Alginate-based encapsulation of edible flower extract: Process optimization, characterization and in vitro release...

Ionic gelation was employed to encapsulate and protect bioactive compounds from Nongmangkha (Phlogacanthus thyrsiflorus) flower extract and enhance its in vitro bioavailability. A central composite design was used to optimize encapsulation conditions with sodium alginate (SA: 1-3 %) and calcium chloride (CaCl₂: 3-7 %) as independent variables and encapsulation efficiency (EE) of total phenolic as the response. The concentration of flower extract was fixed at 2 % (w/v of SA solution). The optimized conditions obtained were 3 % SA and 5 % CaCl₂ with a predicted EE of 72.19 ± 5.19 %. Further, the flower extract concentrations were varied as 1(S1), 2(S2), 3(S3) and 4(S4) % (w/v) and physicochemical properties of encapsulates were studied. With increment of flower extract concentration in encapsulates, TPC varied from 3.63 to 13.23 mg GAEg^-1 and the DPPH radical scavenging activity increased from 48.693to 75.787 %.Additionally, the release of TPC from encapsulates subjected to in vitro gastrointestinal digestion exhibited a biphasic pattern with two distinct rate constants (k₁ » k₂), reflecting an initial rapid diffusion followed by sustained release at the intestinal phase. Crude extract showed marked TPC loss during the gastric phase, whereas encapsulation protected phenolics from acidic degradation and prolonged their availability in the intestinal phase. These findings highlight alginate-based encapsulation as an effective strategy for preserving and delivering phenolic compounds from Nongmangkha flower extract, supporting its potential use in functional foods and nutraceutical.