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Inactivation of Escherichia coli O157:H7 and Staphylococcus aureus in red pepper powder using a combination of radio frequency thermal and indirect dielectric barrier discharge plasma non-thermal treatments

Choi, Eun Ji, Yang, Hui Seon, Park, Hae Woong, Chun, Ho Hyun
Lebensmittel-Wissenschaft + [i.e. und] Technologie 2018 v.93 pp. 477-484
Capsicum annuum, Escherichia coli O157, Staphylococcus aureus, antioxidant activity, color, detection limit, dielectric heating, drying, food pathogens, free radical scavengers, microbiological quality, powders, radio waves, water activity, water content
This investigation evaluated the inactivation of foodborne pathogens and quality of red pepper (Capsicum annuum L.) powders treated via intermittent intervention with a combination of radio frequency thermal treatment (RF-TT) and dielectric barrier discharge plasma treatment (DBD-PT). Microbiological analysis of powders inoculated with Escherichia coli O157:H7 and Staphylococcus aureus following RF-TT and DBD-PT combination indicated reductions in the microbial counts proportional with increasing treatment cycles. The combination of 1500 W RF heating and 1000 W DBD-PT treatment reduced microbial counts to below the detection limit (1 log CFU/g) after 2 repetitions of the treatment cycle. RF-TT and DBD-PT combination (5 cycles) did not affect powder extractable colour or free radical scavenging activity. The combined treatment caused negligible changes in CIE L∗, a∗, b∗, and ΔE∗ and extractable colour values. The moisture content and water activity showed significant (p < 0.05) differences compared to the control, likely owing to the drying of samples during intermittent RF-TT and DBD-PT. Thus, the hurdle technology combining RF heating and non-thermal plasma treatment could be useful in improving the microbiological quality of red pepper powder.