GB2153200A

GB2153200A - Preparation of animal feedstuffs

Info

Publication number: GB2153200A
Application number: GB08502498A
Authority: GB
Inventors: Roger John Meredith; Peter Boddy
Original assignee: MAGNETRONICS Ltd
Current assignee: MAGNETRONICS Ltd
Priority date: 1984-01-31
Filing date: 1985-01-31
Publication date: 1985-08-21
Also published as: GB8502498D0; GB8402520D0

Abstract

The invention describes a method and apparatus suitable for use in increasing the proportion of digestible material in materials, such as cellulosic fibrous materials, intended for animal feedstuffs. The invention includes the steps of subjecting the material to treatment with a caustic compound applied uniformly in liquid form and thereafter to the effects of a source of high frequency energy. This energy may be microwave energy or RF energy and the effect is to raise and maintain the temperature in the material at a level at which the chemical reaction between the material and the compound is accelerated. <IMAGE>

Description

SPECIFICATION Improvements in or relating to the preparation of animal feedstuffs The invention is concerned with improvements in or relating to the preparation of animal feedstuffs, for example fodder prepared from cellulosic fibrous materials.

In the preparation of feedstuffs from for example natural plants, and plant residues such as hay, straw, grass, cereals, root crops or legumes it is desirable to control the quality thereof by regulating the percentage of digestible organic material in a total mass of dry matter. This percentage, known as the 'Dvalue', is measured by known analytical methods using natural or synthetic digestive juices as the reagent. Slightly different values are obtained according to the reagent used, but generally the higher the D-value, the better is the quality of the foodstuff.

It is known to treat fibrous materials with caustic compounds to increase the percentage of digestable fibre. A typical treatment using say 10% by weight of caustic soda in aqueous solution (30% by weight NaOH) will however proceed very slowly, perhaps needing several weeks to complete. The reaction may be accelerated by conventional heating processes but achieving the temperatures required is technically and economically impracticable.

The object of the invention is to provide a more attractive process for the raising of the D-value of ceilulosic fibrous materials in an acceptably reduced length of time.

The invention provides a method of increasing the proportion of digestible material in materials intended for animal feedstuffs comprising the steps of treating the materials with a caustic compound in liquid form in a substantially uniform manner, followed by subjecting the treated material to the effects of a source of high frequency energy to raise the temperature prevailing in said material to a level at which the chemical reaction between the material and the caustic compound is accelerated and maintaining the temperature at an elevated level for the reaction to be completed or substantially so.

The process thus provides a treatment which utilises the conventional chemical break-down of fibres but which provides a significant time saving due to the application of high frequency energy which allows the product to be raised in temperature quickly and substantially uniformly without serious loss of moisture and has the additional advantage that for example in the case of cellulosic fibrous materials such as cereals, root crops and grass, a degree of cooking takes place.

Conveniently, the high frequency energy may be microwave energy or high radio frequency radio energy (RF). By way of example, RF heating may be used at a frequency of between 1-800MHz,preferably between 10 100MHZ. However, in many applications microwave frequencies are preferred, for example in a range 800MHz-2600MHz and advantageously at nominally 2450MHz, 896MHz or 915MHz, because electric field stress at microwave frequencies is less than at lower frequencies and the risk of high-voltage discharge is reduced.

The materials may thus be treated in bales or may be loaded loose onto a suitable conveyor device, being handled in any manner suited to the mode of operation of the method of the invention, whether in a batch treatment or in a continuous or semi-continuous mode.

If desired, maintenance of the elevated temperature level may be ensured by the provision of heat-loss reducing means and/or additional heating sources, for example to supply heat intermittently as required. If preferred the additional heating sources may be of a conventional type.

The invention further provides apparatus suitable for use in the method above referred to, comprising conveyor means for animal foodstuff material which has been treated with a caustic aqueous solution, a heating chamber provided with high frequency energy emitting devices and an exit passage therefrom having temperature maintaining devices to minimise loss of temperature in the treated material until the chemical reaction involving the caustic solution is at least substantially complete.

There will now be described in detail an example of the method according to the invention. It will be understood that the description which is to be read with reference to the drawing is given by way of example only and not by way of limitation.

The drawing is a diagrammatic longitudinal cross-sectional view of apparatus suitable for carrying the example method.

