WO2020214021A1

WO2020214021A1 - Method for pelleting animal feed in hot weather conditions

Info

Publication number: WO2020214021A1
Application number: PCT/MY2020/050023
Authority: WO
Inventors: Ah Kow GOH
Original assignee: Delstasia Sdn Bhd
Priority date: 2019-04-19
Filing date: 2020-04-14
Publication date: 2020-10-22
Also published as: CN114007441A

Abstract

A method for pelleting animal feed comprising the step of mixing 2-4% water and 1-4kg/ton of a composition containing at least one inorganic deliquescent with the raw materials.

Description

METHOD FOR PELLETING ANIMAL FEED IN HOT WEATHER

CONDITIONS

Field of Invention

The invention relates to a method for pelleting animal feed in hot weather conditions.

Background

The purpose of pelleting animal feed is to take a finely divided, sometimes dusty, unpalatable and difficult-to-handle feed material and, by using heat, moisture and pressure, form it into larger particles. These larger particles are easier to handle, more palatable and usually result in improved feeding results when compared to the unpelleted feed.

Animals make better gains on pelleted feed than mash feed because (a) the heat generated in conditioning and pelleting make the feedstuffs more digestible by breaking down the starches, (b) the pellet compacts the feed into a concentrated form, and (c) pelleting minimizes waste during the eating process.

In particular, the application of moisture, heat and pressure on feed ingredients produces a degree of gelatinization which allows animals and poultry to better utilize the nutrients in these ingredients. For example the weight gain in pigs can be increased by around 10- 15% when fed with pellets rather than mash.

A pelleting system typically comprises at least the following components:

1. Mixer for mixing the raw materials together as a mash

2. Steam conditioner for gelatinization of the mash

3. Pelleting die for forming pellets from the conditioned mash

The moisture content of the mash is particularly important with regard to the structure of the final pellet. Too little moisture and the nutrients can break down due to the Maillard reaction (where lysine reacts with sugars), and physically there tends to be more fines as the pellet can disintegrate due to the reduction in gelatinization. However, too much moisture can also cause problems, as the increase in gelatinization can cause the pellets to become sticky and the apparatus to be blocked.

In tropical climates, the moisture content of the raw materials is reduced due to the hot weather conditions, typically less than 12%, which is less than optimal. While the resulting pellets may have a satisfactory pellet durability index e.g. 94%, it is clear from microscopic examination that the quality of the pellets is reduced due to the Maillard reaction. However the environmental heat makes it difficult to increase the moisture content and ensure that it is retained by the mash during the conditioning process.

An aim of the invention therefore is to provide a method for pelleting animal feed in hot weather conditions which overcomes the above issues.

Summary of Invention

In an aspect of the invention, there is provided a method for pelleting animal feed comprising the steps of:

mixing the raw feed materials with a composition and water in a mixer to increase the moisture content of the resulting mash to a first minimum predetermined value; directing the mash into a steam conditioner in which the moisture content is increased in the resulting conditioned mash to a second minimum predetermined value; and

pelleting the conditioned mash using a pelleting die;

wherein the composition comprises at least one inorganic deliquescent. In one embodiment the moisture content of the mash is increased to a first predetermined range of values of around 12-14% (w/w) after the mixing step. Typically the moisture content of the conditioned mash is increased to a second predetermined range of values of around 14-17% (w/w) by the steam conditioner. Advantageously the mixed mash has a higher moisture content of around 12-14%, greater than that of conventional systems in hot weather conditions, where it is typically less than 12%. As a result of the deliquescents, the moisture is retained more effectively in the mash such that when it is passed through steam conditioner the moisture content is raised to an optimal level of around 14-17% for improved gelatisation, whereas in a conventional system it would be less than 14% under hot weather conditions as the higher temperature of the mixed mash would normally limit water uptake during the conditioning step.

This represents an improvement over known methods for increasing quality of some pelleting aspects as for example although fines may be reduced by adding a surfactant to the mash, the surfactant is lipophilic and therefore reduces water uptake which in turn limits or decreases the nutritional content (Kim & Walker 1992).

