Microencapsulação de própolis por coacervação complexa

Abstract

Propolis is a resinous product produced by honey bees from plant sources. This beekeeping product has attracted interest from the food, pharmaceutical and cosmetic industries due to its various pharmacological properties, such as anti-inflammatory, healing, anesthetic, anticarcinogenic properties, among others. The method of microencapsulation of compounds of interest has wide applicability, being characterized as an effective and extremely important method for preserving compounds, protecting them against adverse environmental and/or processing conditions. The application of propolis in foods is still limited, as in addition to being soluble in alcohol, it has an astringent flavor and strong aroma. In addition to the advantages related to stability and maintenance of the functionality of the compounds of interest, microencapsulation can enable the masking of unwanted flavors. Thus, such technology can be seen as a good strategy to reduce problems related to the incorporation of propolis into foods. The objective of the present study was to microencapsulate propolis extract by complex coacervation, using whey proteins and gum arabic, and drying the capsules obtained in an oven, evaluating the effect of pH and proportion of biopolymers on yield. of microcapsules; characterizing the propolis microcapsules produced regarding morphology, humidity, color, hygroscopicity, water solubility, density, content of bioactive compounds, water activity and antioxidant and antimicrobial activities; prepare and evaluate propolis extract for the content of bioactive compounds, antioxidant and antimicrobial activity; evaluate the release kinetics of total phenolic compounds and total flavonoids in different media and evaluate the stability of the propolis microcapsule during storage under different conditions over 90 days. The encapsulation process was evaluated in terms of yield and efficiency. The content of bioactive compounds (total phenolics and total flavonoids), as well as their antioxidant activity by DPPH and FRAP methods and antimicrobial activity, were determined in free and encapsulated propolis extracts. The microcapsules obtained were characterized. The release kinetics of phenolic compounds were evaluated in acidic media (1% acetic acid, pH 2.7 at 37 °C) and neutral media (0.1 mol/L phosphate buffer, pH 7.1 at 25 °C) and the stability of bioactive compounds was evaluated in terms of total phenolic and total flavonoid contents for 90 days. From the results obtained, it was verified that coacervation at pH 4.0 and biopolymers ratio of 3:1 (whey protein and gum arabic) resulted in higher yield (87.33%) and high encapsulation efficiency (80.3%). The microcapsules presented well-defined walls, irregular shapes and sizes, apparent density (0.56 g/mL) in accordance with values observed for powdered foods, low values of water activity (0.30%), humidity (6.7 %), hygroscopicity (3.2%) and water solubility (25.04%). The microcapsules presented IB, 〖h^*〗_ab* e 〖c^*〗_ab values equal to 72.8 ± 1.7; 1.5 ± 0.0 and 19.0 ± 1.1, respectively, tending from red (+a* = 1.0 ± 0.2) to yellow (+b* = 19.0 ± 1.0) more intensely, and presented a lighter color (luminity L* = 81.12 ± 1.62). Propolis extracts and capsules had total phenolic content > 15.9 mg EAG/g, total flavonoids > 0.4 mg EQ/g and antioxidant activity. However, no antimicrobial activity was found against the pathogenic microorganisms tested (Salmonella typhimurium, Escherichia coli and Staphyloccoccus aureus) for the free and encapsulated extracts. In a neutral medium, the retention of phenolic compounds is higher than in a acid medium. The microcapsules showed good conservation of phenolic compounds over 90 days at 25 °C and -75 °C, with a more pronounced reduction in bioactive compounds in capsules stored at 25 °C compared to capsules stored at -75 °C. The results obtained in this study bring perspectives for the use of encapsulated propolis extract in food formulations as a potential additive.