The effect of whey protein-based edible coating containing natamycin and lysozyme-xanthan gum conjugate on the shelf life of ultrafiltrated white cheese

The effect of whey protein concentrate based edible coating incorporating different concentrations of natamycin and lysozyme-xanthan gum conjugate on ultrafiltrated white cheese shelf life was investigated. Escherichia coli O157: H7 (as an indicator for gram negative bacteria), Staphylococcus aureus (as an indicator of gram-positive bacteria), and Penicillium chrysogenum (as a mold) were inoculated to the surface of experimental ultrafiltrated cheese samples followed by coating trials. The microbial, physicochemical, and organoleptic properties of cheese samples were evaluated during 60 days of ripening. The results showed that coating of cheese had inhibitory effect on growth of Penicillium chrysogenum. Natamycin-containing coatings were more effective in reducing the mold population than coatings incorporating lysozyme-xanthan. Coating with 600 ppm lysozyme-xanthan reduced 2.09 log E. coli O157:H7 growth compared to that of control (with no coating). Moreover, the populations of Staphylococcus aureus were lower in all coated samples containing lysozyme-xanthan than that of control. There was no significant difference (P> 0.05) between the pH, acidity, salt, and fat in the dry matter of the coated samples and those of the control sample during 60 days of ripening. Edible coatings reduced moisture loss in cheese (5.03%) during 60 days. Coating improved the textural properties of cheese samples, meanwhile did not have a significant effect (P > 0.05) on the taste and overall acceptance of cheese. The results of this study showed that whey protein based edible coating can be used as a carrier of natamycin and lysozyme-xanthan to increase the shelf life of ultrafiltrtated cheese.