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Question and Flour Problems (Extensograph and Alveograph; Guten Index and Glutomatic)

1.What is measured in an Extensograph and an Alveograph? These instruments measure the resistance of a dough to extension under controlled conditions. The shape of the curve shows the energy input (E in the Extensogram, W in the Alveogram). Different dough properties (short, normal, soft) and different protein levels (low, normal, high) are recorded.
2. How can the effect of flour improvers be measured rheologically? Of course baking tests are the analytical method for determining the nature and amount of the flour improvers to be added in the long term.
But extensogram data, especially, react extremely sensitively to all additives whose effects result from reactions with the proteins in the gluten. It was on the basis of such data that the theory of the Rheological Optimum was established and became acknowledged throughout the world. It gives concrete information on which flour improvers can be used to achieve which changes in the properties of the dough.
3. What is the difference bet…

Question and Flour Problems : Amylograph and Rapid Visco Analyzer; Farinograph and Cansistograph

Amylograph and Rapid Visco Analyzer 1.What does the Amylograph measure? The amylograph records the changes in the viscosity of a flour-and-water suspension caused by gelatinization of the starch during a controlled heating period. The Amylogram therefore shows the changes in water-binding capacity that take place during swelling and gelatinization and in the course of enzymatic and mechanical breakdown of the starch gel.
2. What is the connection between the Amylogram and the Falling Number? There is no direct connection between the Falling Number and the Amylogram data, but a mathematical/statistical orientation in the same direction does exist (if the number of measurements is large enough!). This should be checked for each new harvest.
3. What does a Rapid Visco analyser measure? The RVA is a “micro-amylograph” that combines the advantages of a small sample (2-4g) and the possibility of setting any desired temperature gradient. A distinction is made between a “stirring number” and “ra…

Question and Flour Problems : Rheology & Falling Number

1.What is rheology? Rheology is the branch of physics that deals with the elastic and plastic properties of systems and their flow characteristics. When combined with water, flour forms more or less viscous systems that solidify when baked. The science of rheology can provide information on quality in both states-baked and unbaked.
2. What are “basic rheological properties”? Basic rheological properties are the parameters strength, viscosity, elasticity and plasticity. They are determined by measuring the effects of deformation forces on the dough. These forces may be of any magnitude, and the measurements are correspondingly large or small. For the rheology of dough the most important properties are viscosity and elasticity.
3. What am I to make of the “flowery” descriptions of the properties of dough and baked goods that are so popular with bakers? The observations of experienced bakers and the resulting jargon are still very valuable for describing product attributes that may also b…

Question and Flour Problems : Storage (Wheat, Flour, Bread)

1.We noticed an increase in the temperature of the wheat to 45 0C in parts of the silo during the winter. When we checked the wheat we couldn’t find any signs of infestation. What may the reason have been? Can we still use the wheat? This phenomenon is probably due to self-heating caused by fermentation. This can occur if the wheat is not moved or sufficiently aerated during storage. If only a small amount is affected, the thoroughly mixed wheat can be used (unless the taste and smell are impaired), but the performance should checked. Unusually short dough properties indicate heat damage to a larger proportion of the wheat.
2. If the flour has been treated with enzymes/ ascorbic acid/ bleach, will its properties be maintained during storage? For how long? Most enzymes except glucose oxidase and transglutaminase are very stable in the flour too. In most cases the shelf-life is restricted by the organoleptic properties of the flour rather than by its baking performance. Ascorbic acid slo…

Question and Flour Problems : Colour

1.Although the ash content is only 0.5%, the flour has a dark colour. Why is that? There are wheat varieties with a higher pigment content (compare, for instance, U.S. Hard Red Spring Wheat with U.S. Hard White).
2. How can I brighten the colour of the flour? Chlorine, Chlorine dioxide (both are gaseous) or benzoyl peroxide (powder) can be used for bleaching. In contrast to chlorine and chlorine dioxide, benzoyl peroxide has almost no maturing effect on the flour. The treatment with benzoyl peroxide takes 24 – 72 h to become visible.
3. How can a brighter flour or bread crumb be obtained? A brighter flour can be obtained with a lower extraction rate, because the outer layers of the wheat kernel contain more pigments. Once the flour has been produced, treatment with chlorine and chlorine derivatives achieves a brighter colour, but is not acceptable in many cases for various reasons. The addition of benzoyl peroxide also results in a brighter colour, visible 24 -72 h after treatment of th…

