WO2007035112A1

WO2007035112A1 - Process for increasing the nutritional value in consumable products such as animal feed, especially fish feed

Info

Publication number: WO2007035112A1
Application number: PCT/NO2006/000329
Authority: WO
Inventors: Birger Svihus; Trond Storebakken; Vegard Denstadli; Olav Fjeld Kraugerud; Ståle REFSTIE
Original assignee: Universitetet For Miljø- Og Biovitenskap
Priority date: 2005-09-23
Filing date: 2006-09-25
Publication date: 2007-03-29
Also published as: NO20054430D0; NO20054430L

Abstract

It is disclosed a process for producing modified edible consumable products subjected to extrusion and optionally pelleting, wherein elements of the starting materials for the consumable product, separately or together and prior to the mixing of the components and final extrusion of the consumable product, are treated with at least one degrading enzyme for thus increasing the bioavailability of the thus enzymatically treated component(s) , whereupon the enzymatically treated component(s) is/are mixed with the other consumable product ingredients and is/are extruded and optionally pelleted.

Description

PROCESS FOR INCREASING THE NUTRITIONAL VALUE IN CONSUMABLE PRODUCTS SUCH AS ANIMAL FEED, ESPECIALLY FISH FEED.

Ambit of the invention.

The present invention concerns a process for modifying edible consumable products subjected to extrusion and possibly pelleting, wherein elements of the starting material for the consumable product are separated from the rest of the starting materials for the consumable products or a processed material thereof prior to the final extrusion of the consumable product, wherein the relevant part of the starting material contains more than 30% (v/v) of water and is treated with degrading/digesting enzymes for thereby increasing the bioavailability of the thus enzymatically treated component (s) , whereafter the enzymatically treated component (s) is/are reintroduced to the starting material (s) of the consumable product and this/these are mixed to a mass which may be extruded and possibly pelleted. Such an enzymatic treatment is especially suitable for producing fish feed/fish pellets with an increased utilization rate in the fish, but it is also suitable for producing an extruded and optionally pelleted feed for pets such as dogs and cats .

Background for the invention.

Treatment of feed for animals has been done for times immemorial. As an example it may be mentioned the ensilation of grass for producing feed for ruminants and horses, the fermentation of meat products, cheeses, diary products etc.. In such processes the modification of the food product is achieved through the aid of microorganisms being responsible for the degradation of proteins and other substances in the food product.

Lately it has also become common to add specific enzymes to such food products or starting materials for food products to degrade the relevant parts of the food product prior to the consumption of the food product. In those cases where such a treatment of the food product is performed, it is, however, conducted during a final step and on the entire food product, and especially when producing extrudable food products/feed products the enzymes are conventionally mixed with the food products en bloc for subsequently to be extruded pending a suitable reaction time for the enzymes.

Thus it is known from Norwegian patent application no. 1988 1457 a process for treating a feed raw material with enzymes where the entire feed material is subjected to a combined hydrothermic and enzymatic treatment under certain conditions .

From US patent 5.989.600 it is known a process for improving the solubility of vegetable proteins wherein vegetable material is treated with proteolytic enzymes and phytase. This patent also suggests adding an enzymatic additive comprising phytase and proteolytic enzymes to complete vegetable feed material.

GB patent 1 348 205 discloses a method for removing a- galacto-oligosaccharides from soy by treating entire legume material with an enzyme derived from Aspergillus inuii microorganism.

GB patent 1 483 953 discloses a process for producing wettable and water soluble food additives wherein proteinaceous material is treated with an enzymatic composition for making such materials.

The disadvantage in such processing methods is, however, that the water content and the reaction conditions are not sufficiently optimal for a suitable degradation, that there may exist inhibitors for the relevant enzyme in the food starting material, other enzymes (e.g. proteases) disrupting the added treatment enzymes, that the addition, reaction period, pH, temperature etc. are not optimal for the relevant enzyme (s) , that a further treatment of the food product is unsuitable for the enzymatic degradation etc..

