EFFICACY OF PULSED LIGHT TECHNOLOGY FOR THE INACTIVATION OF SALMONELLA ENTERITIDIS PT 30 ON ALMOND KERNEL SURFACE
Abstract
Almond surfaces can be contaminated with pathogens such as Salmonella.
Traditional thermal processing technologies used for inactivation of Salmonella on
almonds can adversely impact the quality. Therefore, there is a need to investigate the
efficacy of alternative technologies for inactivation of Salmonella on almonds without
adversely affecting the quality. Pulsed light, a novel technology, can potentially be used to
achieve this. Therefore, this study evaluated the efficacy of three pulsed light systems
(operating at 1.8, 3, or 100 Hz) under various electrical input powers (1000, 1250 and 1500
W) and treatment times for inactivation of Salmonella Enteritidis PT 30 on almond
surfaces. More than 4-log reduction was achieved at different treatment conditions for each
of the control units. For instance, a 160 s treatment at 1500 W (100 Hz system) resulted in
a 4.3 log CFU/almond reduction. Whereas, similar reductions were achieved in a shorter
time with the lower frequency systems (1.8 or 3 Hz). Reductions of 4.6 and 5.9 log
CFU/almond were achieved after 80 and 100 s treatment, respectively with the 1.8 Hz
system (1250 W). Similarly, a 100 s treatment with the 3 Hz system (1000 W) resulted in
a reduction of 4.7 log CFU/almond. Statistical analysis showed that the effect of
equipment, treatment time, and electrical power input were significant (p<0.05). The D-values of 1.8, 3, and 100 Hz systems were 0.24, 0.53 and 0.73 min, respectively at 1500
W. In general, lower frequencies resulted in increased inactivation in shorter time. This can
be attributed to the higher instantaneous power at lower frequencies. Similar trends were
observed at other electrical input powers. The D-values found using pulsed light treatment
are lower than the conventional dry heat treatment ones. Also, minimal color change was observed for treated almonds. These results indicate that pulsed light is efficacious for
decontaminating almond surfaces within a relatively short time.