 and 5.0 kGy exhibited no detectable coliforms, coagulase-positive S. aureus and Salmonella sp.	• 2.5 kGy optimizes microbiological safety, TBARS value, and nutritional acceptability in pet food.
			• Lipid oxidation (TBARS), proximate (protein, fat, ash, moisture)	• 2 log reduction in kibble (2.3 CFU.g–1) and powder (2.17 CFU.g–1) pet food was achieved at 2.5 kGy, extending shelf-life of 65 days.
Dry pet food	Dried kibble	Sample were packed in air- impermeable bags then treated with EB irradiation doses 2.5, 5, 10, and 20 kGy	• Microbiological (Total aerobic bacteria)	• Both electron beam (EB) and X-ray (XR) treatments effectively decontaminated dry pet food without compromising its quality.	• EB and XR can significantly promote lipid oxidation.
		XR irradiation doses of 2.5, 5, 10, and 20 kGy	• Lipid oxidation (TBARS)	• No significant differences were found between EB and XR in this study	• The rise in volatile compounds corresponds to the increases in TBARS and carbonyl content values.
			• Volatile compounds in dry pet food
Dog food from chicken meat	Chicken meat	Chicken meats were packed in polyethylene pouch and irradiated at 3, 5, 7, and 10 kGy (6 0 Co).	• In vitro ileal disappearance (IVID)	-	• IVID of dry matter and crude protein not affected by the irradiation intensity.
			Dry matter and crude protein
Pet food from ground chicken	Ground chicken	Ground chicken was vacuum packed in Whirl-Pak bags and treated with gamma radiation a 0.3 and 0.6 kGy at a dose rate of 0.065 kGy/min in refrigeration (4 °C) and (−) 20 °C, respectively.	• Microbiological (bacteria enumeration of E. coli/coliform)	• Ground chicken irradiation doses require inactivating uropathogenic E. coli: 0.28 kGy at 4 °C, 0.36 kGy at −20 °C.	-
				D10 values were 0.28 kGy at 4 °C and 0.36 kGy at –20 °C.

^aAbsorbed dose (kGy).

2.3. Pulsed Light Treatment for Pet Food

Pulsed light treatment is a non-thermal technology that utilizes short-duration, high-intensity light pulses. In the food literature, PL typically denotes broad-spectrum xenon flash systems (μs–ns pulses, 180–1100 nm, very high peak power), which deliver germicidal UV as well as visible and infrared radiation. However, several recent studies on pet food have applied high-intensity LED pulsing at narrow wavelengths (e.g., 365 or 395 nm), which differs in mechanism and energy delivery. For the purposes of this review, both xenon-based PL and LED pulsing are discussed under the same heading, as they share the core principle of microbial inactivation by repeated high-intensity light exposure, but differences in spectral distribution and penetration depth are highlighted where relevant. A Scopus database search over the last ten years has revealed limited research on the application of pulsed light treatment for pet food processing (Table ). While the use of pulsed light is well-documented in the broader food industry, specific research on its application to pet food is still emerging. More studies are needed to optimize treatment parameters for different types of pet food and to fully understand its long-term effects on quality and palatability. Pulsed light treatment in the UV-A range (315–400 nm) shows promise for inactivating pathogenic bacteria in pet food by inducing bacterial cell death. For example, Subedi and Roopesh investigated the use of 395 nm light pulses (0.66 W/cm²) to simultaneously dry pet food pellets and inactivate Salmonella. In this study, the combination of Light Emitting Diode (LED) pulses with hot air and vibration achieved the highest Salmonella reduction (2.26 Log) while effectively lowering water activity. However, these high-intensity LED pulses also significantly increased surface temperatures, which impacted drying rates and led to lipid oxidation (TBARS value). This demonstrates a need for further research to balance microbial inactivation with potential negative effects on food quality. High-intensity pulsed light is a novel approach to inactivating foodborne pathogens, and its application with pet food, particularly in relation to water activity and the need for a non-thermal process, requires further investigation. A Scopus database search revealed limited research on the application of pulsed light treatment for pet food processing during the last ten years (Table ). While the application of pulsed light in the broader food industry is well-documented, specific research on its use in pet food is still emerging, highlighting the need for more studies to optimize treatment parameters and understand its long-term effects on quality and palatability. Pulsed light findings are differentiated by wavelength and water activity, which helps to explain their mode of action. Pulsed light in the UV-A range (315–400 nm) has been reported to induce bacterial cell death, demonstrating potential for inactivating pathogenic bacteria in pet food. Specifically, a study by Prasad found that a 365 nm LED was more effective for inactivating E. coli compared to a 395 nm LED under low water activity conditions (aw = 0.75). In the Near-Ultraviolet to Visible (NUV-Vis) range, research has focused on combining pulsed light with drying effects. Overall, the antimicrobial effectiveness of pulsed LED light is significantly influenced by light exposure time, dose, bacterial strain, and water activity. This suggests that different wavelengths may be more effective against specific pathogens, with the mode of action for NUV-Vis pulses often intertwined with a thermal effect that aids in moisture reduction. Therefore, while pulsed LED light shows promise as a non-thermal decontamination method, its effectiveness requires careful optimization of parameters like light intensity, wavelength, and exposure duration to balance microbial inactivation with maintaining product quality.

