2. Methods of determining the quality of the goods

Depending on the means of analysis and measurement the indices of quality of food goods are determined by organoleptic, by instrument (laboratory), and also expert, measuring, registration, calculated or sociological methods.

Organoleptic method - these are the method of determining the indexes of quality of production on the basis of the analysis of the perceptions of sensory organs - sight, sense of smell, rumor, touch, taste. Accuracy and authenticity of this estimation depend on the qualification, the habits and the abilities of worker, and also on the conditions of conducting the analysis. Merits of the organoleptic method: cheap, rapid, accessible, and drawback is subjectivity (inaccuracy).

In the determination of the quality of foodstuffs the sight plays important role (visual sensations). Estimation is accomplished in the specific sequence and with the observance of the necessary conditions. They will first inspect goods outside and are checked accompanying documents. During the estimation of goods are determined first exterior view, form, color, shine, transparency and other properties. Exterior view characterizes the general visual impression about the product, and color - impression, caused by the light rays of visible light reflected. After this, is determined the smell, consistency finally evaluates taste (juiciness, crumbing, tasting). The color (painting) of product is determined on the standards (fried coffee), according to the color scale (tea) or on the special writings (fault). Shine is characterized by the ability of product to reflect the large part of the rays and depends on the smoothness of its surface (for example, shine of the chandeliers of starch grains). Transparency is determined in the liquid products (fault, juices), in this case the degree of the passage of the light through the layer of the liquid of the specific thickness is evaluated, and they note the content of collapse or mud. Visually is determined as well the presence to the surface of the product of mould or slime, the nature of the figure of surface or section, the presence of foreign inclusions, signs of fermentation and etc.

Such properties of goods as smell, aroma, bouquet, are determined with the aid of the sense of smell. Smell is determined with the excitation of the receptors of sense of smell, located in the quite upper part of the nose cavity. Since the oral cavity communicates with the nose, olfactory sensation frequently merges with the gustatory. The intensity of smell depends on a quantity of volatile substances being isolated from the product and on its chemical nature. The conditions, which facilitate the evaporation of aromatic substances, are created for the best perception of smell, for example they increase surface or increase the temperature of product. Thus, the smell of vegetable oil is determined after its rub along the back side of palm, and it smelled flour and grits - after their warming in the palm by respiration; the smell of flour is set also after its certain persistence in the warm water. With the determination of the smell of products with the dense consistency (meat, fish) uses “the test by needle” or “test to the knife”. In this case wooden needle or the heated knife is introduced deeply into those parts of the product, which are most subjected to spoiling, and smell rapidly is determined after extraction.

By of touch palpable (haptic) sensations are determined consistency, temperature, special features of the physical structure of product, degree of its crushing and some other properties. Consistency is checked by the touch to the product by hand, the lungs by probing product by indicating and large digitally, and also by the application of efforts - by press, by pressure, by pricking, by cutting (stuffing, jelly, meat, jam), by blotting (pie, jam), by chewing (crunch of cabbage, cucumbers, blocks), by rapping frozen goods. With the aid of the touch it is possible to obtain idea about the elasticity of those cooled of meat and fish or gluten of wheaten dough, about baked of the crumb of bread, the insufficiently of the crushing of flour. During the estimation of consistency are considered the tenderness, the juiciness, the elasticity, the hardness, the mealiness, crumbing, softness, uniformity, presence of solid particles (for example, grains in the pie or of sand in tomato products).

Taste and gustatory senses have the greatest value during the estimation of the quality of goods. Taste - this is the sensation, which appears with the excitation of the gustatory receptors, located in the gustatory papillae of the mucous membrane of the upper side of language. Taste cause only the substances, water-soluble or saliva, and to the gustatory senses render influence also consistency and smell of product. Four basic tastes are distinguished: bitter, sweet, acid and salt. They form complex tastes - sour-sweet (taste of fruits and berries), acid- salt (sour vegetables), sweetish- bitter (chocolate). Gustatory senses can be different: the taste astringent, sharp, tart, caustic, which refreshes, burning, oily, mealy.

Taste and gustatory senses depend on the temperature of their determination. Sweet taste better is manifested at a temperature of 37°С, salt - with 18, and bitter - with 10°С. The gustatory senses sharply weaken or disappear at a temperature of 0°С. Therefore one should determine the taste of product at a temperature of 20-40°С.

Sonic and auditory sensations use during the estimation the ripeness of watermelons, with the determination of the saturation of champagne and gassed beverages by carbon dioxide, also, in some other cases.

The scale-number method of estimation - designation is exponential quality with the aid of the conditional system of marks. Qualities use it usually for the expression of the indices, determined organoleptical. In our country are accepted 10, 20- and 100- scale-number of system. Their essence consists in the fact that the most important quality characteristics are evaluated by the specific quantity of marks in the dependence on their significance. The corresponding reduction of marks is done with the presence in goods of defects. The results of ball estimation are summarized. Depending on the sum total of marks (including on the taste and the smell) the commodity type of product is established. The most important indices are taste and smell of product, to which they separate from 40 to 50% of all marks. According to other indices the marks are distributed in accordance with the ponder ability of indices in the formation of the quality of this product. For example, cow's oil is evaluated according to 20- scale-number system, in this case to taste and to smell are removed 10 marks, to exterior view and consistency - 5, to color - 2, to packing and to marking - 3 marks. The general scale-number estimation of cow's oil of the highest type is within the limits of 13-20 marks, including estimation according to the taste and the smell it must be not less than 6 marks, but limiting marks for oil of the 1st type compose 6-12, including on the taste and the smell - 2 marks.

Instrument (laboratory) methods are necessary for the development of chemical composition, innocence, food merit of foodstuffs, physical, chemical, physical chemistry, biochemical, microbiological methods of study are used. The accuracy of results is the merit of laboratory methods.

Expert method - this is the method of determining the indices of quality of production on the basis of the solution, taken by experts. In expert group are included the highly skilled specialists in the evaluated production - scientists, designers, designers, technologists, and also commodity experts and other workers of trade.

Measuring method uses for determining the qualitative indexes with the aid of different instruments, equipment, chemical reagents and dishes. This method makes demands on the people specially equipped accommodation and prepared for conducting the analysis.

With the aid of the registration method the qualitative indexes are determined on the basis of observation and calculation of the number of specific events, objects or expenditures. Method is based on the information, obtained by registration and calculating the number of specific data, for example quantity of defective container or defective articles in the material lot during the inspection, the storage and the realization, with the inventory of physical commodity values.

With the calculated method the qualitative indexes are determined on the basis of the use of theoretical and empirical dependence of the indexes of quality of the production of the parameters.

With the sociological method the indices of quality of production are determined on the basis of collection and analysis of the opinions of its actual or possible users. The attitude of users toward the quality of production is revealed via the calculation of the questionnaires filled by them, and also by organizing of buyer conferences, exhibition- sales, tasting and other measures.

Control questions

1. Advantages and deficiencies in the organoleptic method of evaluating the quality of goods.

2. In what sequence it is necessary to conduct organoleptic estimation?

3. In what does consist the essence of scale-number estimation?

4. What there are laboratory methods of study?