Fungistatis activity of flaxseed in potato dextrose agar and a fresh noodle system

Although numerous researchers have studied flaxseed as a food ingredient for its health benefits, flaxseed (Linum usitatissimum) has never been considered as a food preservative. The objective of this study was to investigate the effect of flaxseed flour (FF) concentration (0, 6, 9, 12, and 15% wt/wt), cultivar (Omega and brown) and source (four seed companies located in Minnesota and North Dakota) on flaxseed fungistatic activity. Fungal radial growth was used to assess the fungistatic activity of FF in both potato dextrose agar (PDA) medium and a fresh noodle system. Strains of Penicillium chrysogenum, Aspergillus flavus, Fusarium graminearum, and a Penicillium sp. isolated from molded noodles were used as the test microorganisms. Results showed that growth of F. graminearum was completely inhibited at all FF concentrations in PDA, and the inhibition of the other three test microorganisms increased with increasing FF concentrations. In the model noodle system, FF concentration at 9% or higher significantly reduced the mold count of fresh noodle during storage. In the inoculated noodle system, 6% FF addition was sufficient to significantly inhibit the growth of F. graminearum and A. flavus, whereas 9% FF concentrations showed fungistatic activity against P. chrysogenum and the Penicillium sp. isolate. Differences in the degree of mold inhibition were found among FFs obtained from different sources and cultivars. Results suggested that flaxseed possesses fungistatic activity and could be used as a multifunctional food ingredient. (Author's abstract)
Mold infestation can have detrimental effects on food qualit and safety. There is an increasing interest in natural preservatives and their application in food products. In previous work by the authors, it was observed that mold spoilage in refrigerated fresh pasta was inhibited by ground flaxseed. This indicated that flaxseed or flaxseed components could serve as natural preservatives. Information regarding the antifungal properties of flaxseed is essential before flaxseed could be used as a food preservative. The objective of this study was to determine the concentration of flaxseed necessary for antifungal activity in both an agar model and a noodle system. The effect of cultivars and sources of flaxseed on the antifungal activity was also evaluated. No correlation could be made between the antifungal activity and flaxseed cultivar or source. The 15% flaxseed concentration inhibited the growth of the molds to a similar degree as a 0.2% propionic acid. Thus, flaxseed has the potential to be used as a multifunctional ingredient in food products due to its health benefits and natural fungistatic properties.  The current study indicates that flaxseed could be used to inhibit molds in foods that do not undergo heat treatments prior to packaging and storage. (Editor's comments)