Survival of Listeria strains and shelf life determination of fresh blueberries (Vaccinium corymbosum) treated with cold atmospheric plasma

Authors: CONCHA-MEYER, ANIBAL - Institute Of Agricultural Research, Chile; GONZÁLEZ-ESPARZA, ALEXANDRA - Institute Of Agricultural Research, Chile; CULLEN, PATRICK - University Of Sydney; VELOSO, FELIPE - Catholic Pontifical University Of Chile; FAVRE, MARIO - Catholic Pontifical University Of Chile; VALENZUELA, JULIO - Catholic Pontifical University Of Chile; TOLOZA, LORENA - University Of Barcelona; Niemira, Brendan

Submitted to: Foods
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/20/2024
Publication Date: 3/1/2024
Citation: Concha-Meyer, A.A., González-Esparza, A., Cullen, P.J., Veloso, F., Favre, M., Valenzuela, J.C., Toloza, L., Niemira, B.A. 2024. Survival of Listeria strains and shelf life determination of fresh blueberries (Vaccinium corymbosum) treated with cold atmospheric plasma. Foods. 13(6):822. https://doi.org/10.3390/foods13060822.
DOI: https://doi.org/10.3390/foods13060822

Interpretive Summary: Fresh blueberries are delicate minimally processed fruits vulnerable to spoilage and contamination. Cold atmospheric plasma (CAP) is a promising antimicrobial technology, therefore, this study evaluated CAP treatment effect on acid tolerant Listeria innocua and Listeria monocytogenes and quality of fruit. Samples were spot inoculated with pH 5.5 and 6.0 acid adapted Listeria species. Samples were treated with blowing arc CAP for 15, 30, 45 and 60 s and evaluated after 0, 1, 4, 7 and 11 days of storage at 4°C and 90% humidity for quality parameters total aerobic counts, yeast and molds, texture, color, soluble solids, pH and titratable acidity. CAP treatments of 30s and over demonstrated significant reductions in all pathogens. 60s CAP achieved 48-75% reduction of L. monocytogenes. Yeast and molds count on day 0 showed statistically significant reductions after 30, 45 and 60s CAP with an average 99.5% reduction when compared to non-treated samples. Quality parameters did not show major significant differences among CAP treatments during shelf life study. CAP is an effective antimicrobial treatment that does not significantly affect fruit quality.

Technical Abstract: Fresh blueberries are delicate minimally processed fruits vulnerable to spoilage and contamination. Cold atmospheric plasma (CAP) is a promising antimicrobial technology, therefore, this study evaluated CAP treatment effect on acid tolerant Listeria innocua and Listeria monocytogenes and quality of fruit. 10g samples were spot inoculated with pH 5.5 and 6.0 acid adapted Listeria species. Samples were treated with blowing arc CAP for 15, 30, 45 and 60 s and evaluated after 0, 1, 4, 7 and 11 days of storage at 4°C and 90% humidity for quality parameters total aerobic counts, yeast and molds, texture, color, soluble solids, pH and titratable acidity. CAP treatments of 30s and over demonstrated significant reductions in pathogens under both resistant pH. 60s CAP achieved 0.54 Log CFU g-1 reduction of L. monocytogenes pH 5.5 and 0.28 Log CFU g-1 for L. monocytogenes pH 6.0. Yeast and molds count on day 0 showed statistically significant reductions after 30, 45 and 60s CAP with an average 2.34 Log CFU g-1 reduction when compared to non-CAP treated samples. Quality parameters did not show major significant differences among CAP treatments during shelf life study. CAP is an effective antimicrobial treatment that does not significantly affect fruit quality.