Influence of polymeric complexes on the stability and releasing behavior of phenol-loaded nano-emulsions: Modeling and optimization

Abstract

Phenolic compounds are well known for their antioxidant and antimicrobial activities. Furthermore, they can be extracted from natural sources. Therefore, phenolic compounds like gallic acid (GA) can be used in different food formulation to improve their healthy properties and extend their shelf life, and as a bioactive compound in the fortification of a number of food products. Double emulsions are novel carrier system which have suitable biocompatibility, complete biodegradability and versatility regarding different oils and emulsifiers in their formulation. Our aim was to encapsulate GA within double nano-emulsions stabilized by pectin-whey protein concentrate (WPC) complexes and reaching the best formulation for minimizing/controlling the release of GA during one-month storage. Other notable goal included designing innovative formulation for enrichment of numerous healthy foods. Five independent variables including Span 80 content, WPC and pectin content, ratio of inner to outer phase, and pH were considered together with size of emulsion droplets, viscosity, color and encapsulation efficiency as the dependent variables. Optimum conditions were identified as, 9.54% WPC, 2.37% pectin, 7.15% Span, 1:4 ratio of inner to outer phase and pH = 6.37. After 30 days storage, double emulsions containing GA (1, 2, 3 and 4 mg/mL) released 31.33, 32.57, 34.69 and 39.68 % of their total content. The results of GA release calculated by artificial neural network were in proportion to those achieved spectrophotometrically. To produce double emulsions with the highest load, samples with 4 (mg/mL) GA were fabricated based on the optimum conditions. The consequences indicated that, a droplet size of 171.5 nm, viscosity of 111.9 mpa. s, color of 79.678 and encapsulation efficiency of 91.45% were successfully obtained. SEM results showed particles with smooth, relatively spherical, with a size range of 100-200 nm, in agreement with the light scattering results. Precise modeling and optimization techniques can result in more accurate monitoring of the release process. Also, the findings of this study can be used in the similar products that can have significant economic and technological advantages.