WO2013029632A1

WO2013029632A1 - Method of manufacturing a fermented dry feed

Info

Publication number: WO2013029632A1
Application number: PCT/DK2012/050328
Authority: WO
Inventors: Jens Legarth
Original assignee: Fermentationexperts A/S
Priority date: 2011-09-02
Filing date: 2012-09-03
Publication date: 2013-03-07
Also published as: DK201170489A; DK177482B1

Abstract

The present invention pertains to a method for producing a dry fermented feed product comprising the step of providing a fermented feed product, wherein said feed product comprises lactic acid bacteria, introducing said feed product of into a dryer chamber, contacting said feed product with a stream of drying gas in said dryer chamber, and obtaining a dry fermented feed product. Moreover the present invention pertains to the dry fermented feed product obtainable by the method of the present invention.

Description

METHOD OF MANUFACTURING A FERMENTED DRY

FEED

Technical field of the invention

The present invention relates to a method for producing a dry fermented feed product. In particular, an improved method for producing a dry fermented feed product comprising high levels of viable lactic acid producing bacteria.

Background of the invention

There is a demand in the art for dry fermented feed products having low spoilage (i.e. low levels of pathogenic microorganisms) and improved nutritional value.

Fungi are the principal cause of spoilage of livestock feed, particularly in feed comprising legumes. Some fungal species may cause serious disease in livestock consuming the feed by elaborating toxins. Bacterial spoilage may also occur although the problem is in particular in liquid feed.

Potential harmful bacteria and organisms are natural inhabitants of soil and vegetation and are accordingly found on feed components and everywhere in the animal's surroundings. The bacteria and other organisms present will ferment, unless prevented e.g. by sterilisation. The fermentation may result in outgrow of pathogenic bacteria or various types of yeast and moulds.

Providing fermented feed products prepared to contain low levels of pathogenic microorganisms and high levels of probiotic bacteria to growing pigs have been reported to decrease pathogenic microorganisms counts along the gastrointestinal tract.

Fermented feed comprising probiotic bacteria in the form of lactic acid producing bacteria is often delivered to the animals in the form of liquid feed using liquid feeding system. However, it may be preferred to deliver the feed as dry feed for various reasons, e.g. certain animals are not able to consume liquid feed. Methods for manufacturing dry fermented feed usually involve the use of conventional dryer to remove the moisture of a (semi)liquid feed to obtain a dry feed. Conventional dryer, such as toasters, operate at very high temperature thus, severely impair the viability of the probiotic bacteria in the feed.

WO 97/19307 (APV Anhydro A/S) discloses a process and an apparatus for drying a material in the form of a paste or a filter cake in a spin flash dryer. The products dried according to WO 97/19307 are fruit and beet pulps, destillers residues, pesticides, pigments, dyes, ceramics, active coal, sludge and zeolites. WO

97/19307 is hereby incorporated by reference.

Hence, an improved method for producing a dry fermented feed low in pathogenic microorganisms and having improved nutritional value would be advantageous, and in particular having a high level of probiotic bacteria would be advantageous.

Summary of the invention

An object of the present invention relates to the provision of an improved method of manufacturing a dry fermented feed product. In particular, it is an object of the present invention to provide an improved method for the production of a dry fermented feed comprising a high level of viable lactic acid bacteria (i.e. probiotic bacteria).

The present inventors have surprisingly discovered that the method of the present invention allows for the provision of a dry fermented feed which simultaneously comprise low levels of pathogenic microorganisms and high levels of viable lactic acid bacteria (LAB). Using traditional drying techniques, such a toasting, the viability of lactic acid bacteria is significantly decreased (if not completely obliterated) during the process of producing dry fermented feed products - however, the inventor surprisingly discovered a gentle drying process, wherein the viability of the lactic acid bacteria in the fermented feed (to be dehydrated) is maintained or only slightly decreased. Thus, a first aspect of the present invention relates to a method for producing a dry fermented feed product comprising the step of (a) providing a fermented feed product, wherein said feed product comprises lactic acid bacteria, (b) introducing said feed product of (a) into a dryer chamber, (c) contacting said feed product of (a) with a stream of drying gas in said dryer chamber, and (d) obtaining a dry fermented feed product.

A second aspect of the present invention relates to the product obtainable by the method of the present invention.

Detailed description of the invention

Definitions

Prior to discussing the present invention in further details, the following terms and conventions will first be defined :

Inoculum

Inoculation refers the placement of a microorganism(s) (e.g. lactic acid bacteria) that will grow when implanted in a culture medium. Inoculum refers to the material used in an inoculation, for example a composition comprising a living organism(s), which is employed to prime a process of interest. For example, an inoculum, where the bacteria are essentially lactic acid bacteria, may be used to direct a lactic acid formation process in a culture medium in a fermentation tank comprising said media (e.g. a feed material). Thus, "to inoculate" refers to the transfer of the inoculum to the media to be processed, for example the transfer of the inoculum to a feed material to be fermented. As the skilled person will realize, the media may inoculated with one or more inoculums. The primary inoculum refers to the generation of the initial inoculum in a repeated series essentially identical inoculation process, for example one or more repetitions of a

fermentation process. An aliquot of the product of the formation process may be used to inoculate a new process of fermentation. Thus, the inoculation may be a fermented feed product which comprises viable lactic acid bacteria in sufficient amount to prime a lactic acid fermentation process of a another feed product to be fermented. The inoculum may be a in a liquid form, dry form, or essentially dry form. The moisture% of the inoculum may be adjusted in order to optimize the fermentation process. Thus, the inoculum used in the method of the present invention may be a fermented feed product. In one embodiment the inoculum is provided as essentially pure viable bacteria (such as bacteria in freeze dried form) or bacteria suspended in a suitable media prior to the application (such as a water, buffer or a growth media).

