Читать книгу Food Chemistry. The Role of Additives, Preservatives and Adulteration онлайн

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 ii. Antioxidants: Antioxidants are additives that are added in to the food to prevent the oxidation reaction. In food material, two types of oxidation reaction may occur: a. enzymatic oxidation of fruits and vegetables; and b. oxidation and rancidity of fats and oils. Antioxidants used in the food material are of following five types:a. radical scavenger or chain breaking antioxidant that is primary antioxidant and it binds with the free radical formed during oxidation reaction, thus preventing the chain reaction;b. chelator binds with metal and prevents them from radical formation;c. quencher that inactivate high energy oxidant;d. oxygen scavenger that removes oxygen from the system;e. antioxidant regenerator that regenerates the antioxidants.Polyphenols are natural antioxidants like flavonoids, tannins, lignans, and coumarins. Natural antioxidant also includes Ferulic acid, Catechin, Ascorbic acid, Tocopherol, Carotenoids like Lycopene, and β-carotene. They are generally used as plant extracts. Synthetic antioxidants include Butylated Hydoxy Anisole (BHA), Butylated Hydroxy Toluene (BHT), tbutylhydroquinone (TBHQ), gallate, and stannous chloride [8–10].In contrast to synthetic antioxidant scientists are finding alternative source of antioxidant in nature. They found that algae contain natural antioxidative compounds that affect various pathogenic organisms with low-cost isolation process. The main antioxidant includes vitamin C and E, carotenoids, polyphenols, and chlorophyll. The red and brown algae contain high levels of folic acid and folate. Two species of cyanobacteria Spirulina platensis and Spirulina maxima are considered as supplements. They have the capacity of lowering lipid content in human body, antioxidant and anti-inflammatory effect. They have high nutritional value. They are considered as important food during long term space mission by NASA. Other important algae include Chlorella vulgaris, Phaeodactylum tricornutum, Gayralia oxysperma, Chaetomorpha antennina, Sargassum vulgare, and Chondrus crispus. They have high antioxidant capacity and have a potential to act as a source of natural antioxidant.