The functional potential of immortelle (Helichrysum italicum) based edible films reinforced with proteins and hydrogel particles

Since most studies regarding immortelle (Helichrysum italicum) are focused on the properties and composition of its essential oil, the aim of this study was to develop edible films based on immortelle water extract. Alginate and pectin combined with various proteins served as carriers for the formulation of biodegradable films and hydrogel particles. Films with different biopolymers and incorporated hydrogel particles were prepared by casting method and hydrogel particles were produced by ionic gelation. The bioactive profile (the content of total (TPC) and specific polyphenols, hydroxycinnamic acids (HCAC) and antioxidant capacity (AC)) of the developed matrices was characterized using spectrophotometric methods and high performance liquid chromatography (HPLC). Zeta-potential and rheological properties of alginate- and pectin-based film-forming solutions and physicochemical (color, particle size, film thickness, dry matter content) and sensory properties of the developed particles and films were evaluated. The highest TPC (31.31 mg GAE/g sample) and HCAC (27.20 mg CAE/g sample) as well as the highest AC (0.15 mmol TE/g sample) was determined in pectin-based films. The addition of proteins decreased the content of the examined bioactive parameters, while the addition of hydrogel particles altered their physico-chemical properties. The obtained results indicate a great application potential of the developed biodegradable matrices.