The proportion of the one or more inoculums added to the feed product may vary. In case it is considered that the load of undesirable microbes are significant in the feed product or the fermentation system, the proportion of the one or more inoculums in the fermentation mixture (inolucum + feed product + additional water) may be increased to insure that the fermentation is directed by the microbes (e.g. lactic acid bacteria) of the one or more inoculums.

Lactic acid bacteria

The class of lactic acid bacteria (or lactic acid producing bacteria) comprise a clade of Gram positive, low-GC, acid tolerant, non-sporulating, non-respiring rod or cocci that are associated by their common metabolic and physiological

characteristics. These bacteria, usually found in decomposing plants and lactic products produce lactic acid as the major metabolic end product of carbohydrate fermentation. This trait has historically linked lactic acid bacteria with food fermentations as acidification inhibits the growth of spoilage agents.

Proteinaceous bacteriocins are produced by several lactic acid bacteria strains and provide an additional hurdle for spoilage and pathogenic microorganisms.

Furthermore, lactic acid and other metabolic products contribute to the

organoleptic and textural profile of a food item. The industrial importance of the lactic acid bacteria is further evidenced by their generally regarded as safe

(GRAS) status, due to their ubiquitous appearance in food and their contribution to the healthy microflora of animal mucosal surfaces. Lactic acid fermentation

Lactic acid fermentation is the simplest type of fermentation. Essentially, it is a redox reaction. In anaerobic conditions, the cell's primary mechanism of ATP production is glycolysis. Glycolysis reduces - transfers electrons to - NAD+, forming NADH. However, there is only a limited supply of NAD+ available in a cell. For glycolysis to continue, NADH must be oxidized - have electrons taken away - to regenerate the NAD+. This is usually done through an electron transport chain in a process called oxidative phosphorylation; however, this mechanism is not available without oxygen.

Instead, the NADH donates its extra electrons to the pyruvate molecules formed during glycolysis. Since the NADH has lost electrons, NAD+ regenerates and is again available for glycolysis. Lactic acid, for which this process is named, is formed by the reduction of pyruvate.

In heterolactic acid fermentation, one molecule of pyruvate is converted to lactate; the other is converted to ethanol and carbon dioxide. In homolactic acid fermentation, both molecules of pyruvate are converted to lactate. Homolactic acid fermentation is unique because it is one of the only respiration processes to not produce a gas as a byproduct.

Homolactic fermentation breaks down the pyruvate into lactate. It occurs in the muscles of animals when they need energy faster than the blood can supply oxygen. It also occurs in some kinds of bacteria (such as lactobacilli) and some fungi. It is this type of bacteria that converts lactose into lactic acid in yogurt, giving it its sour taste. These lactic acid bacteria can be classed as

homofermentative, where the end product is mostly lactate, or

heterofermentative, where some lactate is further metabolized and results in carbon dioxide, acetate or other metabolic products.

The process of lactic acid fermentation using glucose is summarized below. In homolactic fermentation, one molecule of glucose is converted to two molecules of lactic acid : C6H1206→ 2 CH3CHOHCOOH.

In heterolactic fermentation, the reaction proceeds as follows, with one molecule of glucose being converted to one molecule of lactic acid, one molecule of ethanol, and one molecule of carbon dioxide: C6H1206→ CH3CHOHCOOH + C2H50H + C02 Before lactic acid fermentation can occur, the molecule of glucose must be split into two molecules of pyruvate. This process is called glycolysis.

It is preferred that the dry fermented feed of present invention is obtained by lactic acid fermentation. It is also preferred that the fermentation is homolactic fermentation directed by homofermentative lactic acid bacteria.

Feed material

The term "feed material" according to the invention is to be understood in its broadest sense. "Feed material" may suitably be obtained from the dairy industry, food processing industry, the agricultural industry, the wine industry, the alcohol industry, or beer industry, or combinations thereof. Examples of suitable "feed material" comprise one or more of mature and/or immature plants and parts thereof, such cereals, e.g. wheat, barley, rye, rice, maize (cob maize silage (CCM) or ripe), triticale, oat; vegetables (e.g. potatoes, maize, soy; whey, curd, skim milk and the like). The feed to be fermented may also consist essentially of a composition of one or more of proteinaceous plant materials. The feed material to be fermented may include animal products such as industrial animal by-products such as blood meal and bone meal. Another non-limiting example of a useful animal product is mussels.

The terms "fermented product" or "fermented feed" indicate any product or feed that has been fermented. In the context of the present invention the terms "dry fermented product" or "dry fermented feed product" refers to a dry product or dry feed product obtained by reducing the moisture content of a fermented product or fermented feed product to obtain a dry fermented feed product. Bacterial viability

Bacterial viability is to be understood as is the ability of bacteria to survive, grow, and multiply. Bacterial viability can be measured using any known method in the art such as but not limited to (i) measurement of colony forming units (CFU), (ii) staining using e.g. probes for membrane integrity or physiological state and (iii) amplification techniques such as PCR and RT-PCR. Per cent Moisture (% moisture, or % H20)

Per cent Moisture refers to the proportion of water in the material (e.g. in the feed). Volumetric water content, Θ (or vol-%), is defined mathematically as: Θ = V_w/ V_T, where V_w is the volume of water and V_T = V_s + V_v = V_s + V_w + V_a is the total volume (that is material Volume + Water Volume + Void Space). Water content may also be based on its mass or weight (w/w%), thus the gravimetric water content is defined as: u = m_w/m , where mw is the mass of water and mb (or ms for soil) is the bulk material mass. To convert gravimetric water content to volumetric water, the gravimetric water content is multiplied by the bulk specific gravity of the material.

