The Brazilian Journal of Food Technology has recently published a study performed with Gorgonzola cheese to quantify the concentration of Natamycin in its rind and confirm how it migrates, and to assess how Natamycin is reduced in blue cheese during its ripening process.
Gorgonzola is a type of blue cheese that comes from the region in northern Italy, although today it is produced in other parts of the world. The fungus Penicillium glaucum is added to the mass during the manufacturing process to make the characteristic blue-green veins typical of these cheeses which give it its characteristic texture, aroma and flavor and high added value appear. The ripening process takes between three and six months.
As with other cheeses, Natamycin is added to the outer surface of Gorgonzola to prevent contamination during ripening, and does not hinder the fermentation of Penicillium in the cheese mass.
This study sought to compare the presence of Natamycin in blue cheeses produced in Brazil with two samples of other blue cheeses – Italian Gorgonzola (the original) and another cheese from Argentina.
According to Brazilian legislation, Natamycin is an authorised additive in cheeses, but the amount in the rind cannot exceed 5mg/kg, and it must not penetrate the interior of the cheese beyond a depth of 2 mm.
Concentrations of Natamycin higher than those authorised by Brazilian legislation were found in 50% of the cheese samples. One of the samples was of Argentine cheese, and the others were from cheeses made in Brazil.
Except for the Italian Gorgonzola, the other samples contained Natamycin beyond the rind (up to a depth of 6 mm).
The concentration of Natamycin declined in the blue cheeses as they ripened, due to degradation. The researchers concluded that a concentration of 1.5% of Natamycin in the immersion solution was safe for consumption, as after 25 days of ripening the values found in the cheese rinds were below the value recommended by Brazilian legislation, and Natamycin was not detected inside the cheese.
These conclusions of the study highlight the importance of the manufacturing companies applying Natamycin correctly, and the minimum amounts of product required.