EFFECT OF STORAGE TIME ON THE EFFICACY OF CHEMICAL AND IRRADIATION TREATMENTS TO INACTIVATE SALMONELLA ON CILANTRO ( CORIANDRUM SATIVUM L.).

In this work, the efficacy of decontamination treatments to inactivate Salmonella enterica on cilantro throughout storage under different conditions of temperature and relative humidity (RH) was evaluated. Bunches of cilantro (10 g) were inoculated with a rifampicin-resistant S. enterica strain (ca. 106 cfu/mL) and held at 22C/60 min. Inoculated cilantro (ca. 5.8 log cfu/g) was then stored at: (1) 22C for 2 days under 100 or 30% RH; (2) 5C for up to 8 days under 100 or 60% RH. Periodically, inoculated cilantro was treated with water, chlorine (200 mg/L), peracetic acid (80 mg/L) or gamma rays (0.5, 1 and 2 kGy). At time 0, reductions of Salmonella with chlorine, peracetic acid or water were 2.6, 2.1 and 1.0 log cfu/g, respectively. At 22C, the effectiveness of disinfection treatments to remove or kill Salmonella cells from cilantro significantly decreased as the storage time elapsed (P < 0.05). A similar trend was observed at 5C. On day 0, irradiation of cilantro at a dose of 0.5, 1 or 2 kGy reduced the pathogen by 3.5, 4.5 and 6 log cfu/g, respectively. At 22C, the efficacy of irradiation decreased (P < 0.05), while at 5C, it remained constant regardless of RH. PRACTICAL APPLICATIONS This study demonstrates how the efficacy of decontamination treatments is modified during the storage of cilantro under constant temperature and relative humidity. The decrease in treatment efficacy suggests that microorganisms colonizing the cilantro surface may produce biofilms that provide protection; the level of naturally occurring microflora may also have an influence on its effectiveness. The results reinforce the concept that once cilantro is contaminated with Salmonella, the pathogen can survive chemical disinfection or irradiation, and eventually multiply on cilantro throughout its shelf life. [ABSTRACT FROM AUTHOR]