Desenvolvimento de sistema nanoemulsionado contendo óleo de carvacrol como aditivo alimentar antimicrobiano

Abstract

In recent decades, microbial resistance has become a serious risk to public health, a phenomenon resulting from the indiscriminate use of antibiotic antibiotics by health institutions, the population, in agriculture and agriculture, or by gene recombination or mutation between species. With bacterial resistance, food pathogens are a major concern for the food industry, consumers and safety authorities. The use of bioactive products derived from secondary metabolism of vegetables is a viable alternative, as is the case of Carvacrol oil (CV), a phenolic monoterpene with proven antimicrobial activity. However, characteristics, such as its hydrophobia, oxidation facility, instability in the presence of light, heat and humidity, can limit its application as a food additive. With this, the use of emulsified systems, such as nanoemulsions (NEs) appear as an alternative, in order to increase the stability of these compounds and increase their solubility. Furthermore, the choice of nanoemulsified systems as antimicrobial agents is important, as they interact with microbial cell membranes, causing them to stop growing. Thus, the objective of this work was the development, characterization and evaluation of the antimicrobial activity against the bacteria Staphylococcus aureus UFPEDA02, Escherichia coli UFPEDA224, Pseudomonas aeruginosa UFPEDA416, Salmonella enteritidis ATCC13076 and Salmonella typhimurium ATCC14028 of a NE containing CV. To obtain a stable NE, a study of HLB identification of the CV by the microemultocrit method was first carried out, so at the end an HLB value of 11 was found for the CV used in this study. Then, a study was carried out to obtain a NE with greater stability, for that, it varied the proportions of CV (3 and 5%), surfactants (a mixture of Tween 80® and Span 80®) (2, 5 and 9%) and water (86, 88, 90, 92 and 95%). From the prepared NEs, just the one with 3% oil, 9% surfactant and 88% water (NECV) remained stable for up to 90 days. The high energy emulsification methodology was used to obtain the systems, where the NEs went through four cycles of homogenization in the sonicator and ultrasound bath. The amount of oil in the NECV system was performed using analytical methodology developed in the UV-VIS spectrophotometer, which obtained an encapsulation efficiency of 99.45% ± 0.019 (equivalent to 2.98 mg CV per mL of NE). Then, it was characterized as for the macroscopic aspect, presenting liquid aspect with white color. During the 90 days, no creaming formation or phase separation was observed, which NECV remained with an expected average droplet size (D90 = 164.5 ± 0.69 nm), PDI (D90 = 0.118 ± 0.024), zeta potential (D90 = -14.6 ± 0.529 mV) and pH (D90 = 5.52 ± 0.011). After this, the antibacterial activity of the isolated compound and the nanoemulsified system was evaluated by the microdilution method, in which Rezasurin was used as a visual indicator of cellular metabolism. In terms of antibacterial activity, NECV (MIC: 256 µg / mL for E. coli and Samonella spp., 128 µg / mL for S. aureus and P. aeruginosa) obtained a better result when compared to the free compound against strains S. aureus, P. aeruginosa and S. typhimurium. Furthermore, there was a bactericidal effect against E. coli, P. aeruginosa and Salmonella spp. The results obtained indicated that NECV can be incorporated as a food additive to prevent and control microbial growth.