Method for producing a dry fermented feed product

One aspect of the present invention relates to a method for producing a dry fermented feed product, comprising the steps of:

(a) providing a fermented feed product, wherein said feed product comprises lactic acid bacteria;

(b) introducing said feed product of (a) into a dryer chamber;

(c) contacting said feed product of (a) with a stream of drying gas in said dryer chamber, and

(d) obtaining a dry fermented feed product.

In one embodiment, the method comprises the steps of:

(a) providing a fermented feed product, wherein said feed product comprises lactic acid bacteria by

(i) providing an inoculum comprising bacteria,

(ii) providing a feed material;

(iii) combining the materials of steps (i), (i) and fermenting the feed material of step (ii) using the inoculum of step (i) to obtain said fermented feed product;

(b) introducing said fermented feed product of (a) into a dryer chamber;

(c) contacting said fermented feed product of (a) with a stream of drying gas in said dryer chamber, and

(d) obtaining a dry fermented feed product. In further embodiments, the feed product is agitated so as to form an agitated fluid bed within said dryer chamber. Optionally, the agitation may be provided, at least in part, by a rotor mounted close to, or at the base of the drying chamber, such as an axially mounted rotor. The rotor is optionally formed with vanes, which generate a swirling motion of the material inside the drying chamber. Optionally, the rotor also cuts cutting heavier lumps of fermented material into smaller lumps In preferred embodiments the rotor operates with a speed of such as 40-80 rpm, such as 40-75 rpm, 40-70 rpm, 40-65 rpm, 50-80 rpm, 50-75 rpm, 50-70 rpm, 50-65 repm, 55-80 rpm, 55-75 rpm, 55-70 rpm, 55-65 rpm, 58-62 rpm or such as 60 rmp.

In further preferred embodiments the drying chamber is an essentially vertical cylinder, preferably with an inverted conical bottom, a drying gas inlet, such as an annular drying gas inlet and an axially mounted rotor. In particular embodiments the drying gas inlet allows the drying gas to be let into the drying chamber tangentially/circumferentially with a tangential velocity sufficient to generate a swirling flow pattern inside the dryer chamber.

The dryer chamber optionally has a classification orifice, which can be sized to prevent particles over a certain size from passing and being collected.

In yet further embodiments the drying chamber is in a configuration comprising a heater, which is capable of heating the said gas, and/or a collector having a discharge valve and optionally being equipped with an exhaust fan.

A conventional configuration comprising a drying chamber as used in the present invention is shown in Figure 1. The configuration comprises drying gas inlet (A), drying chamber (B), and optionally rotor (C), heater (D), collector (E), discharge valve (F), exhaust fan (G), slit-shaped opening in the drying chamber (H), tangentially arranged outlet (J), and snail transporter for transporting the fermented feed into the drying chamber (K).

In the method according to the invention, the moisture content of the product obtained in step (d) can be controlled by adjusting the amount of fermented feed product feed to said dryer chamber in step (b) and/or adjusting the drying capacity of said drying gas.

In order to obtain sufficient dehydration of the fermented feed product provided in step (a) it may be preferred that the moisture content of the excess drying gas is 0.4 kg moisture per kilogram dry gas or higher, such as 0.5 kg moisture per kilogram dry gas or higher, e.g. 0.6 kg moisture per kilogram dry gas or higher.

Thus, typically the moisture is evaporated at a rate in the range of 600 to 900 kg moisture per hour, such as 650 to 850 kg moisture per hour, e.g. 700 to 800 kg moisture per hour, preferably 725 to 775 kg moisture per hour. Most preferably the moisture is evaporated at a rate at 735kg/h or around 735kg/h.

In an embodiment the flow rate of which the drying gas flows through the drying chamber is in the range of 30000 to 40000 m³ drying gas per hour, such as in the range of 31000 to 39000 m³ drying gas per hour, e.g. in the range of 32000 to 38000 m³ drying gas per hour, such as in the range of 33000 to 37000 m³ drying gas per hour, e.g. in the range of 34000 to 36000 m³ drying gas per hour, such as in the range of 35000 to 35500 m³ drying gas per hour, preferably in the range of 33500 to 34500 m³ drying gas per hour. In a preferred embodiment the flow rate of which the drying gas flows through the drying chamber is 34000 m³ drying gas per hour or around 34000 m³ drying gas.

The term drying gas is to be understood in its broadest context, thus the term covers any gas including air applicable for drying. From a financial point of view it may be preferred that the drying gas is air. In a preferred embodiment the drying gas it hot air. Air is mainly composed of nitrogen, oxygen, and argon, which together constitute the major gases of the atmosphere. Thus, preferably the inlet temperature of the drying gas is in the range of 120 to 250, such as 160 to 220 or 120 to 160 °C, such as in the range from 125 to 155 °C, such as in the range from 130 to 150 °C, e.g. in the range from 135 to 145 °C, such as in the range from 140 to 160 °C. In a preferred embodiment the inlet temperature of the drying gas is in the range of 135 to 145 °C. Clearly, it is important to use an inlet temperature of the drying gas which simultaneously (i) provides a sufficient dehydration of the fermented feed product provided in step (a) and (ii) retain viable lactic acid bacteria in the dry fermented feed product obtained in step (d).

5

As the inlet temperature of the drying gas affect the temperature of the dry fermented feed product obtained in step (d) it may be preferred that the temperature of the product obtained in step (d) is the range of or do not exceed 40 to 75°C, such as 40 to 60 °C or 60 to 75 °C, such as in the range from 65 to 10 70 °C, e.g. in the range from 66 to 69 °C, such as in the range from 67 to 68 °C, preferably measured at the out let of the drying chamber. More preferably, the the dry fermented feed product obtained in step (d) has a temperature from 58- 65 °C, such as from 60-64 °C or such as 62°C.

