IsoGard™: A natural anti-microbial agent derived from white mustard seeds
A. Ekanayake, J.J. Kester, J. J. Li, J.B. Zent.
G. Zehentbauer and P.R. Bunke Newly Weds Foods,
The Procter & Gamble Company, 2501 N. Keeler Avenue,
Miami Valley Innovation Center, Chicago, IL 60639.
11810 East Miami River Rd.,
Cincinnati, OH 45252.
Keywords: Sinapis alba, essential oil, supercritical fluid extraction, 4-hydroxybenzyl-isothiocyanate, anti-microbial properties, stability in aqueous systems.
Abstract
A natural preservative comprising white mustard (Sinapis alba) essential oil has been developed under the brand name IsoGard™. The essential oil is extracted from white mustard seeds (Sinapis alba) by supercritical a fluid extraction after grinding the seeds in the presence of moisture to activate the endogenous enzyme, myrosinase. Myrosinase hydrolyzes the glucosinolate (sinalbin) naturally present in white mustard seeds to yield the active anti-microbial agent, 4-hydroxybenzyl isothiocyanate (4-HBITC). The extracted essential oil contains ~25-35% by weight of 4-HBITC.
Microbial challenge studies have demonstrated that IsoGard is an effective anti-microbial agent at relatively low usage levels. For example, challenge tests in an acidified fruit drink against gram-negative, acid-tolerant bacteria (Gluconobacter species) and preservative-resistant yeast (Zygosaccharomyces bailii) showed that at a [4-HBITC] ~ 25 ppm was sufficient to stabilize the product against microbial growth at ambient temperature. A bactericidal study in neutral pH peptone broth under refrigerated conditions (5-10ºC) demonstrated that IsoGard is efficacious against various pathogenic and spoilage bacteria, including Escherichia coli, Staphylococcus aureus, Campylobacter jejuni, Pseudomonas aeruginosa, Salmonella enteritidis, Listeria monocytogenes, Shigella boydii, and Clostridium perfringens. [4-HBITC] = 60-120 ppm produced a 2-4 log reduction in microbial counts. At [4-HBITC] = 360 ppm, > 6 log reduction was achieved. When injected into beef steaks as part of a brine, a one log reduction in APC’s resulted at an initial [4-HBITC] = 46 ppm.
To dispense such low levels of the anti-microbial into foods, various IsoGard formulations have been developed. These formulations not only provide modes of application but also stabilize the 4-HBITC, which is relatively unstable when exposed to water.
The 4-HBITC active contributes a mild heat sensation to food products that taste fresh. The heat dissipates during storage and/or cooking of the product as the 4-HBITC is hydrolyzed in the presence of moisture. IsoGard has future potential as an all-natural preservative for extending shelf-life and reducing the risk of food-borne disease in a variety of food and beverage products.