November 3/Braga, Portugal/Journal of Engineering -- "The purpose of this study was to evaluate the effects of the application of chitosan coating containing natamycin on the physicochemical and microbial properties of semi-hard cheese. Three cheese groups were prepared: samples without coating, samples coated with chitosan and with chitosan containing 0.50 mg mL(-1) of natamycin, whose minimum inhibitory concentration was previously determinated on cheese surface," scientists in Braga, Portugal, report.

"Microbiological analyses showed that natamycin coated samples presented a decrease on moulds/yeasts of 1.1 log (CFU g(-1)) compared to control after 27 days of storage. Addition of natamycin also affected O-2 and CO2 permeability, increasing from 7.12 to 7.68 x 10(-15) g.(Pa s m)(-1), and from 10.69 to 64.58 x 10(-14) g.(Pa s m)(-1), respectively. The diffusion coefficient values of natamycin from the film to phosphate buffered saline solution and to the cheese were 3.60 x 10(-10) and 1.29 x 10(-12) cm(2) s(-1), respectively," wrote P. Fajardo and colleagues, University of Minho.

The researchers concluded, "This study demonstrated that chitosan-based coating/films can be used as release system containing natamycin to create an additional hurdle for moulds/yeasts in cheese thus contributing to extend its shelflife."

Fajardo and colleagues published their study in the Journal of Food Engineering ("Evaluation of a Chitosan-based Edible Film as Carrier of Natamycin to Improve the Storability of Saloio Cheese." Journal of Food Engineering, 2010;101(4):349-356).

For more information, contact A.A. Vicente, University of Minho, Center Biology Engineering, IBB, Campus Gualtar, P-4710057 Braga, Portugal.

From the November 15, 2010, Prepared Foods E-dition