Edible coatings and application of photodynamics in ricotta cheese preservation

Abstract

The present study evaluated the efficiency of an edible coating of alginate and erythrosine in the preservation of ricotta cheese submitted to the technique of Photodynamic Inactivation of Microorganisms (PDIM). Three treatments were evaluated: samples of cheese coated with alginate solution, with alginate solution and 10 μmol/L erythrosine and with 100 μmol/L erythrosine. Mechanical properties, water vapor sorption, solubility and permeability and the release of erythrosine in aqueous medium were characterized. The antimicrobial effect of the coatings followed by photodynamic application was evaluated during cheese storage for 21 days. The coated cheese samples were physico-chemically analysed during 21 days of storage. Salmonella and S. aureus were not detected in any cheese samples, but a 1 log cycle reduction in the Coliform count was only observed when 100 μmol/L erythrosine was used. The PDMI technique did not induce lipid oxidation in cheese samples. The presence of 100 μmol/L reduced tensile strength by 25% at rupture. The water solubility and water vapor permeability of the roofs were not affected by the addition of erythrosine. The application of edible coatings in combination with PDIM is a good alternative to extend the shelf life of ricotta cheese without compromising sensory attributes and nutritional characteristics.