Antioxidant and antimicrobial properties of nanoemulsions made with rosemary and thyme essential oils and their application in the preservation of meat sausages

In this work, nanoemulsions were developed encapsulating essential oils (EOs) for the preservation of meat products, based on rosemary (Salvia rosmarinus) and thyme (Thymus vulgaris), which possess bioactive and antimicrobial properties that make them ideal for replacing preservative agents in meat products. Two nanoemulsions with an R = 2:5 factor (oil/surfactant ratio) were developed and stored under refrigeration (4 °C), evaluating their stability, particle size, rheology and antioxidant capacity. For the preparation of the sausages, three standard formulations were used according to NTC-1325 to determine the percentages of each nanoemulsion to be added (0.47% rosemary EO and 0.08% thyme EO), substituting the percentage corresponding to nitrates and nitrites. Microbiological tests were carried out on the sausages for coliforms, Staphylococcus aureus, Listeria monocytogenes and Clostridium sulfite reductant to determine the microbial activity of the EOs incorporated in the formulation; moisture, color, texture and sensory analysis were also evaluated. The nanoemulsions remained stable during storage time, without significant changes; while microbiological analyses were below the <10 UFC/g range at 21 days of storage for the nanoemulsion sausages, moisture and texture did not show differences. In the sensory analysis, good comments were obtained with respect to the odor and flavor provided by the EOs; color was the attribute with the lowest acceptance. It was demonstrated that the use of EOs as a replacement for chemical additives in meat products helps to extend their shelf life, taking advantage of their bioactive and antimicrobial properties.