Carrier systems for yerba mate extract (Ilex paraguariensis) to enrich instant soups. Release mechanisms under different pH conditions

The high antioxidant properties of yerba mate (Ilex paraguariensis) extract make it suitable as a natural food additive. Encapsulation of herbal extracts is often necessary to enhance handling and product stability. Release strategies depend on the encapsulation system and the intended use. Calcium alginate capsules, with and without a chitosan layer, containing the yerba mate extract were analyzed, in wet and dried state. Polyphenol release was quantified in gastric (HCl solution, pH = 2) and intestinal (phosphate buffer pH = 7.4) simulated fluids. Most of the encapsulated polyphenols were released in the acidic medium. However, wet capsules with chitosan maintained a higher amount of the active compound before reaching the intestinal medium. Several models were tested to fit kinetic release data; wet and dry capsules showed different release mechanisms in the acidic solution. The dry capsules hydrated, while the wet ones eroded before releasing their content mainly by diffusion. Carrier systems with yerba mate extract were added to instant vegetable soups. Capsules addition increased polyphenols content without modifying the flowability of the soups. The sensory evaluation carried out by a non-trained panel showed no significant differences between enriched and commercial soups.

► Yerba mate extract is encapsulated in calcium alginate beads with or without chitosan. ► In vitro release of polyphenols from wet capsules is governed by diffusion. ► Enrichment of soups with encapsulated antioxidants is undetectable for consumers.