Alginate-based encapsulation of polyphenols from Clitoria ternatea petal flower extract enhances stability and biological activity under simulated gastrointestinal conditions

Microencapsulation of phenolic extracts of Clitoria ternatea (CT) petal flower extract through extrusion method of alginate with calcium chloride (CaCl₂) was studied. Encapsulation efficiency varied in the range from 74.17 ± 0.83% to 84.87 ± 0.29% depending on the percentage of CT (5–20%), alginate (1–2%), and CaCl₂ (1.5–5%). The results showed that the optimized condition of CT-loaded alginate beads (CT beads) was as follows: 10% CT, 1.5% alginate, and 3% CaCl₂ (w/v). Under this condition, the maximal antioxidant capacity of 11.76 ± 0.07 mg gallic acid equivalent/g_beads and the encapsulation efficiency of 84.83 ± 0.40% were obtained. The microencapsulation was found to have smooth surface shape with a particle size distribution of 985 ± 0.53 μm and improve the thermal stability with 188 °C. There was the absence of chemical interactions between CT and alginate as verified by using FT-IR. The microencapsulation of CT significantly retains higher amount of polyphenols and improves antioxidant capacity, pancreatic α-amylase inhibitory activity, and bile acid binding after the gastrointestinal digestion. This study provides a novel food-grade encapsulation formulation to improve the stability as well as the biological activity of plant polyphenols.