Table 1.

Summary of effects of cold plasma processing on quality of food products.

Sample	Plasma	Quality Observation	Microbial Observation	References
Orange Juice	DBD, Air/MA65 (65% O2, 30% CO2, 5% N2), 90 kV, 30–120 s	No significant change in Brix or pH Vit.C is reduced by 22% in air PME activity reduced by 74% in air and 82% in MA65 Maximum total color difference is less than 1.2	Up to 5 log10 reduction of Salmonella enterica	[18]
Prebiotic orange juice	DBD, 70 kV (50 Hz), 15–60 s	Degradation of oligosaccharides in the juice Decrease in pH Increase in L* value and slight reduction in chroma and hue angle Decrease in total phenolic content and antioxidant capacity in some cases	NA	[19]
Cashew apple juice	PE-100, 80 kHz, N2, 10–50 mL/min, 5–15 min, 30 kPa	Decrease in vitamin C at higher flow rate Increase in sucrose content while glucose and fructose contents decreased Longer treatment promoted higher polyhphenol and total flavonoid content	NA	[20]
White grape juice	DBD, 60 Hz, 80 kV, 1–4 min, air	No significant change in pH, acidity and electrical conductivity of the juice An increase in non-enzymatic browning with minimal total color difference Decrease in total phenolics, total flavonoids, DPPH free radicals scavenging and antioxidant capacity An increase in total flavonols content	7.4 log10 CFU/mL reduction in Saccharomyces cerevisiae at 80 kV for 4 min	[21]
Pomegranate juice	Plasma jet, 25 kHz, Ar, 0.75–1.25 dm3/min, 3–7 min	Increase in total anthocyanin content No visual differences in color	NA	[22]
Radish sprouts	Microwave plasma, 2.45 GHz, 900 W, 669 Pa, 1–20 min, N2, 1 L/min	No change in color, water activity, ascorbic acid concentration and antioxidant activity Lower moisture content during storage	2.6 log10 reduction in Salmonella typhimurium 0.8 log10 reduction in total mesophilic aerobes	[23]
Blueberry	DBD, 50 Hz, 60–80 kV, 0–5 min, air	Decrease in firmness, total phenol, flavonoid and anthocyanin on extended cold plasma treatment at the higher voltage level Significant increase in total soluble solid No significant change in acidity and color (except fruit darkening at 80 kv for 5 min)	NA	[24]
Blueberry	Plasma jet, 47 kHz, 549 W, air, 4–7 cubic feet/min, 7.5 cm, 0–120 s	Significant reductions in firmness, color and anthocyanins at higher treatment times	Upto 2 log10 reduction in total aerobic plate count	[25]
Strawberry	DBD, 60 kV, 50 Hz, air, 5 min, indirect exposure	No significant change in color, firmness and respiration rate	2 log10 reduction in background microflora (aerobic mesophilic bacteria, yeast and mould)	[26]
Strawberry	DBD, 60 kV, 50 Hz, 65% O2 + 16% N2 + 19% CO2 and 90% N2 + 10% O2, 5 min, indirect exposure	Strawberries in high oxygen mixture showed higher firmness with similar respiration rates Some changes L* and a* values were observed	~3.0 log10 reduction in microbes in both gas mixtures	[27]
Mandarins	Microwave plasma, 2.45 GHz, 900 W, 1 L/min, 0.7 kPa, N2, He, N2 + O2 (4:1), 10 min	Increased total phenolic content and antioxidant activity No significant change in CO2 generation, weight loss, soluble solids, acidity, pH, ascorbic acid and color	Significant inhibition of Penicillium italicum (84% reduction in disease incidence)	[28]
Kiwifruit	DBD, 15 kV, 10–20 min	Improved color retention and reduced darkened area formation during storage No significant changes in color, hardness, vitamin C and antioxidant activity Longer treatment increase soluble solid content 15% decrease in chlorophyll a on day 0 with no difference on day 4	NA	[29]
Golden delicious apples	Gliding arc plasma, 60 Hz, air, 10–40 L/min, 1–3 min	No changes in color and texture	~3.5 log10 reduction in Salmonella and E. coli O157:H7 reduction	[30]
Apple (Pink Lady apples)	DBD, 12.7 kHz, 150 W, air, 30, 120 min	Up to 10% reduction of antioxidant content and antioxidant capacity No significant difference in total phenolic content but significant decrease in total phenolic index	NA	[31]
Melon	DBD, 15 kV, 12.5 kHz, air, 30, 60 min	No change in acidity, soluble solid content, dry matter, color and texture 17% and 7% reduction in peroxidase and PME activities respectively	3.4 and 2 log10 reductions in mesophilic and lactic acid bacteria respectively	[32]
