Encapsulated powders of Alcea flower polyphenol‐rich extract by different hydrocolloid carriers: characterisation, antioxidant activity and chemical structures

Abstract

Alcea flower (as a natural source of antioxidants and colour) polyphenols might be easily deteriorated during processing and preservation. So, encapsulation is a suitable approach to overcome this problem. In this study, Alcea flower extract (AFE) was encapsulated using different carriers (maltodextrin (MD) and MD with gum arabic (GA), whey protein concentrate (WPC), and GA-WPC). The production yield ( ∼ 70%) was higher when MD-WPC mixture or MD alone were used. The moisture content, water activity (a w ), and wettability time of samples containing MD were less than other samples while their solubility was higher. Bulk and tapped density and also hygroscopicity were lowest in the samples produced using MD-WPC, with improved flowability. The morphological characteristics of particles (matrix-type particles with smooth and spherical surfaces in MD samples and wrinkled and indented in protein carriers) were affected by the carrier composition. Chemical structure evaluation (FTIR) indicated the successful coating of polyphenols in the carrier matrix. Generally, TPC (0.93 mg GAE mL À1 ) and retention of DPPH (82.4%), ABTS (94.1%), hydroxyl radical scavenging (77.2%) and reducing power (87.5%) of the samples produced with MD-WPC were higher than other carriers.