Preferably the moisture content of the mash after mixing is around 13% (w/w), and the moisture content of the conditioned mash is about 16% (w/w). In one embodiment the moisture content is measured by drying in an oven at 104-105°C for 2-3 hours, typically 104°C for 3 hours. This is a‘Loss on Drying’ method in which the weight before and after drying is compared to determine the moisture content, known as NFTA method 2.1.4 or AO AC official method 935.29 & 945.15, and provides the closest results to the‘gold standard’ of Karl Fischer titration. It should be noted that the traditional AOAC 930.15 method (135°C for 2 hours) typically grossly overestimates the moisture content in animal feeds (as the higher temperature boils off volatile compounds), and while discontinuance thereof was recommended by AAFCO’s Laboratory Methods and Services Committee Moisture Best Practices Working Group in January 2018, it is still commonly used in pelleting systems at present.

In one embodiment the inorganic deliquescent comprises magnesium chloride and/or calcium chloride.

Typically the inorganic deliquescent is mixed at a proportion of 0.001-0.05% (w/w) (preferably 0.004-0.008%) (w/w) with the mash. However it will be appreciated that the deliquescent could be mixed at a proportion of up to 0.5% (w/w) with the mash. In one embodiment the composition is DMX-7, comprising 48-53% propionic acid, 1- 12% (preferably 3-5%) magnesium chloride, 0.25-0.35% calcium chloride and 26-38% water. DMX-7 is available from Delstasia Sdn Bhd. In one embodiment the composition substantially consists of 48-53% propionic acid, 4- 5% magnesium chloride, 0.25-0.35% calcium chloride and 35-38% water

Typically the composition further includes any or any combination of ammonia, sodium hydroxide, glycerin and monosodium glutamate. These components help maintain the effectiveness of the deliquescents.

In one embodiment the composition substantially consists of 48.3% propionic acid, 4.4% magnesium chloride, 0.3% calcium chloride, 26.2% water, 6.6% ammonia anhydrous, 10.2% sodium hydroxide, and 4.1% glycerin.

In one embodiment the composition substantially consists of 48% propionic acid, 3.8% magnesium chloride, 0.3% calcium chloride, 26% water, 6.5% ammonia anhydrous, 10.2% sodium hydroxide, 3.7% glycerin, and 1.5% monosodium glutamate. In one embodiment l-4kg (typically l-2kg) of DMX-7 is added for every ton of raw feed materials in the mixer.

In one embodiment 2-4% (w/w) water is added for every ton of raw feed materials in the mixer.

In one embodiment the method takes place under hot weather conditions where the ambient temperature is at least 25°C, typically at least 30°C, more typically at least 35°C, even more typically at least 40°C. In one embodiment the mash is processed in the steam conditioner for 30-120s. It should be noted that conventional processing is typically 25-30s, but an extended period of time tends to provide better quality pellets. Thus even if the mash enters the steam conditioner at a temperature of 38-48°C (as is common in a tropical climate), compared to 10-25°C (as is common in a temperate climate), the deliquescent in the mash ensures that water can still be absorbed and retained.

In one embodiment the compression ratio of the pelleting die is around 17-20. Typically the die has a thickness of 55-60mm and is provided with holes of diameter 3-3.5mm. In contrast conventional systems have a compression ratio of 13-16.

Pellets of 3mm diameter are preferred to 4mm diameter as heat penetration is better in the thinner pellets. In larger pellets friction is increased causing the pellets to be burnt.

In one embodiment the pellets exiting the pelleting die are cooled in a cooler.

In one embodiment the moisture content of the raw materials, mash, conditioned mash, pellets exiting the pelleting die, and/or pellets in the cooler, are measured using NFTA method 2.1.4 as hereinbefore described. Thus the moisture content can be tracked through the pelleting process.

In a further aspect of the invention, there is provided a method for pelleting animal feed from raw materials, comprising the step of mixing l-4kg/ton (typically l-2kg/ton) DMX- 7 and 2-4% water with the raw materials.

