Rheology

Precise Adjustment of Rheological Specifications

Rheological data are quality parameters that have a bearing on the price in an assessment of grain and flour

Measured values like resistance in the Alveograph or water absorption in the Farinograph serve to predict the baking properties of a flour. With enzymatic treatment, rheological parameters can be regulated specifically and adjusted to customers’ requirements.

New crop, unusual varieties, new grain origins … every mill is familiar with problems of adherence to rheological guide values. Consult our applications experts to achieve precise adjustment of the rheological specifications of your flours.

Falling Number

The Falling Number is a measure of the degree of starch-degrading α-amylase activity in grain. To determine this quality indicator, a flour-and-water suspension is heated in a water bath. During this procedure, a starch gel is formed whose viscosity varies with the α-amylase activity of the flour. The Falling Number indicates the time required for a standardized piston to penetrate all the way through this starch paste. In very dry summers, fully ripe wheat grains have low α-amylase activity (Falling Number above 300 s). In wet harvest years, on the other hand, Falling Numbers below 200 s are an indication of sprout-damaged grain.

Falling Number reduction
ProductActive componentsDescription / effects
Deltamalt FN-AAlpha-amylaseNew fungal amylase

Amylograph

The purpose of the Amylograph is to indicate the gelatinization properties of flour and meal. In a rotating measuring bowl, a flour-and-water suspension is stirred continuously and gradually heated; this causes increasing gelatinization of the starch. A measuring sensor records the changes in viscosity as an “amylogram”. From this curve it is possible to read off the enzymatic activity and swelling properties of the flour and draw conclusions as to the enzymatic treatment required.

Amylogram, lowering of gelatinization temperature and maximum
ProductActive componentsDescription / effects
Deltamalt FN-AAlpha-amylaseNew fungal amylase

Farinograph

The Farinograph is used to determine the water absorption capacity and dough formation behaviour of a flour. In a special mixing chamber, the dough is exposed to a defined mechanical stress, during which its resistance to mixing is measured by the electronic system as torque and recorded as a force-time diagram. The resulting curve provides information on the optimum mixing time and the mixing tolerance of the flour.

Farinogram: water absorption
ProductActive componentsDescription / effects
Alphamalt GloxyGlucose oxidaseHigher water absorption only at high dosages
Farinogram: increased dough stability
ProductActive componentsDescription / effects
Alphamalt GloxyGlucose oxidaseVisible at a kneading time over 8 min
Alphamalt PTTransglutaminaseStronger effect with weak doughs

Alveograph and Extensograph

Alveograph

In order to determine the viscoelastic properties of a dough, the Alveograph simulates the deformation of the dough during proofing. In this method, a slice of dough is extended by compressed air after a short resting period until the resulting bubble bursts. The resistance recorded (pressure) and the extensibility measured (volume) also permit a prediction of the behaviour of the dough during baking.

Extensograph

A dough prepared in the Farinograph is shaped into a cylinder and fixed on a tray. After a resting time of 45 minutes it is stretched by a hook until it tears. After re-shaping and a further 45-minute rest each time, two further measurements are made. The behaviour of the dough during the baking process can be estimated on the basis of its extensibility and resistance to extension.

Alveogram / Extensogram: increased P/L or R/E ratio
ProductActive componentsDescription / effects
Alphamalt GloxyGlucose oxidaseHigh dosages greatly reduce extensibility
Alphamalt PTTransglutaminaseOnly visible at high dosages
Alphamalt EFXCarboxyl esteraseIncreases the energy W (area under the curve)
Alphamalt BXEnzyme compoundPowerful effect; contains flour maturing agents
Alveogram / Extensogram: reduced P/L or R/E ratio
ProductActive componentsDescription / effects
Alphamalt HCFHemicellulaseLow ratio, same energy
Alphamalt HHemicellulaseAs above, at higher dosages
Alphamalt BProteaseLow ratio, lower energy
Alveogram / Extensogram: increased energy W
ProductActive componentsDescription / effects
Alphamalt DFXCarboxyl esteraseGreater increase at higher dosages
Alphamalt BXEnzyme compoundWith flour maturing agents; very high resistance (P or R)
Alphamalt TEnzyme compoundAbove the optimum dosage, the energy decreases
Alveogram / Extensogram: reduced energy W
ProductActive componentsDescription / effects
Alphamalt HCFHemicellulaseEnergy scarcely reduced or not at all; very great extensibility
Alphamalt HHemicellulaseAs above, at higher dosages
Alphamalt BProteaseLowers resistance, lowers extensibility at high dosage

Sedimentation test

In the sedimentation test, the gluten proteins are precipitated with lactic acid. The sedimentation volume of the coagulated proteins is a good indication of the baking quality to be expected of the flour.

SRC – Solvent Retention Capacity

SRC is an absorption test for flours, based on the swelling properties of gluten proteins, damaged starch and pentosans. It permits conclusions concerning the contribution made by each of these flour components to the functionality of the flour and the resulting quality of the end product. Unlike the conventional sedimentation test, the SRC test uses four solvents (water, dilute lactic acid, dilute sodium carbonate solution and a concentrated aqueous saccharose solution). Only the four values together make up the complete picture. Derived from this is the Gluten Performance Index (GPI), defined as the ratio of the SRC values of lactic acid / sodium carbonate + saccharose; it permits even more accurate predictions of the behaviour of the gluten during the baking process.

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