sparsely soluble in water and sodium benzoate is more soluble. It inhibits the growth of yeast,mold and some bacteria. The un-dissociated form of benzoic acid is the most effective2
FOOD SCIENCE BY Ms. WINFRED W Mantimicrobial agent with an optimum pH range of 2.5-4.0, making it an effective antimicrobialagent in high-acid foods, fruit drinks, cider, carbonated beverages and pickles. Also used inmargarines, salad dressings, soy sauce and jams.b)Sorbic acidIs a straight chain, trans-transunsaturated fatty acid, 2,4-hexadienoic acid. It has low solubilityin water at room temperature. The sodium or potassium salts are more soluble in water. Sorbatesare stable in the dry form but are unstable in aqueous solutions because they decompose throughoxidation. Sorbic acid and sorbates are effective against yeasts and molds. They inhibit yeastgrowth in a variety of foods including wine, fruit juice, dried fruit, cheese, meat and fishproducts. They are most effective in products of low pH.c)SulfitesSulfur dioxide and sulfites serve both as antimicrobial substances and as antioxidants. Sulfurdioxide dissolves in water to form sulfurous acid. Sulfites can also be used since in water, theyall yield active SO2with the most widely used sulfite as potassium metabisulfite. Sulfur dioxideis used extensively in wine making. The antiseptic activity of SO2is highly dependent on pH,with the lower the pH the greater the antiseptic action.Sulfurous acid inhibits molds and bacteria and to a lesser extent yeasts. Use is not permitted infoods that contain significant quantities of thiamin since the vitamin is destroyed by SO2. 2.AntioxidantsAre substances that have some effect on preventing or retarding oxidative deterioration in food.They are used to prevent lipid and/or vitamin oxidation. Primarily, they are used to preventautoxidation and subsequent development of rancidity and off-flavor. They are especially usefulin preserving dry and frozen foods for an extended period of time.Antioxidants can be classified into the following groups:a)Primary antioxidantsThese terminate free radical chains and function as electron donors and include phenolicantioxidants i.e. butylatedhydroxyanisole (BHA), butylatedhydroxytoluene (BHT), tert butylhydroquinone (TBHQ), alkylgalates, usually propylgallate (PG), and natural and synthetictocopherols and tocotrienols.b)Oxygen scavengers3
FOOD SCIENCE BY Ms. WINFRED W MThese can remove oxygen in a closed system. The most widely used compounds are vitamin Cand related substances i.e. ascorbylpalmitate, and erythorbic acid (the D-isomer of ascorbic acid).Chelating agents or sequestrantsThese remove metallic ions, especially copper and iron, that are powerful pro-oxidants. Citricacid is widely used for this purpose while amino acids and ethylene diaminetetraacetic acid(EDTA) are other examples.
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