3. Pulsed Light Treatment for Pet Food Products during the Last Ten Years .

Food product	Food format	Process condition	Product testing	Microbial inactivation	Other major findings	Ref.
Dry pet food pellets	Pet food pellets	• 395 nm light pulses (irradiance of 0.66 W.cm–2)	• Microbiological test (SalmonellaTyphimurium)	• At 30 min of 395 nm LED pulses, vibration, and 50 °C hot air fluidization reduced Salmonella in pet food pellets by 2.26 Log	• Increased temperature/TBARS
		• 50 °C vibrated hot air fluidization	• Pet food quality (temperature, aw, TBARS)		• Decreased aw
		• Simultaneous application
Dry pet food pellets	Pet food pellets	UV-A/NUV-Vis LED treatment combined with an irradiance (365/395 nm, 0.05/0.114/0.23/0.55 W/cm2, 60% power) Lamp distance 4 from the LED head.	• Microbiological test (E. coli, Salmonella)	• Salmonella (more susceptible than E. coli) showed 1.76 log CFU.g–1 reduction in pet food (a w 0.75) under 365 nm LED (658 J/cm2), which outperformed 395 nm LED.	• Increased surface temperature of pet food pellets
			• Physicochemical (weight loss, moisture, aw)		• Accelerated drying Reduced pet food aw

^aWavelength (nm).

2.4. Plasma Treatment for Pet Food

Plasma technology utilizes ionized gas as a non-thermal sterilization method to enhance microbial safety while minimizing undesirable physical, chemical, and sensory alterations in food products. , Plasma can be categorized into two primary types: thermal plasma and low-temperature plasma. The advantage of using low temperature plasma technology in sterilization is that it is beneficial for heat-sensitive products so that it has a minimal impact on product quality. The primary mechanism for microbial inactivation by plasma treatment is the generation of a complex mixture of Reactive Oxygen and Nitrogen Species (RONS). When an electrical discharge passes through a gas (often air), it ionizes the gas, creating highly reactive and short-lived species such as hydroxyl radicals (^•OH), atomic oxygen (O), and nitric oxide (NO), as well as longer-lived species like ozone (O₃), hydrogen peroxide (H₂O₂), nitrites (NO₂ ^–), and nitrates (NO₃ ^–). These RONS work synergistically to drive inactivation by causing oxidative stress, damaging bacterial cell membranes, and disrupting vital cellular components like lipids, proteins, and DNA. Plasma offers advantages for sterilizing products that contain high levels of protein and fat, such as pet food. Pet food poses a significant health risk due to the potential contamination by Salmonella and L. monocytogenes, affecting pets, their owners, and individuals in proximity, including family members and handlers. Table presents plasma processing methods for pet food and raw ingredients utilized in pet food in the last ten years. Yadav and Roopesh demonstrated the efficacy of cold atmospheric plasma treatment in inactivating Salmonella in freeze-dried pet food pellets. After a 10 min atmospheric cold plasma treatment, the highest reduction of Salmonella observed was 3.03 CFU^.cm^–2 on pet food with an aw of 0.54. Also, a 14-day post-treatment period resulted in a reduction more than 4.6 log CFU^.cm^–2. The effectiveness of in-package atmospheric cold plasma (ACP) treatment for pet food was influenced by a_w and post-treatment storage conditions. The reduction successfully lowered the bacterial count beneath the detectable threshold, demonstrating the potential of in-package atmospheric cold plasma technology to enhance pet food safety. ACP and dielectric barrier discharge have been utilized on various raw animal-origin ingredients in pet food, such as chicken breast, − chicken drumsticks, fresh pork, , mackerel, , and Atlantic herring fillets. In-package ACP treated raw broiler breast meat surfaces at 70 kV for 60 s achieved log reductions exceeding 0.5, 0.7, and 0.4 in psychrophiles, Campylobacter jejuni, and Salmonella Typhimurium, respectively 5 days of refrigerated storage. But it resulted in a paler surface color. In contrast, Moutiq demonstrated that samples treated with ACP (100 kV for 5 min) and in-pack for 24 h achieved a minimum log reduction of 1.5 log CFU^.g^–1 in the populations of mesophiles, Enterobacteriaceae, and psychrophiles, without causing a paler surface color. The initial microbial loads were 3.5 log CFU^.g^–1 for mesophiles, 2.8 log CFU^.g^–1 for Enterobacteriaceae, and 4.1 log CFU^.g^–1 for psychrophiles. Zhao et al. presented a novel inactivation method that achieved 100% inactivation of Pseudomonas aeruginosa on chilled chicken breasts using air and nitrogen-CAP in 5 and 9 min, respectively. Kang et al. demonstrated that pairing plasma with acetic acid significantly enhanced Salmonella Typhimurium reduction in chicken drumsticks. The initial population on the skin was 6.91 log CFU^.cm^–2. Treatment with 0.8% plasma-activated acetic acid reduced S. typhimurium levels by 2.75 log CFU^.g^–1, which was 1.19 log greater than the reduction achieved by acetic acid alone (1.56 log CFU^.g^–1). Moreover, plasma-activated water (PAW) is water that has been treated with atmospheric pressure plasma. It is produced by exposing water (or aqueous solutions) to plasma, either by bubbling plasma gas through the water, generating plasma directly above the water surface, or even within the water. Sammanee et al. revealed that PAW, which naturally contains reactive species such as H₂O₂ (formed in situ), nitrites, and nitrates, effectively inhibited S. enteritidis, S. typhimurium, E. coli, and C. jejuni on pork without impacting its color, pH, or water activity. No exogenous H₂O₂ was added unless explicitly specified in the original study. Zhao et al. found that plasma-activated peracetic acid reduced total mesophilic and psychrotrophic bacteria in mackerel by 0.38 and 0.68 log^.g^–1, respectively with minimal impact on fish quality. These findings highlight the potential of plasma-based technologies as effective and minimally invasive treatment methods for a wide range of food products, including pet food, by inactivating pathogens while preserving product quality and safety. Although plasma-based treatments are effective, potential side effects such as lipid oxidation (TBARS increase) and surface color changes (e.g., paleness observed in poultry) have been reported. In pet food matrices, these effects can be mitigated through process optimizationsuch as adjusting gas composition, exposure time, or combining plasma with protective agentsto balance microbial safety with product quality.

