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Methods of laboratory analysis of food quality
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Methods of laboratory analysis of food quality
1. Organoleptic - colour, taste, smell and consistence
2. Physical – density, temperature, etc.
3. Chemical - contents of proteins, fats, carbohydrates and others nutrients.
4. Microscopic - finding foreign substances, ova of helminths, etc. in product by microscope
5. Bacteriological - finding micro-organisms in the products
6. Biological - biological test on the laboratory animal for dangerous products
7. Radiometric - the level of radioactivity of the product
After the obtaining it data it is compare with the specifications of the product.
Documents, regulating the quality of products:
1) State Standard of food product. It is the document defining necessary value of main parameters of the given product and including unified standard procedures of it definition.
2) Temporaly Technical Conditions of food product. It is designed for new products and includes main parameters of the given product.
Classification of food products by quality
1. Good-quality product:
a) Standart - Product, parameters of which correspond the all requirements of the State Standart (Example: milk with fat content 3, 2 %)
b) Non-standart – product have 1-2 unessential non-standart parameters. (Example: the milk with fat lower than 2, 5 %)
2. Conditionally - suitable - product demand the preliminary processing before usage (acidic milk - is subjected for processing for kefir, curd, cheese and other milk products).
3. Bad quality - product have parameters, making it usage impossible for nutrition of man (for example: milk with high contamination by pesticides). The further perspective of such products - destruction or utilisation (on forage for cattle etc. )
4. Falsificated products. (“Falsificatio” – Latin word – it means deception). Properties of such products are changed specially for deceiving the customer (example: Dilute milk by water). Falsification of products is prosecuted.
Substitute - Except for these categories of products quality there is another concept - the substitute of the product - substitute of a natural product officially released by the state at lack of the natural products (for example: margarine - substitute of cow butter). It is estimated according to the State Standard and may belong to one of the quality categories of products.
Sanitary-hygienic characteristic of some food products
(fish, meat, eggs).
Fish - it is rich in proteins with a good biological value. The proteins of fish has a satisfactory amino acid balance. The fat of fish is rich in unsaturated fatty acids family omega – 3 (antysclerotic action) and A and D vitamins. Fish liver oils are the richest source of calcium, phosphorus and A, D vitamins. Fish are less rich in iron. Sea fish contain iodine, but fresh water fish do not contain iodine.
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But fish may be the source of some diseases - Fish-borne Diseases:
1. Helminthosis: Dibothriocephalus latus, opisthorchiasis
2. Bacterial infections: salmonellosis, botulism
3. Viral infections: viral hepatitis type A.
Eggs. Egg contains all the nutrients, except carbohydrates and vitamin C (Table). But in the eggs it is contained Cholesterol in dose 250 mg in 1 egg. Cholesterol promotes hyper-cholesterolaemya and the risk of atherosclerosis. Elderly peaple can eat only 2 eggs at week.
Egg -borne Diseases: Toxico-infection: salmonellosis
Meat. Meat contains 15 to 20 % of protein. Meat proteins are a good source of essential amino acids. The energy provided by meat depends upon its fat content. Iron is contained in meat in dose 2 to 4 mg per 100 g. (Table). Iron from meat is more easly absorbed than Iron from plants and it is another major quality of meat. Meat contains some vitamins (A, B6, B2, and PP), minerals as phosphorus, iron, zinc. It is poor in Calcium and carbohydrates.
All meat should be examined by veterinar inspector before sale. It is necessary strict sanitary control of plases of sale and conditions of keeping fresh meat. Fresh meat must be wet with pink colour, elastic and agreeable odour. It must be clear from pathogenic bacteria. If in slid (40 cm2) of meat is find not more than 3 cysts of gelmints — special cooking.
Meat-borne Diseases:
1. Helminthisms: Taenia saginata, Taenia soliumand, Trichinella spiralis
2. Bacterial infections: tuberculosis, anthrax, brucellosis, salmonellosis
3. Viral infections: spongy encephalitus
Nutritive value of Meat, Fish, and Eggs ( g/100 g)
| Proteins (g ) | Fats ( g ) | Carbohydra-tes ( g ) | Iron ( mg ) | |
| Meat | 21. 4 | 3. 6 | - | 2-4 |
| Fish | 19. 5 | 2. 4 | - | 0. 7-3. 0 |
| Eggs* | 10. 0 | 10. 0 | - | 2. 5 |
| * Two large eggs by weight about 100g | ||||
Sanitary-hygienic characteristic of the milk and milk products
Milk is the most valuable food with high nutrition value. It is an ideal food for infant and children. The milk protiens contains Casein, Lactatalbumin and Lactoglobulin, milk fat is easily digestible. Carbohydrates are present in milk as lactose. Milk contains vitamins, but vitamin С is present only in very small quantities. Human and animals milks are compared in Table.
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