GB2325845A - Oats product - Google Patents

Abstract

A process for preparing a quick cooking oats product in which there are two distinct cooking processes, the first is cooking of the whole oat grains followed by dehusking to give groats then, a final cooking process of the cut groats followed by flaking to produce an organoleptically acceptable cereal product. The hulls of the grain may be used for providing a power source.

Description

"A Process for Producing a Food Product" Introduction The present invention is directed towards providing a process for preparing a quick-cooking oats product which will be satisfactory in use, have a good shelf-life and sufficient organoleptic qualities. The invention relates specifically to a porridge product.

A diet which is high in dietary fibre has many advantages, including normalisation of bowel function, reduction of occurrence of certain diseases, lowering of blood glucose concentrations, post-prandial insulin levels, plasma cholesterol levels to name but some. Thus, diets high in soluble fibre are recommended by health authorities.

Oats are one of the few foods in which soluble fibre is found and thus are of considerable importance in the provision of dietary fibre.

One of the problems is that a convenient oat product cereal such as porridge, which, when made should be quickcooking or instantly cooked, such as, for example, with the addition simply of hot water, are often unacceptable when so made due to their texture, mouth feel and general taste. At the same time there is no doubt but that when milled oats or oatlets are raw and are cooked as porridge, they do provide an acceptable food, but unfortunately it requires a long time to prepare porridge. There is thus a balance between the less conveniently made food product, which contains a high level of soluble fibre, and a convenience food which is less acceptable. Unfortunately, what appears to happen is that soluble fibre absorbs undesirable amounts of moisture during processing and this leads to a product which has poor texture and mouth feel, which has been described as gummy or slimy. Many attempts have been made to produce a quick-cooking or instant oat cereal which still contains soluble fibre as is its nature and which does not have this undesirably poor texture.

The amount of work that has been carried out in this area of instant or rapidly cooked cereal products is enormous with considerable concentration on preparation time and the often poor keeping qualities of the once prepared oatmeal. Generally the stability of oat products is reliant upon the inhibition of enzymatic and oxidative reactions which may occur when the grain is damaged.

While heating has been used to deactivate enzymes, it has been found that many of the processing techniques have exacerbated the enzymatic and oxidative reactions. Thus, for example, heat treatment may inhibit enzyme activity, but accelerate oxidative rancidity. Many of these processing techniques include the heat treatment of hulled oats and what has been found, particularly when products are made from stabilised hulled oats which are flaked and eaten, for example as various forms of cooked porridge, is that they have a raw chewy texture and retain the chewiness after toasting. This apparent rawness is probably the single most important reason why oats have not become more prominent in the cereal market, particularly in view of the added concentration by many a consumer on dietary requirements.

Considerable work has been done on techniques that would gelatinise the starches. For example, WO 95/33384 (The Quaker Oat Company) describes and claims a process for producing uniformly gelatinised hulled oats which are translucent in appearance and have uniform colour.

However, such a process requires the step of cooking moist hulled oats (also called dehusked oats or groats) under pressure in an environment containing steam for a considerable period of time. This is a very complex expensive process which, while producing a relatively uniform and acceptable product, does not produce a product with the required taste and texture required by the consumer. One of the ways of overcoming some of the problems in preparing such cereal products has been described by the same company in European Patent Specification No. 0 626 138 Al and U.S. Patent No.

5,510,130. In this method edible particulate matter is embedded in the cereal flakes to improve texture and taste and general food quality.

For example, some of the present inventors of this patent application were co-inventors of an invention described and claimed in British Patent Specification No. 2 209 457 (Food & Cereal Research Ltd) which claimed a process for manufacturing a reconstituted cereal particularly oats which included conditioning the cereal with water so as to elevate the moisture content and then cooking and extruding the cereal. While this produced an acceptable cereal product, it was not a porridge. The process further included the dehusking, cleaning and steaming of the raw oats prior to cooking to inactivate the naturally occurring enzymes.

It is has also been proposed to compensate for the reduction in general nutritional value of the cereal product occurring during the processing of it by enriching the cereal product with vitamins. Essentially this addition of vitamins while, on the one level advantageous and desirable, is perceived by many nutritionists as being undesirable in that in as far as possible, the product should be retained as close to its natural state as possible. A good example, for example of this method is described in European Patent Specification No. 0 196 930 (Nabisco Brands Inc.). Consumer resistance is generally growing to the use of food additives with increasing demand for natural products.