4. Plasma Processing for Pet Food and Its Ingredients during the Last Ten Years .

Food product	Food format	Process condition	Packaging	Product testing	Microbial inactivation	Other major finding	Ref
Plasma processing for pet food
Dog treats	Freeze-dried dog treat	• Cold plasma: 0–30 kV, 3.5 kHz, atm, 2.5–10 min	Modified atmosphere (78% N2 + 21% O2 + 1% CO2) in 76.2 μm nylon/PP vacuum bags	• Microbiological test (Salmonella)	• Salmonella in 0.54 a w pet food (initial 8.2 log CFU.cm–2) was reduced by >4.5 logs (below detection) after a 10 min treatment and 7-day storage.	• Increased peroxide and TBARS in pet food
		• Storage conditions (7 and 14 days at 21 ± 2 °C)		• Lipid oxidation: Peroxide value and TBARS value		• H2O2 concentration reached detection limit (300 ppm) after 5 min of cold plasma treatment
Plasma processing for ingredients
Chicken breasts	Fresh chicken breasts	Cold plasma: 20% humidity, 10 cm, air/N2 (5L/min, 800W), 0–10 min	-	• Total viable bacteria	• Using air and N2 cold plasma reduced P. aeruginosa on chicken breasts by ∼2.58 and 2.38 log CFU.g–1, respectively.	• 100% inactivation: 5 min (air-plasma), 9 min (N2-plasma)
				• pH, color, lipid oxidation (TBARS value), texture profile
Chicken breast	Fresh chicken breast	In-package cold plasma at 100 kV, 233 ± 5 Watts; 60 Hz for 1, 3, and 5 min.	Polypropylene rigid package placed inside a high barrier polypropylene film (Cryovac). Storage at 4 °C for 24 days.	• Microbiological test (Mesophiles, psychrotrophs, and Enterobacteriaceae)	• 100 kV (5 min) reduced mesophiles to 2.6 log CFU.g–1, psychrotrophs to 3 log CFU.g–1, and Enterobacteriaceae to 1.3 log CFU.g–1 after 24 h of storage.	• No significant difference (p > 0.05) in pH, color and TBARS between control and plasma-treated samples after 24 h. of storage.
				• pH, water holding capacity, color, lipid oxidation (TBARS)	• Cold plasma extended the shelf life of refrigerated chicken breast by 6 days.	• Reduced water-holding capacity to 17 mL/100 g with plasma treatment from 3 to 5 min.
Chicken breast cutlet and fille	Fresh chicken breast	Meat samples were packaged in trays and treated with in-package cold plasma at 70 kV for 0, 60, 180, or 300s. Average electric power was 58.5 ± 3.2 Watts.	Polymeric trays and stored at 4 °C for 5 days. Ozone concentrations increased with treatment time from 60 sec to 180 sec in range of 1850 to 2550 ppm.	• Microbiological test (Psychrophiles, Campylobacter and Salmonellatyphimurium)	• Cold plasma reduced spoilage microbes, Campylobacter and Salmonella on refrigerated chicken breast for 5 days.	• The L* value and paleness were increased.
				• Surface color measurement	• A 60s reduced psychrophiles by 0.5 log, Campylobacter by 0.7 log, and Salmonella by 0.4 log.