Cherry tomatoes	DBD, 100 kV, 150 s, air	No significant difference in color, firmness, pH or total soluble solids	>5 and 3.5 log10 cfu/sample reduction in E. coli and Listeria innocua Up to 3.5 log10 cfu/sample reduction on spoilage microflora (mesophiles, yeast and mold)	[33]
Fresh fruit and vegetable slices (pears, cucumbers and carrots)	Plasma micro-jet, 30 mA, 500 V, 1–8 min	Less than 5% moisture loss in all three samples after 8 min treatment Minimal change in total color difference 3.6%, 3.2% and 2.8% reduction of vitamin C in cucumber, carrot and pear slice, respectively	90%, 60% and 40% Salmonella inactivation in carrot, cucumber and pear slice, respectively	[34]
Red chicory	DBD, 19.15 V, 3.15 A, 15 min, deionized water	No detrimental effects on color, freshness and texture Odor and overall acceptability slightly decreased during storage	>4 log10 cfu/cm2 reduction of L. monocytogenes and >5 log10 reduction of VTEC (E. coli)	[35]
Red chicory (radicchio)	DBD, 15 kV, 12.5 kHz, 15–30 min, air, 1.5 m/s	No significant effects on antioxidant activity and external appearance	1.35 log10 MPN/cm2 reduction of E. coli O158:H7 2.2 log10 cfu/cm2 reduction of L. monocytogenes	[36]
Romaine lettuce	DBD, 42.6 kV, 1.5 A, 10 min, air	No significantly change in the surface morphology, color, respiration rate and weight loss	0.4–0.8 log10 cfu/g reduction of E. coli O157:H7 in the leaf samples in the 1, 3, and 5 layer configurations 1.1 log10 cfu/g reduction in bulk stacking with 7 layers	[37]
Fresh produce (romaine lettuce, baby carrots and cocktail tomatoes)	Atmospheric pressure cold plasma, 3.95–12.83 kV, 60 Hz, Ar, 0.5–10 min	No significant changes in color in any samples	0.5, 1.7 and 1.5 log10 reduction of E. coli in carrot, tomato and lettuce, respectively	[6]
Lamb’s lettuce	Plasma jet, 7.12 MHz, 35 W, Ar, 20.000 sccm, 40 s	Strong reduction of phenolic acids and flavonoids Low levels of mono- and polyphenols in leaf after treatment Significant erosion of upper epidermis on leaf surfaces	NA	[38]
Unpeeled almond	Diffuse coplanar surface barrier discharge, 20 kV, 15 kHz, Air, O2, N2, CO2 and 90% CO2 + 10% Ar, 15 min	Plasma treatment with air and N2 resulted in a browning of the unpeeled almond surface color	>5.0, 4.8, 2.3, 3.0 and 2.0 log10 Salmonella Enteritidis PT30 reduction was observed for air, O2, CO2, CO2 + Ar and N2 plasma respectively	[39]
Black gram	Radio Frequency plasma, 2 Pa, air (0.15 mbar), 13.56 MHz, 30–50 W, 5–15 min	Surface etching and hydrophillization of surface Decrease in hardness, cooking time, ash and moisture content	NA	[40]
Brown rice	Radio Frequency plasma, air (0.15 mbar), 13.56 MHz, 40–50 W, 5–10 min	Decrease in cooking time, hardness, chewiness, contact angle, and moisture content Higher degree of gelatinization Increase in water uptake, L value and whiteness index	NA	[41]
Brown rice	DBD, 15 kHz, 250 W, air, 5–20 min	Decrease in pH and hardness Increase in L* and decrease in a* and b* values	Microbes studies: Bacillus cereus, Bacillus subtilis, E. coli O157:H7 and total aerobic bacteria 20 min plasma treatment resulted an approximately 2.30 log10 cfu/g bacterial reduction	[42]
Grains: wheat, bean, chick pea, soy bean, barley, oat, rye, lentil and corn	Low pressure cold plasma, 1 kHz, 20 kV, 500 mTorr, 300 W, air and SF6, 5–20 min	Slight change in moisture content of legume and wheat No difference in water soaking, yield and cooking time of legumes No change in wet gluten content, gluten index and sedimentation in wheat	3 log10 reduction of Aspergillus spp. and Penicillum spp. after 15 min treatment in SF6	[43]
Refined wheat flour	DBD plasma, 1–2.5 kV, 50 Hz, 1–5 min	No significant color change was observed on refined wheat flour	Significant increase in Tribolium castaneum (Herbst).	[44]
Wheat flour (soft and hard)	DBD, 60–70 kV, 5–10 min, air	An increase in the peak time, peak integral, elastic modulus, viscous modulus, dough strength and optimum mixing time No significant variation in tan σ for both flour	NA	[45]
Rice starch	Radio frequency plasma, 13.56 MHz, 40–60 W, 0.15 mbar, air, 5–10 min	Decrease in amylose content, turbidity, gelatinization temperature, retrogradation tendency, degree of starch hydrolysis and pasting temperature Increase in leaching of amylose, pasting, final viscosities, water absorption index, solubility, swelling power and syneresis	NA	[46]
