The present invention is concerned with a high protein feed additive and with the production thereof from grass and other plants. The product is intended to be used as a feed additive for all types of domestic animals, e.g. fish and fur animals, and also for ruminants. In purified form it can also be used as a protein supplement for humans.

The shortage of protein in the world is well-known, especially the shortage of cheap animal and fish proteins for human consumption. In order to overcome the protein shortage a variety of biosynthetic methods were developed in the 1970s whereby micro-organisms were caused to grow on inexpensive carbon-containing substances, especially hydrocarbons. However, there is a serious difficulty in the way of these biosynthetic methods, namely, that it is necessary to maintain a three-phase system in which two of the phases are fluid. This entails high energy consumption and a lower efficiency of oxygen absorption. Moreover, it is necessary to keep the two fluid phases separate from each other, since otherwise, if the protein product is contaminated with traces of hydrocarbons, a risk of poisoning will exist. Furthermore it is difficult, and very expensive, to achieve sufficiently high concentrations of the living cells produced. The fact that such low concentrations of living micro-organism cells are achieved results in high costs for concentrating and drying the micro¬ organisms.

It is a known practice to extract the natural proteins in grass and other green plants by expressing the sap therefrom. The cake is washed and the washing liquor is heated together with the expressed sap until the protein coagulates. The protein is then separated from the liquor by centrifuging or filtration. It is then dried, yielding a product with high protein content. This method, first described by N.W. Pirie, is now used by Anhydro in the Vepex method and by Alfa- Laval in the Alfaprox method. However, the protein recovery of this process is low — only around 30 percent.

It is further known from BRD Patent No. 2 010 486 to treat plants in order to extract the sap and to inoculate this sap with micro-

organisms, such as yeasts, bacteria, protozoa, and fungi, e.g. tricho- mycetes.

Unlike the above-mentioned processes, the procedure of the pres¬ ent invention utilizes the whole plant, that is, without expression of the sap.

The product according to the present invention has, as has been mentioned, a high protein content, namely, in excess of 70 percent protein calculated on the dry matter, e.g. approximately 72 percent protein. In leaching and precipitation according to the invention, however, between 90 and 98 percent of the protein is extracted, i.e. three times the yield of the Vepex method above-mentioned. In fer¬ mentation according to the invention a yield twice that of the said Vepex method is achieved.

In the method of the invention the proteins are first dissolved in water at a pH value between 8 and 9 and a temperature of approx. 80°C for a period of 20 minutes. This is known from U.S. Patent No. 3 290 155, whereby soya flour is treated with alkalis at a concentra¬ tion of 20 percent soya flour by weight. The residence time may vary with the temperature and the concentration of soya flour and may be lower at lower temperatures and at higher concentrations.

The difference between the procedure of the present invention and the methods described above is that in the present procedure the whole of the input material is ut lized. The product of the invention is suitable as an admixture to feedstuffs for fish, for fox, mink, and other fur animals, and for such domestic animals as pigs and cattle. The steps of the process according to the invention are as fol- 1ows:

1) The proteins are leached out of the plants with alkali, e.g. NaOH, at approx. 80 C or higher, and at a pH value of at least 8, preferably between 8 and 9. The temperature should not exceed 100°C.

2) The liquor is separated from the undissolved residue, which is washed with water.

3) The washing water from 2) is treated with acid, e.g. H _? S0,. The proteins are preferably precipitated at the isoelectric point at pH 3.8-4.2.

4) The proteins are removed from the liquor by centrifuging or filtration, though decantation can also be used.

5) The residue from 2) is neutralized with acid, e.g. H^SO,. 5) The residue is placed in water and acidified to pH 5-6.

7) The residue in water is inoculated with cellulotic micro¬ organisms, e.g. Trichoderma viriide or Trichoderma hanzianum. N and P salts and micro-nutrients are also added.

8) The mass from step 7 is heated, preferably to 25°C for Tricho¬ derma hanzianum and 35°C for Trichoderma viriide.

9) Oxygen, preferably in the form of air, is blown through the bath. The micro-organisms multiply, using the cellulose as their source of carbon, and convert the entire mass into a mass of living micro-organisms. The part consisting of lignin is not converted.

10) The mass of living micro-organisms is separated from the bath, which contains water and lignin, by centrifuging or filtration.

11) The proteins precipitated in steps 1, 2, 3, and 4 and the micro¬ organisms separated in step 10 are dried in a fluidized bed or by other means.

12) To the product of step 11 are added other ingredients as set forth in the following examples of protein feed as salmon feed and as feed for large animals.