E.g. when producing fish feed it has previously been suggested to add enzymes subsequent to the extrusion of the feed product, but this has been proven to have poor effect, especially when producing feed for cold water fish because the temperature is too low for an optimal effect of the enzyme. The addition of enzymes to animal feed is also known to increase the nutritional feed value, but until now this has not been performed on extruded feed because the extrusion process denatures the enzymes. Mainly the use of enzymes has been effected on feed materials for degrading carbohydrates and phytinic acid. As an example the enzymes that are used today increase the nutritional value in feed for poultry up to 10%. Thus there exists a need for a process for producing extruded food/feed products wherein enzymes are added to one or more of the starting materials of the food/feed during the processing of the starting materials under suitable and preferably optimal conditions for exerting their effect on the material, whereafter the material subsequently is mixed and subjected to an extrusion process and optionally a pelleting process.

General disclosure of the invention.

The present invention provides a process for producing extruded and optionally pelleted food/feed products wherein one or more ingredients for the food/feed product is/are added at least one enzyme and is brought to a state where the enzyme may subject the material to its effect, whereafter the ingredient (s) is/are combined to the final extrudable food/feed composition and is/are extruded in a conventional manner. In the first instance each of the feed components will already prior to the creating/mixing of the final feed be added the relevant enzyme (s), and these materials will be brought to suitable/optimal conditions for activating the enzymes, and the enzyme (s) will exert their effect over a given period of time for degrading the relevant feed components, whereupon the treated and non-treated feed components is/are brought together and are extruded to a final end product.

After the enzymatic treatment it may also be relevant to inactivate the enzyme (s) or bring the material to conditions that are not optimal for the enzymatic effect. This may e.g. be done by increasing the temperature in the material to denature or inactivate the enzyme (s) , change the pH, add inhibitors, change the ionic strength etc.. It is preferred to inactivate the enzyme by changing the temperature.

The addition of enzymes to food or feed materials has as a purpose to degrade substances in these materials so that the consumer of the food/feed may use this in an improved manner by compounds that prior to the enzymatic treatment were not bioavailable, after the treatment have become completely or partially degraded to products that the digestive system of the consumer may assimilate and/or make use of for further degradation/digestion. This type of enzymes which thus may be added, may be of a natural or artificial origin, e.g. bacterial or microorganism enzymes (yeast, fungal, plankton (vegetable or zooplankton) , etc. ) or may be from multicellular organisms (plant enzymes, animal enzymes, etc.) . It may be relevant also to add more than one enzyme to the materials that are to be treated according to the present invention.

Generally there may in one embodiment of the present invention be used enzymes that specifically digest chemical compounds that have an anti-nutritive effect or inhibit the digestibility of components involved in the binding/feed combination.

A number of enzymes with relevant properties are known for the person skilled in the art. It may e.g. be mentioned polysaccharide-degrading enzymes such as β(l-3) (1-4)- glucanases, mannases or xylanases, fatty acid degrading enzymes such as lipases, protein-degrading enzymes such as proteases (trypsin, chymotrypsin, katalase, etc.) or starch-degrading enzymes such as amylases, phytinic acid- degrading such as phytase, etc.. The optimal reaction conditions for such enzymes are also known.

The present invention is not per se limited to the use of unmodified enzymes. It may also be of interest to use modified enzymes and/or hybrid enzymes where the specificity and/or reactivity of the enzyme has been modified or where the specificity and/or reactivity of the enzyme has been maintained but wherein other properties such as the water solubility or degradability of the enzyme has been changed.

Detailed description of the invention.

In a first aspect of the invention the material that is to be extruded comprises several starting materials that prior to the extrusion are mixed with each other. According to the present invention one or more of these starting materials may be treated with one or more enzymes for increasing their individual bioavailability. Thus it may e.g. be relevant to mix two or more plant materials with each other for obtaining an extrudable product. Such plant materials may e.g. be in the form of a cereal (possibly in a ground/milled form, flour) that is added water to produce a porridge/soup. For the enzyme to get conditions under which it may work, the water ratio of this material may be larger than 30% (v/v) . To this porridge it may be added digesting enzymes to modify the relevant substances such as sugar compounds in the corn material. After the enzyme treatment is ended the substances are combined with each other and brought to an elevated temperature (70-90°C) to inactivate the enzyme (s) whereafter the material is extruded in a conventional manner. The extrusion may in this case be combined with a pelleting to provide feed pellets of the composition. Such cereal-based feed compositions/pellets may e.g. be suitable as feed for poultry, feed for horses or cattle or as feed for pigs.