15 In a preferred embodiment the temperature of the product obtained in step (d) is the range of or do not exceed 40 to 60 °C, preferably measured at the outlet of the drying chamber.

In one embodiment, the drying chamber is the drying chamber of a spin flash 20 dryer. One reason for preferring a drying chamber/drying chamber configuration as disclosed above, including the drying chamber of a spin flash dryer, in the context of the present invention is that it is able to produce a uniform powder on a continuous basis from high viscosity fluids, cohesive pastes and sludges.

Traditionally such a drying chamber/drying chamber configuration has been used 25 for drying fruit and beet pulps, destillers residues, pesticides, pigments, dyes, ceramics, active coal, sludge and zeolites. In addition, the present inventors surprisingly discovered that such a drying chamber/drying chamber configuration as disclosed above can be used in a process of dehydrating fermented feed comprising probiotic bacteria as provided with present invention - i.e. a process 30 wherein the viability of the lactic acid bacteria in the dry fermented feed product is maintained or only slightly decreased when compared to the fermented feed product from which it is derived.

In the case of operation of a drying chamber/drying chamber configuration as 35 disclosed above, such as a spin flash dryer, the drying gas creates a high velocity, whirling a fluidised bed of drying particles which moves up through the chamber during the process. Heavy, still wet lumps are forced towards the chamber walls. Disintegration, attrition and drying cause particles to become smaller and lighter and, as a consequence, a balanced fluid bed is created in which smaller particles move towards the axis of the drying chamber.

By selecting operating conditions, a state of equilibrium is obtained in which the feed rate of moist is in balance with the corresponding drying capacity (a principle, known to the skilled person in the art of drying) and with the discharge rate of the dried product. It is a special effect of the drying chamber/drying chamber configuration as disclosed above, such as the spin flash dryer, that the particles remain in the drying zone until they obtain the desired size. The dryer and lighter particles become "air"-borne in the drying gas stream and rise up the walls of the dryer chamber and providing, in effect, a continuous back mixing action within the heart of the dryer. At the top of the chamber, they optionally pass through a classification orifice, which can be sized to prevent the larger particles from passing on to be collected. These larger lumps tend to fall back into the fluid bed to continue drying. In order to prevent spoilage of the dry fermented feed product it is important that the moisture content is kept low. Thus, in a preferred embodiment the moisture content of the dry fermented feed product obtained in step (d) is in the range of 2 to 15 w/w%, such as in the range of 3 to 14 w/w%, e.g. in the range of 4 to 13 w/w%, such as in the range from 5 to 12 w/w%, such as in the range of 6 to 11 w/w%, e.g. in the range of 7 to 10 w/w%, such as in the range from 8 to 9 w/w%, such as in the range of 5 to 15 w/w%. In a preferred embodiment the moisture content of the dry fermented feed product obtained in step (d) is 11 w/w% or around 11 w/w%. In further preferred embodiments, the moisture content in the dried fermented product is advantageously 10-15 wt % to make it possible for the bacteria to multiply in the dried feed. Generally, dried fermented feed contains 8-9 wt % moist. However, in the feed provided according to the present invention, a slightly higher content of moist is particular advantageous in the event that there has been a reduction in the number of viable bacteria during the drying process. In particular embodiments, the moisture content in the dried fermented product from 10-14 wt %, such as from 10-13 wt %, such as 10-12 wt %, such as 10-11 wt %, such as 11-14 wt %, such as 11-13 wt %, or such as 11-12 wt %. The drying efficiency is affected by the consistency of the fermented feed provided in step (a). Thus, it is preferred that such fermented feed is either liquid or semisolid (such as a paste or a filter cake). Thus, in one embodiment the moisture content of the feed provided in step (a) is in the range of 25 to 95 w/w%, such as in the range of 30 to 90 w/w%, e.g. in the range of 35 to 85 w/w%, such as in the range of 40 to 80 w/w%, e.g. in the range of 45 to 75 w/w%, such as in the range of 50 to 70 w/w%, e.g. in the range of 55 to 65 w/w%, such as in the range of 40 to 60 w/w%.

In further embodiments of the invention the dried, fermented product is cooled prior to storage. To accomplish this, a cooling section is provided downstream of the collector E and may utilise a stream of cold air directed towards and into the dried fermented product. Preferably, the temperature of the product is lowered to ambient temperature, such as 15-25 °C within 10 seconds to 10 minutes from leaving the dryer chamber, such as from 10 seconds - 5 minutes, from 10 seconds- 2 minutes, from 10 seconds - 1 minutes or such as from 10 - 30 seconds after leaving the dryer chamber.

Lactic acid bacteria

It follows that the lactic acid bacteria provided with the fermented feed of step (a) is essentially or for the major part viable since the object is to provide a dry feed comprising high amount of viable (probiotic) lactic acid bacteria. As previously mentioned the inventor surprisingly found that high levels of viable lactic acid bacteria present in the fermented feed provided in step (a) can be retained in the dry fermented feed product obtained in step (d) by use the method of the present invention. Lactic acid bacteria are probiotic organisms - i.e. organisms which when administered in adequate amounts confer a health benefit on the host (i.e. the animal consuming them). Thus, using a dry fermented feed product comprising high levels of viable lactic acid bacteria may provide significant benefits in terms of improved health and improved growth of the animals consuming them. Clearly, the nutritional value of the dry fermented feed product maintained and the probiotic property of the feed is improved when compared to traditionally produced dry fermented feed products, such a dry feed obtained by toasting of a fermented (semi)liquid feed.

