| Abstract [eng] |
Anthocyanins (ANC) are naturally occurring phenolic compounds responsible for the red, blue, and purple colors of fruits, vegetables and flowers [1]. These colorful compounds possess strong antioxidant, antiinflammatory and antimicrobial properties, thus they could be utilized in such fields like pharmaceutics, food and active packaging. Introduction of ANC into these fields has proved to be a major challenge since ANC have low stability to environmental conditions during processing and storage [2]. ANC, due to their cationic nature could form complexes with natural or modified biopolymers having oppositely charged groups such as pectin (PCN) or sodium alginate (ALG). The aim of present work was to obtain complexes of ANC and cross-linked PCN or ALG by using adsorption method, as well as to assess their properties. PCN was cross-linked with epichlorohydrin to obtain insoluble low cross-linking degree PCN powder for ANC adsorption. Obtained cross-linked PCN with a cross-linking degree of 0.05 was denoted as CPCN0.05. ALG with a M/G ratio in the interval of 0.9–1.1 was used for ANC adsorption. For the formation of ANC and CPCN0.05 or ALG complexes the desired amount of CPCN0,05 or ALG powder was added to a desired amount of aqueous ANC solution and stirred for 90 min at room temperature, mixtures were centrifuged to isolate insoluble ANC and CPCN0.05 or ANC and ALG complexes, the former was air dried at room temperature and the latter was freeze-dried afterwards. The residual concentration of ANC was determined and the amount of adsorbed ANC on CPCN0.05 or ALG (expressed as grams of ANC per gram of CPCN0.05 or ALG) was calculated. ANC-CPCN0.05 and ANC-ALG complexes having 0.09 g/g and 0.1 g/g of adsorbed ANC were obtained. Release of ANC from ANC-CPCN0.05 (0.09 g/g) and ANC-ALG (0.1 g/g) complexes to different media, such as distilled water, 0.1 M HCl solution (simulated gastric medium), phosphate buffer solution of pH 6.8 (simulated intestinal medium) was investigated. 0.1 M HCl solution was the best medium for the release of ANC. Antioxidant activity of ANC-CPCN0.05 (0.09 g/g), ANC-ALG (0.1 g/g) complexes, ANC extract, ALG and CPCN0.05 was evaluated by a modified ABTS method. ANC extract scavenged ABTS•+ instantly within the few minutes of the experiment. Neither CPCN0.05 nor ALG alone showed antioxidant activity. Meanwhile, ANCCPCN0.05 (0.09 g/g) and ANC-ALG (0.1 g/g) complexes scavenged ABTS•+ gradually, which resulted in prolonged antioxidant activity. |