Brief Description of Drawings

It will be convenient to further describe the present invention with respect to the accompanying drawings that illustrate possible arrangements of the invention. Other arrangements of the invention are possible, and consequently the particularity of the accompanying drawings is not to be understood as superseding the generality of the preceding description of the invention. Figure l is a schematic overview of the apparatus used for the method of pelleting animal feed according to an embodiment of the invention.

Figure 2 illustrates the effect of water, heat, residence time and shearing to form (a) poor quality pellets; and (b) good quality pellets.

Figure 3 illustrates microscope images of the changes in the morphology of maize starch granules throughout the gelatinisation range (a-e) Figure 4 is an image of (a) poor quality pellets; and (b) good quality pellets

Figure 5 is a chart illustrating the variation in mash hydrolysation efficiency with respect to ambient temperature

Detailed Description

With respect to Figure 1, the apparatus used for the method of pelleting animal feed comprises a mixer 2, preferably a ribbon mixer as this is more effective than a paddle mixer, for mixing the raw feed materials together. The raw materials may include ground com e.g. 55% w/w, soy meal 25% w/v, vitamins, etc. Example mixtures of raw feed materials are indicated in Tables 1- below.

Table 2: corn-based (continued)

able 3: corn-based (continued)

able 4: wheat-based

able 5: wheat-based (continued)

The average moisture content of the raw materials in hot weather conditions is less than in cold weather conditions, typically no more than 9-12%, but it will be appreciated that this will vary depending on the constituents thereof. For example a corn/soy mixture typically has a moisture content of 11-11.5% whereas the addition of wheat to the mixture typically reduces this to around 9%. Thus where wheat is the primary component of the raw food materials, as illustrated in Tables 4-5 for example, the moisture content is somewhat lower than corn-based materials.

With further regard to Figure 5, the variation in mash hydrolysation efficiency is indicated with respect to ambient temperature. In cold weather (such as found in temperate climates), the uptake of water by the mash is relatively good, and the moisture content after steam conditioning is 16-17%. However in hot weather (such as in tropical climates) the uptake of water is reduced such the moisture content after steam conditioning is only around 12-14%, which results in poor quality pellets if the mash is not further treated.

According to an embodiment of the invention, about 0.1-0.4% w/w (i.e. l-4kg/t) of DMX- 7 is mixed with the raw materials. DMX-7 comprises 48-53% propionic acid, 1-12% (preferably 3-5%) magnesium chloride, 0.25-0.35% calcium chloride and 26-38% water.

It will be appreciated that magnesium chloride and calcium chloride are inorganic deliquescents which absorb moisture and ensure water is retained throughout the pelleting process and thereafter. The proportions of deliquescent to mash is therefore around 0.00325-0.0214% (w/w) in this example. However, it will be appreciated that higher levels of deliquescent may be used if appropriate e.g. up to 0.5% (w/w), which is a tolerable level for ruminants. Propionic acid is an antimicrobial agent which helps to ensure that the pellets made from the mash are resistant to antimicrobial growth and degradation. Like most compounds, the antimicrobial activity of DMX-7 reduces over time, but the half-life is still around 1 month.

Water is added to the mixture, typically 2-4% w/w, to increase the moisture content, preferably to at least 12%, more preferably to around 13%. After mixing for around 4-6 minutes the resulting mash is transferred via a chain conveyor

4 and bucket elevator 6 to the feeder 8 of a steam conditioner 10.

In the steam conditioner the mash is heated by steam for 30-120s (25-30s is the industry standard and is difficult to change, but longer is better) which causes gelatinisation of the starch within the raw materials. Gelatinisation increases digestability of the starch in the pellet as well as ensuring that the mash particles bind together to reduce fines. The moisture content is also increased, preferably to at least 14%, more preferably to at around 16% so that the nutrients do not break down due to the Maillard reaction. The DMX-7 ensures that the steam penetrates the mash and moisture is retained thereby more effectively.

