Production of nanocapsules carrying astaxanthin extracted from Haematococcus pluvialis with maltodextrin-sodium caseinate combined coating and evaluation of physical, antioxidant and color properties of the product

The aim of the present research in the first stage was to extract astaxanthin from Haematococcus microalgae (Haematococcus pluvialis) by combined acid-acetone method and evaluate the efficiency of the process. Then, astaxanthin extracted was nanoencapsulated with maltodextrin-sodium caseinate combined coating and physical, antioxidant and color properties of nanocapsules were evaluated along with the pure form of the pigment (during one month of storage at refrigerator temperature). The results showed that with saponification and primary and secondary purification, the efficiency of the extraction process increased and the amount of pigment during the mentioned steps increased from 8.11 to 21.76 mg/g. According to the findings, the size and zeta potential of the produced nanocapsules were 269.1 nm and +46.71 mV, respectively; In addition, the efficiency of the nanoencapsulation process was recorded as 85.19%. The release profile of astaxanthin from nanocapsules in Simulated Gastric Fluid (SGF) and Simulated Intestinal Fluid (SIF) showed that the release of the pigment varies from 3.21 to 14.28 in SGF and from 18.49 to 41.89% in SIF. Based on the results, the DPPH free radical scavenging activity of pure pigment and nanocapsules (at concentrations of 100 and 200 μg/ml and 0, 15 and 30 days) was ranged from about 21 to 57 and 53 to 70%, respectively. This amount for the reduction power of ferric ion was reported from 0.12 to 0.54 and 0.55 to 0.71 absorbance at 700 nm wavelength, respectively. In the metal chelating activity test, the range of changes was recorded from 23 to 52 and 52 to 75%, respectively. With the nanoencapsulation of the pigment and increasing the concentration, its antioxidant activity increased significantly (p<0.05). Also, unlike the pure form of astaxanthin, the antioxidant activity of its carrier nanocapsules remained constant during storage (p>0.05).