Posts

Dough Rheology as a Function of Flour Treatment

Image
3. Extensibility and Resistance The Extensograph and the Alveograph have many properties in common. Nevertheless it is interesting to note that most inquiries on optimization concern the Alveogram. In particular, wishes for modification include the extensibility and resistance of the Extensogram, the L-value and the P-value of the Alveogram, and also the P/L ratio of the Alveogram. Sometimes the areas beneath the curves (equivalent to the energy input) need to be modified.

Increasing the resistance of the Extensogram or the P-value of the Alveogram does not seem to be difficult, since hardly any inquiries ask for it. And in fact applying oxidizing agents effectively increases both. Fig. 141 depicts the effect of ascorbic acid and potassium bromate respectively on the resistance of the Extensogram. As potassium bromate is a rather slowly-reacting oxidizing agent, its effect can hardly be observed after only a short incubation time (Fig. 141, curve PBr 45'). Consequently, its impact…

Dough Rheology as a Function of Flour Treatment

Image
2. Mixing Resistance Four main wishes have been identified concerning the modification of the Farinogram curve: increased or reduced water absorption and increased or reduced stability. Enhancing the water uptake of a dough means reducing its stickiness and increasing the potential for adding more water, e.g. to achieve a longer shelf-life of the finished product. Besides adding hydrocolloids or vital wheat gluten, more elegant means exist – for instance xylanase, that only acts on water-insoluble xylan. The resulting solubilized xylan absorbs more water (Fig. 137). Xylanase preparations for improved volume yield do not only enable this activity; they also contain xylanases which degrade the pentosan fragments further, releasing water again. Although this improves the volume yield, the water uptake is reduced. Enzymes creating hydrocolloids in situ also improve water absorption; they include alternan sucrase (Popper, 2002) and dextran sucrase.

Farinogram stability can be improved with…

Dough Rheology as a Function of Flour Treatment

Image
Determination of the rheological properties of a dough is part of the quality assessment of flour. The rheological properties depend to a large extent on wheat variety, crop properties and the milling process. Provided that a sufficient supply of wheat with different rheological behaviour exists, the miller will be able to adjust the desired properties by blending different lots. Nevertheless, fine tuning will require using additives such as enzymes or oxidizing agents. If raw material of adequate quality is unavailable or in short supply, more extensive flour treatment will be required. Although the author supports the idea of adjusting the rheological properties, he also insists that we should not believe in numbers only; ultimately, the properties have to suit the flour user's requirements in a chosen application.
1. Viscosity High Falling Numbers can be reduced by adding α-amylase. Since the conventional method of determining the Falling Number includes heating almost to boili…

Vital Wheat Gluten

Image
To describe all the aspects of gluten and its production would fill a separate book, so this section will concentrate on the issues relating to flour improvement. Information on the rheological properties of gluten is also given in The Role of Gluten Elasticity in the Baking Quality of Wheat But like many other articles, that articles only deals with native gluten, i.e. as it is extracted from wheat flour. If wheat gluten is to be used commercially as an additive, it first has to be extracted from wheat and converted into powder. This is a multiple-step process (Fig. 133), starting with the milling of the wheat grains. Milling is followed by aqueous separation of the starch and soluble substances from the aggregated gluten, disintegration of the gluten in a pin mill or the like and finally hot air drying, for example in a ring dryer.
Only about 82% of the protein of flour is insoluble in water and contributes to wet gluten formation. Furthermore, some of the watersoluble proteins a…

Flour Treatment : Bleaching Agents

Image
1.Benzoyl Peroxide For a long time, benzoyl peroxide was a familiar oxidative bleaching agent and it is still used to this day in many countries. In addition to its good bleaching effect it has a slight influence on the structure of the gluten, but this is not apparent when other flour improvers such as AA are used.

The dosage for benzoyl peroxide is about 5 - 10 g to 100 kg of flour (50 - 100 ppm) into the flour stream. It is usually sold as a 27 - 32% product (to enable safe transportation it is diluted with an inert carrier), and the dose is then correspondingly higher. The effect of benzoyl peroxide on the flour is already visible after 6 hours of storage and complete after 24 to 72 hours. Benzoyl peroxide decomposes to benzoic acid (Fig. 132), a substance found in various fruits and berries and used as a food preservative, e.g. in cream and fruit fillings for pastry at dosages of 0.05 - 0.15% (500 - 1,500 ppm).
2. Enzyme-Active Bean Flour and Soy Flour Enzyme-active flour made fro…

Acidulants and Acidity Regulators

Image
Sprouting in rye and wheat results in a high level of amylase activity in the grain itself with the usual effects on baking properties. It is generally known that even flours with very low Falling Numbers can produce good baking results if well acidified. However, not every bread consumer likes acidity and bakeries may also have less and less time and personnel available to develop acidity by sour dough fermentation. Other ways are available, and these consist in adding fruit acids, the salts of these and also carbonates and phosphates approved for use in foods. It is then possible to adjust the pH of the dough slightly so that it moves out of the range in which the enzymes of the grain have their strongest effect.
Moreover, these substances (Acidulants and Acidity Regulators) influence the swelling of the flour constituents and the protein structure, and this helps to counteract the negative effects of excessive enzyme activity (e.g. water release). The most suitable preparations ar…

Flour Treatment : Emulsifiers

Image
3. Emulsifier Complexes
In many cases it is possible to enhance the properties of an emulsifier by combining it with another emulsifier. An example of this is the mono- and diglycerides, that achieve their optimum suitability for use in flour treatment through combination with lecithin. The lecithin improves their solubility and dispersion, and clearly their interaction with constituents of the flour as well. Well-known and widely used organic flour improvers fall into this category. The combination makes it possible to reduce the dose necessary for optimum effect to 100 - 300 g with 50% emulsifier in the complex.
Diacetyl tartaric esters of mono- and diglycerides are also receptive to enhancement with lecithin: the addition of as little as 10% lecithin improves their emulsifying effect and also reduces the vinegar smell. The above combinations are only effective if the emulsifiers are mixed before being converted into their powdered form. Interestingly, it is not sufficient just to m…