The conditioned mash is then directed to a pelleting chamber 12 containing a pelleting die driven by a motor 14. The conditioned mash is compressed and forced through holes in the die to produce the pellets. The die thickness is typically 55-60mm with holes of around 3 -3.5mm in diameter, which produces a compression ratio (die thickness/hole diameter) of 17-20. It has been found that the penetration of heat (due to friction and compression) is better with holes of 3-3.5mm diameter compared to larger holes of 4mm or higher. The pellets are then cooled in a cooler 16. If smaller pelleted feed particles are required, the pellets can be fed into a crumbier 18. The retained moisture minimises the fines produced by the crumbling process. Different pelleting parameters in hot weather conditions and the effect of the DMX-7 treatment thereon can be seen in Table 6 below.

In the examples of Table 6 the raw materials were pelleted using with four sets of parameters for comparison:

· Control: no additives

• Conventional: addition of 0.5kg/t surfactant-type mold inhibitor product and 1% Water.

• Treatment 1 : addition of lkg/t DMX-7 and 2% Water

• Treatment 2: addition of 1 5kg/t DMX-7 and 3% Water

Table 6

In these examples the raw materials comprised a wheat/com/soy mix, which is particularly challenging as the water content thereof in the hot weather conditions indicated (i.e. around 39-40°C) was less than 9% in the control group (with no additives) when properly measured using the Loss on Drying method of 104°C for 3 hours. With the conventional product the fines were reduced and the moisture content was increased to some extent, but increasing the amount of water further (e.g. to 1.5%) resulted in roller slipping. This is because too much water and surfactant on the surface of the conditioned mash means that the rollers cannot push the mash into the die as they slip on the surface. The apparatus then jams as a result of the buildup of mash not passing through the die. The surfactant/emulsifier also has the adverse effect of stabilising the proteins by complexation on the surface of the pellets, reducing denaturation and digestion thereof. Furthermore with the moisture content being limited in the steam conditioning step, the nutritional content of the resulting pellets quickly degrades due to the Maillard reaction.

However, when DMX-7 was included in the mix a greater amount of water (e.g. 3%) could be added to the mixture, without roller slipping (as the deliquescents ensure that the water uptake is improved without the aforementioned adverse effects), allowing the gelatinisation and moisture content to be increased optimally. This method of pelleting is known as‘Mash Hydrolysation’™

Furthermore while the conventional product treatment reduced electricity consumption by up to 10%, the electricity consumption under the DMX-7 treatment was reduced much further, by around 25-30%. Thus together with the aforementioned improvements, the return of investment for using DMX-7 is in the order of 200-300%.

With regard to Figure 2a, the raw materials 20 are processed using water, heat, residence time and shearing to form pellets, but if any of these factors is insufficient the result is a poor quality pellet 22 (note the defined striations). This is because:

(i) The raw materials contain raw starch (amylose and amylopectin);

(ii) Addition of water breaks up the amylose crystallinity and the granule swells

(iii) Without sufficient water, the starch granules STOP progressing and revert back to raw starch...

(iv) ... forming Resistant Starch (resistant to enzyme attack) However, it can be seen from Figure 2b that if the raw materials 20’ are processed using increased water, heat, residence time and shearing to form pellets, the result is a good quality pellet 24 (note the smoother appearance). This is because:

(i) The raw materials contain raw starch (amylose and amylopectin);

(iii) Addition of water and heat causes more swelling. Amylose begins to diffuse out of granules.

(iv) The granules (now containing amylopectin) have collapsed and are held in a matrix of amylose forming a gel. The gelatinized starch is Rapidly Digestible Starch (RDS).

Thus with sufficient water and heat, native protein is denatured and able to bind with gelatinized starch and form a stable gel. The European Performance Index (EPI) of pellets made in cold weather conditions is around 400-480. However under hot weather conditions the WPI drops to around 300- 350. However, pellets made under hot weather conditions with the addition of DMX-7 to the mash increases the EPI to 440. This translates to an improved feed conversion of 1.35- 1.41 compared to 1.50 (feed conversion is the kg of animal feed required to achieve a kg weight gain of animal).

