Antioxidant Nano Phlorotannin Powder from Brown Algae Sargassum serratum: Spray Drying, Antioxidant Activities, Physic-Chemical Characterization

Abstract

Introduction: Phlorotannins are bioactive-value polymers existing in brown algae and useful for pharmaceutics and functional food. Therefore, the study focused on the spray drying conditions survey, the evaluation of antioxidant activities, and physico-chemical characterization of antioxidant nano phlorotannin powder prepared from brown algae Sargassum serratum. Methods: To survey the effect of spray drying conditions (carriers, carrier-to-solution ratio, compressed air pressure, liquid feed speed, inlet air temperature) on antioxidant activities (total antioxidant, reducing power, DPPH free radical scavenging), and physico-chemical (solubility degree, moisture, particle morphology, and bulk density) of antioxidant phlorotannin powder from brown algae Sargassum serratum commonly growing in the Vietnam sea area. Results: The optimum spray drying condition consisted of the carrier-to-solution ratio of 10%, compressed air pressure of 0.8 bar, the liquid feed speed of 10 ml min-1, and the inlet temperature of 110°C. At the optimization condition, the antioxidant activity of phlorotannin powder possessed total antioxidant (4.347 ± 0.018 g ascorbic acid equivalent 100-1 g DP), reducing power activity (9.390 ± 0.024 g FeSO4 equivalent 100-1 g DP), DPPH free radical scavenging activity ((70.02 ± 0.26)%), physico-chemical of antioxidant phlorotannin powder consisting of moisture content (5 ± 0.5%), phlorotannin content (2.268 ± 0.010 g phloroglucinol equivalent 100-1 g DP), solubility degree (100%), and bulk density (<1 g/ml). Phlorotannin content and antioxidant activities were affected by the spray drying condition (p < 0.05) and a strong correlation to each other (R2 > 0.9). Antioxidant phlorotannin particles possessed nanometer size and the morphology of irregular and microspheres. Conclusion: Antioxidant nano phlorotannin powder could be usefulas functional food and pharmaceuticals.