Chicken skin, breasts, and drumsticks	Raw chicken skin, breasts, and drumsticks	Meat samples were exposed to plasma discharge in 20 mL of 0.2%, 0.6%, and 0.8% (v/v) acetic acid for 30 min, atmospheric air at 2.2 kHz and 8.4 kVpp.	-	• Microbiological test (Salmonella Typhimurium)	• Plasma-activated 0.8% acetic acid reduced Salmonella Typhimurium by 0.98 log CFU.g–1 on chicken breasts and 1.19 log CFU.g–1 on drumsticks.	• Reduced pH, TBARS, and yellowness (b*).
				• Color, pH and lipid oxidation (TBARS value)
				• Electronic nose analysis
				• Morphological
Pork belly and chicken breast fillet	Wet/fresh pork belly and chicken breast	Meat samples were immersed in 500 mL of 60 ppm of H2O2 for 15 min at 25.5 °C. The treatment used a 15 kV; 125 Watts; 50 Hz; Ar carrier gas.	Storage in sterile plastic sealed bags at 4–6 °C for 10 days.	• Microbiological test (Salmonella enteritidis, Salmonella typhimurium, Escherichia coli Campylobacter jejuni, Staphylococcus aureus and Pseudomonas aeruginosa	• A 15 min reduced S. Enteritidis, S. typhimurium, E. coli, and C. jejuni on pork and chicken surfaces at days 0, 3, 4, and 10. Reduction was less effective for S. aureus and P. aeruginosa.	• Reduced the redness (a*), yellowness (b*), pH, and a w of pork and chicken.
				• Color, a w and pH
Pork longissimus dorsi muscle	Fresh pork muscle	Cold plasma (He, Ar, N2; 0.8 MPa, 20–100 kHz, 1.2 kVA) was applied for 5 and 10 min.	-	• Psychrotrophs, yeast and molds.	• Reduced psychrotrophs and yeasts/molds	• No significant in color and pH
				• Color and pH
Mackerel fillet	Raw Mackerel fillet	Fish cube placed in the ultrasonic bath for 10 min and submerged into 60 mL of a plasma beam system at 300-Watt, 20 kHz (30 °C for 10 min).		• Microbiological test (Mesophilic bacteria, psychrotrophic bacteria, and inoculated bacteria (Escherichia coli, Listeria innocua, and Pseudomonas fluorescens).	• Reduced Mesophilic and psychrotrophic bacteria. Treatment demonstrated the greatest inactivation of 0.72, 0.62, and 0.5 log CFU.g–1 for L. innocua, E. coli, and P. fluorescens respectively.	•
				• Color, peroxide value and TBARS
Atlantic herring fillet	Fresh fillet	Dielectric Barrier Discharges: 70/80 kV, 5 min, 50 Hz at 15 °C and 50% RH	270 μm PET trays sealed with 50 μm barrier film and storage at 4 °C for 11 days.	• Microbiological test (Psychrotrophic, Lactic acid bacteria (LAB), Pseudomonas spp., Enterobacteria)	• Reduced Psychrotrophic, Lactic acid bacteria (LAB), Pseudomonas spp., Enterobacteria	• Lower voltage treatments (70 kV) minimized negative quality impacts (lipid oxidation, color)
				• Color, pH and lipid oxidation (TBARS value)
Atlantic mackerel fillet	Fresh fillet	Dielectric barrier discharge: 70 and 80 kV, 1, 3, and 5 min at 15 °C and 50% RH	270 μm PET trays sealed with 50 μm high barrier film and stored at 4 °C.	• Microbiological test (Aerobic mesophilic bacteria, aerobic psychrotropic bacteria, LAB, Pseudomonas spp.	• Reduced Aerobic mesophilic bacteria, aerobic psychrotropic bacteria, LAB, Pseudomonas spp.	• No adverse effect on pH and color
				• pH, proximate composition, Lipid oxidation and Color		• Lipid oxidation sensitivity

^aVoltage (kV) and Frequency (kHz).

