WO2001082722A1

WO2001082722A1 - Production of improved cereal grain or cereal flour

Info

Publication number: WO2001082722A1
Application number: PCT/EP2001/000741
Authority: WO
Inventors: Rinka Banerjee; Lex Van Buren; Gunender Kapur; Chandrika Mohanan; Gopinath Babasaheb Rajale; Herbert Smorenburg; Ancha Venkataramana
Original assignee: Hindustan Lever Ltd; Unilever NV
Current assignee: Hindustan Unilever Ltd; Unilever NV
Priority date: 2000-04-28
Filing date: 2001-01-19
Publication date: 2001-11-08
Anticipated expiration: 2002-10-28
Also published as: AU2001226809A1; AP2002002645A0; BR0110277A; MXPA02010577A; ZA200207747B

Abstract

Cereal flours, in particular wheat flour and maize flour with good properties for application in chapati, respectively in ugali can be made by a heat treatment at 100 to 350 °C for 10 - 120 sec, while agitating it slightly. The grains so obtained can be milled and the flour resulting from the milling can be blended with conventional flours. Applying the process to maize grains results in novel products.

Description

Production of improved cereal grain or cereal flour

The present invention relates to improved cereal grains and flour and in particular to a synergistic mix of flour and flour obtained from high temperature treated cereal grains suitable for use in particular but not exclusively for flat breads such as chapa ti making and a process for obtaining the same. According to another embodiment of the same invention maize products can be obtained with improved performance for use in ugali.

Cereal grains are conventionally converted into a flour for the preparation of various food products such as breads, cakes, biscuits, and flat breads such as chapati etc. The flour is obtained by passing the grains through different types of mills such as roller mill, hammer mill, disc mill etc. Improving the water absorption capacity of the flour helps in making the finished product softer and in improving consumer appeal. Other applications for these flours in particular maize flour are its use in: porridge; ugali; snacks (such as pumplings) ; knδdels; chips; tortilla's; enchilada's or taco's.

Chapati is a well known product in the Asian culture which nowadays becomes more and more popular outside Asia as well. A Chapa ti needs to meet a number of quality requirements in order to be considered as acceptable for the consumer. E.g. the Chapa ti needs to be soft and the softness (pliability) and tearing ease (shear value) of a Chapati (as a criterium for toughness) needs to be correct to provide the desired product characteristics to the chapa ti . Moreover the known production processes for making a Chapa ti often lack the ease of kneading the dough, whereas the way the dough resulting from these known processes can be sheeted is also often very difficult. Moreover the puffing of the sheeted dough, resulting from these known processes also is often insufficient. It would further be very beneficial if softness (pliability) and tearing ease (shear value) of Chapa ti could be increased over a period of 4 hours after baking.

It is thus the basic objective of the present invention to improve the water absorption capacity of the wheat flour while maintaining the texture and taste of the final product in an economical way.

Ugali is a traditional food product in the African region. It is based on maize and is made by adding to cooking water about 20 to 50 wt % of a maize flour whereupon cooking is continued for about 30 min until the product is well cooked. So far for the preparation of ugali the traditional maize flours were used. However these traditional maize (or corn) flours have a number of disadvantages. E.g. the appearance (colour) and flavour of the traditional maize flour is not very attractive, its structure is very coarse which leads to inhomogeneous areas in the final product resulting in insufficient softness and smoothness of the ugali, its water absorption capacity is not very high leading to less easy processing of the maize flour during the preparation of the ugali (in particular stirring problems will occur due to high resistance during stirring) whereas also the cooking times are rather long. Further the known maize flours have a limited shelf life, in particular because of their sensitivity for oxidation leading to rancidity problems during storage. It is another object of the invention to obtain an improved maize flour and a process to make this that can overcome the above problems.

It is another object of the invention to obtain a synergistic mix of flour which would provide for especially flat breads having good taste, softness/ pliability, tearing ease, aroma and related characteristics by blending flour obtained from high temperature treated cereal grains.

Another object of the present invention is to provide for a process of treating cereal grains at high temperature in a controlled manner and obtaining a flour of the heat treated grains that would be suitable for blending with cereal flour to improve their water absorption capacity and thus obtain a superior end product.

Acording to another embodiment of the present invention there is provided a process for the preparation of an improved flour comprising flour along with 1 to 40% by weight of flour obtained by a high temperature treatment of one or more cereal grains in particular of grains having a bulk density of upto 0.75 kg/1.

