The objective of this study was to determine the lethal effectiveness of pulsed electric fields on the inactivation of the porcine blood endogenous microflora. Furthermore, the impact of pulsed electric field application on physico-chemical and sensory properties in this medium should be proved. Blood samples from a commercial abattoir in Germany were processed by a continuous pilot plant-pulsed electric field system at electric field strength of 11 kV/cm for treatment times of 163 and 209 µs. The applied pulse frequencies of 134 and 175 Hz correspond to an energy input of 91 and 114 kJ/kg, respectively. In these conditions, the effectiveness of pulsed electric field processing on microbial inactivation was limited: 1.35 log10 CFU/mL reduction of total aerobic plate count (p < 0.05), 1.0 log10 CFU/mL for Pseudomonas spp. (p < 0.05), 0.97 and 0.66 log10 CFU/mL reduction for Enterobacteriaceae and sulfite-reducing anaerobic bacteria, respectively. However, the storage experiment (14 days at +3 ) showed a significant reduced growth of total aerobic plate count (p < 0.05) and Pseudomonas spp. (p < 0.05) in the pulsed electric field-treated blood samples. Pulsed electric field processing leads to a complete hemolysis of the red blood cells, in addition significant decreased L* (lightness), a* (redness) and b* (yellowness) values (p < 0.0001) were observed. Furthermore, changes in the sensory attributes color (changed from red to dark brown) and odor (changed from fresh to musty and tangy) were noticed.
Keywords: Porcine blood; microbial shelf life; native microorganism inactivation; physico-chemical properties; pulsed electric fields.