2.5. Ozone Treatment for Pet Food

Ozone (O₃) is a powerful oxidizing agent used for disinfecting food, food-contact surfaces, and for water treatment. However, its application had limitations for publication and patents specifically within the pet food sector as shown in Table . In 2001, the U.S. Food and Drug Administration (FDA) approved ozone for use as a direct food additive, classifying it as “Generally Recognized as Safe” (GRAS). Ozone is high aseptic utilized for disinfection of processing equipment, treatment of wastewater, fumigation of stored grains, and surface decontamination of various perishable commodities, including meat carcasses, seafood, fresh fruits, and vegetables. , Ozone can be applied in aqueous form for sanitizing processing water and fresh produce, while its gaseous form is effective for extending shelf life and controlling microbial contamination during the storage of vegetables. Traditional thermal processing is often inadequate in preventing fungal contamination post-packaging. Aspergillus flavus and its aflatoxins are mainly found in in cereals commercial dry food for dogs and ingredients. Silva, Pereira and Scussel investigate the effectiveness of gaseous ozone treatment for reducing Aspergillus flavus contamination in extruded dry dog food. The concentration of ozone gas at 60 μmol/mol for 120 min resulted in the highest reduction (98.3%) on Aspergillus flavus spores in contaminated extruded dry food. Moreover, ozone gas did not affect the lipid stability of the lipid-coated kibble dog food. Chandran, Baker, Hamilton, Dhulappanavar, Jones and Gibson evaluated the application of batch wash and spray wash ozone sanitation systems for reducing foodborne pathogens on vegetables used in raw meat-based diets for pets. Listeria monocytogenes and Salmonella were inoculated on the surfaces of carrots, sweet potatoes, and butternut squash that commonly used in raw meat-based diets for dogs and cats. The results demonstrated that ozone treatment effectively reduced pathogen levels across all substrates, with the highest microbial reduction observed on butternut squash, followed by sweet potato and carrot.

5. Ozone Treatment for Pet Food Products during the Last Ten Years.

Food product	Food format	Process condition	Product testing	Microbial inactivation	Other major findings	Ref.
Extruded dry dog food	Pet food kibble	• O3 gas generator, corona discharger (5–60 μmol/mol): 40 and 60 μmol/mol concentrations at flow rate of 1 L/min for 30, 60, and 120 min	• Microbiological test (Total fungi load)	• O3 gas: treatment 40 and 60 μmol/mol at 120 min achieved the highest reduction (98.3%) on Aspergillus flavus spores in contaminated extruded dry food.	• O3 treatment remained below moisture content and aw that safe from fungal growth.
			• Humidity moisture content/aw, and peroxide index		• O3 gas did not affect sample lipid stability.
Butternut squash, carrot and sweet potato	Raw meat-based pet food	• Aqueous O3: (i) batch wash and (ii) spray wash system; 0 and 5 ppm for 20s and 60s	• Microbiological test (inoculated Salmonella and Listeria monocytogenes)	• Batch wash ozone achieved the highest log reduction (1.56 CFU.mL–1), with no significant difference between 5 ppm and 0 ppm treatments for Salmonella and L. monocytogenes.	-
		• Produce either remained at room temperature for 2 h or were frozen at −20 °C and then tempered overnight at 4 °C		• Spray wash ozone at 5 ppm resulted in the highest log reduction (4.67 CFU.mL–1) of each of bacteria compared to 0 ppm treatment.

