Cold air plasma combined with D-limonene nanoemulsion to control Bacillus cereus in soy-based beverages

Bacillus cereus is a foodborne pathogen whose spores can withstand pasteurization, posing a risk to food safety, particularly in soy-based beverages where its presence has been frequently reported. The aim of this study was to evaluate the efficacy of cold plasma as a disinfection technology for B. cereus contaminated soybean flour and soy protein isolate (SPI), as well as to assess its combined effect with nanoemulsified D-limonene, a well-known antimicrobial compound, to inhibit/reduce the growth of B. cereus in simulated soy drinks. Soybean flour and SPI inoculated with B. cereus spores were exposed to cold plasma treatment with synthetic air (20 % O2 and 80 % N2) at 80 Pa and 300 W for 30 min. Subsequently, these treated matrices were used to simulate soy beverages. Afterwards, remaining spores were germinated (80 degrees C, 10 min) and a 0.05 mol/L D-limonene nanoemulsion was added to the beverages. The viability of B. cereus was then monitored under different storage conditions (30 degrees C and 20 degrees C for 24 h, and 10 degrees C for 10 days). Cold plasma treatment reduced the spore load in soy-based matrices by approximately 1 log cycle and significantly slowed B. cereus growth after the lag phase at 20 degrees C and 30 degrees C. While D-limonene had no effect on B. cereus growth in beverages made with soy flour, it exhibited a bacteriostatic action in SPI drinks, suggesting a potential strategy to enhance food safety.