Effects of pulsed electric fields and ozone treatments on disinfection of cabbage seeds surface and quality features

Seeds harbor different microorganisms of soil originated, and the contamination of pathogenic microorganisms adversely affects the quality of the seeds causing product loss. Widespread use of chemicals to maintain seed quality is well known, however, because these chemicals cause important health and environmental problems; alternative microbial inactivation methods have been developed. Pulsed electric fields (PEF) and ozone are commonly used from food industry to the health sector. However, studies involved disinfection of the seed surface in the literature are very limited. Therefore, effects of PEF and ozone treatments on the inactivation of Alternaria brassica and Xanthomonas campestris pathovar campestris (Xcc) pathogenic microorganisms, in addition to the inactivation of natural microflora (total aerobic mesophilic bacteria, TAMB and total yeast-mold, TMY) were investigated in this study. In addition, effects of both applications on seed vigor have also been tested. The seed moisture content of the seeds was adjusted to 6, 10.5 and 15 % in order to observe the influence of moisture content on inactivation level. While 16.4 kV/cm electric field strength, 50, 170 and 290 Hz frequencies and 60, 240 and 420 s treatment times used for PEF; 8.5, 16.5 and 24.5 g/m3 ozone concentrations for 15, 27.5 and 40 min treatment times were used for ozone applications. PEF treatments resulted in 1.9 and 1.2 log cfu/g inactivations on TAMB and TMY, and ozone treatments resulted in 6.5 log cfu/g inactivations on both TAMB and TMY, respectively providing surface disinfections of the seeds. PEF treatment provided 0.7 and 0.42 log cfu/g reductions of A. brassica and Xcc whereas ozone treatment provided 2.43 log cfu/g and 4.3 log cfu/g reductions, respectively. According to the results obtained in the seed vigor tests, it was determined that both the applications, in general, did not adversely impress the seed quality. Therefore, both PEF and ozone technologies carry significant importance in agriculture and especially in the organic agriculture concept for the production of organic seeds.