CZ293044B6 - Treatment process of amaranth flour - Google Patents

Abstract

Oil fraction is extracted from a flower with disintegrated structure of amaranth grain by the treatment thereof with liquid carbon dioxide below critical point thereof at pressure ranging from 0.1 to 0.4 MPa and at a temperature in the range of 18 to 80 degC, preferably from 18 to 20 degC. After extraction of the oil fraction, the flour is further agitated within an aqueous solution having pH higher than 7 at a temperature above 18 degC for a period of 5 to 60 minutes. Subsequently the obtained mixture is separated and the separated solution pH value is adjusted to 3.5 to 6.5 to thereby causing precipitation of proteins therefrom. From sediment, obtained by separation of a protein extract, starch is obtained. After starch has been obtained, fibrous material is then obtained from the same sediment.

Description

Technical field

The invention relates to a process for the treatment of amaranth flour, in particular to the isolation of oil, protein, starch and fiber fractions.

BACKGROUND OF THE INVENTION

It is known that amaranth grain has a high nutritional value and has traditionally been used as a source of quality proteins and natural antioxidants that have replaced essential native amino acids with a lack of important minerals, vitamins and proteins. In the amaranth grains, the protein content is on average 15-16% by weight. higher when compared to conventional cereals. Higher levels of lysine and tryptophan are comparable to animal proteins. The fat content in the amaranth grains, which is concentrated in its germ and which is higher than that of conventional cereals, reaches 6 to 9% by weight in the case of light-seed varieties, and even higher in the dark-grain species. Amaranth starch is concentrated in the polyhedral parenchymatous cells of the perisperm and constitutes up to 70% by weight in the light grains. Morphologically, amaranth starch is an extremely small, round to polygonal particle size of 1 to 3 µm compared to other cereals; chemically dominated by amylopectin, amylose is either absent at all or only at low concentrations (4 to 6 wt%), which is a significant difference from conventional cereals. According to some data, small amaranth starch particles occupy a larger area compared to larger starch grains of conventional cereals in the same volume, allowing them to be hydrolysed more rapidly by glucoamylase. Therefore, they are better utilized for the energy needs of the human organism. The size of the starch particles and their chemical composition affect its physico-chemical properties, important for digestion and absorption. The higher water-binding capacity of amaranth starch can have a beneficial effect on weakened intestinal motor. Small starch particles also find use in cosmetics and are ideal for starching laundry. Amaranth seeds are also richer in fiber (about 3.2 to 5.8% by weight) on average than wheat, barley, rye, rice, corn. Dark grains contain more fiber than light grains. Individual food fractions of amarat seed have not yet been used in food production, grain and flour are added to food products entirely. To obtain protein and starch fractions and amaranth grain pulp, it is advisable to first crush the grain structure by grinding it into flour and thus making the inner part accessible. Repeated grinding is useful to increase the yield of starch after fat extraction. The industrially applicable processes for the extraction of oils from flour are based on the use of organic solvents, which, however, can sensitize the raw material to some extent and, moreover, are not suitable in terms of yield. The recovery of the amaranth protein is industrially carried out by extraction in a slightly alkaline aqueous solution, using NaOH (0.02 M) solutions at a pH of 9.0 to 9.5. The ratio of flour to extraction bath is 1:15, the temperature is 45 ° C and the extraction time of 5 minutes is optimal for the maximum protein extracted. After separation of the extract, the proteins are precipitated by adjusting the pH to 5.5 and separated by sedimentation or centrifugation. Protein extract is recommended as a high protein food and emulsifier. The isolation of starch from amaranth flour has been the subject of research; extraction with sodium hydroxide, calomel and sulfur dioxide has been described. Of these methods, the alkaline method is the most commonly used, which in its modification represents a one-stage extraction method with 0.25% sodium hydroxide. Amaranth fiber also has many valuable nutritional properties. It can be obtained as a residue after separation of proteins and starch from whole wheat flour.

SUMMARY OF THE INVENTION

These disadvantages are largely eliminated by the process of treating amaranth flour according to the present invention. It is based on extracting an oil fraction from flour with a broken amaranth grain structure under the action of liquid carbon dioxide below its critical point at a pressure of 0.1 to 0.4 MPa and a temperature ranging from 18 to 80 ° C. The extraction of the oil fraction is preferably carried out at temperatures ranging from 18 to 20 ° C. The use of liquid carbon dioxide does not leave undesirable solvent residues behind; carbon dioxide is completely volatile. This method is oil-friendly and fully retains its sensory properties. The amaranth grain fiber becomes brittle, better wetted and improves the flour processing process.

After extraction of the oil fraction, the flour is further stirred in an aqueous solution having a pH greater than 7 at a temperature above 18 ° C for 5 to 60 minutes, then the resulting mixture is centrifuged and the centrifuged solution is subsequently adjusted to a pH ranging from 3.5 to 6.5, thereby precipitating proteins. The aqueous solution is preferably NaOH (0.02 M). The centrifuged solution is adjusted to pH 5.5 by dilution with phosphoric acid. After adjusting the centrifuged solution to pH, the solution is allowed to stand and after protein precipitation, the proteins are separated by centrifugation. After removal of oils, the feedstock is better extractable with aqueous solutions, increasing the wettability due to the reduction of the interfacial tension in the phase interface between the aqueous and solid phases. By adjusting the centrifuged solution to a pH of 5.5, the protein is minimally soluble in this pH range and coagulated.