Many patent specifications disclose the two-stage cooking of cereal grains in which the dough is partially or completely cooked with added moisture and after this cooking step, the mixture is rendered homogeneous, for example by passing it through an extruder, drying it, and then compacting and shredding the dried dough and finally cooking further the now shredded product. For example, U.S. Patent Specification No. 4,734,294 (Nabisco Brands Inc.) describes such a process and comprises cooking groats in a pressure cooker, which increases the moisture content of the oats, generally somewhere in the range 15 to 25% by weight. Then a second stage cooking is carried out to further gelatinise the starch in the grain and to increase the moisture content to about 40% to 50% by weight. Generally speaking the two cooking stages are done in the same cooking vessel. After cooking, the oat particles are cooled and surface dried and then shredded in accordance with standard practice. For example, U.S.

Patent Specification Nos. 4,485,120 (The Quaker Oats Company) and 4,438,150 (The Quaker Oats Company) describe and claim another method of producing a dehydrated readily reconstitutable cereal porridge product. In these specifications there is produced a gelatinised cereal flour and water mixture having a reduced viscosity by mechanically shearing the gelatinised mixture after peak gelatinisation viscosity has been achieved. Thus, the fluidity of the mixture is increased as the viscosity is reduced.

It has long been recognised that the hulls of grain are a major heat source having a relatively high calorific value. These have been used for incinerators such as, for example, described in EP Patent Specification No. 0 509 150 (Chang, Chwen Fu and Chang, Huei Lang). There are however considerable difficulties in burning such husks, because of their relatively high moisture content and because of the general problems of handling, etc. It has been known to form the organic matter fibrous material such as corn husks into pellets so as to provide uniformity in burning. This process for example is described and claimed in GB Patent Specification No. 1 581 692 (Gunnerman). One of the problems with such husks is that generally when the oats have been dehusked, the husks are moist and handling and burning is very difficult, such as for example described and claimed in GB Patent Specification No. 2 145 732 (K-Fuel/Koppelman Patent Licensing Trust).

The present invention is directed towards providing an organoleptically acceptable oat cereal product which can be prepared with minimal cooking, such as in less than 5 minutes in boiling water which will have the satisfactory characteristics of flavour, aroma and texture which can be obtained from the boiling of raw, milled oat products to produce such a porridge. Further it is directed towards providing an efficient way of utilising husks as a fuel.

Statements of Invention According to the invention there is provided a process for preparing a quick-cooking oats product comprising: performing an initial cooking of the whole oat grains; cooling the cooked whole oat grains; dehusking the oat grain to provide groats; cutting the groats into pinheads; further cooking the groats; flaking the groats; and cooling the flaked groats.

The advantage of this process is that by cooking the whole oat grains initially before any other operations are carried out on them it has been found that a subsequent oats lake has a better quality and taste characteristics than if this initial cooking is not carried out. The cooking is somewhat similar to other forms of heat treatment used, however, it has the added advantage that as well as cooking the grain, it also dries and roasts the husk, which in turn adds further flavour to the kernel of the grain. It should also be appreciated that as well as roasting the husk, it also dries it and makes it more useful for subsequent use as a fuel.

In one way of carrying out the invention, the husks removed after the initial cooking are incinerated to provide power. While it has long been appreciated that husks have a high calorific value, there have been considerable difficulties in trying to burn the husk subsequent to the dehusking operation. However, by precooking the husks before they are removed the husks are dry, they do not coalesce into lumps or other masses of material which is difficult to handle, but remain easy to handle and then subsequently relatively easily burned, while husks carrying more moisture would cause considerable difficulties. This dries and separates the husks much better than if the husks are removed prior to a subsequent drying operation. It appears that when in effect dried on the grain they are easier to handle.

Ideally the power is in the form of hot air for cookers, dryers and other hot air utilising equipment. Hot air is used for both cooking and other operations and thus this is a particularly suitable way of providing it.

In one embodiment of the invention the process comprises: delivering the husks to a burner; burning the husks to provide high pressure steam; delivering the burnt hot ash into water; and delivering the cooled hot ash out of the water into a storage pit in the form of a slurry.