Onion powder	Microwave plasma, 170 and 250 m Wm−2, 2.45 GHz, 400–900 W, 10–40 min, 0.7 kPa, He, 1 L/min,	No effect on color, antioxidant activity and quercetin concentration	2.1 log10 spores/cm2, 1.6 log10 spores/cm2 and 1.9 cfu/cm2 reduction of Bacillus cereus, A. brasiliensis spore, and E. coli O157:H7, respectively	[47]
Bacon	Atmospheric pressure plasma, 75–125 W, 13.56 MHz, 60 s and 90 s, He (10 lpm) and He + O2 (10 lpm and 10 sccm)	Increase in L* value No change in pH Lower TBARS values at day 0, while after 7 days of storage, plasma treated samples had higher TBARS value than control	Pathogens studied: Listeria monocytogenes; Escherichia coli and Salmonella typhimurium Helium plasma reduce the pathogens in 1–2 log10 range Helium/oxygen gas mixture shows a reduction of pathogen in a range of 2–3 log10 4.53 log10 cfu/g reduction in total aerobic count	[48]
Fresh and frozen pork	Plasma jet, Air, 20 kV, 58 kHz, 1.5 amp,0–120 s	No significant changes in volatile basic nitrogen, peroxide value and TBARS No significant impact on the sensory characteristics on frozen pork Significant changes in color for both fresh and frozen pork	1.5 log10 reduction of E. coli O157:H7 >1.0 log10 unit Listeria monocytogenes	[49]
Fresh pork	Microwave plasma, air, 5–10 min, 2.45 GHz, 1.2 kW, 20 slm	Increased a value and decreased b values of pork meat Difference in reflectance and fluorescence. Significant changes in pH	Aerobic viable count remained between 102 and 103 cfu/g during the storage period of 20 days	[50]
Fresh pork and beef	Thin-layer DBD plasma, 1–10 min, 100 W, N2 + O2	No significant effect on texture, L* and b* value Decrease in a* values after 5 min exposure Significant lipid oxidation after 10 min exposure No change sensory parameters except taste, which was negatively influenced	Up to 2.7 log10 cfu/g reduction of Listeria monocytogenes, E. coli O157:H7 and Salmonella tryphimurium in pork and beef	[51]
Pork Loin	DBD, He or He + 0.3% O2, 5–10 min, 3 kV, 30 kHz, 10 slm	Decrease in pH and L* values with no change in a* and b* values Higher lipid oxidation in Helium- oxygen plasma Significant reductions in sensory quality parameters (appearance, color, odor, acceptability)	Up to 0.55 log10 reduction of E. coli reduction in helium and helium-oxygen plasma Up to 0.59 log10 reduction of L. monocytogenes reduction in helium and helium-oxygen plasma	[52]
Beef jerky	RF plasma, Ar, 20,000 sccm, 200 W, 0–10 min	No significant change in fatty acid composition, color and shear force	1.8 log10 reduction in Staphylococcus aureus after 8 min treatment	[8]
Pork	Pulsed plasma, 0.8 MPa, 20–100 kHz, 1.2 kVA, N2, He, Ar	No significant differences in color and pH	Up to 3 log10 cfu/cm2 reduction of psychrotroph bacteria, yeast and mold	[53]
Raw pork	Low-pressure plasma, 0–10 min, He, 20 kPa	Significant changes in total color difference, hue angle and chroma Decreased Ferric reducing ability after 14 days of storage 3% increase in polyunsaturated fatty acids during storage No oxidative processes were observed	NA	[54]
Ground pork	Plasma jet, 7 kV, 25 kHz, 600 W, 1.67 × 10−4 m3/s, 60 min	Increase in nitrite content from 0.64 to 60.50 mg/kg No difference from control in nitrosyl hemochrome, color, residual nitrite, texture, lipid oxidation and protein oxidation Higher score in taste and overall acceptability	No effect on total aerobic count	[55]
Fresh mackerel fillets	DBD, 70–80 kV, 50 Hz, air, 1–5 min	No changes in pH, color (except decrease in L* value), fat and moisture content Higher oleic and eicosapentaenoic acid in plasma treated samples Significant primary oxidation (PV and Dienes) No significant difference in TBARS values. Decrease in T21 (dense myofibrillar network) with increased T22 (extramyofibrillar water)	No significant reduction in the total aerobic mesophilic count Significant reduction in psychotropic bacteria, lactic acid bacteria and Pseudomonas	[56]

Vit.C: vitamin C; MA: Modified atmosphere; NA: Not available; DBD: Dielectric barrier discharge; PME: Pectin methylesterase; TBARS: Thiobarbituric acid reactive substance; PV: peroxide value.