DE2814922C2 - Method of cleaning potato protein coagulum - Google Patents

Description

The invention relates to a method for cleaning potato fruit water by thermal coagulation obtained potato protein coagulate according to the preamble of the main claim.

Various processes are already known for utilizing the amniotic fluid that is obtained from potato starch production in potato starch factories (Siebert, K .: Ernahrungforschung, 4 (1959), 183; Heyns, K. and Graefe, G .: Z. Lebensmittel-Unters, and Forschungs. 89 (1949) 255).

The various processes (Porter, WL Siliciano, J. Kruiick, SuHeissier, EG: Membrane Science and Technology: Plenum Press (1970); Metiser, FuSmoInik, H.-D .: Strength 28 (1976) 271; Delanay, RAM u Donelly, J. K-: Proc. Biochemistry 3 (1973) 2I] L the production of native potato proteins that appears to be potentially possible and is also to be strived for, which, if necessary, would be suitable for direct human consumption in processed form, is still on an industrial scale today not yet succeeded. the problem of protein extraction from potato juice is so far solved only in the segment of exploitation of the resulting products as animal feed mainly. the obtained in the potato starch amniotic fluid can be treated thenriisch this by known methods to the dissolved ^r coagulable proteins easily Way to gain as solids (Oosten, BJ: Strength 28 (1976) 135), the gelallten proteins are separated from the solution and ans finally dried. However, it occurs with the methods used to date for this purpose

κι products that, in terms of composition, des achieved degree of denaturation and the keratinization of the protein particles for human nutrition as well as are not suitable for the production of certain foods. The adding of eggs by spray,

r> DC or drum drying recoverable Products to, for example, baked goods with a high water content always lead to considerable disadvantages Changes in the taste, color and texture of the baked goods. Negative changes in taste

. '(I and olfactory components are mainly used in such baked goods are obtained whose dough is loosened up by fermentation. This is apparently related with accompanying substances from the dried coagulant concentrated from the treated amniotic fluid

2ί late. Similar negative changes in taste come when using potato protein coagulate in the manufacture of other foods, such as for example pasta, long-life baked goods and soups.

From "Die Stät ke" 1955, pages 173 to 177, is already a method of the generic type known in which the procedure is carried out in such a way that the still moist potato protein coagulate is washed out several times with fresh water without pressure, whereupon

J5 then follows a pressing process before the final drying takes place. It is not possible in this case to remove the negative flavoring substances associated for the most part with lipid-like substances, so that the protein coagulate obtained can be used

even after any subsequent cleaning of the dried coagulate using polar solvents not possible. Rather, it can be achieved by washing out the undried proteins with pure water the known process only has a maximum sample concentration in the dry matter of about 88% reach.

Furthermore, from DE-OS 25 51 342 a process for obtaining lipids from potatoes is known in which the potato protein coagulate obtained is first thermally dried and then extracted with organic solvents. Achieve 89%, apparently because the cells of the coagulate close on the surface during drying, so that a further extraction of the lipids and the associated flavorings by the subsequent treatment with polar solvents is no longer possible. 342 also mentioned drying of the potato protein coagulate obtained by thermal coagulation by means of freeze-drying before the treatment with the organic solvents leads to a higher degree of purity of the remaining protein coagulate, but the industrial production of potato protein coagulate usable for human nutrition in the freeze-drying process is not possible because of the high costs associated with it (see »Ullmann's Encyclopedia of Technical Chemistry«,

3. Edition. Vol. I, ropes 559).

The invention is therefore based on the object of developing the method of the type mentioned in such a way that a taste and odorless dry protein coagulate with a high degree of purity can be obtained, which can be used directly for human nutrition.

According to the invention, this object is achieved by the features listed in the characterizing part of the main claim solved.

The subclaims characterize advantageous developments of the invention.

