High Pressure Processing for Decontamination of Orange Juice from Natural Flora and Salmonella serovars
Despite advancements in public health interventions for over a century after identification of Salmonella serovars, foodborne non-typhoidal Salmonella are currently leading etiological agent for foodborne hospitalizations and deaths in the United States. With recent improvements in commercial feasibility of high pressure processing units, the technology is gaining rapid acceptability across various sectors of food manufacturing, thus requiring extensive validation studies for effective adoption.
Various times (1 to 10 minutes) and intensity levels (0 to 380 MPa) of elevated hydrostatic pressure (Pressure BioSciences, Inc) were investigated in two separate experiments for decontamination of background microflora and inoculated Salmonella in fresh-press, and sterilized fresh-press orange juice, respectively. Unit and sample temperatures were maintained precisely at 4ºC by a circulating water bath and stainless steel jacket surrounding the chamber. Each experiment was conducted in two biologically independent repetitions, as blocking factors of a randomized complete block design, containing three repetitions per time/treatment within each block. For Salmonella-inoculated experiment, a five-strain habituated mixture of the pathogen were prepared at target level of 7.5 log CFU/ml. Results were analyzed by GLM procedure of SAS using Tukey-and Dunnett-adjusted ANOVA. The Kmax and D-values were calculated using best-fitted (maximum R2) model obtained by the GInaFits oftware.
At 380 MPa, for treatments of 1 to 10 minutes, D-value of 1.35, 4-D reduction of 3.4, and inactivation Kmax of 3.34 were observed for salmonella serovars. D-values were 5.90 and 14.68 for treatments of 241 and 103 MPa, respectively. Up to 1.01and >7.22logCFU/mL reductions (P<0.05) of habituated Salmonella serovars at planktonic stages were achieved using application of pressure at 380MP for 1 and 10minutes, respectively.
Similarly, background microflora counts were reduced (P<0.05) by 1.68 to 5.29 log CFU/mL after treatment at 380 MPa for 1 and 10 minutes, respectively. Treatments below two minutes were less efficacious (P ≥0.05) against the pathogen and background microflora, in vast majority of time and pressure combinations. Results of this study could be incorporated as a part of risk-based food safety management systems and risk assessment analyses for mitigation of public health burden of non-typhoidal Salmonella serovars.