Figures 3a-e show the changes in the morphology of maize starch granules throughout the gelatinisation range, showing birefringence when observed under polarised light microscopy. As starch starts to gelatinise with sufficient moisture and temperature, an increase in granule size, loss of integrity, granular disruption and the eventual loss of birefringence is observed, until the glass transition surface is visible.

Figure 4a is an image of pellets made from untreated Palm Kernel Expeller (PKE) exported from Malaysia to Japan after 90 days becoming rancid and looking dull due to loss of nutrients (uncontrolled moisture migration). In contrast, Figure 4b is an image of pellets made from DMX-7 treated Palm Kernel Expeller (PKE) exported from Malaysia to Japan after 90 days, where the freshness has been maintained, and the luster and nutrients profile are substantially unchanged. It will be appreciated by persons skilled in the art that the present invention may also include further additional modifications made to the system which does not affect the overall functioning of the system.

Claims

1. A method for pelleting animal feed comprising the steps of:

mixing the raw feed materials with a composition and water in a mixer to increase the moisture content of the resulting mash to a first predetermined range of values;

directing the mash into a steam conditioner in which the moisture content is increased in the resulting conditioned mash to a second predetermined range of values; and

pelleting the conditioned mash using a pelleting die;

wherein the composition comprises at least one inorganic deliquescent.

2. The method according to claim 1 wherein the first predetermined range of values is around 10-13% where wheat is the primary component of the raw feed materials, or around 12-14% otherwise.

3. The method according to claim 1 or 2 wherein the second predetermined range of values is around 12-15% where wheat is the primary component of the raw feed materials, or around 14-17% otherwise.

4. The method according to any preceding claim wherein the moisture content of the mash after mixing is around 13%, and the moisture content of the conditioned mash is about 16%.

5. The method according to any preceding claim wherein the moisture content of a sample is measured by drying the sample in an oven at 104-105°C for 2-3 hours.

6. The method according to any preceding claim wherein the inorganic deliquescent comprises magnesium chloride and/or calcium chloride.

7. The method according to any preceding claim wherein the inorganic deliquescent is mixed at a proportion of 0.001-0.05% (w/w) with the mash.

8. The method according to any preceding claim wherein the composition is DMX-7, comprising 48-53% propionic acid, 1-12% magnesium chloride, 0.25-0.35% calcium chloride and 26-38% water.

9. The method according to claim 8 wherein the composition further includes any or any combination of ammonia, sodium hydroxide, glycerin and monosodium glutamate.

10. The method according to claim 8 or 9 wherein the composition substantially consists of 48.3% propionic acid, 4.4% magnesium chloride, 0.3% calcium chloride, 26.2% water, 6.6% ammonia anhydrous, 10.2% sodium hydroxide, and 4.1% glycerin.

11. The method according to any of claims 8-10 wherein the composition substantially consists of 48% propionic acid, 3.8% magnesium chloride, 0.3% calcium chloride, 26% water, 6.5% ammonia anhydrous, 10.2% sodium hydroxide, 3.7% glycerin, and 1.5% monosodium glutamate.

12. The method according to any of claims 8-11 wherein l-4kg DMX-7 is added for every ton of raw feed materials in the mixer.

13. The method according to any preceding claim wherein 2-4% water is added in the mixer for every ton of raw feed materials.

14. The method according to any preceding claim wherein the steps take place under hot weather conditions where the ambient temperature is at least 25°C, typically at least 30°C, more typically at least 35°C, even more typically at least 40°C s.

15. The method according to any preceding claim wherein the mash is processed in the steam conditioner for 30-120s.

16. The method according to any preceding claim wherein the die has a thickness of 55-60mm and is provided with holes of diameter 3-3.5mm.

17. A method for pelleting animal feed from raw materials, comprising the step of mixing l-4kg/ton DMX-7 and 2-4% water with the raw materials.

18. Animal feed pellets made according to the method of any preceding claim.