All types of lactic acid bacteria may be present in the in the fermented feed provided in step (a). However, in a preferred embodiment the lactic acid bacteria comprises at least one bacteria genus selected from the list consisting of

Enterococcus, Lactobacillus, Pediococcus and Lactococcus.

In a further embodiment the lactic acid bacteria comprises at least one species selected from the list consisting of Enterococcus spp., Lactobacillus spp.,

Lactococcus spp., and Pediococcus spp.. In yet a further embodiment the method according to any of the preceding claims, wherein said lactic acid bacteria comprises at least one species selected from the list consisting of Enterococcus faecium, Lactobacillus rhamnosus, Lactobacillus plantarum, Pediococcus acidililactili, and Pediococcus pentosaceus. The inventor surprisingly discovered that a dry fermented feed comprising viable lactic acid producing bacteria may be obtained by briefly exposing the feed to a hot drying gas (such as in a spin flash dryer). Although the bacteria are exposed to drying gas having a high temperature, the viability of the bacteria are less affected than by conventional drying processes such as toasting (See Example 1).

By using the method of the present invention 60 to 100% such as 80-100% of the viable lactic acid bacteria present in the fermented feed provided in step (a) may be retained in the dry fermented feed product obtained in step (d), such as 81-99 %, e.g. 82-98%, such as 83-97 %, e.g. 84-96%, such as 85-95 %, e.g. 86-94%, such as 87-93 %, e.g. 88-92%, such as 89-91 %, e.g. 90-99%.

In one embodiment, the amount of viable lactic acid bacteria in the dried fermented feed obtained in step (d) is at least 10⁶ colony-forming units (CFU) per gram dried feed such as at least 5 x 10⁶, at least 10⁷, at least 2 x 10⁷, at least 3 x 10⁷, at least 4 x 10⁷, at least 5 x 10⁷, at least 6 x 10⁷, at least 7 x 10⁷, at least 8 x 10⁷, at least 9 x 10⁷, at least 10⁸, at least 2 x 10⁸, at least 3 x 10⁸, at least 4 x 10⁸, at least 5 x 10⁸, at least 6 x 10⁸, at least 7 x 10⁸, at least 8 x 10⁸, at least 9 x 10⁸, at least 10⁹, or such as 10⁷ - 10⁸ CFU per gram dried feed. Preferably, the dired feed has a dry matter content of 88 %.

The fermented feed product

Probiotics such as lactic acid bacteria are commonly consumed as part of fermented feed - thus, the fermented feed product provided in step (a) may be obtained essentially by homo-fermentative fermentation. "Essentially homofermentative" means, that the predominant bacterial flora driving the fermentation is homofermentative. In one embodiment, 99% or more of the bacteria are homofermentative. In another embodiment of the invention, 95% or more of the bacteria are homofermentative. In yet another embodiment, 90% or more of the bacteria are homofermentative. In one embodiment, 80% or more of the bacteria are homofermentative In yet another embodiment, 70% or more of the bacteria are homofermentative. "Essentially homofermentative" indicates also that the major fermentation product is lactic acid, and the levels of acetic acid and ethanol are either below taste threshold, around taste threshold or slightly above taste threshold. Alternatively, "essentially homofermentative" indicates a ratio of lactic acid to acetic acid or lactic acid to ethanol (mM/mM) of 7: 1 or 10: 1 or more, 20: 1 or more, 50: 1 or more, or 100: 1 or more. In an embodiment the ratio of lactic acid to acetic acid or lactic acid to ethanol

(mM/mM) may be 1 : 1. In another embodiment of the present invention the fermented feed product in step (a) is obtained essentially by hetero-fermentative fermentation.

"Essentially heterofermentative" means, that the predominant bacterial flora driving the fermentation is heterofermentative. In one embodiment, 99% or more of the bacteria are heterofermentative. In another embodiment of the invention, 95% or more of the bacteria are heterofermentative. In yet another embodiment, 90% or more of the bacteria are heterofermentative. In one embodiment, 80% or more of the bacteria are heterofermentative In yet another embodiment, 70% or more of the bacteria are heterofermentative. "Essentially heterofermentative" indicates also that the major fermentation product is acetic acid, and the levels of lactic acid are either below taste threshold, around taste threshold or slightly above taste threshold. Alternatively, "essentially heterofermentative" indicates a ratio of acetic acid to lactic acid (mM/mM) of 7: 1 or 10: 1 or more, 20: 1 or more, 50: 1 or more, or 100: 1 or more. In an embodiment the ratio of lactic acid to acetic acid or lactic acid to ethanol (mM/mM) may be 1 : 1.

As mentioned previously the difference between homo- and heterofermentation is essentially the class of bacteria performing the fermentation. These lactic acid bacteria can be classed as homofermentative, where the end product is mostly lactate, or heterofermentative, where some lactate is further metabolized and results in carbon dioxide, acetate or other metabolic products.

In order to prevent spoilage of the fermented feed product provided in step (a) it may be preferred that the fermented feed product provided in step (a) has a pH between 3.5 and 5, such as between 3.6 and 4.9, e.g. between 3.7 and 4.8, such as between 3.8 and 4.7, e.g. between 3.9 and 4.6, such as between 4.0 and 4.5, e.g. between 4.1 and 4.4, such as between 4.2 and 4.3, e.g. between 3.7 and 3.9. It is further preferred that said fermented feed product provided in step (a) has a pH of 4.2 or lower, between 4.2 and 3.5, or around 3.8.

Besides from preventing spoilage the acidic components produced also contribute to the organoleptic and textural profile of the fermented feed product provided in step (a) thus, also affecting the organoleptic and textural profile of the dry fermented feed product obtained in step (d).