3. Patents in Non-thermal Processing Technologies for Pet Food

Non-thermal processing technologies including HPP, pulsed light, plasma, and irradiation are increasingly recognized in the pet food industry for their ability to improve microbial safety and extend shelf life while maintaining nutritional quality. Recent patents in this field emphasize novel applications and process enhancements aimed at increasing the safety and stability of pet food (Table ). Patent data were collected from multiple international databases, including USPTO (United States Patent and Trademark Office), WIPO (World Intellectual Property Organization), EPO (European Patent Office), CNIPA (China National Intellectual Property Administration), and KIPO (Korean Intellectual Property Office). Searches were performed using International Patent Classification (IPC) and Cooperative Patent Classification (CPC) codes related to non-thermal food processing technologies (e.g., A23Kanimal feeds; A23Lfood preservation; A23Jprotein compositions) in combination with keywords (“pet food,” “dog food,” “cat food,” “animal feed”) and processing terms (“high pressure processing,” “HPP,” “plasma,” “cold plasma,” “irradiation,” “gamma,” “UV,” “pulsed light,” “ozone”). The timespan covered January 2014 to December 2024, aligned with the publication search window. Duplicate records across offices were de-duplicated, and only patents with explicit application to pet food (ingredients, treats, or complete diets) were retained. Representative patents were then summarized by processing type, country, claims, and application scope (Table ). The uniqueness of individual HPP patents in pet food is their focus on optimizing safety, quality, and convenience for these products. For instance, Marsden and Moody patent highlights the advantage of in-package pathogen elimination, preserving crucial sensory and nutritional aspects. Similarly, Sherk specifically focuses on the application of high pressure to raw bones, ensuring their safety and extended shelf life while retaining natural nutrients. Furthermore, the integration of cleansing plasma technology alongside HPP in other patented approaches underscores the focus on multi-stage pathogen reduction throughout processing. These distinct patented methods showcase varied strategies within HPP to address the unique challenges and requirements of producing safe, nutritious, and appealing pet food products, from raw meat and bone applications to enhanced processing environments. Plasma technology utilizes ionized gases at ambient temperatures to eliminate microorganisms on food surfaces. Feng published China Patent on application of atmospheric and room temperature plasma (ARTP) technology to induce mutations in Chlamydomonas reinhardtii (CHL). These engineered microalgae strains can serve as sustainable, protein-rich ingredients or functional additives in pet food formulations, offering nutritional enhancement with reduced sensory off-notes. This novel approach has led to the development of unique non-green mutant strains with improved sensory characteristics, such as reduced chlorophyll content and a milder, less fishy odor. Notably, these mutant strains maintain high levels of essential nutrients like protein and polysaccharides. ARTP technology offers significant advantages over conventional mutagenesis methods. It eliminates the need to introduce foreign DNA, simplifies the operational process, ensures environmental safety, and exhibits high mutation efficiency. These strains have diverse applications, ranging from food and cosmetics to dietary supplements. Furthermore, integrating ARTP technology with closed fermentation systems facilitates clean and sterile production processes, while also optimizing manufacturing costs and minimizing environmental impact. Recently, Shanghai Yuanjiang Pet Food Co. utilizes low-temperature plasma technology as a sterilization method during food preparation in Chinese Patent. This technique employs nitrogen gas as the plasma source, operating at a discharge power between 250 and 400 watts for 3 to 6 min, with a gas flow rate of 10 to 14 cubic centimeters per minute. This approach effectively eliminates microorganisms from food components, such as frozen zucchini, while safeguarding their nutritional value.

6. Patents of Non-thermal Processing for Pet Food Products.

Food product	Processing	Country of publication	Patent Number	Claims	Ref.
Raw material for pet food	HPP and Plasma technology	USA	US 2010/0034936 A1	Combined high hydrostatic pressure and plasma surface treatment within a freezer dryer effectively reduces pathogens in raw food
Ground raw bone compressed	HPP	USA	US 2014/0248409 A1	Ground raw bone was pressurized at ≥4000 atm for a set time and maintained rigid at ≤40°F.
Substitute protein product	Plasma technology	China	CN118497001A	Chlamydomonas reinhardtii mutants were generated via atmospheric and room temperature plasma (ARTP) mutagenesis and screened through culture, preparation, and character confirmation.
Freeze-dried raw bone and meat	Plasma technology and irradiation	China	CN118452334A	Uniform zucchini blocks were rapidly frozen (−40 to −70 °C, 0.5 h), then low-temperature plasma sterilized (N2, 250-400W, 3–6 min, 10–14 cm3/min). Freeze-dried, high-nutrition bone meat was prepared for irradiation sterilization, aiding absorption and intestinal health.
Pallet type of a pet food	Infrared/UV drying with dehumidification	South Korea	KR101346696B1	Salmon, pollack head, sweet potato, spinach, carrots, and rosemary are sequentially sterilized and dried using infrared and ultraviolet lamps, hot air, and dehumidification to a 5–15% moisture content.
Pet fresh food	Irradiation (UV sanitation + Co-60 gamma)	China	CN111149938A	Fresh pet food production involves cleaned raw materials, UV sterilization, and 20–25 min Co 60 gamma radiation.

Irradiation treatment such as gamma rays can penetrate deep into food products, effectively eliminating microorganisms. However, consumer acceptance and regulatory approval are crucial factors that will determine the extent of its adoption in the pet food industry.

Ultraviolet (UV) irradiation, particularly UV–C, is effective in reducing microbial contamination on food surfaces. Although primarily used for water and surface disinfection, UV irradiation could be adapted for specific pet food products, especially those with smooth surfaces. Korea Patent and Chinese Patent describe UV-based sterilization systems integrated with drying and dehumidification steps to sanitize pellet-type or fresh pet food while preserving nutritional quality. This process effectively eliminates harmful microorganisms while preserving the essential nutrients and structural integrity of the raw materials. The patent emphasizes UV sanitation as an efficient and noninvasive approach to producing high-quality, nutrient-rich pet food that maintains its safety and freshness.

