WO2004071198A1

WO2004071198A1 - Durum wheat flour

Info

Publication number: WO2004071198A1
Application number: PCT/GB2004/000579
Authority: WO
Inventors: Janet Masih
Original assignee: Janet Masih
Priority date: 2003-02-15
Filing date: 2004-02-13
Publication date: 2004-08-26
Also published as: GB2386537A; GB0303530D0

Abstract

A flour made substantially or exclusively from durum wheat, wherein between 15 and 35% inclusive of grains of the flour are sufficiently small to pass through an aperture 150µm in diameter.

Description

Title: DURUM WHEAT FLOUR Description of Invention

The invention relates to an improved flour, particularly, but not exclusively to atta flour used for making flat breads such as roti, chapatti, paratha or naan.

Although atta flour may be made from any kind of wheat, durum wheat is typically used as the resulting flour has favourable properties for making flat breads such as chapatti. According to a first aspect of the invention, I provide a flour made substantially or exclusively from durum wheat, wherein between 15% and 35% inclusive of grains of the flour are sufficiently small to pass through an aperture 150μm in diameter.

A dough for a flat bread such as chapatti made using flour according to the invention is easier to mix than a dough made from conventional atta flour, and is also easier to handle as the dough tends to be less sticky. In addition, a dough made using flour according to the invention keeps better and for longer in a refrigerator, whilst retaining a firm consistency, than dough made with conventional, atta flour. Finally, the colour of a dough, both before and after baking, made with a flour according to the invention is brighter and hence more attractive to a typical consumer, compared with a dough made with conventional atta flour.

Preferably substantially all of the grains are capable of passing through an aperture 670 μm in diameter. Less than 30% of the grains may be sufficiently small to pass through an aperture 150μm in diameter.

Less than 25% of the grains may be sufficiently small to pass through an aperture 150μm in diameter. 150μm in diameter.

Preferably the flour has an ash content of between 0.65 and 1% at 14% moisture base. The flour may have an ash content of less than 0.9% at 14 % moisture base.

Preferably the flour has a starch damage of between 5 and 8%. According to a second aspect of the invention, I provide a flour made substantially or entirely from durum wheat, wherein between 10 and 40% inclusive of grains of the flour are too large to pass through an aperture 340μm in diameter.

Preferably all of the grains are capable of passing through an aperture 670μm in diameter.

More than 15% of grains of the flour may be too large to pass through an aperture 340 μm in diameter.

More than 20% of grains of the flour may be too large to pass through an aperture 340μm in diameter.

More tharr 25% of grains of the flour may be too large to pass through an aperture 340μm in diameter. 30% of grains of the flour may be too large to pass through an aperture

340μm in diameter.

More than 50% of grains of the flour may be too large to pass through an aperture of 212μm in diameter.

The flour according to the second aspect of the invention may have any of the features of the flour according to the first aspect of the invention.

According to a third aspect of the invention, we provide a method of making a flour according to the first aspect of the invention, the method including the step of grinding durum wheat until substantially all of the grains are sufficiently small to pass through an aperture 670μm in diameter, between 15 and 35% inclusive of the grains are sufficiently small to pass through an aperture 150μm in diameter and between 10 and 40% inclusive of the grains are too large to pass through an aperture 340μm in diameter. An embodiment of the invention will now be described by way of example only.

An embodiment of a flour according to the invention was made from 100% durum wheat, or at least substantially 100% durum wheat taking into account normal levels of impurities, to have the following grain size distribution, as determined using a Buhler laboratory sifter (4 minute test):

Size>670μm 0%

460μm<Size<670μm 2%

340μm<Size<460μm 30%

212μm<Size<340μm 30%

150μm<Size<212μm 17%

Size<150um 21%

The percentage of particles with a grain size of less than 150μm, corresponds to the percentage of grains which are incapable of passing through a sieve with a mesh size of 150μm. The percentage of particles with a grain size of less than 212μm but more than 150μm corresponds to the percentage of grains which are capable of passing through a sieve with a 212μm mesh size but are incapable of passing through a sieve with a 150μm mesh size, etc.

