STUDY OF THE FRACTIONAL STRUCTURE OF PROTEINS OF AMARANTH SEEDS

Автор - | 05.02.2019

Many articles have been written about amaranth protein. They literally praise him, describing as the highest quality and close to ideal, surpassing even milk protein in its performance, not to mention vegetable protein from other cultures.

Today we want to acquaint you with the material prepared by the staff of the National University of Food Technologies A. Shapovalenko. Doctor of Technical Sciences, Prof., Yanyuk T.I. Ph.D., Assoc., Grunwald N.V. asp .. It presents research data on the fractional composition of proteins of amaranth seeds.

In particular, a detailed classification of simple proteins of cereal crops is described, the principle of the method for determining protein fractions and the results of studies of the fractional composition of the protein of amaranth seeds are described. The authors demonstrate the comparison of protein fractional composition:

  • rye flour;
  • wheat flour;
  • amaranth seed.

All the information provided is interesting and useful. Allows you to understand all the features of amaranth and evaluate its benefits to the body.

Why did such studies
Proteins occupy a special position among all the compounds that make up any living organism. They form the main substrate, in which very complex metabolic processes are carried out, directly affecting the existence of the organism.

Proteins are complex high-molecular compounds, which include carbon, nitrogen, oxygen, sulfur, hydrogen, and sometimes phosphorus.

Protein substances of cereals, different in properties, containing the following number of these elements (in percent):

  • carbon 51.0-53.0;
  • oxygen 21.0-23.0;
  • nitrogen 16.5-18.5;
  • hydrogen 6.8-6.9.

In plants, proteins perform completely different functions, the most important and valuable of which are:

  • catalytic;
  • spare;
  • protective;
  • structural.

The largest part of the grain proteins of cereal and legumes (up to 80%) are the so-called reserve proteins. They accumulate in grains, cereals directly at the time of grain development. These proteins are extremely important because they are necessary for the embryo developing in the early stages of germination.

Each protein is characterized not only by the sequence of individual amino acids in the protein molecule and their quantitative ratio, but also by the structural features of higher orders (degree of twist, polymerization).

The physicochemical state of proteins in seed tissues and in vegetative organs depends on the degree of mobility and the nature of the association of proteins with each other, with water, and with other cell substances.

These links define a biological property that cannot be explained by the composition and properties of the isolated and purified protein preparations. It should be noted that the property due to the interaction of proteins with other substances, has great biological and practical importance.

All natural proteins (proteins) are divided into two large classes: simple and complex. Simple proteins are hydrolyzed by acids or alkalis and do not produce other organic and inorganic compounds during hydrolysis. They consist only of α-amino acid residues.

For the grain of most cereals and legumes, the fractional composition of the protein is known and widely described. But information about new cultures that have just begun to be used in food production is very short or almost absent.

Why it is so important to study amaranth seed protein
For amaranth seeds, determining the content of protein fractions is of considerable interest. Having described amaranth protein, one can judge its digestibility, digestibility, consistency of the endosperm (density of linking starch grains and protein bodies in it), which is important both for technological indicators (output and quality of the finished product, density, vitreousness), and for consumer properties products of its processing.

Research results
The separation and quantitative determination of protein fractions of amaranth grain was carried out according to the method proposed by A.I. Ermakov. in modification Sozinova A.A. and Poperelya F.A. with some changes.

The principle of the method of determining protein fractions is the removal of proteins by different solutions, used in two different sequences:

  • salt, alkaline and alcohol;
  • salt and alcohol.

With this sequence, two different groups of alcohol-soluble proteins can be identified.

Saline solutions are used as follows: most are dialyzed; at the smaller part of the solutions determine the total nitrogen, as well as nitrogen after precipitation of proteins.

The size of the sample and the volume of extraction, which is obtained by withdrawal of individual proteins, depend on the stipulated amounts of individual fractions.

The determination of the fractional composition of proteins is carried out in dry seeds and in fresh vegetative organs in order to assess the quality of proteins of varieties of individual crops. The completeness of protein extraction depends on the degree of grinding of the material, on the complete destruction of cells, the volume of solvents and the number of treatments. To ensure complete extraction of proteins, it is necessary to flour, and the more other material to grind thoroughly in a mortar with steel.

The amount of nitrogen removed in the form of protein and non-protein fractions should be at least 85-90% of the total amount of nitrogen. The results should be checked by the amount of nitrogen in the residue after extraction with solvents.

A small sample (not more than 0.5 g) was taken from freshly ground grain or amaranth meal and water-soluble, alcohol-soluble and alkali soluble protein fractions were successively extracted from it. For this, aqueous solutions of 2% sodium chloride, 70% ethanol solution and 0.2% sodium hydroxide solution were used.

The flasks with the sample were added 10-15 times the amount of the solution and shaken for one hour at room temperature. After shaking, the extracts were separated from the precipitate in a centrifuge at 6000 revolutions per minute. The removal of each fraction was performed three times.

The extracts determined the protein content by the Keldahl method (according to GOST 10846-91) with some changes. Before adding the catalyst and concentrated sulfuric acid, the extract was evaporated in a Keldahl flask to obtain 1 ml of solution. Then, burning, stripping and titration were carried out according to the standard procedure. In parallel, the protein content of amaranth seeds as a whole was determined.

The discrepancy between the sum of the protein of all fractions and the protein content of the whole seed did not exceed 5%.

When recalculating the nitrogen content in the protein content, a ratio of 6.25 was used (as for high protein cultures). The separated fractions were determined as a percentage of the total protein content of the taken sample. The difference between parallel definitions did not exceed 0.3%.

The calculation of protein content X,%, in each fraction was carried out according to the formula:

where V1 is the volume of solution of sulfuric acid, followed by titration of ammonia in

solution, cm3;

W is the grain moisture content,%;

m is the mass of the sample,

The obtained results will allow to calculate the percentage of non-protein substances, the amount of salt-soluble proteins (albumin and globulins), the amount of alcohol-soluble proteins (based on the release of 2 groups of prolamins) and alkali-soluble proteins as a percentage of the total amount of nitrogen in the grain. The obtained calculation results are tabulated.

The comparative characteristic of the fractional composition of the protein of seeds of amaranth, wheat and rye flour is shown in the figure.

Summarizing
Studies have shown that the fractional composition of proteins of amaranth seeds is characterized by a high content of easily digestible water-soluble fraction (albumin and globulins) – 41-55% of the total protein content and the almost complete absence of gluten-forming proteins, which implies only partial replacement of bakery flour with amaranth seed processing products during production bakery products.

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