Therefor our invention concerns in the first instance a process for the production of improved cereal grains or flour wherein i) cereal grains are heated to a temperature of 100-350 °C for a period of 10 to 120 seconds under slight agitation ii) and optionally milling of the grains obtained. Blends of cereal flours can then be made by blending 1-40% of the grains/flour obtained above with ordinary cereal grains or flours, that have not been subjected to the heat treatment. According to a preferred aspect of the invention there is provided a process for obtaining improved grains or flour comprising heat treating the grains at a temperature of 100-350 °C using a solid, in particular sand and/or salt as a heat conductor, for a period of 10 to 120 seconds under slight agitation and optionally milling the grains; These products can be blended with ordinary cereals as described above.

According to a more preferred aspect of the invention there is provided a process of obtaining improved grains or flour comprising presoaking the grains in water and/or other liquids prior to heat treating the grains at a temperature of 100-350 °C for a period of 10 to 120 seconds under slight agitation and optionally milling the grains; Of course the products so obtained can be blended again with ordinary cereals as described above.

Pre-soaking conditions are typically: soaking in an amount of water, that is 2-3 times the amount of the grains at 20-60 °C, during 1-6 hrs.

According to a more preferred aspect of the invention there is provided a process of obtaining improved wheat grains or flour suitable for making flat breads comprising heat treating the wheat grains at a temperature of 200-350 °C using sand as a heat conductor, for a period of 10 to 75 seconds under slight agitation optionally followed by milling the grains. The products so obtained can be blended in amounts of 5-15% with ordinary cereals.

In the above blending processes it is beneficial to subject the blended product to milling to produce the flour from the blended grains/flour and cereals.

The normal grains and high temperature treated grains can be blended and milled or the flours obtained from these grains can be blended. Alternatively the flour from any one and the grains from the other can be mixed and milled.

The high temperature treatment of grains is carried out in any suitable roaster, fluidised bed and preferably in a sand roaster where the grains are heated along with sand. A very suitable equipment for the sand roasting is a revolving drum, filled with sand, which can be heated. The high temperature treatment can cause damage of starch. This e.g. will happen to an extent of 25-80% when wheat is used, while the degradation of gluten will be almost 100%.

The cereal grains that can be selected for the heat treatment are wheat, barley, maize, rice, sorghum, pearl millet or other millets or a mixture thereof.

Applying the process of the invention to maize grains leads to novel maize grains that are characterised by a kernel density as measured according to the method disclosed below of 0.9-1.1 kg/1 and which are substantially free of popcorn. Making of popcorn is a well known process. Herein maize grains are heated and the intention of the heat treatment is that the grain kernels pop (i.e. they burst open). In our process however we want to avoid that the maize grains pop and therefore our products are substantially free of popcorn. Substantially free meaning that less than 5 wt %, preferably less than 2 wt % and most preferably less than 0.5 wt % of the maize is popped into popcorn.

The density of the maize kernels has been measeured by bringing a volume of maize-kernels (V) in a measuring -glass, filled with ethanol. The measuring-glass with ethanol has been weight before and after the addition of the maize-kernels. So the mass (M) of the maize-kernels is known, even as the volume (V) of the maize-kernels.

DENSITY maize-kernels = M/V = g/1

The maize product so obtained can be milled by applying a standard milling and so a novel maize flour is obtained which can be characterised by a particle size of 20 to 1500 micron and a water absorbing capacity as measured by the method disclosed in our co-pending patent application EP 00203401.5 of 150 to 250 wt %, in particular 150 to 250 wt %.

The maize flour obtained will contain a certain but limited amount of damaged starch. In general this amount will be less than 7.5 wt % and in particular this amount will be limited to 1.5 to 7.5 wt %. This damaged starch cannot be absent completely because a certain amount is required to obtain the desired water absorbtion capacity. Damaged starch content can be measured by the enzymatic method disclosed in above EP patent application.

The maize flour so obtained can be blended with ordinary maize flour (so with a maize flour obtained without using the heat treatment .). Suitably 1 to 40 wt % of the novel maize flour are blended herefore with 99 to 60 wt % of the ordinary maize flour. The use of this blend enables us to make an ugali with a similar performance as known ugali however using less of the maize flour or to make an ugali with the same maize flour content as tradional ugali however with an improved performance compared with the tradional ugali.

Therefore our invention also concerns ugali comprising 25 to 50 wt % of a gelatinised blend of the maize flours according to the invention and balance water.

The details of the invention its objects and advantages will be more apparent from the ensuing description made with relation to the non-limiting exemplary embodiments.

EXAMPLES

1 - 4. Preparation of high temperature treated wheat grains: The wheat grains were fed into the sand roaster which was maintained at a temperature of 250 °C for 40 seconds under continuous agitation. The roasted grains are cleaned and milled in a disc mill. The flour thus obtained was blended at 10% (Example 1) and 20% (Example 2) by weight with flour from ordinary wheat.

