There has been a steady increase in consumer demand for convenient and nutritious minimally processed produce like fresh-cut apples. However, the fresh-cut produce industry is challenged with potential outbreaks of illness that could be associated with microbial growth during the extended shelf life of these products. These current trends in the fresh-cut apple industry have led to a growing interest in investigating natural antimicrobial agents that are compatible with the chemical properties of post-cut dipping solutions of fresh-cut apples.

Dr. Vasantha Rupasinghe, Tree Fruit Bio-Product Research Chair and Assistant Professor at Nova Scotia Agricultural College (NSAC) investigated the antimicrobial effects of vanillin against pathogenic and spoilage organisms in refrigerated fresh-cut apples. Vanillin is the predominant phytochemical that occurs in vanilla beans and is a flavoring compound used widely in ice cream, beverages, biscuits, chocolate and desserts. Research shows that vanillin has antimyotic and bacteriostatic properties, which means it potentially has the ability to destroy or kill fungi and prevent bacteria from multiplying. According to Dr. Rupasinghe, “the possibility of extending the shelf life of certain products could potentially satisfy consumer demand for convenient and nutritious minimally processed foods.”

Dr. Rupasinghe and his team studied the antimicrobial effect of vanillin against four pathogenic organisms: E.coli, P. aeruginosa, E. aerogenes, and S. Newport and four spoilage organisms: Candida albicans, Lactobacillus casei, Penicillum expasum, and Sacchromyces cerevisie. These organisms could be generally associated with contaminated fresh-cut produce. The two apple cultivars used in this experiment were “Empire”, and “Crispin” and were harvested at the commercial maturity from a commercial orchard.

The vanillin treatment was also combined with an existing fresh-cut processing technology called NatureSeal™ (a post-cut dip solution that contain calcium ascorbate) that prevents enzymatic browning and softening of sliced apples. An investigation of antimicrobial properties of vanillin when incorporated with NatureSeal™ could offer new opportunities for extending the shelf life of fresh-cut fruits.

The research demonstrated that incorporation of vanillin in the post-cut dipping solution of apple slices could inhibit the microbial growth during the 19-day post-cut storage by 37 and 66% in the “Empire” and “Crispin” apple slices, respectively, during storage at 4°C. When incorporated with the commercial anti-browning dipping solution NatureSeal™, vanillin did not influence the control of enzymatic browning and softening of the anti-browning dipping solution.

“These results provide new insight into the possible use of vanillin as a natural antimicrobial agent in processing of sliced apples and others,” says Dr. Rupasinghe. While this research has promising results, further research is required in order to obtain information about the organoleptic (sensory) quality and consumer acceptance of fresh-cut apples treated with vanillin before making a recommendation for its use as a preservative in post-cut dipping solution.

The results of this research are presented as a paper in:
Rupasinghe, H.P.V., J. Boulter-Bitzer, T. Ahn, and J.A. Odumeru. 2006. Vanillin inhibits pathogenic and spoilage microorganisms in vitro and aerobic microbial growth on fresh-cut apples. Food Research International. 39:575-580.