A quantity of straw in loose particle form was sprayed with a 10% NaOH aqueous solution and formed into bales which in the present example measured approximately 0.3 x 0.5 x 0.75 metres. Each bale B was then placed on a conveyor belt 2 on which the bales travelled in convoy into an entry tunnel 4 leading to a heating chamber 6 in which the bales were subjected to microwave radiation at a nominal frequency of 896 MHz.

In the present example, the radiation elements 8 were conventional horns arranged about the path of the conveyor belt 2 to ensure irradiation of the upper, lower and side surfaces of each bale. Dwell time in the heating chamber 6 was approximately 5 minutes, at the end of which the temperature of the material in the bales had been raised to between 70"--90"C and the bales then passed into an exit tunnel 10 forming an extension to the chamber. It will be understood that the entrance and exit tunnels (4, 10) of the heating chamber are provided with conventional devices 12 to limit the leakage of microwave energy from the open ends thereof.

The exit tunnel 10 is provided with conventional heating means 1 4 to ensure that the temperature of the baled material did not fall appreciably until the bale had left the exit tunnel. The total dwell time in the heating chamber and the heated exit tunnel may be less than fifteen minutes and was 10 minutes in the present example. The D-value of the material after treatment was approximately 65, compared with 50 for the untreated material.

The length of the exit tunnel and therefore the duration of the dwell time may be increased as required by the nature of the material whether in bales as straw, grass and hay would usually be treated, or whether it is treated in loose particle form. It will be appreciated that the effective time for the chemical reaction to be completed may effectively be extended by for example close stacking of the bales, the treated material to retain heat for as long as possible. Careful containment of loose material will also tend to retard the rate of cooling.

The invention has been described principally with reference to vegetable products.

However, the process may also be applied with advantage to meat products based on treating animal carcase portions. Various modifications may be made within the scope of the invention as defined in the following

Claims

claims. CLAIMS

1. A method of increasing the proportion of digestible material in materials intended for animal feedstuffs comprising the steps of treating the materials with a caustic compound in liquid form in a substantially uniform manner, followed by subjecting the treated material to the effects of a source of high frequency energy to raise the temperature prevailing in said material to a level at which the chemical reaction between the material and the caustic compound is accelerated and maintaining the temperature at an elevated level for the reaction to be completed or substantially so.

2. A method as claimed in claim l,wherein the materials are cellulosic fibrous material.

3. A method as claimed in claim 1 or 2, wherein the high frequency energy is microwave energy.

4. A method as claimed in claim 3, wherein the microwave frequency lies between 800 MHz and 2600 MHz.

5. A method as claimed in claim 3, wherein the microwave frequency is a nominal 2450 MHz.

6. A method as claimed in claim 3, wherein the microwave frequency is a nominal 915MHz.

7. A method as claimed in claim 3, wherein the microwave frequency is a nominal 896MHz.

8. A method as claimed in claim, wherein the high frequency energy is high radio frequency radio energy (RF).

9. A method as claimed in claim 8, wherein the RF energy is in the range of 1 MHz-800MHz.

1 0. A method as claimed in claim 9 wherein the RF frequency range is between 1OMHz and 100MHz.

11. A method as claimed in any of the preceding claims, wherein the caustic compound is a aqueous sodium hydroxide solution.

1 2. A method according to any of the claims 2-11, wherein the cellulosic fibrous materials are treated in baled form.

1 3. A method according to any one of claims 2-11 ,wherein the cellulosic fibres are treated in a loose condition.

14. A method as claimed in any one of claims 2-13,wherein additional heat is sup piied to the cellulosic fibres during treatment to compensate for heat loss.

1 5. Apparatus for use in the method according to claim 1, comprising conveyor means for animal foodstuff material which has been treated with a caustic aqueous solution, a heating chamber provided with high frequency energy emitting devices and an exit passage therefrom having temperature maintaining devices to minimise loss of temperature in the treated material until the chemical reaction involving the caustic solution is at least substantially complete.

16. Apparatus as claimed in claim 1, wherein the high frequency energy emitting devices are microwave energy horns arranged about the path of said conveyor.

1 7. Apparatus as claimed in either one of claim 1 5 and 16, wherein the temperature maintaining devices are conventional heating means.

1 8. A method of increasing the proportion of digestible material in cellulosic fibrous material substantially as hereinbefore described with reference to the Example.

1 9. Apparatus for use in increasing the proportion of digestible material in fibrous materials for animal feedstuffs constructed and arranged substantially as hereinbefore described with reference to the drawings.