In the same way as with plant materials, the composition of singular components may comprise plant materials and animal materials (minced, ground, softened meat or ground beef) or only one of such animal materials. Again there is added to at least one of the components at least one enzyme (e.g. a protease such as collagenase and/or pepsin and/or trypsin and/or chymotrypsin when treating the meat component of the composition) , the substance is added water to a water content of at least 30% (v/v) and the composition is brought to conditions being suitable/optimal for the relevant enzymatic effect (depending on which enzyme is added, known for the person skilled in the art) to be kept at these conditions over a time period being sufficient for the enzyme to effect it action (e.g. 5 minutes or more) . After the end of the reaction time the temperature in the substance is increased to inactivate/denature the enzyme, or the pH is changed so that the enzyme no longer functions optimally or is inactivated. Each substance making up the end product is then mixed with each other and the mixture is extruded conventionally.

Also in this example it may be relevant to combine the extrusion with a pelleting process.

Other starting materials which may be possible for the production of feed for aquatic organisms such as fish, but also as starting materials for land-dwelling animals (pigs, pets such as dogs and cats, etc.) may comprise animal or vegetable microorganisms such as algae, shrimps and shrimp waste (shrimp shells) , fish raw materials (waste from the fish industry, cuttings, fish innards) etc. The relevant enzymatic treatment will in this case depend on which components of the raw materials that are to be degraded for increasing the feed value of the end product. Such a consideration may be effected by the person skilled in the art based on the disclosure of the present invention.

Such extruded consumable products wherein the protein part has been pre-treated with enzymes, may be used as feed for e.g. fish or pigs or as pet feed (for e.g. dogs or cats) .

In another aspect of the invention there may be used only one starting material or the mixing of the components may be done beforehand so that it is present a homogenous starting material for performing the process according to the invention.

After ending the treatment with the relevant enzyme, the enzyme may be inactivated as indicated supra, or it may remain in its normal and active form if there no longer is present any substrate for the enzyme in the relevant liquid phase (aqueous phase) . The disadvantage of deleting an inactivation of the enzyme in such a process may be that the enzyme may acquire further substrate from the solid phase when the elements are remixed with each other, something which may be unwanted. In many cases such a possible further enzymatic degradation is, however, of no consequence in the end product. The determination of whether or not an inactivation of the enzyme (s) is to be performed is left to the person skilled in the art since this person will have knowledge of the wanted properties of the end product and may select an enzymatic treatment accordingly.

If it is wanted an end product wherein the water part is reduced in relation to the material that is treated enzymatically or possibly is lower than 30% (v/v) , it may be possible to perform the enzymatic treatment on a material that has a larger water ratio than 30% (v/v) and after having ended the enzymatic treatment mixing this feed component with dry matter to the relevant end material which then is extruded and optionally pelleted.

After ending the enzymatic treatment and reintroducing the enzymatically treated elements to the end product, the end product will be extruded in a conventional manner and optionally be pelleted.

If the solid "dehydrated" component of the starting material is to be treated enzymatically, it is preferred that this is not present in a completely dry condition. A water content in the enzymatically treated product being larger than 30% (v/v) is preferred. A water content being larger than 40% (v/v) is more preferred, and even more preferred is a water content being larger than 50% (v/v) .

In one aspect of the invention there will be used a water content in the enzymatically treated material that is larger than 30% (v/v) , a treatment time being longer than 5 minutes and a temperature being higher than 40°C. At such conditions the process according to the invention may be adapted to an on-line-process wherein the preconditioned raw material composition may be added to the other ingredients in the ordinary conditioning process. The end product in the form of a feed material may then be extruded in a conventional manner.

Examples .

Example 1 :

In this example there is produced an extruded fish feed being suitable for feeding salmon/trout in a raising plant. Many types of carbohydrate from plants are hard to digest for fish because their digestive system is not equipped with enzymes that may degrade such carbohydrate types.

Fish feed has conventionally been made from animal protein sources such as herring meal, meal of whale meat, bone meal, blood meal, dried skimmed milk, whey powder, etc.

When using whey powder or powder of skimmed milk, the feed may easily contain too much carbohydrate to be of use to the fish, and consequently it may be relevant to treat such a material with enzymes by the process according to the present invention.

Also vegetable feed substances may be relevant as fish feed additives. Examples of such feed substances are powdered soy, flour of cotton seed, maize gluten as well s barley, oats, corn and wheat or bran thereof.

