Natural Food Preservation System as Allyl Isothiocyanate and Edible Brown Seaweed Laminaria japonica Against Aspergillus flavus and Rhizopus stolonifer

Allyl isothiocyanate (AITC) is a major compound in mustard essential oil and found in some species of Brassicaceae. It is well-recognized antimicrobial agent against many foodborne pathogens. Its using as a natural preservative is limited by its high volatility, strong pungency, and poor water solubility. We demonstrate AITC antifungal activity against R. stolonifer and A. flavuswhich cause food spoilage. In agar diffusion disk assay, the inhibition zone diameter for A. flavus and R. stolonifer were 30.00 mm and 33.00 mm respectively at 20.26 mg/ml of AITC. The minimum inhibitory dosage (MID) for both fungi were 5 µL in disk volatilization assay. A new natural food preservative system by vapor and solution deposition methods into raw and de-oiled Laminaria japonica powder, an edible seaweed, we proved AITC vapor-phase activity against both fungi. Up to 97% colony deactivation occurred within 72 h for both R.stolonifer and A,flavus, both vapor- and solution-deposited were parallel in their decay behavior. The de-oiled L.japonica powder was adsorbed AITC twice that of the raw powder at 72 h approaching 99% theoretical maximum amount. The activity of AITC after contact proves that the L. japonica + AITC system would represent a viable natural system for food preservation.