The advantage of this is that the hot ash is cooled and the subsequent slurry can be readily easily handled.

In a preferred way of carrying out the invention the initial cooking step is a two-stage process utilising steam and air/steam draw-off.

Ideally this two-stage cooking process comprises a first stage cooking process to reduce the moisture content of the whole oat grains to between 9.5% and 12.5% by weight; and a second stage conditioning process fed directly from the first stage conditioning cooking process to provide a partially whole oat grain with a dry roasted husk and a moisture content of between 7.5% and 10.5% by weight; and ideally the moisture content in the first stage of the whole oat grains is between 10% to 12% by weight and in the second stage is between 8% and 10% by weight.

In the process the oat grains in the first stage of the cooking process are in the temperature range 900C to 1050C and in the second stage of the cooking process are in the temperature range 70"C to 900C and preferably in the first stage of the cooking process is in the temperature range 980C to 1020C and in the second stage of the cooking process in the temperature range 75"C to 850C. It has been found that hot air used in this way is particularly suitable for cooking the grain as it ensures that the grain does not stick together and further that its taste characteristics are enhanced.

The advantage of air at these particular temperatures is that it produces a well dried relatively moisture free product which can be stored until further processing without any possibility of damage or deterioration and further the two-stage cooking process enhances the taste characteristics of the subsequent flaked oats. It has been found that these ranges of moisture produce the most acceptable product for the consumer and also an easily handled product for subsequent processing.

In one method according to the present invention, prior to performing the initial cooking the whole oat grains are cleaned and some husks are removed and in which subsequent to this cooking, a further cleaning operation is performed prior to storage. It has been found that by cleaning the grain both before and after cooking the subsequent grain is extremely clean, easily stored and does not deteriorate during storage. This also ensures that the subsequent cooking is effectively carried out as dirty grain does not cook uniformly.

Ideally the final cooling of the groats comprises the steps of: delivering hot air in contra-flow to the passage of the hot groats to remove moisture therefrom; and then delivering cold air to the travelling groats.

It has been found that if the grain is simply cooled that moisture adheres to the groats and that these have to be subsequently dried by using hot air. Sufficient moisture is entrained in the hot air which is flowing in contraflow to the groats such that on subsequent cooling moisture is not produced on the groats.

Detailed Description of the Invention The invention will be more clearly understood from the following description of an embodiment thereof given by way of example only with reference to the accompanying drawings in which: Fig. 1 is a flow diagram of a process for producing flaked oats according to the invention; Fig. 2 is an outline of a two-stage cooker to illustrate the first cooking step; Fig. 3 is an outline of the coolers used for the final product cooling; and Fig. 4 is an outline of the steam generating boiler which is used to power the plant.

Fig. 1 is a flow process diagram which illustrates the full operation of the process and Figs. 2, 3 and 4 illustrate in outline some of the equipment used to carry out the process.

Referring thus to Fig. 1 principally and to Figs. 2, 3 and 4 when necessary, the equipment and process are described simultaneously.

Whole oat grains are delivered to an intake hopper 1 and then to storage bins 2. The whole oat grains are delivered out of the storage bins 2 to a grain clipper 3 and then to a kiln cleaner 4. The husks and dirt are delivered from the kiln cleaner 4 by a fan 6 to a hull storage bin 7. The initially cleaned whole oat grains are delivered to a service bin 8 and through a weigher 9 to a two-stage cooker comprising a first kiln 10 feeding a second kiln 11. Any hulls or husks removed in the twostage cooking process are delivered by a fan 13 to the hull storage bin 7. The partially cooked whole grain is then delivered to a cooler 14, all of which is illustrated in more detail in Fig. 2.

Referring now specifically to Fig. 2 oats are delivered through a duct 110 and a further duct 111 into the first kiln 10. The first kiln 10 is indirectly heated by high pressure steam delivered to it through a duct 112 and thus the kiln 10 forms a heating zone. Evaporated steam and dust are delivered out through a further duct 113 and are drawn off by the fan 13 (not shown in this Figure). Any condensate in the kiln 10 is drawn off through a pipe 114 to a main condensate draw-off pipe 115. The partially cooked oats are then delivered out of the kiln 10 to the tempering zone formed by the kiln 11 through a duct 116.