Lactic acid bacteria produce lactic acid during fermentation of a fermentable carbon source, which results in acidification of the environment. Depending on the starter culture or starter cultures used, as well as on the availability of

fermentable sugar(s), thus the lactic acid concentration of the fermented feed product in step (a) may vary.

Thus, if the fermented feed product provided in step (a) has been obtained essentially by homo-fermentative fermentation, it may be preferred that the fermented feed product provided in step (a) has an lactic acid concentration in the range of 50-100 mM, such as 100-150 mM, e.g. 150-200 mM, such as 200-250 mM, e.g. 250-300 mM, or 300 mM or more.

If the fermented feed product provided in step (a) has been obtained essentially by hetero-fermentative fermentation, it may be preferred that the fermented feed product provided in step (a) has an acetic acid??? concentration in the range of 50-100 mM, such as 100-150 mM, e.g. 150-200 mM, such as 200-250 mM, e.g. 250-300 mM, or 300 mM or more. The fermentation should be continued until reaching a desired pH thus,

fermentation may be continued up to 6 weeks, such as 4 weeks, such as 3 weeks, such as 2 weeks, e.g. 1 week. In a preferred embodiment fermentation the fermentation product provided in step (a) has been fermented for 12-24 hours, e.g. 8-12 hours, such as 6-8 hours, e.g. 4-6 hours, or less than 4 hours.

In an embodiment the fermented feed product provided in step (a) has been fermented at a temperature between 10-50°C, 15-40°C, 18-30°C, 20-25°C, or 22-24°C or around 23°C. In an embodiment of the present invention the fermented feed provided in step (a) is obtained by fermenting one or more industrial products. Such industrial products may be by-product such as one or more of whey, curd, spent grain, yeast, fungus, bacteria, plants or parts thereof, potato or parts thereof. The fermented feed provided in step (a) may sometimes comprise one or more of ripe or unripe plants or parts thereof. Accordingly, the fermented feed provided in step (a) comprises one or more of barley, wheat, rye, oat, maize, rice, beans, peas, sorghum, triticale, soy, rape or other proteinous plant material. If the plant is maize the fermented feed provided in step (a) may thus, comprise grain maize and corn cob mix (CCM maize).

Inoculum

In a further embodiment the pH of the inoculum is between 3.5 and 5, such as between 3.6 and 4.9, e.g. between 3.7 and 4.8, such as between 3.8 and 4.7, e.g. between 3.9 and 4.6, such as between 4.0 and 4.5, e.g. between 4.1 and 4.4, such as between 4.2 and 4.3, e.g. between 3.7 and 3.9.

The pH of said inoculum may also be 4.2 or lower, such as between 4.2 and 3.5, or around 3.8.

The lactic acid concentration in the inoculum for the fermentation in step (a) can be higher than the lactic acid concentration in the fermented feed obtained in step (a). The lactic acid concentration in the inoculum for the fermentation in step (a) can be higher than the lactic acid concentration in the fermented feed obtained by the fermentation in step (a). In another embodiment of the invention, the lactic acid concentration in the fermented feed obtained by the fermentation in step (a) is higher than in the inoculum. In a further embodiment, the lactic acid

concentrations of inoculum and fermented product are approximately the same.

Preferably the inoculum is obtained essentially by homo-fermentative or hetero- fermentative fermentation - thus, the fermentation is driven and controlled by lactic acid bacteria as the most predominant fermentative organisms.

The inoculum used for the fermentation of the feed material preferably comprises lactic acid producing bacteria. Accordingly in one embodiment, said inoculum preferably comprises lactic acid bacteria. Thus, in another embodiment of the present invention the inoculum comprises lactic acid bacteria selected from the group consisting of one or more of

Enterococcus spp., Lactobacillus spp., Lactococcus spp., and Pediococcus spp..

In yet another embodiment the inoculum comprises has been obtained by fermentation with an inoculum comprising lactic acid bacteria selected from the group consisting of one or more of Enterococcus spp., Lactobacillus spp.,

Lactococcus spp., and Pediococcus spp..

In a further embodiment the inoculum comprises has been obtained by fermentation with an inoculum comprising lactic acid bacteria selected from the group consisting of one or more of Enterococcus faecium, Lactobacillus

rhamnosus, Lactobacillus plantarum, Pediococcus acidililactili, and Pediococcus pentosaceus. Most yeasts and moulds are indeed able to grow under very acetic conditions, however, it has been recognised that quick and efficient production of lactic acid by the lactic acid-producing bacteria cause very reduced or even eliminated growth of such yeasts and moulds. It follows that the inoculum preferably comprises lactic acid-producing bacteria in sufficient amount to control the fermentation process in order to obtain a feed, which is a product of lactic acid fermentation. Accordingly, lactic acid-producing bacteria with the inoculums in amount sufficient to outgrow bacteria, yeast or moulds present in the feed material to be fermented. Thus in one embodiment, the bacteria present in the inoculum of step (a) are essentially lactic acid-producing bacteria and where the concentration of lactic acid-producing bacteria in the inoculum of step (a) are sufficient to outgrow any bacteria, yeast or moulds present in the feed material of step (ii) or at least significantly inhibit further proliferation of said bacteria, yeast or moulds. Dry fermented feed product

The present invention further provides a dry fermented feed product

obtained/obtainable by the method of the present invention.

The dry fermented feed product obtained/obtainable by the method of the present invention may be mixed with other dry fermented feed products such as a dry fermented feed product obtained by the method of the present invention using different fermented feed products as the starting material.

It should be noted that embodiments and features described in the context of one of the aspects of the present invention also apply to the other aspects of the invention.

All patent and non-patent references cited in the present application, are hereby incorporated by reference in their entirety. The invention will now be described in further details in the following non-limiting examples.

