GB2078083A

GB2078083A - Animal feeds based on spent grains

Info

Publication number: GB2078083A
Application number: GB8118800A
Authority: GB
Original assignee: AG Patents Ltd
Current assignee: AG Patents Ltd
Priority date: 1980-06-19
Filing date: 1981-06-18
Publication date: 1982-01-06
Also published as: GB2078083B

Abstract

The invention provides an animal feed material comprising spent grain having an overall dry-matter content of 23-30% by weight and containing added nutrient materials. The invention also provides a process for the preparation of animal feed material in which spent grains containing less than 25% by weight of dry-matter are subjected to mechanical de-watering e.g. centrifuging to raise the dry-matter content thereof to above 30% by weight, followed by addition of water and at least one nutrient whereby the dry matter content of the grains is reduced to 23-30% by weight. The water and nutrient may be added simultaneously in the form of spoilt beer, acid whey or a suspension of yeast or malt in water. Other specified nutrients are ice cream or coffee residues. <IMAGE>

Description

SPECIFICATIQN Novel grain-based animal feed material and a method for its production The present invention relates to a novel grainbased animal feed material and a method for its production.

In brewing, and in related processes such as distilling and vinegar brewing, crushed malt and other cereals are treated with water to extract carbohydrate for fermentation, leaving a wet residue known as "spent grains" which consist primarily of the protein and fibre from the original material. Such spent grains normally contain about 18-25% by weight of dry matter.

Spent grains are commonly used as a feed stuff for ruminant animals, in view of their high protein content and the ability of ruminants to digest fibre.

However, demand for such feed material is commonly seasonal, particularly in countries such as the United Kingdom where cattle are out to grass in the Summer, and it is normally necessary, therefore to store the grains in an acceptable state for feeding during the Winter.

In general, such storage is achieved either by ensiling the grains in bulk in the wet state in which they come out of the brewery or by drying. In the drying process, the spent grains are normally de-watered by mechanical means such as screw presses or centrifuges but this procedure is capable of increasing the dry matter content to no more than about 35% by weight and in order to remove sufficientwaterto stabilise the spent grains, a great deal of energy is required. This is expensive and generally undesirable.

The bulk ensilage of the wet spent grains can be achieved satisfactorily in such moist conditions only if procedures are adopted to reduce the pH to 4.0 or below as quickly as possible for example by promoting the growth of bacteria producing lactic acid, thereby inhibiting the growth of infecting organisms.

In some cases, acids such as formic acid or other preservatives may be added. However, when the dry matter of the spent grains is below about 23%, they are more difficult to transport and handle, as well as having a lower nutritional value in relation to their gross weight and may give rise to effluent problems on the farm. Furthermore, the free liquid associated with the grains consists mostly of incompletely removed carbohydrate-extract which would more profitably be utilised in the brewing process.

On the other hand, mechanical de-watering of the spent grains generally increases the dry matter content to above 30% and while this may be beneficial in recovering further liquid for re-cycling to the brewing process and could reduce transport cost by reducing the amount of liquid to be transported with the grain, the resulting material commonly does not ensile weil. De-watering tends to remove lactic-acid producing microorganisms and also the nutrient substrate for their growth. Furthermore, de-watering introduces air into the spaces between the grains, favouring an undesirable change in the relative growth rates for the essentially anaerobic lactic-acid producing bacteria compared to other microorganisms. A reduction in the rate at which the pH is reduced is an indication that the inhibition of the growth of infecting organisms has been inadequate.

Consequently the ensilage of such de-watered spent grains requires great care in maintaining the correct conditions and it is found in practice that some farmers cannot ensure that such standards are always maintained.

We have now found that spent grain can be ensiled very satisfactorily at a dry matter content of 23-30%, thus avoiding some of the principal disadvantages normally associated with wet spent grain as produced directly by the brewery and also those associated with the conventional de-watered material. We have further found that a particularly improved product can be obtained by subjecting spent grains from the brewery to mechanical dewatering followed by addition of water and nutrient material (which may be present in a single liquid such as spoilt beer or acid whey, or may be added separately) to bring the dry-matter content to within the above percentage range while adding to the nutrient content in the grains. Thus a lorry load of the same gross weight will contain a greater weight of nutrient material.The valuable carbohydratecontaining solution provided by mechanical dewatering can be re-cycled to the brewing process while the water and nutrient material which partiaily replace the liquid thus removed may advantageously be a waste-product of the food industry, and in particular of the brewing industry, such as spoiled beer, yeast and the like. There is thus a substantial economic benefit, including savings on costs of waste disposal and the feed value of the added materials. In general, grains at below 27% dry matter, especially in the range 23-26%, are more suitable for conventional grains conveying systems than those at above 27%.

According to the present invention, therefore, we provide an animal feed material comprising spent grain having an overall dry-matter content of 23-30% by weight and containing added nutrient materials.

According to a further feature of the invention we provide a process for the preparation of animal feed material in which spent grains containing less than 25% by weight of dry-matter are subjected to mechanical de-watering to raise the dry-matter content thereof to above 30% by weight, followed by addition of water and at least one nutrient whereby the dry-matter content of the grains is reduced to 23-30% by weight.

