Optimization of alginate alkaline extraction technology from Sargassum latifolium and its potential antioxidant and emulsifying properties

Abstract

Alginate was recovered from Sargassum latifolium biomass using different conditions of alkali treatment. Box-Behnken experimental design was evaluated to study the influence of alkali:alga ratio, temperature and time on alginate yield, and its molecular weight (MW) and mannuronic/guluronic acid ratio (M/G). The second-order polynomial equations were analyzed by appropriate statistical methods. Extraction temperature and time were the most important factors during alginate alkaline extraction. MW and M/G ratio played an important role in controlling the reducing power of alginate. Increasing pH of the alginate solutions enhanced its reducing capacity, while thermal treatment showed a negative effect. Additionally, alginate exhibited good emulsion stabilizing capacities with diverse hydrophobic compounds. Emulsifying activity was less sensitive to temperature, ionic strength and more stable at acidic pH.

Keywords: Alkaline treatment; Antioxidant stability; Citric acid (PubChem CID: 311); Emulsifying activity; Ethanol (PubChem CID: 702); FTIR; Iron trichloride (PubChem CID: 24380); M/G ratio; Potassium ferricyanide (PubChem CID: 26250); Sodium alginate; Sodium alginate (PubChem CID: 5102882); Sodium carbonate (PubChem CID: 10340); Trichloroacetic acid (PubChem CID: 6421); d-Mannuronic acid (PubChem CID: 439630); l-Guluronic acid (PubChem CID: 6857369).