Efecto de la inclusión de microencapsulados de tomillo en la elaboración de queso fresco

Abstract

The antimicrobial properties of essential oils, especially thyme for its thymol content, has allowed its use as an antimicrobial. The thyme essential oil was microencapsulated by spray drying, using maltodextrin and gum arabic as polymer wall materials, its effect on the physicochemical, microbiological, organoleptic and sensory properties of fresh cheese was evaluated. The cheese was compared with inclusion of microencapsulated in a concentration of 0.5 percent compared to a control cheese (without inclusion of microencapsulated). The microencapsulation contained 20 percent (w over w) of thyme essential oil load, a microencapsulation efficiency of 90 percent was achieved. The main compounds identified in the essential oil of free thyme and in the oil extracted from the microencapsules were thymol, carvacrol, linalool, p-cymene and terpineol, which were quantified by gas chromatography. The count of aerobic-mesophilic microorganisms, molds and yeasts, Staphylococcus aureus and Escherichia coli in the cheese including the thyme essential oil microcapsules was lower than in the cheese without inclusion of the microencapsulation. The microencapsulated oil allowed a reduction of the microbial count after 17 days of storage of the control cheese with respect to which the microencapsulation of 5.05 CFU per gram to 3.90 CFU per gram was included for the aerobic-mesophilic count of 8. 38 CFU per gram to 7.57 CFU per gram for the mold and yeast count, from 6.25 CFU per gram to 5.00 CFU per gram for the S. aureus count, from 8.18 CFU per gram to 7.51 CFU per gram for the E. coli count, which extended the shelf life of the product. The study confirmed the antimicrobial effect of the microencapsulated thyme essential oil and the maintenance of the micro-encapsulated antimicrobial activity during the storage time without modifying the physicochemical, organoleptic and sensory properties of the fresh cheese.