4. Market Trends of Pet Food Treated by Non-thermal Processing

Mintel’s Global New Products Database (GNPD) provides insights into the number of pet food products treated with non-thermal processing technologies between January 2014 and December 2024 (Figure A). The data reveals a significant increase in irradiation-treated pet food products compared to other technologies. Many product claims emphasize the role of non-thermal technology in enhancing product freshness and quality. Most irradiated pet food products fall within the category of shelf-stable treats, with significant emphasis on dog treats compared to cat treats (Figure B–D). Common examples include dried chicken bites, beef rawhide twists, pig ears, chicken or beef jerky and sweet potato bites etc. The ingredients mostly used in irradiated pet food include real poultry (chicken and duck) and meat (350 items), rawhide (beef, buffalo, or pork) (168 items), sweet potato (74 items), edible offal (42 items) and various ear chews (pig ears: 6 items, beef ears: 1 item). Among HPP, irradiation, and radiation treatments, only 2% of snacks and treats undergo radiation treatment which marketed as having a great taste to appeal to discerning palates. In 2023, Ku Ai Pet Product Trading in China introduced a novel dry cat food product featuring a triple sterilization process for enhanced safety. This process includes 30 min pasteurization during baking; 50s instant microwave sterilization after cooking; and UV sterilization prior to packaging. Mintel’s GNPD data shows limited use of HPP. HPP has the potential to extend the shelf life of both frozen wet and shelf-stable dry dog and cat foods (Figure B). In 2024, Metz Pet Food Technology in China launched a new dry dog and cat food product (“Red Brick”) using HPP as a sterilization method. These products are marketed as safer and more efficient than irradiation due to their ability to eliminate harmful bacteria at low temperatures using ultra-high pressure. However, based on the data presented in Mintel’s GNPD, the utilization of pulsed light technology for pet food sanitization is limited.

3.

(A) Annual number of pet food products by non-thermal technology, (B) irradiation (N = 559), (C) radiation (N = 12), and (D) high-pressure processing (HPP) (N = 7). Product claims (e.g., “treated by radiation” or “treated by irradiation” or “HPP sterilization” etc.) are reported as stated by manufacturers in the Mintel database; independent technical validation of these claims was not available. The search for products was conducted using full text search matches “Irradiation”, “Radiation”, “High Pressure Processing” or “HPP” with word variants and category matches “Pet Food” and date published is between Jan 2014 and Dec 2024, without applying regional filters. All product formats (dry, wet, treats/snacks) were included.

5. Regulatory Considerations

Regulatory considerations for innovative non-thermal technologies in pet food are evolving, but they are primarily guided by the fundamental principles of ensuring safety and accurate labeling, similar to conventional pet food processing. In the United States, the Food and Drug Administration (FDA) enforces the Food Safety Modernization Act (FSMA), including 21 CFR part 507 (Current Good Manufacturing Practice, Hazard Analysis, and Risk-Based Preventive Controls for Food for Animals), which requires hazard analysis and preventive controls for facilities using irradiation or other novel technologies. Specific rules for irradiation of animal feed and pet food are provided under 21 CFR part 579.22, which permits ionizing radiation up to a maximum absorbed dose of 50 kGy for complete diets, feed ingredients, and treats, subject to labeling requirements. The Association of American Feed Control Officials (AAFCO Model Bill and Official Publication, 2024 edition) provides ingredient definitions, nutritional standards, and labeling guidance widely adopted into state law. In the European Union, irradiation of food and feed materials is governed under Regulation (Euratom) 2016/52 and supplemented by national provisions for pet foods. Together, these frameworks ensure that non-thermal technologies meet safety, quality, and consumer transparency standards. As innovative non-thermal technologies like HPP and irradiation gain traction for their ability to reduce pathogens and preserve nutritional quality in pet food, regulatory bodies will likely concentrate on evaluating their effectiveness in pathogen inactivation, potential effects on nutrient bioavailability, and the necessity for specific labeling to ensure consumer understanding and safety.

