Almond gum-sodium caseinate complexes for loading propolis extract: Characterization, antibacterial activity, release, and in-vitro cytotoxicity

Propolis is a natural antioxidant but, its application is limited due to its strong flavor and alcohol-soluble nature. Soluble complexes and coacervates of almond gum (AG) and sodium caseinate (CAS) were produced at pH = 7 and 4.6, respectively for encapsulation of alcoholic extract of propolis. Despite the higher process yield of complexes at pH = 7, the sample at pH = 4.6 indicated higher encapsulation efficiency, antioxidant activity, and total phenolic content. The results of FTIR and XRD supported the interaction of propolis with biopolymeric complexes. Moreover, the thermal stability and antibacterial activity of propolis were improved after encapsulation; propolis showed higher antibacterial activity against Gram-positive than Gram-negative bacteria. Also, encapsulated propolis showed a controlled release in various food simulants and gastrointestinal environments. Apoptosis evaluation and MTT assay confirmed that the encapsulated propolis induces lower cytotoxicity than pure propolis against fibroblast cell line possibly due to the delayed release of propolis.