The oats are then tempered within the kiln 11 by low pressure steam delivered into the kiln 11 through the duct 117, again this steam is not in direct contact with the oats. Any condensate is delivered out the pipe 118 to the main condensate draw-off pipe 115. Evaporated steam and dust are delivered through a further duct 118 to the fan 13. The partially cooked conditioned whole grain is then delivered to the cooler 14 through the duct 119.

The advantage and purpose of the use of a two-stage cooking process is that in the first kiln 10 the temperature is raised and the steam stabilises the grain.

The second kiln 11 operates as a conditioning zone where the temperatures are maintained but not raised further.

It is important that the temperatures are not raised further as this can cause a burned or toasted flavour.

Finally, most of the drying takes place in the cooler 14 where steam is flashed off. If the grain is too dry and dried too quickly, then there will be insufficient moisture within the kiln to achieve the hydrothermal stabilising reaction.

Referring now again to Fig. 1 any hulls or husks that separate from the oats in the cooler 14 are delivered by a fan 15 to the hull storage bin 7.

When it is desired to further process the partially cooked oats, they are delivered out of the kilned oats bins 16 to a destoner 20, where any stones are removed by a fan 21 to any suitable storage containers, such as bags at an outlet 22. The destoned oats are then sent to a cleaner 23 and through further cleaning cylinders 24 and 25, respectively. They are then delivered to a series of sequentially arranged screens 26, 27 and 28 where the grain is sorted in large, medium and small sizes and these in turn are delivered to large oats, medium oats and small oats storage bins 29, 30 and 31, respectively. Any oats which are too small to mill, oat fragments and dust from the starchy portion of the grain which have separated from the grains in the cleaners are delivered from the cleaning cylinder 25 to a "sussex bin" 33. The term "sussex" is derived from an old term used for a type of ground oats called "sussex ground oats". Essentially the sussex bin contents are analytically similar to whole oats. What is contained in the hulls storage bins will be largely the outer shell of the grains, associated fragments of dusts, straws and other trash. The contents of both the hulls storage bin 7 and the sussex bin 33 can for example be sent to a provender mill in due course. However, as will be described hereinafter, only the contents of the hulls storage bin 7 are delivered to a boiler to generate heat.) The appropriate quantity of large-sized, medium-sized and small-sized largely whole oat grains are delivered from the large oats storage bin 29, medium oats storage bin 30 and small oats storage bin 31, respectively to a sheller service bin 40 and from the sheller service bin 40 which is a holding bin to any of a number of shellers 41 and then through aspirators 42 and a polisher 43. All of the remaining husks separated in the aspirators 42 are delivered by a fan 44 to the hull storage bin 7. After the polisher 43 the groats, as they now are, are delivered to a further aspirator 45 where any loose husks are again delivered by the fan 44 to the hull storage bin 7. The aspirator 45 then delivers groats to a first table separator 46 from which the groats are sent to a second table separator 47. The still whole oat grains, i.e.

those rejected by the first table separator 46 are delivered to return bins 48 from whence they are recycled into the sheller service bin 40. Rejects out of the second table separator 47 are recycled to the aspirator 45 and the groats are delivered through a weigher 49 to groats storage bins 50. The groats are then delivered to pinhead cutters 60 which in turn feed a pinhead sifter 61.

Pinheads can be delivered in a number of ways out of the pinhead sifter 61. They can be delivered directly out of the pinhead sifter 61 to pinhead bins 62 or through to an intermediate holding bin 63 which in turn feeds a sieve 64. The pinheads are delivered to either a holding bin 65 or directly to a bagging plant from an outlet at 66 (the bagging plant is not illustrated). Any rejects from the pinhead sifter 61 are fed through a further cylindrical screen 67 for a further screening where some pinheads are sent to the pinhead bins 62 through a pinhead aspirator 68. Rejects from the cylindrical screen 67 are recycled to the pinhead cutter 60. Dust formed by tiny particles of the ground oats are removed from the pinhead sifter 61, the cylindrical screen 67, the pinhead aspirator 68 by a fan 69 to the sussex bin 33. The duct connecting the fan 67 to the sussex bin 33 is not shown. Pinheads are delivered from the pinhead bins 62 to a holding bin 70 which in turn feeds a second cooker 71 in which the cooked pinheads are delivered through a roller 72 to a cooler 80 which is also illustrated in Fig. 3.