Also grass meal and kelp meal have been used as ingredients in fish feed. However, most substances that have a cellulose or cellulose-like chemical structure will be indigestible for fish and it may therefore be relevant to add enzymes capable of partly or completely breaking down such substances when producing such feed.

The starting material for the feed material in this example is: 30% fish meal, 20% soy meal, 30% fish oil, 15% ground wheat and 5% minerals and vitamins.

Before the ingredients for this feed are mixed with each other, the enzyme phytase is added to the components wheat and soy meal to break down phytinic acid to inositol and phosphate. This component is added water to a water content of 45% and the enzyme is allowed to work for 20 minutes at 45 °C. After ended treatment the feed components are mixed with each other in a conventional manner and are extruded in an extruder to an extruded fish feed with an improved degree of utilization. Such an enzyme-treated fish feed is consumed by the fish to an equal degree as the previously known fish feed, but the growth rate of all the fishes is improved based on an improved bioavailability of the enzyme-treated feed components.

Example 2.

In this example it is produced an extruded feed for piglets consisting of 60% corn, 20% soy meal, 10% fish meal and 10% other ingredients.

Piglets have an incompletely developed digestive system and it is therefore advantageous to produce a feed with partly digested nutritional components. The soy meal and the fish meal are mixed and are added water to a water content of about 45%. Then the pH is adjusted to the value optimal for the relevant enzymes, and trypsin, chymotrypsin and phytase are added. The mixture is heated to 4O⁰C and is treated for 10 minutes. Then this semi-wet mixture is mixed with the other components in a conditioner, is heated and is extruded. The result is an extruded product that the piglets will assimilate in exactly the same way as other feeds, but the present feed will have a higher digestibility because phytinic acid is broken down and the protein is partially digested.

Claims

C l a i m s

1. Process for producing modified edible consumable products being subjected to extrusion and optionally pelleting, c h a r a c t e r i z e d i n that elements of the starting materials for the consumable product, separately or together and prior to the mixing of the elements and final extrusion of the consumable product, are treated with at least one degrading enzyme for thereby to increase the bioavailability of the thus enzyme-treated components (s) , whereafter the enzymatically treated component (s) is/are mixed with the other consumable product material (s) and is extruded and optionally pelleted.

2. Process according to claim 1, c h a r a c t e r i z e d i n that the degrading enzyme is an enzyme that specifically degrades chemical compounds that have an antinutritive effect or inhibits the digestibility of components involved in the binding/feed mixture .

3. Process according to claims 1 or 2, c h a r a c t e r i z e d i n that there are used in the modification enzymes that are selected from the group consisting of polysaccharide-degrading enzymes, e.g. β(l- 3) (1-4 ) -glucanases, mannases or xylanases, fatty acid- degrading enzymes such as lipases, protein-degrading enzymes such as proteases (trypsin, chymotrypsin, katalase, etc.), starch-degrading enzymes such as amylases and/or phytinic acid-degrading enzymes such as phytase.

4. Process according to claims 1 - 3, c h a r a c t e r i z e d i n that the starting material for the modification is selected from the group consisting of plant products, microorganisms, meat products and/or fish products.

5. Process according to any of the previous claims, c h a r a c t e r i z e d i n that the material to be treated has a water-content or is added water to a water- content of at least 30% (v/v) , more preferred at least 40% (v/v) , even more preferred at least 50% (v/v) .

6. Process according to any of the previous claims, c h a r a c t e r i z e d i n that the enzyme treatment is conducted for at least 5 minutes at a temperature being at least 40°C.

7. Process according to any of the previous claims, c h a r a c t e r i z e d i n that the enzyme (s) after ended reaction process is/are deactivated, e.g. by changing pH, by adding inhibitors or by denaturing such as through heating, preferably by heating.

8. Process according to any of the previous claims, c h a r a c t e r i z e d i n that the enzymatic treatment is performed on the feed components that that initially have the highest water content, wherein these feed components, after the enzymatic treatment, are mixed with the dry matter component of the feed material.

9. The use of a process according to any of the claims 1 - 8 for producing a modified and extruded and optionally pelleted feed being suitable as feed for fish; domestic animals such as poultry, horses, pigs, goats etc.; birds; reptiles or pets such as dogs or cats.