What Are the Most Important Aspects To Control in Flour?

One of the main ingredients in baking is Flour. Usually, in the industry, it is observed that the specified parameters are very brief and even not controlled or considered in process control. There are different types of analysis that can be performed, where it is necessary to have expensive equipment and even available personnel for the execution of the tests. Even if the equipment and people are available, in certain industries, the volume of consumption is really important and consequently, the resources needed to analyze these flours make it almost impossible. Below, I detail the different tests that can be performed to characterize the quality of flours and develop some of them.

PHYSICO-CHEMICAL PARAMETERS 

% Moisture

One of the simplest parameters to determine is moisture. For this parameter, it is important to consider that variations in the moisture content of the flour, where participation is important, must include adjustments to water in the recipe.

% Ash

The ash content, usually associated with the quality of the flour, is normally also associated with the extraction level (yield) of the mill. Consequently, more damaged starch is usually produced and therefore more water absorption takes place. This will have an influence on dough texture, gluten formation, enzymatic activity and even affect performance in subsequent stages.

Macropolímero de Gluteninas (GMP)

Glutenin Macropolymers (GMP) are the fraction of glutenins that can be separated as an insoluble gel layer in Sodium Dodecyl Sulfate (SDS). It is an indicator of the baking quality of flour, affecting the rheological properties of the dough and the volume of bread. The following shows the effect of kneading and subsequent resting on the GMP content in doughs.

"The GMP produced from flour is different from that obtained from the dough. During kneading, the GMP decreases due to depolymerization. Then, during rest, the interactions are restored and re-polymerization occurs. That's why it's so important to respect the resting times of the dough, and we can consider it as one of the advantages of continuous kneading vs. batch type. 

Damaged starch

Damaged starch is the fraction of starch granules that suffer mechanical damage as a result of milling."

Influence of damaged starch: · It modifies the hydration capacity, absorbing a high percentage of water. In excess, it has a negative effect on the production of cookies and bread. There is a smaller amount of water available for gluten development. On the other hand, it causes a loss of consistency in leavened products. It increases the production of dextrins (reducing the volume of bread and increasing the crust color).

· A small amount of damaged starch has positive effects on fermented doughs.

FALLING NUMBER

This test detects the level of amylase activity in the flour. As the time is shorter, the enzymatic activity is higher. This generates softer and stickier doughs. A defect in enzymatic activity (longer falling times) generates less development in the bread.

FARINOGRAPH 

This test measures the resistance that a dough offers to mechanical work overtime. And it allows evaluating water absorption and properties related to the kneading process.

From the same graph, the following can be evaluated:

Arrival time (To): Time it takes for the upper part of the curve to reach 500 BU. Indicates hydration time.

Development time (TD): Time it takes for the measured part of the curve to intercept 500 BU. Associated with the protein quality of the flour. Higher TD indicates higher protein quality and therefore a stronger gluten.

Stability (E): Time interval during which the dough maintains 500 BU. It is measured at the top of the curve, from when it intercepts the 500 BU line (To) until it intercepts it again (Tf). Indicates the flour's tolerance to kneading. Higher E: implies greater tolerance.

Degree of decay (GD): Difference in BU between the center of the curve at 500 BU and the center of the curve 12 minutes later. Gives an idea of softening or loss of consistency of the dough due to over-kneading.

The first graph shows a strong flour. More stable, it takes more time (during kneading) to develop gluten. This is a really important parameter, to define the process parameters to work during the mixing.

Alveograph

Alveograph is a test used to measure the amount of gluten in flour. 

But, what can be see with this test?

"A strong flour has a high WHEAT and a low L VALUE."

A weak flour has a LOW P and a HIGH L. Stretchy Flour.

BALANCED DOUGH. Convenient for leavened products.

Prediction Tests

Solvent Retention Capacity (SRC) 

Measures the ability of a flour to retain a group of four solvents (water, 50% sucrose, 5% sodium carbonate, and 5% lactic acid).

• WATER. Indicates the flour's ability to retain water and form a cohesive dough.
• LACTIC ACID. Glutenins tend to unfold and interact when the pH of the medium is slightly acidic. Consequently, the higher the % of glutenins, the greater the swelling and therefore the greater the retention of the Lactic Acid solution. It is an indicator of the relative strength of gluten and is useful for predicting the baking quality of flour. Marks the elasticity of the dough.
• SODIUM CARBONATE 5%. It is positively correlated with damaged starch content. It will indicate the level of hydration required for the flour.
• 50% SUCROSE. Greater absorption indicates higher content of total and soluble Pentosans.

Attached is a reference table for each of the four solvents.

In any case, each person must conduct their own experiment based on the quality of flour consumed in their region and thus seek to have the greatest possible stability over time.

As a conclusion, we can observe a large number of tests that serve to characterize flour and contribute to predicting the behavior that the raw material will have during the process. However, it is usually complex to perform each test on different batches, especially if the plant consumption is excessive. For this reason, rapid analysis methods such as NIR take precedence in detecting deviations and anticipating problems, mainly in fermented products.

Therefore, for these contexts, it is convenient to have equipment that can quickly analyze different characteristics (NIR technology). This way we can monitor the characteristics of the flour we are consuming, the variability of different suppliers, and based on this, establish an action plan based on the impacts that different characteristics of our raw material generate in the process.

This survey is key to establishing a work plan with mills and building a technical specification that is appropriate for the needs of products and the process they have in their industry. It is also important to mention that when deviations are detected by rapid methods, it is always important to analyze the raw material using traditional methods since they have greater accuracy.