The wheat grains having a moisture content of 15-20% were fed into the sand roaster which was maintained at a temperature of 250 °C for 60 seconds under continuous agitation. The roasted grains were cleaned and milled in a disc mill. The flour thus obtained was blended at 10% (Example 3) and 20% (Example 4) by weight with flour from ordinary wheat.

Evaluation of end product:

The flour obtained from the blend of roasted wheat and ordinary wheat (10%+90% and 20%+80%) were compared with flour obtained from ordinary wheat. The characteristics of the chapati obtained were studied.

Table 1

The data show that blending of roasted wheat flour obtained by roasting the grains either dry or with presoaking to increase the moisture level gives superior benefit to the dough obtained and the quality of Chapa ti made therefrom.

5 - 12. Puffed corn and sorghum were obtained by heating the grains in a commercially available popcorn making machine. The bulk density of the grains before and after the treatment is given in Table 2.

Table 2: Bulk density of untreated and treated grains

The grains were then milled.

Properties of blended flours

The corn flour thus obtained was blended at 5% (Example 5) , 10% * (Example 6), 15% (Example 7) and 20% (Example 8) by weight of flour from ordinary wheat. The data are shown in Table 3.

Table 3:

Water absorption is therefore improved by adding the flour from the heat treated grains. The sorghum flour obtained by heat treatment and milling was blended at 5% (Example 9), 10% * (Example 10), 15% (Example li; and 20% (Example 12) by weight of flour from ordinary wheat. The data are shown in Table 3.

Table 4:

Sensory Analysis of Chapati

The characteristics of the chapati made from Example 8 and Example 12 were studied and compared with the chapati made from a control wheat flour. The data are shown in Table 5. An expert panel of 14 members evaluated the chapati and gave a score on the 0-10 scale.

For the sensory attributes of pliability and taste, higher scores are desirable and indicate more pliability and a sweeter taste. For the sensory attributes of chewability and tearability, a higher score is not desirable and indicates that the product is difficult to chew and tear.

Table 5 :

The chapati made from the flour of the invention thus has superior sensory attributes to chapati made from ordinary wheat flour.

The data presented shows that blending of wheat flour with flour obtained from cereal grains having a bulk density of 0.03 to 0.75 kg/1 with wheat flour gives superior benefit to the dough and the quality of chapati obtained.

13. The process of example 1 was repeated, however using Kenyan maize grain as cereal. The heating was performed as indicated in table 6 (temperature/time) . The properties of the products obtained are indicated as well.

The maize flour was blended with non-treated maize flour (convential maize flour) in an amount of 25 wt %. Ugali was prepared from this blend, using 30 wt % maize flour and 70 wt i water. The processing was easier than when applying the conventional maize flour only, while the performance of the flour and the ugali was better than for the traditional products . Table 6

Results after soaking of the maize grains for 2 hrs and drying overnight .

Claims

1. Process for the production of an improved cereal grain or cereal flour, wherein: i) cereal grains are heated to 100 to 350 oC for 10 to 120 sec under slight agitation ii) and optionally the grains obtained are milled.

2. Process according to claim 1, wherein the grains are pre- soaked with water or another liquid prior to the heat treatment.

3. Process according to claims 1 and 2 wherein the cereal grains are heated, in the presence of a solid heat conductor.

4. Process according to claim 3 wherein the solid heat conductor is sand and/or salt.

5. Process according to claims 1 to 4 wherein the heating is performed in a sand roaster.

6. Process according to claims 1 to 5 wherein the cereal grain is selected from wheat, maize, rice, barley, sorghum, pearl millet or other millets.

7. Process for making a blend of cereal flours wherein 1 to 40 wt % of the product obtained as result of the process of claims 1 to 6 are blended with 99 to 60 wt % of a cereal flour that has been obtained from a cereal grain that has not been subjected to the heat treatment according to claims 1 to 6.

8. Maize grain, having: i) a kernel density of 0.9-1.1 kg/1 ii) and which is substantially free of popcorn.

9. Maize flour, having: i) a particle size of 20 to 1500 micron ii) a water absorsorption capacity of 150 to 350 wt %.

10. Maize flour according to claim 9 having an amount of damaged starch of less than 7.5 wt %, preferably 1.5 to 7.5 wt

11. A blend of maize flours comprising 1 to 40 wt % of the maize flour according to claim 9 or 10 or as obtained by the process according to claims 1 to 6 and 99 to 60 wt % of an ordinary maize flour , not being heat treated.

12. Ugali, comprising 25 to 50 wt % of a gelatinised blend with the composition according to claim 11 and balance water,