Treatment of pastirma with pulsed UV light: Modeling of Staphylococcus aureus inactivation and assessment of quality changes

Abstract

The efficacy of pulsed UV (PUV) light treatment carried out in a wide range of fluence was investigated on pastirma slices by characterizing Staphylococcus aureus inactivation using mathematical models and by assessing the treatment effects on quality attributes. Pastirma slices inoculated on top surface with S. aureus were subjected to pulsed UV light for 5, 15, 25, 35, and 45 s at 5, 8, and 13 cm from the quartz window. Although the 5 cm/45 s treatment (72.3 J/cm2) yielded a maximum reduction of 2.99 log cfu/cm2 for S. aureus, this treatment changed the color, moisture, and thiobarbituric acid-reactive substances (TBARS) values of pastirma significantly ( p < 0.05). The quality of pastirma tended to change above 20 J/cm2, below which the highest log reduction of S. aureus was ∼1.3 log cfu/cm2 obtained after the 8 cm/15 s treatment (18 J/cm2). Kamau’s model provided better fit to inactivation data (root mean square error: 0.049–0.116, Af: 1.013–1.046, R2: 0.991–0.999) than Cerf’s and Weibull models.