After adjusting the centrifuged solution to pH, the solution is allowed to stand and after protein precipitation, the proteins are separated by centrifugation. The pellet obtained by centrifuging the protein extract 25 is stirred in a dilute alkaline solution such as sodium hydroxide and after gentle stirring for 20 to 60 minutes the solution is filtered, centrifuged or decanted and adjusted to pH 4 with dilute acid such as phosphoric acid. to 7 and again filtered, centrifuged or decanted to obtain a starch layer which is dried. Drying can be carried out by conventional food methods, for example by warm air in a chamber or tunnel dryer.

After filtering, centrifuging or decanting the starch extract, the pellet is stirred in water, neutralized with a dilute solution of an acid such as phosphoric acid to a pH in the range of 4 to 7, centrifuged, optionally filtered or decanted and the fiber obtained is subsequently dried.

It is advantageous to complete the processing of the amaranth flour according to the invention and to obtain an oil, protein and starch fraction and fiber.

DETAILED DESCRIPTION OF THE INVENTION

1. Extraction of oils from flour:

The starting material is whole-wheat amaranth flour. The extraction process takes place under the action of liquid carbon dioxide at a pressure of 0.4 MPa and a temperature of 18-20 ° C, below the critical point of carbon dioxide.

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2. Isolation of proteins:

A total of 75 g of wholegrain amaranth flour was removed for extraction after removal of the oils. Extraho50 was stirred under stirring in 1125 ml of aqueous NaOH solution (0.02 M), heated to 45 ° C at wt.

The ratio of flour to solution was 1: 15. This process was carried out for 5 minutes while stirring the solution. Then the mixture was centrifuged in a glass rocker at 1500 rpm on a laboratory centrifuge and the top solution transferred to a beaker where the pH was adjusted dropwise to 5.5 with dilute phosphoric acid (1:10). The solution was allowed to stand for 15 minutes, during which time a light brown precipitate separated 55, which was separated by centrifugation in a cuvette at 2500 rpm.

-2GB 293044 B6 minute. The centrifuged protein was dried with warm air in a conventional food process. The yield was 21.51 g (29.4% by weight based on the amount of flour).

3. Isolation of starch:

A starch obtained by centrifuging the protein extract from amaranth flour was used to isolate the starch. This pellet was slurried in 0.25% NaOH solution in a 10% v / v ratio and after gentle stirring for 30 minutes the mixture was centrifuged in a cuvette at 1500 rpm for 5 minutes. The upper layer was poured into a beaker, adjusted to pH 6.5 with dilute phosphoric acid and centrifuged again at 2500 rpm for 5 minutes. The deposited starch layer was transferred to a tray and dried. The yield was 16.90g (23.1% by weight based on the amount of flour).

4. Insulation of pulp:

Fiber is a residue obtained after separation of proteins and starch from amaranth flour. It was prepared from the sediment after centrifugation of the starch extract by stirring in water (1: 10 vol), neutralized with dilute phosphoric acid solution (1: 10 vol) to pH 6.5 and centrifuged. The sediment was dried. The yield was 34.84 g (47.5% by weight based on the amount of flour).

Industrial applicability

The process of treating amaranth flour according to the invention is intended for obtaining oil, protein and starch fractions and pulp.

Claims (8)

PATENT CLAIMS 1. A process for the treatment of amaranth flour, characterized in that oil is extracted from the broken amaranth grain flour by the action of liquid carbon dioxide below its critical point at a pressure of 0.1 to 0.4 MPa and a temperature of 18 to 80 [deg.] C. fractions. Process according to claim 1, characterized in that the extraction of the oil fraction is carried out at temperatures ranging from 18 to 20 ° C. A process according to claim 1 or 2, characterized in that, after extraction of the oil fraction, the flour is further stirred in an aqueous solution having a pH greater than 7 at a temperature above 18 ° C for 5 to 60 minutes, then the mixture is centrifuged and the centrifuged solution is subsequently adjusted to a pH in the range of 3.5 to 6.5 to precipitate proteins. The method of claim 3, wherein the aqueous solution is 0.02 M NaOH. The process according to claim 3, characterized in that the centrifuged solution is adjusted to pH 5.5 by dilution with phosphoric acid. Method according to one of Claims 3 to 5, characterized in that after adjusting the centrifuged solution to the desired pH value, the solution is left to stand and after protein precipitation, the proteins are separated by centrifugation. -3GB 293044 B6 7. The process according to claim 6, wherein the pellet obtained by centrifuging the protein extract is stirred in a dilute alkaline solution, for example sodium hydroxide, and after gentle stirring for 20 to 60 minutes, the solution filtered, centrifuged or decanted and adjusted to a pH of 4 to 7 with dilute acid such as phosphoric acid and again 5 is filtered, centrifuged or decanted to obtain a starch layer which is dried. The process according to claim 7, characterized in that the deposit after filtration, centrifugation or decantation of the starch extract is stirred in water, neutralized with a dilute solution of an acid, for example phosphoric acid, to a pH in the range of 4 to 7. , the filtrate is filtered or centrifuged and the fiber obtained is subsequently dried.