6. Challenges and Future Opportunities

Innovative non-thermal technologies, such as HPP, cold plasma, irradiation, and pulsed light, present a compelling frontier for enhancing pet food safety and quality. These methods offer significant advantages over traditional thermal processing by minimizing nutrient degradation, preserving organoleptic properties (taste, aroma, and texture), and reducing energy consumption. Scaling up innovative non-thermal technologies for pet food presents both opportunities and challenges. While these technologies like HPP, pulsed electric fields, and irradiation offer benefits in terms of preserving nutritional quality and enhancing safety without harsh heat treatment, their widespread industrial adoption requires overcoming hurdles. Despite the promise of non-thermal processing, several scientific gaps limit the broader adoption of non-thermal technologies. These include: (i) achieving uniform dose distribution in complex pet food matrices (notably for plasma, irradiation, and pulsed light, where surface penetration is limited); (ii) developing nutrient-retention kinetics to quantify the effects of HPP and irradiation on sensitive vitamins, amino acids, and lipids; and (iii) controlling bacterial spores, which remain resistant under HPP and often require pressure-assisted thermal processing (PATP) or hurdle combinations. Addressing these gaps will require systematic experimental data and model development tailored to pet food formulations. Beyond technical gaps, commercialization faces distinct hurdles. These include: (i) high capital expenditure (CapEx) for HPP vessels and irradiation facilities, which limits throughput; (ii) packaging compatibility, as not all flexible films withstand HPP or irradiation; (iii) process throughput limitations, especially for batch HPP and plasma treatments; and (iv) consumer acceptance and labeling concerns, particularly for irradiation and plasma, where perception may hinder adoption despite demonstrated safety. Addressing these barriers will require engineering innovation, cost reduction strategies, and transparent communication with consumers and regulators. Furthermore, maintaining product quality attributes like texture and palatability during scale-up is crucial for consumer acceptance. Addressing regulatory requirements for these novel processes at industrial scales and ensuring adequate training for personnel are also vital for successful commercialization in the pet food industry. Moreover, a key challenge lies in the need for extensive research to validate their efficacy against a broad spectrum of pet foodborne pathogens and spoilage microorganisms, ensuring safety comparable to or exceeding thermal treatments. Standardization of protocols, optimization of treatment parameters for diverse pet food matrices (dry kibble, wet food, and treats), and the development of cost-effective, scalable industrial equipment are crucial hurdles to overcome. Consumer perception and acceptance of these novel technologies, particularly irradiation and cold plasma, require transparent communication and education regarding their safety and benefits. Regulatory frameworks need to evolve and harmonize globally to facilitate the adoption and trade of pet food processed with non-thermal methods. Despite these challenges, the future opportunities are substantial. The market trends section is further bolstered by Klinmalai, showing increasing innovation in palatant technologies (e.g., multilayer coatings, plant- or insect-derived hydrolysate), which suggests opportunities for combining non-thermal processing with formulation strategies to maintain flavor, acceptance, and shelf-life. Non-thermal technologies can enable the creation of minimally processed pet foods with higher nutritional value and enhanced palatability, catering to the growing demand for premium and health-conscious pet food options. Furthermore, these technologies offer a sustainable approach to pet food production by reducing energy usage and potentially extending shelf life, minimizing waste. Continued research, technological advancements, and collaborative efforts between industry, academia, and regulatory bodies will pave the way for the widespread adoption of these innovative non-thermal technologies, ultimately leading to safer, higher-quality, and more sustainable pet food for companions.

7. Conclusions

Based on the Scopus database, non-thermal treatment methods by plasma is the most researched for pet food safety. While pulsed light technologies show potential but require further investigation for uniform treatment. The combination of HPP with lactic acid demonstrates a significant reduction of pathogens in raw formulations. In contrast, gamma irradiation can provide advantages when dose is optimized. However, it requires careful dose optimization to avoid lipid oxidation. Emerging technologies such as pulsed light and cold plasma treatments demonstrate potential but need further optimization for light intensity, exposure duration, uniformity and product quality. Patent trends highlight growing innovation in HPP, atmospheric and low-temperature plasma, UV irradiation, and ionizing radiation, reflecting industry efforts to improve food safety. Despite increasing adoption, particularly in irradiation-treated shelf-stable dog treats, Mintel’s GNPD data suggests limited but growing use of HPP, while pulsed light remains minimal use in pet food sanitization. The future of non-thermal processing in pet food treatment looks promising, with opportunities to enhance efficiency, combine various technologies, tackle regulatory hurdles, broaden applications, strengthen safety monitoring, and boost sustainability efforts. HPP applies uniform hydrostatic pressure throughout the product and has repeatedly achieved ≥5-log pathogen reductions in raw formulations when parameters such as pressure intensity, holding time, acidulation, and storage conditions are optimized. Plasma and pulsed light treatments offer surface-level decontamination with low energy input, making them suitable for dry treats. Gamma irradiation can provide robust microbial reduction for shelf-stable products, though careful dose optimization is required to prevent lipid oxidation. Ozone treatment, although less explored in pet food applications, shows promising potential as a non-thermal, energy-efficient method for microbial control. Gaseous ozone has been used to reduce Aspergillus flavus spores in extruded dry dog food without affecting the lipid stability of kibble. Additionally, batch and spray-wash ozone systems effectively reduced Listeria monocytogenes and Salmonella on vegetables used in raw meat-based diets. Ultrasonication, ozone, and supercritical CO₂ remain promising for specific ingredient treatments but require further validation in pet food matrices.

The authors declare no competing financial interest.