Dough and Rheology Lab

Falling number (FN) measures the activity of α-amylase enzyme and is based on the ability of α-amylase to liquefy a starch gel. It is defined as time in seconds required to stir and allow stirrer to fall a measured distance through a hot aqueous flour or meal gel undergoing liquefaction. α-Amylase activity is associated with kernel sprouting, and both of these are inversely correlated with FN. The method is applicable to both meal and flour of small grains and to malted cereals.

Amylograph is used to estimate the alpha-amylase activity (diastatic activity) in an aqueous suspension of flour as it gelatinizes during heating. The high viscosity of the starch gel is counteracted by the action of alpha-amylase, which liquefies starch granules as the slurry is heated. The amylograph value, or peak viscosity, also called malt index, is therefore inversely correlated with alpha-amylase activity.

The glutomatic system is used to determine the quantity and quality of gluten in wheat, flour, and semolina. It washes the starch, water-soluble pentosans and water-soluble proteins away from dough, isolating wet gluten, the elastic protein network. The weight of wet gluten is then forced through the sieve and the total weight of wet gluten (passed through and remaining on the sieve) are weighed and a ratio called the gluten index (GI) is calculated which provides an indication of wet gluten quality.

Glutopeak is a rapid, shear-based rheological method used to evaluate the quality and functional properties of gluten in wheat flour and wholemeal. It measures the aggregation behavior of gluten by creating a slurry of flour and solvent and subjecting it to high-speed stirring. As the gluten proteins separate from the starch and begin to bond, they create mechanical resistance (torque). The instrument records this resistance in real-time, generating a precise curve that identifies the strength and quality of the gluten network.

The Rapid Visco Analyser (RVA) measures wheat flour quality by generating a complete pasting profile during a controlled heating and cooling cycle of a water–flour slurry. It evaluates key properties such as viscosity, gelatinization, and enzyme activity. Important parameters include Peak Viscosity (starch swelling), Breakdown (stability), and Final Viscosity (gel strength and staling). The RVA is widely used to assess baking performance, detect sprout damage, and analyze starch functionality.

The LECO analyzer is a high-throughput, combustion-based system (Dumas method) used to accurately measure nitrogen and protein content in food samples. It delivers fast results with a 2.8-minute cycle time (up to 21 samples per hour), providing a safe, efficient, and reliable method for protein determination.

The Micro Visco-Amylo-Graph evaluates the gelatinization behavior of starch and starch-based products while also measuring viscosity in liquids, suspensions, and pastes. For flour samples, it is additionally used to assess enzyme activity, particularly α-amylase.

Solvent Retention Capacity (SRC) measures the amount of solvent retained by flour after centrifugation, expressed as a percentage of flour weight (14% moisture basis). Four solvents are independently used to produce four SRC values: water, 50% sucrose, 5% sodium carbonate, and 5% lactic acid that together define flour functionality. These results help to predict the baking performance and assess quality. Generally, lactic acid SRC is associated with glutenin characteristics, sodium carbonate SRC with levels of damaged starch, and sucrose SRC with pentosan characteristics. Water SRC is influenced by all of those flour constituents.

A moisture oven is used to determine flour moisture content. The sample is dried under controlled temperature conditions, and moisture is calculated based on weight loss to ensure accurate and reliable results. Flour moisture is a critical factor in many analytical and baking tests, as results are often standardized to a specific moisture basis. Accurate moisture determination is essential for ensuring consistency, comparability, and proper interpretation of test results.

The Farinograph measures and record the rheological properties of a dough during mixing, providing key insights into flour performance. 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.

The Extensograph measures the viscoelastic properties of dough by evaluating its resistance to uniaxial extension and its extensibility over time. Dough samples (with salt) are tested at set intervals, either using the quick method (30, 60, 90 minutes) or the standard method (45, 90, 135 minutes). Key parameters from the resulting force–distance curves, such as maximum resistance (Rmax), extensibility (E), area (A), resistance after 5 cm of extension (R5), and ratios like Rmax/E and R5/E provide insights into flour quality and protein functionality. The Extensograph also allows evaluation of the effects of flour improvers and dough conditioners, making it a vital tool for baking performance assessment.

The Alveograph measures dough’s rheological properties under biaxial extension by evaluating its ability to stretch and resist deformation. Dough is mixed with salt water solution, sheeted, cut into patties, and expanded into a bubble until rupture. The resulting curve provides key parameters: resistance to deformation (P), extensibility (L), and deformation energy (W) offering a clear assessment of protein quality and baking performance.