Allyl Isothiocyanate Reduces Foodborne Pathogens on the Surface of Whole Cantaloupe

Introduction:   Cantaloupes (Cucumis melo L.) can be washed or dipped in 200 ppm chlorine or 5% hydrogen peroxide to reduce the microbial load on the surface; however, neither treatment is completely effective.  Allyl isothiocyanate (AITC), a plant derived antimicrobial compound, has been shown to have antimicrobial activity in its liquid and vapor states, and may be successful in reducing foodborne pathogens on the surface of cantaloupes.

Purpose: The purpose of this study was to determine if AITC (in liquid and vapor phases) reduced populations of Salmonella enterica serovar Michigan and Listeria monocytogenes on the surface of ‘Athena’ and ‘Hales Best Jumbo’ cantaloupes. 

Methods:  Fifty µl of S. Michigan or L. monocytogenes were inoculated onto whole cantaloupes in 22 mm diameter circles, allowed to dry for 90 min resulting in 7.05 log CFU/circle, and received either AITC liquid treatment (5 µl; applied directly), vapor treatments or control (no treatment).  For vapor treatments, liquid (100 or 300 µl) was applied to Whatman No. 1 filter paper attached to the lid of a glass desiccator.  All cantaloupes were stored in sealed glass desiccators and after 24 h, the 22 mm diameter sections of the rind were removed, homogenized and plated onto appropriate agar.

Results: No significant differences existed between cantaloupe cultivars.  Concentrations of S. Michigan and L. monocytogenes on the control melons increased to 7.3 and 7.8 log CFU/10 g, respectively.  Log reductions from each treatment were not significantly different (P < 0.05) for each pathogen.  However, the reduction in S. Michigan on the ‘Athena’ cultivar was significantly different for the vapor treatment levels (3.9 log CFU/10 g for 300 µl and 1.9 log CFU/10 g for 100 µl, respectively).

Significance: Liquid and vapor phases of AITC reduce populations of S. Michigan and L. monocytogenes on the surface of cantaloupe up to 3.9 log CFU/10 g.