Dryer chamber and auxiliary elements

Reference is made to fig. 1, which shows schematically and in a 2-dimensional cross sectional view a dryer according to the present invention. The dryer is embodied as a spin flash dryer and comprising a dryer chamber B, formed by cylindrically shaped wall I with a rounded top, inside which drying chamber B the fermented product is dried.

The dryer comprising a drying gas inlet A through which gas at elevated temperature is fed into the dryer chamber B. As indicated in fig. 1, the drying gas inlet comprises a tube encircling a distal end of the cylindrically shape wall of the dryer B having a diminising cross section similar in tangential direction to provide an even inflow of drying gas through the slit-shaped opening H provided at the bottom of the cylindrally shaped wall. The inlet A is furthermore arranged so that the drying gas enters into the drying chamber B with a tangential velocity component so as to generate a swirling flow pattern inside the dryer chamber B. The dryer further comprises an tangentially arranged outlet J through which the dry fermented product leaves the dryer. Fermented product to be dried is transported by the snail transporter K into the drying chamber B above the inlet A. Fermented product introduced into the drying chamber gets in contact with the drying gas swirling inside the drying chamber. The fermented product is typically particulate material and lumps of fermented product above a certain size and weight will depending on the swirling velocities be transported upwardly and to the outlet J, whereas heavier lumps of fermented products will fall towards to the bottom of the drying chamber B. In the bottom of the drying chamber B, a rotor may be provided. The rotor is formed with vanes supporting the swirling motion of the material and gas inside the drying chamber B and cutting heavier lumps of fermented material into smaller lumps, which then will be transported upwardly due to the swirling motion, which also includes a upwardly going velocity component. The swirling motion will force heavier lumps of material, which are to light to fall to the bottom, upwardly and towards the cylindrically shaped wall of the dryer. To avoid such particles from escaping the drying chamber (as they ofter are not fully dried due to their relative large sizes), a discriminator L in the form of a

5 downwardly inclined disc is provided below the outlet. The discriminator will force such heavier lumps of material out to the periphery of the drying chamber B where the entraiment velocity is so small that the action of the gravity will transport the lumps of material towards the bottom of the drying chamber and into contact with the rotor, which in turn will cut the lumps into smaller ones.

10

Dried material leaves the drying chamber A together with gas. A collector E optionally in the form of a cyclone is provide at the outlet J and being operated so that dried fermentented material is extracted from the process at the bottom of the collector through a discharge valve F. The flow through the collector may be 15 assisted by an exhaust fan G.

The temperature of the drying gas is elevated by use of the heater D which typically is embodied as a heat exchanger.

20 The dimensioning of the dryer and the auxiliary elements disclosed in fig. 1 is made in accordance with the desired capacity of the dryer. Control of the drying process is typically performed by measuring the temperature of the dryied fermented product at the outlet J and adjusting the amount of fermented product being fed into the drying chamber to obtain a pre-selected temperature such as

25 62°C; other process parameters, such as air flow, rotational speed of the rotor C is kept constant while the amount of infeed of fermented product is adjusted to match the preselected temperature at the outlet.

Further, the moisture content in the dried fermented product is advantageously 30 around 10-15 wt % to make it possible for the bacteria to multiply in the dried feed.

In further embodiments of the invention the dried, fermented product is cooled prior to storage. To accomplish this, a cooling section (not shown) is provided downstream of the collector E and may utilise a stream of cold air directed towards and into the dried fermented product.

Examples

Example 1

Fermented feed comprising large amounts of lactic acid producing bacteria was obtained by providing an inoculum comprising lactic acid producing bacteria and mixing the inoculum with a feed material (including rape) and fermenting the mixture to obtain a fermented feed (liquid feed). Samples of the fermented feed were subjected spin flash drying and conventional drying in the form of toasting, respectively. The counts of viable bacteria in the feed were measured. The data are presented in table 1 below; values are given as CFU and Log CFU per gram dried feed having a dry matter content of 88 %:

The above data demonstrate that lactic acid producing bacteria in fermented feed are sensitive to the drying method applied to produce dry fermented feed from (semi)liquid feed. The data surprisingly demonstrate that spin flash drying may successfully be applied in order to obtain a dry fermented feed with a high count of viable lactic acids producing bacteria.

References

WO 97/19307 (APV Anhydro A/S)

Claims

1. A method for producing a dry fermented feed product comprising the step of: (a) providing a fermented feed product, wherein said feed product comprises lactic acid bacteria;

(b) introducing said feed product of (a) into a dryer chamber;

(c) contacting said feed product of (a) with a stream of drying gas in said dryer chamber, said drying gas being let into the dryer chamber tangentially, with a velocity sufficient to generate a swirling flow pattern inside the dryer chamber; and

(d) obtaining a dry fermented feed product.

2. The method according to claim 1, comprising agitation of said feed product introduced in (b) so as to form an agitated fluid bed within said dryer chamber.

3. The method according to claim 2, wherein said agitation is provided in part by a rotor mounted at the base of the dryer chamber.

4. The method according to claim 3, wherein said rotor operates at a speed of 50- 70 rpm.

5. The method according to any of the preceding claims, comprising cooling of said dry fermented feed product in (d), such as by contacting said dry fermented feed with a stream of cold gas directed towards and into the dried fermented product.

6. The method according to any of the preceding claims, wherein said feed product comprising lactic acid bacteria defined in (a) is obtained by

(i) providing an inoculum comprising bacteria,

(ii) providing a feed material;

(iii) combining the materials of steps (i), (ii) and fermenting the feed material of step (ii) using the inoculum of step (i) to obtain said fermented feed product.

