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54 Physical Dough Tests Methods​

54-10.01 Extensigraph Method, General

The Extensigraph allows for the measurement of the viscoelastic properties of dough by measuring the resistance to uniaxial extension and extensibility of a prepared dough sample (containing salt) at various time periods (quick method 30, 60, 90 minutes or normal method 45, 90, 135 minutes). Characteristics of force-distance curves, or extensigrams, such as maximum resistance (Rmax), extensibility (E), and other parameters, such as area (A), resistance after 5 cm of extension (R5),​ and the ratio of resistance to extensibility (Rmax/E and R5/E), are used to assess flour quality and more specifically protein functionality. The effects of improving agents can also be measured using the Extensigraph.

54-21.02 Rheological Behavior of Flour by Farinograph: Constant Flour Weight Procedure

The Farinograph is an instrument that is used to measure and record the rheological properties of a dough during mixing. It is used to evaluate the absorption of flours and to determine dough mixing characteristics such as development time (DDT), stability, mixing tolerance index (MTI) and other parameters. Two different procedures are in common use: the constant flour weight procedure (CFW), described herein, and the constant dough weight procedure (CDW; AACC Approved Method 54-22.01). Since the two procedures may not yield identical results, the method employed must be specified when absorption and other farinogram values are reported. 

54-22.01 Rheological Behavior of Flour by Farinograph: Constant Dough Weight Procedure

The farinograph is an instrument that is used to measure and record the rheological properties of a dough during mixing. It is used to evaluate the absorption of flours and to determine dough development time (DDT), stability, mixing tolerance index (MTI) and other dough mixing characteristics. Two different procedures are in common use: the constant dough weight procedure (CDW), described herein, and the constant flour weight procedure (CFW; AACC Approved Method 54-21.02). Since the two procedures may not yield identical results, the method employed must be specified when absorption and other farinogram values are reported.

54-28.02 Farinograph Table for Constant Dough Weight Method Only

The Farinograph is an instrument that is used to measure and record the rheological properties of a dough during mixing. It is used to evaluate the absorption of flours and to determine dough development time (DDT), stability, mixing tolerance index (MTI) and other dough mixing characteristics. The following Table is used to determine the flour and water requirements for the constant dough weight procedure (AACC Approved Method 54-22.01) for the large bowl (480 g dough) or small bowl (80 g dough) over a range of absorptions.​

54-29.01 Approximate Corrections for Changing As-Is Farinograph Absorption to 14.0% Moisture Basis, for Constant Dough Weight Method Only

The Farinograph is an instrument that is used to measure and record the rheological properties of a dough during mixing. It is used to evaluate the absorption of flours and to determine dough development time (DDT), stability, mixing tolerance index (MTI) and other dough mixing characteristics. Two different procedures are in common use: the constant dough weight (CDW) procedure (Method 54-22.01) and the constant flour weight (CFW) procedure (AACC Approved Method 54-21.02). Since the two procedures may not yield identical results, the method employed must be specified when absorption and other farinogram values are reported. The following Table is used to correct the as-is absorption to a 14.0% moisture basis for the constant dough weight (CDW) procedure. It is based on the assumption of a uniform absorption correction of 1.8 for every 1% difference between as-is flour moisture and 14% moisture basis within the range of absorption values of 58-64%. Corrections for absorptions are only approximate below 58% and above 64%.

54-30.02 Alveograph Method for Soft and Hard Wheat Flour

The Alveograph measures the rheological properties of dough to biaxial extension and the extent to which it can be stretched under the conditions of the method. In this method, a dough is mixed with a salt water (saline) solution, sheeted to a defined thickness and then cut into patties under specified conditions. The prepared dough patties are then expanded by air pressure into a bubble until they rupture. The internal pressure in bubble is graphically recorded allowing for the measurement of the resistance of the dough to deformation (P), the length of the curve at rupture (L), the deformation energy of the dough (W) as well as other parameters that provide an indication of protein quality. A video of the method being performed is available.

A video demonstration accompanies this method.

54-40.02 Mixograph Method

The Mixograph measures and records the rheological properties of a dough during mixing. The mixing curve (mixogram) provides an indication of time to maximum curve height (minimum mobility), maximum height of curve, ascending and descending angles of the curve as well as other dough mixing parameters. The Mixograph has been used to study the effects of added ingredients on mixing properties, dough rheology, blending, and quality control and for evaluation of hard, soft, and durum wheats. Two mixing bowl sizes are available (10 g and 35 g).

54-50.01 Determination of the Water Absorption Capacity of Flours and of Physical Properties of Wheat Flour Doughs, Using the Consistograph

Using the Consistograph, a dough is made from wheat flour to which an amount of water, based on the initial moisture content of the flour, is added in order to reach a constant hydration level on a dry matter basis. During the kneading of the dough sample, the pressure on one side of the mixer is continuously monitored. The peak pressure recorded during kneading is used to calculate the water absorption of the flour sample at a given “consistency" (target pressure, HYDxxxx). In a subsequent test performed at the hydration level previously determined, physical properties of the wheat flour dough are determined including time to PrMax (TPrMax) and the loss in dough consistency by measuring the drop in the curve height at 240 s and 480 s after the start of mixing. This method is applicable to all wheat flours.

A video demonstration accompanies this method.

54-60.01 Determination of Rheological Behavior as a Function of Mixing and Temperature Increase in Wheat Flour and Whole Wheat Meal by Mixolab

Dough behavior during the mixing process is related to many parameters. Some, such as water uptake, dough development time and dough stability during mixing, are related to protein content and quality. Others, such as gelatinization, setback, and gelling, are related to starch content and quality.

By measuring the torque of the dough during mixing as temperate increases during a set temperature heating/cooling profile, the Mixolab makes it possible to obtain information on both the protein and starch characteristics of a sample, allowing the user to better understand the wheat or flour characteristics. The resulting mixing curve provides information on protein development and water absorption (C1), protein quality (C2), starch gelatinization (C3), amylase activity (C4), and starch retrogradation (C5).

This method is applicable to flour obtained from wheat milled from laboratory or industrial mills. It can also be applied to whole meal of wheat ground under standardized conditions.

54-70.01 High-Speed Mixing Rheology of Wheat Flour Using the doughLAB

This method determines the mixing quality (rheological properties) of wheat flour doughs using the doughLAB, which measures the resistance of a dough to mixing and gives dough quality measures such as water absorption, dough development time (DDT), stability, and other mixing characteristics. The method describes a procedure that simulates the high rate of mechanical energy input commonly used in modern commercial dough mixers integral in rapid-bake systems. This method is applicable to any flour, including, but not limited to, flours that are very strong or are difficult to develop.