Effect of High-Pressure Processing and Nisin on Microbial Inactivation and Quality of Avocado Dressing

Abstract

HighlightsA =7-log reduction of E. coli and L. innocua was accomplished using HPP at 600 MPa for 3 min.There was a synergy between HPP and nisin in all treatments to inactivate both E. coli and L. innocua.HPP and nisin did not affect the color, pH, and total soluble solids content of avocado dressing.Viscosity measurements of avocado dressing samples after HPP showed a good fit to a power-law model.Abstract. The effect of high-pressure processing (HPP) (200, 300, 400, 500, and 600 MPa) and nisin (0, 100, and 200 ppm) on L. innocua and E. coli inactivation and on the color, pH, TSS, and viscosity of avocado dressing was investigated. HPP at 600 MPa for 3 min resulted in 7 log CFU mL-1 reductions of both L. innocua and E. coli in avocado dressing. Combining HPP at =500 MPa with 100 ppm nisin exhibited significant additional L. innocua and E. coli inactivation, indicating high synergy between HPP and nisin. Pressure levels up to 600 MPa did not affect the color, pH, and total soluble solids of avocado dressing. The avocado dressing followed pseudoplastic flow behavior, and the viscosity of the samples decreased with increasing pressure and temperature. HPP was effective in controlling E. coli and L. innocua in avocado dressing without significant quality loss. Keywords: Color, Escherichia coli, High-pressure processing, Listeria innocua, Nisin, Viscosity.