The effect of combining microwave and ultraviolet methods of plant materials processing on Salmonella culture inhibition

Abstract

The research results concerning the application of physical methods of plant raw materials influencing - fresh beetroot - to inhibit microorganisms of Salmonella genus were presented in the work. Pathogenic microorganisms of Salmonella genus pose a threat to humans, being causative agents of typhoid fever, paratyphoid fever and other salmonellosis. The use of effective and available physical methods of influence in the fruit and vegetable processing technology allows us to ensure the maximum conservation of physiologically valuable components of the raw material and its safety. Microwave (microwave field) and ultraviolet radiation were chosen as physical methods for research. The sterilizing effect of the microwave field was clearly expressed - the bacteria survival after such a treatment was 2 or more times less than during heat treatment. Treatment with ultraviolet radiation has a bactericidal effect and is characterized by a minimal effect on the plant materials organoleptic properties. A comparative assessment of the effectiveness of the inhibition of the Salmonella test culture on diced fresh beets after treatment with the selected physical methods was carried out during the study. The samples temperature rose up to 43–46 °C under the influence of a microwave field in the selected mode with a power of 400 W, a duration of 40 s, and a flux density of 0.44 W / cm2. Treatment with ultraviolet (UV) radiation in the C-band (wavelength 253.7 nm) was carried out for 15 min with a dose of 50 kJ / m2 with a total power of ultraviolet lamps equal to 60 V. Processing of fresh chopped beets with UV radiation reduced the number of microorganisms by 5 orders of magnitude from the initial amount. Processing in a microwave field allowed to reduce the initial seed contamination of raw materials by 7 orders of magnitude. Sequential processing in a microwave field and subsequent ultraviolet radiation allowed us to reduce the initial beets seedling by 8 orders of magnitude. The combination of processing methods (microwave + UV) showed the effectiveness of their application to reduce pathogenic microflora.