Question and Flour Problems (Flour Components; Vitamins and Fortification)

1.What are the most important vintamins and minerals for flour fortification? The most important vitamins and minerals for flour fortification are folate and iron. Other substances often used are the vitamins B1, B2 and niacin, and also the mineral zinc. Vitamin A is only added to flour in a very few countries, possibly for reasons of cost.
2. What is the basis for the legal requirements in countries where fortification is prescribed by law? The legal requirements depend on the specific needs of the population in each country. These are determined in studies carried out by various organizations such as UNICEF, WHO and FFI. The FFI also recommends fortifying flour with at least iron and folate in every country.
3. How do vitamins and minerals react to storage? Vitamins are especially sensitive to heat, moisture, oxygen and light. Nevertheless, they can be stored for at least 1-2 years in the tightly closed original container in a cool, dry place (20 0C, 50% relative humidity). Minerals s…

Question and Flour Problems (Flour Components; Lipids, Dietary Fibres, and Mineral)

Lipids
1.Do the lipids present in wheat play an important role in the processing of wheat flour? Wheat flour lipids are mostly unsaturated lipids. When the kernel is milled, the lipids are exposed to endogenous enzymes and to oxygen, which results in rancidity. More than 50% of the lipids are located in the bran and the germ. So thorough separation is a prerequisite for a long shelf-life of the flour with unimpaired sensory properties. Flour lipids, and galactolipids, improve the volume yield of baked goods.
2. What is the composition of the wheat lipids? The wheat lipids are composed of roughly 1/3 non-polar lipids (oil) and 2/3 polar lipids (lechitin, galactolipids and others). They contain mainly unsaturated fatty acids.
3. Do the phospholipids contained in the wheat fats have any technological significance? They most probably contribute to volume yield.
4. Are there interactions between the constituents of flour improvers/ baking agents and the lipids present in the wheat? Lipolytic en…

Question and Flour Problems (Flour Components; Proteins)

1.What is Gluten? Gluten is often equated with the proteins of the wheat that are insoluble in water. It is a fact that glutenin and gliadin are the main constituents of gluten in terms of quantity and determine its basic character. But smaller components such as lipids or pentosans are firmly and in some cases even covalently bonded to the gluten and have a corresponding influence on its properties. Commercial gluten (dried vital wheat gluten) also contains starch and minerals that cannot be completely removed by aqueous extraction. That is why dried gluten only contains about 80% protein.
2. Is there a connection between the quality of the protein and its chemical structure? The baking properties of wheat flour depend to a large extent on the amount of protein, the ratio of gliadin to glutenin and the properties of the latter, especially the disulphide bridges.
3. How are proteins and gluten determined analytically? Protein in wheat flour can be determined chemically by the Kjeldahl m…

Question and Flour Problems (Flour Components; Starch)

1.What is the percentage of starch in wheat flour? Wholemeal flour contains 60% starch, and light-coloured flour with an extraction level of 75 to 80% contains about 70% starch. In both cases this is based on a moisture content of 14%.
2. What are the differences between the starch fractions? Wheat starch consists of about 25% amylose and 75% amylopectin. The amylose is made up of glucose chains, i.e. of linked alpha-D-glucopyranosyl groups joined to the C1 and C4 atoms, with very few branching points at some C6 atoms. One amylose molecule contains about 200-2,000 glucose sub-units. Amylose molecules have the structure of left-handed single or double helices. Amylopectin is a much larger molecule (approx. 6,000-100,000 glucose sub-units) characterized by frequent branching at the C6 atom.
3. How are starch and damaged starch determined analytically? The amount of starch in a wheat flour can easily be determined by washing the starch out and drying the suspension thus obtained. The deter…