In general, the dry-matter content of the spent grain after the treatment according to the invention will be 25% by weight or greater whereas that of the spent grain prior to treatment will have been lower, being generally in the range 18-23% when a lautertun is used to filter the grain.

The de-watering of the initial spent grains can be achieved by a screw press or, more preferably, by centrifugation. Care should be taken not to damage the husk of the grain to a significant extent. The nutrient may be added separately from the water or, more conveniently may be in solution or suspension therein. The water may contain other dissolved or suspended substances such as common salt. The nutrient may be added in a liquid such as spoilt beer to which further water or water containing liquid is added so as to adjust the dry matter content of the grain to the desired level.The nutrient to be used in re-wetting the de-watered spent grains may, as indicated above, be a liquid waste material from a brewery, which would otherwise create an effluent or pollution problem, such as spoilt beer, or may be malt or other nutrient dust or yeast which may be added in suspension in waterorwater-containing liquid, or less conveniently be added in solid form with separate addition of liquid. The added nutrient may, however, be derived from some other industry, for example acid whey from the cheese industry or coffee or ice-cream residues.

As indicated above, it is important that the grains to be ensiled should be capable of permitting rapid growth of lactic-acid producing bacteria, so that the pH is rapidly reduced to a favourable level, for example about 4.2. The replacement of the liquid removed by de-watering restores the anaerobic conditions within the mass of grains and the addition of nutrients provides a fresh substrate for the growth of the favourable bacteria. It may be preferable to assist the reduction of the overall pH of the grain mass by adding a nutrient liquid at a relatively acid pH, for example about 3.5-4.5. Acid whey is particularly suitable in that it not only provides the required conditions for the growth of lactic-acid bacteria but actually itself contains such bacteria together with some nutrient matter.

The following Example is given by way of illustration only: Example 1 Spent grains issuing from the lautertun at 22% by weight dry matter (10,000 kg) are de-watered in a Sharples P3400 decanter centrifuge to produce 7,330 kg spent grains (having 30% dry matter) and 2,667 kg liquor (containing 53 kg dry matter) for re-cycling.

500 Kg spoilt beer (pH 4.0) containing 45 kg dry matter 200 kg malt dust containing 190 kg dry matter and 1548 kg water are mixed and added to the dewatered grains to yield 9530 kg spent grain having a dry matter content of 25% by weight.

The product produced by the above procedure ensiles well using the normal method recommended by the Ministry of Agriculture, Fisheries and Food and is readily acceptable to cattle.

Example 2 Spent grains (1000 kg) from the brewery silo at 22.9% by weight dry matter were de-watered in a Sharpies P3400 decanter centrifuge to produce 763 kg spent grains having 30.0% by weight dry matter and 237 kg liquor for re-cycling. 80 Kg acid whey (pH 4.45) at 6% dry matter were added to the de-watered grains to produce 843 kg spent grain having a dry matter content of 27.8 by weight.

A sample of the grains produced as above was ensiled in a 15 gallon hermetic container. The content of iactobacilli at the start of ensilage was 56 x 105 per gram, comprising 87% homofermentative lactobacilli. The pH of the grains as ensiled was 4.9; after 14 days ensilage, the pH fell to 3.9. After a further 7 days, with the grains open to the air, the pH fell to 3.7.

Claims

1. An animal feed material comprising spent grain having an overall dry-matter content of 23-30% by weight and containing added nutrient materials.

2. Animal feed material as claimed in claim 1 having an overall dry-matter content below 27% by weight.

3. Animal feed material as claimed in claim 2 having an overall dry-matter content of 23-26% by weight.

4. Animal feed material as claimed in any of claims 1-3 having an overall dry-matter content of 25% by weight or greater.

5. Animal feed material as claimed in any of the preceeding claims in which the added nutrient material is waste nutrient material from a brewery.

6. Animal feed material as claimed in any of claims 1-4 in which the nutrient material is spoilt beer, malt, yeast, acid whey or coffee or ice-cream residues.

7. Animal feed material as claimed in any of the preceeding claims substantially as herein described with reference to eitherofthe examples.

8. A process for the preparation of animal feed material in which spent grains containing less than 25% by weight of dry-matter are subjected to mechanical de-watering to raise the dry-matter content thereof to above 30% by weight, followed by addition of water and at least one nutrient whereby the dry-matter content of the grains is reduced to 23-30% by weight.

9. A process as claimed in claim 8 in which the dry-matter content of the spent grain before dewatering is in the range 18-23% by weight, and after addition of water and nutrient material, is 25% by weight or greater.

10. A process as claimed in claim 8 or claim 9 in which the dry-matter content of the grains after addition of water and nutrient is in the range 23-26% by weight.

11. A process as claimed in any of claims 8-10 in which the water and nutrient are added simultaneously in the form of spoilt beer, acid whey and/or malt or other nutrient dust or yeast in suspension in water.

12. A process as claimed in any of claims 8-11 in which a nutrient liquid at a pH in the range 3.5-4.5 is added to the spent grain after de-watering.

13. A process as claimed in any of claims 8 to 12 in which de-watering of the initial spent grains is achieved by centrifugation.

14. A process as claimed in claim 8 substantially as herein described in either of the Examples.