Cold plasma from flexible and conformable paper-based electrodes for fresh produce sanitation: Evaluation of microbial inactivation and quality changes
}, volume={137}, ISSN={["1873-7129"]}, url={https://doi.org/10.1016/j.foodcont.2022.108915}, DOI={10.1016/j.foodcont.2022.108915}, abstractNote={Two types of cold plasma generating paper-based electrodes (CPPE) made with flexible metallized paper were developed to decontaminate fresh produce. As opposed to conventional rigid volume dielectric barrier discharge electrodes currently used for in-package plasma generation for which voltage increases as a function of thickness, two flexible CPPE configurations based on surface dielectric barrier discharge provided high local concentrations of plasma with less voltage which was independent of the thickness of the package. For decontaminating E. coli and Listeria innocua, a circular design for spinach and a kirigami and origami based two-cone design for tomato were used. Generation of ozone and other reactive oxygen and nitrogen species by both CPPE were identified. Activation of the circular CPPE for 10 min reduced E. coli by 4.6 ± 0.6 log CFU per spinach leaf and 4.6 ± 0.5 log CFU per tomato, whereas for Listeria innocua the reductions were 4.8 ± 1.7 log CFU per spinach leaf and 2.0 ± 0.4 log CFU per tomato, respectively. No changes in quality attributes were observed in the post-treated tomatoes, while surface browning was observed on spinach leaves. The results demonstrated the effectiveness of the innovative CPPE for in-package sanitation of fresh produce and its impact on quality. Package conformability, surface properties, and bacterial characteristics played important role in overall inactivation efficacy.}, journal={FOOD CONTROL}, publisher={Elsevier BV}, author={Wang, Qingyang and Pal, Ramendra K. and Yen, Hao-Wei and Naik, Siddhant P. and Orzeszko, Mark K. and Mazzeo, Aaron and Salvi, Deepti}, year={2022}, month={Jul} } @article{rivero_wang_salvi_2022, title={Impact of plasma-activated water washing on the microbial inactivation, color, and electrolyte leakage of alfalfa sprouts, broccoli sprouts, and clover sprouts}, volume={81}, ISSN={["1878-5522"]}, url={http://dx.doi.org/10.1016/j.ifset.2022.103123}, DOI={10.1016/j.ifset.2022.103123}, abstractNote={This study investigated plasma-activated water (PAW) as a sanitizer for the washing of sprouts. Alfalfa sprouts, broccoli sprouts, and clover sprouts were washed with PAW, chlorine (Cl, 200 ppm), or deionized water. The inactivation of aerobic mesophilic microorganisms and inoculated Escherichia coli DH5α was evaluated. The quality of sprouts was assessed based on visual color change ( ΔE ) and plant tissue damage (measured by electrolyte leakage). Significant reductions of 1–2 log CFU/g in aerobic mesophilic microorganisms were achieved by PAW and Cl on clover sprouts and alfalfa sprouts. Reductions of E. coli ranging between 1.4 ± 0.4 log CFU/g and 3.5 ± 0.9 log CFU/g were achieved by PAW on the sprouts (original counts: 6.4 to 8.1 CFU/g), which were comparable to Cl except for the case of alfalfa sprouts where Cl achieved the highest inactivation. No significant quality difference in terms of visual color change or electrolyte leakage was observed in sprouts washed by PAW and Cl. • Plasma-activated water (PAW) was evaluated as a novel sanitizer on 3 sprouts. • PAW (5 min) reduced E. coli DH5α from 8.1 to 3.5 log CFU/g in alfalfa sprouts. • PAW and chlorine had comparable reductions of total plate counts and E. coli. • Reductions varied (1.4–7.1 log CFU/g) depending on the types of sprout and washing. • PAW and Cl had similar impacts on the quality of sprouts (color and tissue damage).}, journal={INNOVATIVE FOOD SCIENCE & EMERGING TECHNOLOGIES}, publisher={Elsevier BV}, author={Rivero, W. C. and Wang, Qingyang and Salvi, Deepti}, year={2022}, month={Oct} } @article{wang_salvi_2021, title={Evaluation of plasma-activated water (PAW) as a novel disinfectant: Effectiveness on Escherichia coli and Listeria innocua, physicochemical properties, and storage stability}, volume={149}, ISSN={["1096-1127"]}, url={https://doi.org/10.1016/j.lwt.2021.111847}, DOI={10.1016/j.lwt.2021.111847}, abstractNote={Plasma-activated water (PAW) is an emerging disinfectant with high antimicrobial activity due to a variety of reactive oxygen and nitrogen species. This study evaluated the inactivation efficacy of PAW against planktonic Escherichia coli and Listeria innocua as representatives of gram-negative and gram-positive bacteria, characterized the physicochemical properties of PAW, and investigated the storage stability of PAW. The effectiveness of PAW increased by extending the plasma activation time over water during PAW preparation or the incubation time of bacteria in PAW. PAW also showed higher effectiveness against E. coli than L. innocua: PAW5 (PAW prepared by plasma activation of water for 5 min) reduced E. coli by > 5 log CFU/mL and L. innocua by 1.8 ± 0.5 log CFU/mL within 5 min of bacterial incubation time, while PAW15 (PAW prepared by plasma activation of water for 15 min) reduced E. coli by > 5 log CFU/mL and L. innocua by 3.5 ± 0.6 log CFU/mL within 5 min of bacterial incubation time. Acidic pH and nitrogen species such as NO2− synergistically contributed to the inactivation efficacy of PAW. Fresh PAW showed the highest inactivation efficacy while refrigerated PAW maintained the inactivation efficacy compared to PAW stored at room temperature due to delayed dissipation of reactive species.}, journal={LWT-FOOD SCIENCE AND TECHNOLOGY}, publisher={Elsevier BV}, author={Wang, Qingyang and Salvi, Deepti}, year={2021}, month={Sep} } @article{wang_salvi_2021, title={Recent progress in the application of plasma-activated water (PAW) for food decontamination}, volume={42}, ISSN={["2214-8000"]}, DOI={10.1016/j.cofs.2021.04.012}, abstractNote={Plasma-activated water (PAW) is a novel and promising alternative to traditional food sanitizers. Recently, the inactivation efficacy of PAW has been demonstrated on a wide range of food products against foodborne pathogens, spoilage microorganisms, and harmful chemicals. The effectiveness of PAW relies on various factors related to the plasma generation mechanisms, the target microorganisms, and the food matrix. The inactivation mechanisms of PAW are attributed to the damage of cell integrity and intracellular components by various reactive oxygen and nitrogen species (RONS). Utilization of plasma-activated liquids and hurdle technologies can enhance the inactivation efficacy and diversify the application of this technology. Scaling-up of PAW is still at the very beginning stage and needs further studies before industrial application.}, journal={CURRENT OPINION IN FOOD SCIENCE}, author={Wang, Qingyang and Salvi, Deepti}, year={2021}, month={Dec}, pages={51–60} }