GlutoPeak

Over the years, wheat breeders and industrial and academic institutions have looked for reliable methods to test the functional quality of wheat at early stages, with a limited amount of sample, rapid testing methods, and quick results. Test instruments such as the Farinograph and Mixograph require much larger amounts of sample and labor, and longer test times, making them impractical to rapidly assess the gluten quality of a flour sample.

The milling industry requires fast and reliable methods for assessing the quality of wheat cultivars, right at the receiving station of a mill. Similarly, the baking industry looks for suitable methods that can predict dough processing conditions, and end product quality (baked goods). The GlutoPeak test fills these gaps by objectively measuring the properties of gluten-containing products.

Application

A flour sample of 8–10 g is dissolved in water (liquid-to-solid ratio 1–1.5), usually at 25–35°C, and tested by the GlutoPeak instrument. The stirring action of a paddle mixer (rotating at 1500–4000 rpm for 5–10 min) causes the gluten to separate from the slurry/suspension (it is washed out from the starch and other soluble solids from the sample). After a certain time, which is characteristic of each flour/gluten-containing sample, proteins start to aggregate abruptly.²

The GlutoPeak instrument then measures and graphs the torque required to stir the suspension by measuring its resistance to the mixing action of the paddle blades (power consumption/electrical current consumed by the mixer). The mixing time–torque (in Brabender Equivalent Units) curve is used to characterize the strength and mechanical properties of the gluten (measured as aggregation time).

Shorter aggregation times of a given flour indicate stronger gluten structures and properties (that directly correlate with “average” baking potential). Flour samples with a higher protein content (high glutenin and gliadin ratio and content) have longer aggregation times. In this case such samples have the potential to exhibit excellent baking properties and quality.

However, extremely long aggregation times are not ideal. Although the product sample would not be suitable for baking applications, the flour might be a good option for production of pasta.³

How to use a GlutoPeak²

1. Attach paddle to the shaft (head)
2. Prepare/weigh water
3. Pour water into the cup
4. Place cup in double jacket container
5. Define sample parameters and click start
6. Prepare/weigh the sample (dry product)
7. Add dry product (flour sample) to the warm liquid in the cup
8. Push the measuring head down
9. Instrument starts automatically
10. Equipment automatically records and graphs data collected during test
11. Analyze data
12. Conclude and report

Approved methods that make use of the GlutoPeak instrument

Since there is not an official method for GlutoPeak analysis, researchers and industries select and perform a number of trials to obtain the most reproducible and reliable mixing curves. The conditions for the tests are a function of the wheat cultivar, amount of sample, milling quality of the flour, and final application of the product being tested.

References

1. Xiao Fu, B., K. Wang, and B. Dupuis. “Predicting water absorption of wheat flour using high shear-based GlutoPeak test.” Journal of Cereal Science, vol. 76, 2017, pp. 116–121.
2. Brabender. “GlutoPeak — Rapid Method for the Measurement of the Gluten Quality.” https://www.calibrecontrol.com/assets/shop/products/downloads/15062_e_gpt.pdf. Accessed 3 March 2018.
3. Freund, W., and M.Y. Kim. “Determining the Baking Quality of Wheat and Rye Flour.” Mühlenchemie’s Solutions Manual, 2017, pp. 111–113.