The use of Natamycin as a food additive to prevent the growth of mould on shredded cheese is common among producers of this popular ingredient in pizzas and other baked foods in the United States. The shredded cheese used in the United States is Cheddar, for which Natamycin has an application limit of 20 mg/m2 on the rind, with penetration to a maximum depth of 5 mm.
A recent study published by Oregon State University in March of this year has once again shown that this food preservative is still the most effective compared to others that may be studied as alternatives.
The study compared the effect of natamycin with thyme and clove oils and chitosan.
The most interesting aspect of this experiment was the new methodology used – image analysis – to quantify the extent to which mould growth was inhibited by each substance, using a cheese-mimicking matrix.
The images were captured at the same time for each sample, every 24 hours over 7 days, using a light box. After the experiment was completed, software was used to measure the extent of growth of each mould colony at the time each specific image was captured.
The results are presented in the diagram below:
The darker blue indicates a greater effect of the substance over time, i.e. a longer preservative effect time. Light blue and even white indicates a shorter effect time, or no anti-fungal effect at all. The maximum duration of the study was 168 hours.
As is apparent, the area with the coloured bars showing Natamycin has the most dark blue squares. This result once again confirms the greater efficacy of Natamycin, while the other substances slow down growth of mould to a lesser extent, even when applied in higher doses.
Natamycin was also effective against all the species of mould used in the experiment.
Despite their potential as fungal inhibitors, the drawback of essential oils is that their aromatic qualities interfere with the aroma and flavour of the products to which they are applied.