The grains of known durum wheat atta flours tend to be finer than those of a flour according to the invention, and typically over fifty percent of the grains of a known atta flour would pass through a sieve with a mesh size of 150μm, none of the grains of known atta flours are greater than 460μm in size, and only a small percentage (3% for example) are greater than 340μm in size. It is believed that a consequence of the coarse grain size is that a dough for flat bread such as chappati is easier to handle and is less sticky when made with a flour according to the invention than when made with a known atta flour. The ash content of the flour is 0.894%, as determined at 14% moisture basis, using the AACC (American Association of Cereal Chemists) method 08- 01.

The ash contents of known atta flours are greater than 1%, thus flours according to the invention are more refined, i.e. contain less bran than known atta flours. It is believed that the low bran content further enhances the handling characteristics of dough made from the flour, and also imparts to the flour and any resulting dough, a particularly attractive bright cream colour.

The flour also has the following characteristics.

The protein content of the flour, determined using Combustion Nitrogen Analysis in a Leco analyzer corrected to 14% moisture basis, is 13.5%.

The wet gluten content is 35%, the dry gluten content 11.9%, and the gluten index 20.9, as determined using AACC (American Association of Cereal Chemists) method 38-- 12A (two stage procedure).

The moisture content of the flour is 12.91%, as determined using the AACC method 44-15A (one hour at 130°C).

Farinogram related measurements, determined using AACC method 54- 21, constant flour weight procedure using a 300g bowl, are: percentage absorption 61.8%, development time^' 3.6 minutes, mixing tolerance 70 B.U., and stability 2.3 minutes. The starch damage, determined using the megaZyme method (AACC

76-31), was found to be 5.7%, which is lower than in typical atta flours. ^■

Flour according to the first aspect of the invention is made as follows. Durum wheat, preferably Canadian durum wheat, No.l CWAD or No. 2 CWAD, is cleaned using any combination of the following techniques.

Foreign material which is larger, or smaller and lighter than the wheat is first removed using a conventional grain separator with an aspirator. The wheat is then passed through a de-stoner for the removal of stones that are similar in size to wheat.

A pair of disc separators or indented cylinders are then used to remove any seeds from the wheat that are either shorter and longer than the wheat itself. The wheat is then placed on a gravity table for further removal of lighter seeds and other impurities from the wheat.

Once it has been cleaned, the wheat is then tempered as set out below.

The wheat is transported to a tempering bin in a conveyor, and water is sprayed onto the wheat as it is conveyed to the bin. This ensures that the water and wheat are sufficiently well mixed before the wheat reaches the temper bin. Sufficient water is added to the wheat to bring the moisture content up to about 16 weight percent. Exactly how much water is added varies, depending on the original moisture content of the wheat.

The wheat is left to rest in the tempering bin, typically for 8 to 10 hours, and is then given a final clean using a scourer, which removes surface contamination such as crease dirt, or any outermost layer of bran that has become loosened during tempering, from the wheat.

Following scouring, the wheat is lightly sprayed with water to toughen up the bran, which helps the bran maintain its shape and resist powdering during milling. This typically increases the water content of the wheat by around a further 0.5%. The wheat remains in the tempering bin for around a further 30 minutes, before milling.

In order to separate the wheat into endosperm and bran, the wheat is passed through at least one rollermill. A rollermill houses two pairs of cylindrical iron rolls with a hardened rolling surface. The rolling surface may be corrugated or may be smooth. The two rolls in each pair run in opposite directions, and one rolls runs at a higher speed, typically 450 to 550 rpm, than the other, which typically runs at between 180 and 440 rpm. The ratio of the speed of the fast roll to the speed of the slow roll is typically between 2.5:1 and 1.25 : 1. The roll diameter is typically between 225mm and 250mm.