Referring now specifically to Fig. 3 the cooler 80 comprises an elongated closed hopper 81 having an inlet pipe 82 through which the flaked oats are delivered. A fan 83 delivers hot air at 84 in contraflow to the incoming flaked oats. The flaked oats fall down the hopper 81 against the incoming air and are then subjected to cold air directed through a conduit 85. The fan driving the cold air is not illustrated. The flaked oats are now cooled as they fall further down the hopper and out through an outlet pipe onto a sieve 86.

Referring again to Fig. 1 the cooled oatflakes are then delivered to portable bins 87 which are used to bring the oats lakes to a packing line 88. Optionally, the oats lakes make be delivered to a bran flour plant indicated generally by the reference numeral 90 which doesn't form part of the present invention. Similarly before cooking the pinheads the pinheads may be delivered from the pinhead bins 62 directly to a storage tank 91 for subsequent sale, again this is not part of the present invention.

The hull storage bin 7 feeds directly to a grinder 96 and similarly the sussex bin 33 in turn feeds a provender plant, not shown. The hull storage bin 7 may feed the provender plant and additionally feeds a steam generation plant.

Referring now specifically to Fig. 4 there is illustrated a steam generation plant indicated generally by the reference numeral 100 which is fed with husks. The steam generation plant 100 comprises an inlet hopper 101 fed with husks through a pipe 102 and incorporates a chain link conveyor 103, which is shown in outline. The husks are burned on the conveyor bed and the burnt husks are delivered out through a discharge outlet 104 into a transversely arranged screw auger 105 which is mounted in a water-bath. The burnt ash forms a slurry in the screw auger and is delivered out of the building to storage.

The steam generation plant generates steam which in turn heats air which is used to power the plant.

It has further been found that the surplus husks can be used to provide roughage in animal feed.

The invention is not limited to the embodiment hereinbefore described which may be varied in both construction and details.

Claims (14)

1. A process for preparing a quick-cooking oats product comprising: performing an initial cooking of the whole oat grains; cooling the cooked whole oat grains; dehusking the oat grain to provide groats; cutting the groats into pinheads; further cooking the groats; flaking the groats; and cooling the flaked groats.

2. A process as claimed in claim 1 in which the husks removed after the initial cooking are incinerated to provide power.

3. A process as claimed in claim 2 in which the power is in the form of hot air for cookers, dryers and other hot air utilising equipment.

4. A process as claimed in claim 2 or 3 comprising: delivering the husks to a burner; burning the husks to provide high pressure steam; delivering the burnt hot ash into water; and delivering the cooled hot ash out of the water into a storage pit in the form of a slurry.

5. A process as claimed in any preceding claim in which the initial cooking step is a two-stage process utilising steam and air/steam draw-off.

6. A process as claimed in claim 5 comprising: a first stage cooking process to reduce the moisture content of the whole oat grains to between 9.5% and 12.5% by weight; and a second stage conditioning process fed directly from the first stage conditioning cooking process to provide a partially whole oat grain with a dry roasted husk and a moisture content of between 7.5% and 10.5% by weight.

7. A process as claimed in claim 6 in which in the first stage of the cooking process, the moisture content of the whole oat grains is between 10% to 12% by weight and in the second stage is between 8% and 10% by weight.

8. A process as claimed in claim 6 or 7 in which the oat grains in the first stage of the cooking process is in the temperature range 90"C to 1050C and in the second stage of the cooking process is in the temperature range 70"C to 90cm.

9. A process as claimed in claim 6 or 7 in which the hot air in the first stage of the cooking process is in the temperature range 98"C to 1020C and in the second stage of the cooking process is in the temperature range 75"C to 85"C.

10. A process as claimed in any preceding claim in which prior to performing the initial cooking the whole oat grains are cleaned and some husks are removed and in which subsequent to this cooking, a further cleaning operation is performed prior to storage.

11. A process as claimed in any preceding claim in which the final cooling of the groats comprises the steps of: delivering hot air in contra-flow to the passage of the hot groats to remove moisture therefrom; and then delivering cold air to the travelling groats.

12. A process as claimed in claim 11 in which the hot air is at a temperature within the range 90"C to 1l00C.

13. A process for preparing a quick-cooking oats product substantially as described herein.

14. A quick-cooking oats product produced in accordance with the process as claimed in any preceding claim.