7. The method of any of the preceding claims further comprising controlling the moisture content of the product obtained in step (d) by adjusting the amount of feed product to said dryer chamber in step (b) and/or adjusting the drying capacity of said drying gas.

8. The method according to any of the preceding claims, wherein moisture content of the excess drying gas is 0.4 kg moisture per kilogram dry gas or higher.

9. The method according to any of the preceding claims, wherein said moisture in is evaporated at a rate in the range of 600 to 900 kg moisture per hour.

10. The method according to any of the preceding claims, wherein the flow rate of which the drying gas flows through said drying chamber is in the range of 30000 to 40000 m³ drying gas per hour.

11. The method according to any of the preceding claims, wherein the inlet temperature of said drying gas is in the range of 120 to 160 °C.

12. The method according to any of the preceding claims, wherein the inlet temperature of said drying gas is in the range of 135 to 145 °C.

13. The method according to any of the preceding claims, wherein the

temperature of the product obtained in step (d) the range of 40 to 60 °C.

14. The method according to any of the preceding claims, wherein said drying chamber is the drying chamber of a spin flash dryer.

15. The method according to any of the preceding claims, wherein the moisture content of the feed product obtained in step (d) is in the range of 10 to 15%.

16. The method according to any of the preceding claims, wherein the moisture content of the feed provided in step (a) is in the range of 25 to 95%.

17. The method according to any of the preceding claims, wherein the fermented feed product provided in step (a) is provided in the form of a liquid feed or a paste.

18. The method according to any of the preceding claims, wherein said lactic acid bacteria comprises at least one bacteria genus selected from the list consisting of Enterococcus, Lactobacillus, Pediococcus and Lactococcus.

5 19. The method according to any of the preceding claims, wherein said lactic acid bacteria comprises at least one species selected from the list consisting of Enterococcus spp., Lactobacillus spp., Lactococcus spp., and Pediococcus spp..

20. The method according to any of the preceding claims, wherein said lactic acid 10 bacteria comprises at least one species selected from the list consisting of

Enterococcus faecium, Lactobacillus rhamnosus, Lactobacillus plantarum,

Pediococcus acidililactili, and Pediococcus pentosaceus.

21. The method according to any of the preceding claims, wherein said fermented 15 feed product provided in step (a) is obtained essentially by homo-fermentative or hetero-fermentative fermentation.

22. The method according to any of the preceding claims, wherein said fermented feed product provided in step (a) has a pH of 4.2 or lower, between 4.2 and 3.5,

20 or around 3.8.

23. The method according to claim 22, wherein said fermented feed product provided in step (a) has a lactic acid concentration in the range of 50-100 mM, 100-150 mM, 150-200 mM, 200-250 mM, 250-300 mM, or 300 mM or more.

25

24. The method according to claim 22, wherein said fermented feed product provided in step (a) has an acetic acid concentration in the range of 50-100 mM, 100-150 mM, 150-200 mM, 200-250 mM, 250-300 mM, or 300 mM or more.

30 25. The method according to any of the preceding claims, wherein said fermented feed product provided in step (a) has been fermented for 12-24 hours, 8-12 hours, 6-8 hours, 4-6 hours, or less than 4 hours.

26. The method according to any of the preceding claims, wherein said fermented feed product provided in step (a) has been fermented at a temperature between 10-50°C, 15-40°C, 18-30°C, 20-25°C, or 22-24°C or around 23°C.

27. The method according to any of the preceding claims, wherein the pH of said inoculum is 4.2 or lower, between 4.2 and 3.5, or around 3.8.

28. The method according to any of the preceding claims, wherein said inoculum has been obtained by essentially a homofermentative or heterofermentative fermentation.

29. The method according to any of the preceding claims, wherein said inoculum comprises lactic acid-producing bacteria.

30. The method according to any of the preceding claims, wherein said bacteria are essentially lactic acid-producing bacteria and where the concentration of lactic acid-producing bacteria in said inoculum are sufficient to outgrow bacteria, yeast or moulds present in the feed material of step (ii).

31. The method according to any of the preceding claims, wherein said inoculum comprises lactic acid bacteria selected from the group consisting of one or more of Enterococcus spp., Lactobacillus spp., Lactococcus spp., and Pediococcus spp..

32. The method according to any of the preceding claims, wherein said inoculum comprises has been obtained by fermentation with an inoculum comprising lactic acid bacteria selected from the group consisting of one or more of Enterococcus spp., Lactobacillus spp., Lactococcus spp., and Pediococcus spp..

33. The method according to any of the preceding claims, wherein said inoculum comprises has been obtained by fermentation with an inoculum comprising lactic acid bacteria selected from the group consisting of one or more of Enterococcus faecium, Lactobacillus rhamnosus, Lactobacillus plantarum, Pediococcus

acidililactili, and Pediococcus pentosaceus.

34. The method according to any of the preceding claims, wherein the fermented feed provided in step (a) is obtained by fermenting one or more industrial products.

35. The method according to claim 34, wherein said industrial product is a byproduct.

36. The method according to claim 35, wherein the by-product or the waste product is one or more of whey, curd, spent grain, yeast, fungus, bacteria, plants or parts thereof, potato or parts thereof.

37. The method according to any of the preceding claims, wherein the fermented feed provided in step (a) comprises one or more of ripe or unripe plants or parts thereof.

38. The method according to any of the preceding claims, wherein the fermented feed provided in step (a) comprises one or more of barley, wheat, rye, oat, maize, rice, beans, peas, sorghum, triticale and soy.

39. The method according to any of the preceding claims, wherein the fermented feed provided in step (a) comprises grain maize and corn cob mix (CCM maize).

40. A product, which is obtainable by the method according to any of the preceding claims.

41. The product according to claim 40, said product having a moisture content of 10-15 wt %.