Laboratory work № 5 determination of benzoic acid

In the food industry are widely used in food supplements. It is a natural or synthetic substances intended Merano introduced into food productss to give them the defined properties. Among the specially added substances special the value for conservation are chemical compounds called preservatives. Preservatives prevent microbial spoilage, showcase. The mechanism of action of preservatives on a variety of pathogens. 27 It is possible to allocate: – preservatives that inhibit a specific phase of germination spores of microorganisms; – preservatives that reduce water activity in the substrate and thereby suppressing the growth and development of microorganisms. The amount of preservative agent is regulated standards, as their behavior in the body is ambiguous. Their usage is permitted only when they are technologically necessary, do not represent a risk to health and are used in the interests of the consumer. There are several options for participation preservatives in metabolism: 1) insoluble substances which, as a rule, are unchanged through the intestines; 2) substances absorbed from the gastro-intestinal tract, but chemical conversion is not exposed. They do not give toxic metabolites and excreted through the kidneys; 3) substances absorbed from the gastrointestinal tract, but after biodegradation removed from the body. At the first stage they are oxidized on the second purchase hydrophilicity (by binding with glucuronic, sulfuric, phosphoric acids one way or another) i.e. they have the ability to the development from the body. For these substances, and metabolizing so way, characterized by fairly rapid biochemical harness-tion and the lack of accumulation of metabolites in the body. For example, benzoic acid in the human body forms with glycine the hippuric acid and excreted through the kidneys. Benzoic acid (SN COOH) and its sodium salt (With 6Н5СООNa) are used in concentrations up to 0,1 % for canning of various food products. Despite low preservative effect of sodium benzoate use more often than acid, because of its better solubility in water.

Efficiency the preservative is increased in an acidic environment (pH less than 5). Activity against the above yeasts than against moulds. Benzoic acid affects the enzyme system of microorganisms, as well as acts on cell membranes. She is a good preservative for sour fruit and vegetable products. Benzoic acid and its salts used for canning fruit and berry purees, juices, used in confectionery manufacture, fruit 28 jam, fruit juices, caviar fish, fish preserves not more than 1000 mg/kg, and marmalade, marshmallow, melange intended for the production of biscuits, in the amount of no more than 700 mg/kg; – compounds that are absorbed and metabolised like the substances of the third group, but their elimination or excretion their metabolites is slow. For example, boric and salicylic acid; connection, which after absorption are used by the body the same way as conventional nutrients. They are subjected to biochemical decomposition like proteins, fats, carbohydrates. For example, propionic and sorbic acids. Reagents: 15 %-s ' solution iron-sinergistom potassium; 30 % solution of sulphuric acid for zinc; 10 % solution of hydrochloric acid; chloroform; 95 % ethyl alcohol; phenolphthalein; 0,095 mol/DM 3 sodium hydroxide solution; 10 % solution of sodium hydroxide.