Improving the shelf life of low-fat cut cheese using nanoemulsion-based edible coatings containing oregano essential oil and mandarin fiber

Abstract

Nanoemulsion-based edible coatings containing oregano essential oil (OEO) as antimicrobial were applied onto low-fat cut cheese to extend its shelf life. Nanoemulsions formulation was 2.0% (w/w) sodium alginate, 0.5% (w/w) mandarin fiber, 2.5% (w/w) Tween 80 and 1.5%, 2.0% or 2.5% (w/w) of OEO. Particle size, ζ-potential, apparent viscosity and whiteness index of nanoemulsions were assessed. Water vapor resistance of coatings was evaluated as well as their antimicrobial efficiency against inoculated Staphylococcus aureus and native microbiota growth during refrigerated storage. Headspace gases were measured as an indicator of bacterial activity and sensory alterations such as color and texture of cheese pieces were studied. Coatings with at least 2.0% (w/w) OEO decreased Staphylococcus aureus population from 6.0 to 4.6 log CFU/g after 15 days. Coated-cheese pieces containing 2.5% (w/w) OEO inhibited psychrophilic bacteria or molds and yeasts growth during 6 or 24 days of storage, respectively. Consequently, the atmosphere into the sealed tracks was stabilized and the outward appearance of cheese pieces was preserved. Thus, the present work evidences the feasibility of using mandarin fiber with high nutritional properties and sodium alginate acting as texturizing agents, to form OEO-loaded coatings onto low-fat cut cheese in order to extend its shelf life.

This study was supported by the Ministry of Science and Innovation (Spain) throughout project AGL2009-11475 and by the MINECO (Spain) throughout project AGL2012-35635. Authors María Artiga-Artigas and Alejandra Acevedo-Fani thank the University of Lleida for their pre-doctoral fellowship.