Typically a roller mill with corrugated rolls which are configured to grind the wheat to release the endosperm from the bran, preferably without shredding the bran, are used in the first instance. Shredding of the bran should be avoided, as it increases the difficulty of separating the finer pieces of bran from the endosperm.

The ground wheat is then sifted in a plansifter using various sizes of sieves to grade the ground wheat according to particle size.

The ground wheat, which includes unseparated endosperm and bran, is then returned to the roller mill(s) for further grinding. This process is repeated, typically five or six times, until substantially all of the endosperm is separated from bran.

The resulting material or stock is sifted through sieves of various aperture size, to separate, it into grades of different grain size, and then each grade is passed through a purifier which is used to separate the endosperm from the bran. The ground wheat is spread over a long shaking sieve, and air is drawn through the wheat and sieve in a controlled manner. As a result, the wheat separates into layers according to the density of the grains, and the denser grains, which are pure endosperm, pass through the sieve for collection first and the least dense grains, which are partially or entirely bran, pass through the sieve for collection last. Thus, pure endosperm may be separated from bran or bran contaminated grains.

If necessary to reduce the bran content to an amount corresponding to an ash content of between 0.6 and 1%, bran contaminated grains may be passed through a further set of corrugated rolls in order to scratch the remaining bran from the endosperm.

The wheat germ is also separated from the endosperm during the grinding and separating process. The pure endosperm grains are sifted and graded, and if necessary, passed through a roller mill with smooth rolls in order to reduce the grain size further. This process is repeated until the flour is produced with the desired grain size distribution.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

1. A flour made substantially or exclusively from durum wheat, wherein between 15 and 35% inclusive of grains of the flour are sufficiently small to pass through an aperture 150μm in diameter.

2. A flour according to claim 1 wherein substantially all of the grains are sufficiently small to pass through an aperture 670μm in diameter.

3. A flour according to any preceding claim wherein less than 30% of the grains are sufficiently small to pass through an aperture 150μm in diameter.

4. A flour according to any preceding claim wherein less than 25% of the grains are sufficiently small to pass through an aperture 150μm in diameter.

5. A flour according to any preceding claim wherein 21% of the grains are be sufficiently small to pass through an aperture 150μm in diameter.

6. A flour according to any preceding claim wherein the flour has an ash content of between 0.6 and 1%.

7. A flour according to claim 6 wherein the flour has an ash content of less than 0.9%.

8. A flour according to any preceding claim wherein the starch damage of the flour is between 5 and 8%

9. A flour made substantially or entirely from durum wheat, wherein between 10 and 40% inclusive of grains of the flour are too large to pass through an aperture 340μm in diameter.

10. A flour according to claim 9 wherein substantially all of the grains are capable of passing through an aperture 670μm in diameter.

11. A flour according to claim 9 or 10 wherein more than 15% of grains of the flour are too large to pass through an aperture 340 μm in diameter.

12. A flour according to claim 9, 10 or 11 wherein more than 20% of grains of the flour are too large to pass through an aperture 340μm in diameter.

13. A flour according to any one of claims 8 to 12 wherein more than 25% of grains of the flour are too large to pass through an aperture 340μm in diameter.

14. A flour according to any one of claims 8 to 13 wherein 30% of grains of the flour are too large to pass through an aperture 340μm in diameter.

15. A flour according to any one of claims 8 to 14 wherein more than 50% of grains of the flour are too large to pass through an aperture of 212μm in diameter.

16. A flour according to any one of claims 8 to 15 wherein the flour has any of the features of the flour according to any one of claims 1 to 7.

17. A flour substantially as hereinbefore described.

18. A method of making a flour including the step of grinding durum wheat until substantially all of the grains are capable of passing through an aperture 670μm in diameter, between 15 and 35% inclusive of the grains are sufficiently small to pass through an aperture 150μm in diameter and between 10 and 40% inclusive of the grains are too large to pass through an aperture 340μm in diameter.

19. A method substantially as hereinbefore described.