Composite Flours

5.3. Europe and North America

These two continents produce sufficient quantities of bread cereals, so theoretically they have no need to market and use composite flours at all. But constantly widening ranges of bread and small baked goods and the emergence of certain types of bread as "functional food" have led to an interest in mixtures of wheat flour with other agricultural raw materials (Abdel-Kader, 2000; De Ruiter and Kim, 1969).

Composite flours are an ideal partner in programmes to combat coeliac disease. In making up composite flours it is important to ensure that they contain no wheat, rye, triticale, barley or oats at all. Instead, they may contain products derived from rice, millet or buckwheat, maize or wheat starch, cassava flour and starch, potato starch or soy grits; milk and egg products and also vegetable swelling substances may be used additionally. Even in normal bread production, more and more vegetable substances that are not bread cereals are now being used (e.g. multi-grain bread, oilseed bread).

5.4. Asia

Traditionally, rice and tapioca have been cultivated as carbohydrate sources. Today, in particular India and China are also growing wheat in considerable amounts for human consumption, and all other Asian countries are importing large quantities of wheat. Nevertheless, the traditional crops are sometimes subsidized by the government in order to reduce the demand for hard currency. Therefore, flour from tapioca (tapioca starch) is used to replace wheat flour in some applications, mainly in pastry, if it can contribute to cost reduction.

6. Treatment of Composite Flours

When bakery products are made from composite flour, their overall quality (odour and flavour, chewing properties, appearance, shelf-life) should be as similar as possible to those of products made from wheat. To achieve this, the wheat flour contained in the composite flour must be suitably treated. The familiar flour improvers potassium bromate and ascorbic acid have proved very satisfactory for this purpose. The amount added must be adjusted to the quality of the wheat flour. As a rule it is between 20 and 50 ppm.

Fig. 100: Pan bread from composite flour treated with flour improving agents.

All samples treated with ascorbic acid, azodicarbonamide and α-amylase.

(A) 90/10 wheat/cassava (%) + 0.3 % Mulgaprot (mono- and diglycerides co-emulsified with lecithin);

(B) 100 % wheat;

(C) 80/20 wheat cassava + 0.5 % Mulgaprot + 0.1 % DATEM + enzyme mix;

(D) 70/30 wheat cassava + 0.8 % Mulgaprot + 0.16 % DATEM + enzyme mix

Modern enzyme preparations are also capable of compensating for the loss in volume resulting from the composite flour as compared to pure wheat flour. Hemicellulases and also lipases can be used as well as amylases. Fig. 100 shows the effects of flour improvers on the appearance of pan bread made from a composite flour consisting of wheat flour and up to 30 % cassava flour.

Tab. 77: Influence of flour treatment and pregelatinized starch on loaf volume of composite flour from cassava starch and wheat flour (50/50 %)

The technical problem for the baker is usually poor dough formation in the mixing and kneading process. Pre-gelatinized starches and certain emulsifiers have proved useful here. Numerous tests have been carried out on the use of emulsifiers (Khalil et al., 2000). Especially in the case of mixtures containing only a small proportion of wheat flour, glyceryl monostearate (1%, flour basis) as an emulsion (GMS:water = 9:1) has proved useful when added during preparation of the dough. Tab. 77 gives an overview of the improvements that are possible in respect of volume when certain emulsifiers and pre-gelatinized starches are used in bread production. Oxidative flour treatment with 25 ppm ascorbic acid was also used in these tests.

Apart from oxidative treatment f.i. with potassium bromate and ascorbic acid, it is also important to use sufficient amounts of waterbinding substances such as pre-gelatinized products and to ensure that the wheat flour has optimum baking properties in accordance with its percentage of the mixture. In addition to monoglycerides, other emulsifiers – CSL and SSL – have proved very satisfactory. 

7. Rheology of Dough

In nearly all countries the wheat and rye flours used in baking are tested for the rheological properties of the dough. The aim is to achieve the rheological optimum of each dough in the production process. But the extensive literature available makes it plain that doughs made with composite flours cannot be evaluated and classified by the usual rheological methods. Nor does the literature give any indication that specially adjusted rheological methods have been used for evaluating doughs made from composite flours.

8. Outlook

In recent years, too, research into optimizing composite flours has continued internationally. There are publications on the use of bean meal in Egyptian baladi bread (Abdel-Kader, 2000) and the addition of zein to a mixture of wheat and millet flour (Bugusu et al., 2001). There are numerous research studies on the subject of improving dough rheology (Khalil et al., 2000, Sharma et al., 1999) and the use of pseudo-cereals (Kuhn and Götz, 1999). But so far the composite flours have not achieved a noticeable commercial breakthrough in any country. Success is only to be expected if all the sensory attributes of baked products or pasta made from composite flours differ only slightly from those of the products with which they are compared.

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