Effect of Spirulina platensis and kelp on the antioxidant activity of wheat bread

Abstract

Introduction. The effect of some edible seaweed (Spirulina platensis and Kelp) on the antioxidant activity of wheat bread was studied. Materials and methods. Bread is obtained from wheat flour with the addition of Spirulina platensis and Kelp (powder) in the amount of 2 or 4% by the weight of flour. The antioxidant activity of ethanolic extracts was evaluated by three methods: FRAP (ferric reducing antioxidant power), DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging method and hydroxyl radical (OH) scavenging assay (HRSA). Results and discussion Significant differences in total polyphenol content were found among different quantities of Kelp and Spirulina platensis added in breads. The highest polyphenols content had bread sample containing 4% Spirulina platensis: 0.88±0.02 mg GAE/g DW, and the lowest sample with 2% Kelp: 0.44±0.05 mg GAE/g DW. There is a correlation between DPPH radical scavenging activities and total polyphenol and flavonoid contents. The highest DPPH radical scavenging activity was measured in Spirulina supplemented bread (4%) 3.11±0.05 mmol TE/g DW. In contrast, the lowest DPPH scavenging capacities was observed in ethanol extracts from bread with 4% Kelp (0.89±0.02 mmol TE/g DW). Antioxidant ability of ethanol extracts for reducing Fe3+ by the FRAP values reflecting the ranged from 2.77 (for the sample with 4% Kelp) to 5.04 μmol Fe2+/g DW (for the sample with 4% Spirulina). With an increased S. platensis concentration, significant changes were noted in the hydroxyl radical scavenging activity. The highest values were 27.8±0.4 μg BHT/g DW in the sample prepared with 4% Spirulina platensis, and 17.16±0.42 μg BHT/g DW in the bread containing 2% of the same algae. The result for the control sample was 13.85±0.37 μg BHT/g DW higher value than the sample with 2% Kelp (11.85±0.42 μg BHT/g DW) and 4% Kelp (7.94±0.34 μg BHT/g DW), as with other two methods for determining the antioxidant activity. Conclusions Ethanol extracts from bread prepared with the addition of 4% Spirulina platensis had the highest content of phenolic compounds and antioxidant activity measured with all the methods used.