The invention is based on the surprising finding that it is possible to completely remove the low-molecular-weight flavors, which are mostly associated with lipid-like substances in the coagulate and which have hitherto negatively influenced the usability of the potato protein coagulate for human nutrition, if in the manner claimed the lipids are removed from the coagulate by suspension extraction. It should be noted that the potato protein coagulate industrially obtained with the known process consists of 80 to 85% protein (N · 6.25), 8 to 10% of lipid-like substances and 1 to 2% of minerals. The resulting low molecular weight flavors are mostly associated with the lipid-like substances in the coagulate and are soluble in polar solvents, v / ie water, ethanol, methanol and the like, so that according to the invention it is possible to remove the lipids together with the flavors .

As the lipids are enclosed by the forming in the coagulation Proteiiteilchen, they can be difficult ERNT ^f enf of the coagulate by normal extraction process. In the known processes, the protein particles also form a dense, closed layer which the solvent can only slowly penetrate. For this reason, the extraction effect in conventional processes is both incomplete and tedious.

In contrast, the invention surprisingly succeeds in completely dissolving the lipids and flavorings by keeping the protein particles in suspension in a two-stage cleaning process in the manner claimed, the concentration of the suspension and its temperature as well as the type of solvent being of decisive importance. It is important that the suspension is pressure cooked in both cleaning steps, the temperature of the suspension being above the boiling point at normal pressure and, accordingly, the pressure also being above atmospheric pressure. It is also important that a polar solvent is used in both cleaning steps, an organic polar solvent having to be used in the second cleaning step. The merging into the solvent impurities are mechanically, for example by Zentrifugalabscheidu.ig, from the protein isolated, the purification is carried out in the inventive manner in two stages, the decanted coagulum is suspended in water of more than 100 ⁰ C in the first cleaning step. In this process step alone, the protein content of the coagulate is increased to approx. 90%, the mineral content is reduced to below 1% and the taste properties of the dry product are significantly improved. In the second stage, the decanted coagulate is turned into one

organic polar solvents, e.g. B. ethanol, with one above the boiling point of the organic Solvent lying temperature suspendie.t. A further 3 to 5% of the LJpidstoffe go over into the solvent of ethanol and water, so that the Protein content of the coagulum freed from the solvent between 93 and 95% dry matter. This protein content results as long as the ethanol concentration of the solvent does not drop below 70% (kg / kg).

In contrast to the generic Sland of technology, the industrially obtained potato protein coagulate in the process according to the invention is not only suspended and washed out with fresh water, but the suspension is subjected to a two-stage pressure cooking process in the manner claimed, namely once in water and the other in the organic polar solvent, preferably Ethanol, which means that the previously used potato protein coagulate for : preventing human nutrition can be deposited together with the lipids with a reasonable expenditure of energy and thus bearable costs. By means of the pressure cooking process according to the invention, potato protein coagulates with degrees of purity of about 94% can be obtained, as they would previously have been possible using freeze-drying, which is too expensive for industrial use, with analogous application of the organic extraction process according to DE-OS 25 51 342.

The advantages that can be achieved with the invention are, in particular, that a pure, tasteless Potato protein is created. This can either be done directly or after further work-up, as described, for example, in DE-PS 26 05 541, for human Diet to be used. The shelf life of the ^ protein is considerable due to the removal of the lipids 'improved. The product therefore also offers advantages for the supply of countries in which a protein deficiency present in the diet. Due to the simple manufacturing process and the special high nutritional value (Kofranyi, E. and Jekat,] .: Hoppe-Seylers Z. physio !. Cr-em. 335 (1964) 174.) the product obtained according to the invention is superior to other vegetable proteins.

An exemplary embodiment of the invention is described below using the schematic diagrams A and B in FIG individually explained.

example

The exemplary embodiment (Figs. A, B) shows a cleaning system for processing 1 t / h of coagulate with approx. 30% TS, with (1) a coagulation container and (2) a separation device. The coagulate (I) is boiled in a ratio of one part of coagulate and 5.9 parts of water (3), 5 t of fresh water (II) being fed in countercurrent to the system to achieve this amount of water per ton of coagulate. Cooking time is 10 to 15 minutes. The suspension is separated by centrifugal separation, preferably by hydrocyclones (4). The upper course is discharged as waste water (III). The underflow is washed with hot water in two further hydrocyclones (5, 6) and the underflow from the last hydrocyclone is then decanted for drainage (7). The product (IV) obtained has about 30% TS and contains

about 90% T. S. protein.