Example 1

Composi tion of a salmon feed % by. weight

Protein concentrate prepared as descri bed above 55.0

Carbohydrates , partly cooked 26.5

Binders etc. * 3.0

Oil and/or fat 13.0

Vitami ns , mi neral s 2.5 ^'

100.0

*E.g . al gi nates and perhaps l acking ami no acids .

Chemical composition

Protei n , mi nimum 42.0

Fat (whereof 90% marine) 18.0

NFE 27.0 .

Meal , per kg , minimum 3.50

Example 2

Composition of a feedstuff for large animals % by weight Protein concentrate prepared according to the invention 26.95 Barley grits 38.96 Oat grits 16.00

Wheat bran 9.72

Melasses 4.00

Hardened marine fat 2.00

Mineral mixture 1.75 Powdered algae 0.50

Powdered limestone 0.12

100.00 Example 3 Conversion of whole grass into protein concentrate The process takes place in two steps:

1) First the protein is extracted from the grass with NaOH, the liquor strained off, and the protein precipitated with H ₂ S0». The residue is washed and a second precipitation carried out. In practice this takes place in a countercurrent apparatus. 2) To the residue, which is now free from protein, there is added the micro-organism Trichoderma hanzianum or Trichoderma Viriide, N and P salts, and icronutrients in aqueous solution, and the mixture is caused to ferment at 25°C for T. hanzianum or 35°C for T. viriide. With the grass residue serving as a source of carbon, the icro- organisms grow on this and the inorganic salts. They convert all this into a living mass containing approx. 45% proteins and 39% carbo-- hydrates, calculated on the dry content of the living mass. The micro-organisms are concentrated by centrifuging and cooked, the protein extracted in step 1 is added, and the product used as a high protein fish feed after addition of capelin oil or other fish oil, e.g. according to the recipe above. Example 4

125 grams of dried grass containing approx. 80% dry matter was weighed in. The grass thus contained 100 grams of dry matter. To this was added 1875 ml of water, making a total weight of 2 kg and 5 percent dry matter. A quantity of 2 grams of NaOH, or 0.1 percent of the whole mixture, was then added. The mixture was heated to 80°C

and held at that temperature for 20 minutes. Before heating the pH value was between 10 and 11, after 10 minutes' heating it was 9, and after 20 minutes' heating it was 8.

The water was strained off and 1.25 ml cone. H ₂ S0 ₄ (sp.g. 1.84) 5 was added. The pH value dropped to 5 and some protein was precipi¬ tated.

A further 1.25 ml H-SO, was added and the pH value dropped to 4, whereupon most of the protein was precipitated.

The residue was washed, water and 1% NaOH added, and the mixture 10 heated - still at 80°C — for half an hour. The liquor was then strained off and concentrated H-SO, added to pH 3.5. A little protein was precipitated, but the amount was too small to be of practical importance.

The liquor with the precipitated protein from the first heating 15 step was evaporated at 105°C. After evaporation the protein and the salts formed' by the NaOH and the H-SO, were weighed and the weight was found to be 22.7 g.

Total protein weighed in 22-7 ^' g Total reagents 5.7 g

20 17.0 g

Example 5

1 kg of silage was weighed in after extraction of protein with NaOH, neutralization, and drying to 22% solids. 10 litres of water, 2 g NH^NO _j , 1 g (NH^ O,, micronutrients, and 1 g of Trichoderma 25 hanzianum were added.

The mixture was allowed to ferment in a 20 litre tank which was sparged with air from a perforated hose at the bottom of the tank. The temperature of the bath was 25°C, this being the optimal tempera¬ ture for Trichoderma hanzianum. The pH value was kept in the range 30 5-5.5. The ammonium ions were consumed in the course of fermentation, and hence the micro-organisms tend to acidify their own environment. This was corrected by the addition of NH.OH, at first once a day, finally several times a day. The bath was inspected several times a day. After 3 days it appeared that half the grass was used up. 35. After 5 days there was only lignin waste left.

The liquid was filtered off and half of the mass was centrifuged. The yield was 150 g of micro-organisms with a dry content of 20%, equivalent to 30 g. _/ ^VJREA

Yield of fermentation :

Dry matter in ori ginal sample 220 g

Ligni n approx . 20 g

200 g The weight of dry matter obtained after centrifuging half the mass was approx. 30 g. Hence the amount of dry matter in the whole of the mass was approx. 60 g, i.e. 60 g x 0.45 = 26 g protein.

Example of the composition of a protein concentrate in accordance with the invention Protein extracted 36 g

Micro-organisms from ferment¬ ation, containing 45% protein 27 g

Total 63 g protein concentrate containing 73% protein and approx. 25% carbohydrates, both in terms of dry matter, the remainder being fat and salts.