Objective: Blood plasma is a quickly perishable product. The aim of this study was to determine the impact of pulsed electric fields (PEF) on the inactivation of the endogenous microflora and on physico-chemical parameters of porcine blood plasma. Methods: PEF application was performed at an initial temperature of 30 °C, electric field strength of 12 kV/cm, a frequency of 169 Hz which corresponds to a specific energy input of 113 kJ/kg and for a total treatment time of 130 µs. To determine the initial amounts of bacteria in the raw material and to investigate the effect of PEF on the inactivation of the endogenous microflora, samples were taken before and after PEF treatment, as well as on storage days 4, 8 and 14. Results: We found a 1.44 log10 CFU/mL reduction in total aerobic plate count (TPC; p<0.001). For Pseudomonas spp. and Enterobacteriaceae subsequent to PEF application, counts were below the detection limit (p<0.0001 and p<0.05, respectively). A storage experiment showed significantly lower TP (p<0.01), Pseudomonas spp. (p<0.01) and Enterobacteriaceae (p<0.001) counts in the PEF treated plasma after storage for 14 days at 3 °C. There was no difference between native and PEF treated blood plasma samples concerning values of protein, ash, pH, electrical conductivity and aw. Conclusion: In conclusion, PEF application and low temperature storage at 3 °C resulted in a strongly retarded growth of microorganisms in the PEF treated plasma samples, extending its shelf-life to 14 days based on strictest criteria for microbiological acceptability (5 x 104 CFU/mL for TPC, 5 x 103 CFU/mL for Pseudomonas spp., 5 x 102 CFU/mL for Enterobacteriaceae, 5 x 102 CFU/mL for coagulase-positive staphylococci and 1 x 102 CFU/mL for sulphite-reducing anaerobic bacteria). Thus, PEF treatment may be considered as an appropriate method for reducing microorganisms in porcine blood plasma and for extending shelf life.
Boulaaba et al. (Mon,) studied this question.