Table 2. Summary of plasma sterilization standards for meat and fish raw ingredients commonly used as pet food ingredients

Raw ingredients Processing conditions Experimental results Reference
Chicken (chicken breast) Normal pressure plasma (10 s, 30 s, 1 min, 2 min, 3 min)Gap: 1.0–1.5 cmVoltage: 6.0–11.0 kVFrequency: 23.0 to 38.5 kHzHe: 5.0 L/minO2: 50, 100 mL/min - The thicker and rougher the surface of the sample, the less effective the plasma treatment.- The sterilization of L. innocua on skinless chicken breast has been reported with a gap of 1 cm, voltage of 8–11 kV, frequency of 30–38.5 kHz, and O2 flow rate of 0–25 mL/min for 4 min.- The sterilization of L. innocua on chicken breast with skin has been reported with a gap of 1 cm, voltage of 7 kV, frequency of 38.5 kHz for 3 min, and with a gap of 1 cm, voltage of 8 kV, frequency of 38.5 kHz for 30 s.- Voltages above 9 kV caused overheating of the transformer, and stable operation was achieved at a frequency of 23 kHz. Noriega et al. (2011)
Total microorganisms (TSA, 30°C, 24 h)Listeria innocua (TSB, 30°C, 48 h)
Chicken/pork (chicken breast/ pork belly) Plasma-activated water (PAW) (immersion, 25.5°C, 15 min)Voltage: 125 W, 15 kVFrequency: 50 Hz60 ppm H2O2, 500 mL - Treatment of pork and chicken with hydrogen peroxide PAW resulted in a greater reduction of C. jejuni compared to other microorganisms.- Hydrogen peroxide PAW treatment on the surface of pork resulted in an increase in pH, CIE L*, temperature, and water activity, and a decrease in CIE a* and CIE b*.- Hydrogen peroxide PAW treatment on the surface of chicken resulted in an increase in pH and CIE a*, and a decrease in CIE L*, CIE b*, and temperature. Sammanee et al. (2022)
Salmonella typhimurium (XLD, 37°C, 24 h)Campylobacter jejuni (mCCD, 41.5°C, 48 h)Escherichia coli (ECD, 44°C, 24 h)Staphylococcus aureus (BPA, 37°C, 48 h)Pseudomonas aeruginosa (GSP, 30°C, 48 h)
Storage conditions0, 3, 7, 10 days4°C to 6°C
Pigs (sirloin) Vacuum plasma (5, 10 min)Frequency: 20–100 kHz - When treated with helium gas and plasma, total microorganisms, psychrophilic bacteria, yeasts, and molds were detected at 2.49, 2.56, and 1.35 Log CFU/cm2, respectively.- When treated with argon gas and plasma, total microorganisms, psychrophilic bacteria, yeasts, and molds were detected at 3.13, 3.13, and 1.86 Log CFU/cm2, respectively.- When treated with nitrogen gas and plasma, total microorganisms, psychrophilic bacteria, yeasts, and molds were detected at 5.02, 5.09, and 3.37 Log CFU/cm2, respectively.- pH showed no significant effect when treated with vacuum plasma. Ulbin-Figlewicz et al. (2015)
Total microorganisms (PCA, 30°C, 72 h)Total yeast and mold (SDAC, 25°C, 5 day)
Beef (10 g) PAW (1 mL spray, 0, 5, 10, 20, 30 min)Voltage: 10 kVFrequency: 8 kHz40 mL deionized water - A 5 min treatment with PAW resulted in a pH decrease of 3.7 compared to the control.- Longer treatment with PAW led to an increase in volatile basic nitrogen (VBN) and thiobarbituric acid reactive substances (TBARS).- PAW treatment resulted in a decrease in CIE a* after 4 days of storage. Zhao et al. (2018)
Total microorganisms (PCA, 37°C)Total bacteria (PCA, 27°C)
Storage conditions6, 12, 24, 48, 96, 192 h, 4°C
Mackerel (fillet) PAW (immersion, 25°C, 10 min)Voltage: 550 WFrequency: 25 kHz200 ppm CH3COOH 30 mL - A 10 min treatment with plasma-activated peracetic acid (PA-PAA) resulted in a 3.8 Log CFU/g reduction in total microorganisms.- PA-PAA treatment had no significant effect on color and TBARS. Zhao et al. (2021)
Total microorganisms (30°C, 48 h/6.5°C, 10 day)E. coli (MacConkey, 37°C, 24 h)L. innocua (Oxford, 37°C, 24 h)Pseudomonas fluorescens (CFN, 30°C, 24 h)
TSA, tryptic soy agar; TSB, tryptic soy broth; XLD, xylose lysine desoxycholate agar; mCCD, modified charcoal cefoperazone deoxycholate agar; ECD, Escherichia coliform detection agar; BPA, Baird Parker agar; GSP, glutamate starch phenol red agar; PCA, plate count agar; SDAC, sabouraud dextrose agar with chloramphenicol; CFN, cetrimide fucidin nalidixic acid agar.