For further purification, the moist product (I V) is boiled with ethanol (V) in a pressure vessel (8), whereby per ton of coagulate (I) 21 ethanol in countercurrent to the System are supplied. A cooking time of 10 to 15 minutes at the temperature above the boiling point of ethanol is sufficient to achieve a protein purity of> 93%.

The suspension is separated in the hydrocyclone (9). The overflow is used to recover the ethanol

(VI) distilled. Lipid substances fall as a residue

(VII) which have strong emulsifying properties. The underflow is washed in the hydracyclone (10, 11) with heated ethanol. The underflow of the last hydrocyclic ion is separated from the liquid phase with a decanter (12) or some other suitable device. The solvent is evaporated and condensed from the thus purified coagulate. The product (VIII) has a protein content of 93 to 95% and a mineral content of 1%. It is tasteless and suitable for human consumption without further purification

The superiority of the process according to the invention and the surprising technical progress compared to the state of the art, the following comparison test shows:

Comparative test

500 g potato protein coagulate with approx. 30% obtained industrially through thermal coagulation Dry matter was mixed with 2.51 of water in one Pressure vessel under a pressure of 2 bar for 12 minutes

cooked. Then centrifuged (bucket centrifuge); the still wet centrifugal was twice in each 11 water of 60 ° C resuspended and centrifuged again. The intermediate product thus obtained was boiled in 1.3 F ethanol in a pressure vessel under a pressure of 2 bar for 12 minutes. Afterward was centrifuged. The centrifugate obtained in this way was washed twice with warmed ethanol. After the final centrifugation, the product was dried at 100 ° C. in a drying cabinet. Of the The degree of purity of the protein coagulate obtained in this way according to the invention was 94% (N-6.25).

Furthermore, prior to the state of the art according to DE-OS 25 51 342 or - "The strength" J955, S, 173-177, 500 g industrial by thermal Potato protein coagulate obtained from coagulation with approx. 30% dry matter with 2.5 l of water each about 30 "C washed three times, centrifuged and finally dried in a drying cabinet at 105 ° C.

The intermediate product thus obtained was then exhaustively extracted with ethanol in a Soxhlet apparatus. The extracted coagulate was dried in a drying cabinet at 100 ° C. The degree of purity of the protein coagulate obtained in this way was 89% (N - 6.25).

The comparative experiment described above shows that the degree of purity achievable according to the invention despite the use of a conventional drying process is significantly higher than that Extraction process according to DE-OS 25 51342, from which the surprisingly advantageous effect of the two-stage pressure cooking process according to the invention emerges.

For this purpose 2 sheets of drawings

Claims (5)

Patent claims: 1. Process for cleaning potato fruit water obtained by thermal coagulation Potato protein coagulate with approx. 30% dry matter by treating with polar solvent, in which the potato protein coagulate separated by thermal coagulation in one first cleaning step suspended in water and subjected again to a mechanical separation step and thereby the solid components are separated out, characterized in that that the aqueous suspension of the potato protein coagulate at a temperature of more than 100 ° C is boiled; that after the renewed mechanical separation step the still moist Solid components in a second cleaning step in an organic polar solvent! suspended and boiled therein, the temperature being above the boiling point of the organic polar solvent and its concentration is not less than 70% by weight; and that finally the solvent suspension is subjected to a further mechanical separation step and finally the solid constituents separated out are dried. 2. The method according to claim 1, characterized in that the organic polar solvent Ethanol is used. 3. The method according to claim 1 or 2, characterized in that the further mechanical Separation step, the solid constituents obtained are washed out with heated ethanol and are then dried. 4. The method according to any one of the preceding claims, characterized in that the cooking time 10 to 15 minutes for the first cleaning step amounts to. 5. The method according to any one of the preceding claims, characterized in that the cooking time the second cleaning step is 10 to 15 minutes.