Laboratory work # 15. Receptions falsify identification of contaminants in food raw materials and products.

The purpose of work: To carry out identification examination of starch and food iodized salt using measurement and test methods.

Theoretical part:

A characteristic feature of the commodities of this group is their raw material use and the inability to use it as an independent food product.

 Another feature is that they are often used for prescription falsification to give the products the necessary organoleptic properties that are identical to natural, and/or increase their mass. For example, food additives (dyes, flavors identical to natural, sweeteners, stabilizers) and consistency improvers contribute to the formation of organoleptic properties that mimic the color, smell, taste and consistency of natural products, and in some cases make them even more attractive and stable when stored.

Of the commodities of this group most often falsified biologically active additives, starch, spices, much less common salt, mostly iodized and fluorinated. BAA - biologically active additives of vegetable, or animal, or mineral, or combined origin, containing biologically active substances and having physiological value.

Auxiliary commodities include a very diverse in chemical composition products, so there are no identifiable features common to this group. Each type of commodities s in this group has specific characteristics. This is largely due to the fact that many representatives of this group are substances that are monocomponent (for example, dyes) or polycomponent compounds with predominance of a certain leading substance (for example, sodium chloride, starch, pectin).

The specified composition features facilitate their species assortment identification by the main substance. Methods for the qualitative detection of the leading substances of a number of auxiliary commodities are well known and widely used for their identification, both as an independent product and as part of multicomponent food products for which they were used (Table 14). Chemists say iodine is a reagent for the presence of starch, and starch is an indicator of the presence of iodine.

Table 14 -Methods and indicators of identification of auxiliary products

No.	Type of commodities	Identification		Signs of detection
		Indicators	Method
1	Starch, including modified	Starch	Iodine-starch reaction	Appearance of blue staining
2	Soda drinkable	Hydrocarbonate sodium	Titration with acid	Release of CO2 by reaction with acid
3	Food pectin	Pectin	Calcium-pectate	Formation of white precipitate of calcium pectate
4	Acidifiers	Food acids	Titration with alkali in the presence of phenolphthalein	Disappearance of red color
5	Synthetic dyes of red color	Synthetic dyes	Addition of alkali or soda	Stain stability
6	Natural dyes	Anthocyanins, betanine	Same	Change in color to blue or violet
		Chlorophyll	Boiling in water	On the brown-green
		Carotene and carotenoids	Boiling in a weak alkali solution	Discoloration

Starch is a stabilizer and improver for the consistency of many products. However, different types of it have different ability to stabilize and improve consistency. The most valuable technological properties are potato starch, the least valuable - corn. Therefore, often enough potato, more expensive starch is replaced with cheap corn.

Falsification of starch can be assorted, qualimetric, quantitative and informational. Storing starch in rooms with high humidity in order that it absorbs moisture and becomes heavier, leads to quantitative falsification.

Assortment falsification is carried out only at the species level, when potato or rice starch is partially or completely replaced by less valuable corn. In addition, a partial or complete replacement of starch as a more expensive product with wheat flour is possible. You can detect falsification by the shape and size of the starch grains, and the addition of wheat flour - when washing by the presence of gluten.

Qualitative falsification manifests itself in the form of re-sorting, while the Extra variety and Extra variety (in potato starch) are partially or completely replaced by the lower ones - 1st or 2nd grade. To identify this type of falsification, reliable identification features are known (ash content, number of craters per 1dm², color, chandelier (shine) - in higher grades).

Information falsification often serves as reinforcement of the first two types of falsification and is almost not used as an independent species.

Table salt is one of the cheapest products, so it rarely undergoes falsification. Exceptions are only two types of salt: iodized and fluorinated, in which valuable trace elements of iodine and fluorine are absent due to falsification of formulations and are not included in their composition. In addition, iodized salt after the expiration of the storage period (6 months) loses iodine due to its oxidation and destruction.

The salt is a crystalline free-flowing product in which foreign mechanical impurities are not allowed, not related to the origin and nature of the salt. The color of the salt is white with possible shades of grayish, yellowish or pinkish color, depending on the place of salt production and its grade, determined by the degree of purification. The smell of table salt is absent. According to the method of production, the salt is divided into stone, self-planting, batch and evaporation. The quality is classified by salt: extra, higher, first and second grade.

Iodized salt is a common salt with a small amount of iodide or potassium iodate. With prolonged or improper storage, loss of iodine ions or, accordingly, of useful functional properties occurs, and therefore a constant control over the iodine content is necessary.

In table salt as salts of various acids or acid residues, lead, copper, potassium, arsenic, mercury, zinc and other elements can be contained. However, their allowable content should not exceed the level established by the SanPiN. To determine the degree of safety of goods, including food, in recent years test methods are widely used based on determining the presence of a component in the product according to the sensitivity limit of the chemical or biochemical reaction. Test methods are close to measuring values, and from simplicity to sensory methods, so now these methods are increasingly used in identification and replace more expensive measuring methods.