**1. Introduction**

Today, the greatest danger of humans is free radicals, the source of about 80 different human diseases including aging [1–14]. Free radicals are produced from the pollution of the climate environment, water, food, human life, and work, and also from the natural transformation of the earth [8, 15]. In order to reduce free radicals, nature itself also has complex metabolic processes to produce inactivates and convert free radicals to a more stable form in nature. Free radicals are known as products of antioxidants that occur naturally or are produced by biosynthesis [1, 7]. These antioxidants are mainly in the form of biopolymers such as proteins, polysaccharides, and secondary metabolites (polyphenols, alkaloids, flavonoids). Each group of antioxidants possesses different antioxidant properties for different applications. They are found in a loose or persistent bond in natural resources and are difficult to extract in varying concentrations into different species. Under the increasing pressure of society and nature, human aging and disease are increasing [4, 9]. To meet the social needs

and personal development. Antioxidant supplements are increasingly popular and welcomed by consumers, and are more interested in by regulators, manufacturers, and researchers.

Hence, the chapter focus on the functional-antioxidant food composing of the structure, the extraction process, and the production technology of antioxidants into functional food, the mechanism of functional-antioxidant food. Functionalantioxidant food will mainly contain protein, polysaccharides, and secondary metabolites, for example, polyphenols (phlorotannins, lignins, polyphenols), alkaloids, and flavonoids. Antioxidant polysaccharides focus on fucoidans, alginates, glucosamines, inulins, laminarins, ulvans, and pectins, while protein is collagen from marine resources. Antioxidant functional foods will exist in the capsule, the tablet, tube, and the effervescent tablet. The materials used for extracting bioactive substances are diverse from terrestrial flora and fauna to the sea.
