Effect of mixing time and speed on experimental baking and dough testing with a 200g pin-mixer

Authors: Brabec, Daniel - Dan; ROSENAU, SAM - National Manufacturing Company; SHIPMAN, MARY - National Manufacturing Company

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/27/2015
Publication Date: 10/1/2015
Publication URL: http://handle.nal.usda.gov/10113/62727
Citation: Brabec, D.L., Rosenau, S., Shipman, M. 2015. Effect of mixing time and speed on experimental baking and dough testing with a 200g pin-mixer. Cereal Chemistry. 92(5): 449-454. doi: 10.1094/CCHEM-02-15-0021-R.

Interpretive Summary: Bread dough preparation requires mixing flour and water and other minor ingredient into a smooth dough. The mixing requires some time for the dry ingredients to hydrate and the gluten in the flour to develop into a smooth and uniform texture. Under mixing or over mixing the dough results in varied experimental loaf volumes. Bread preparation requires a trained baker to evaluate dough development and determine stop points of mixer. Instrumentation and electronic control of the dough mixer would allow for automatic mixing. This study used a 200g mixer, which provided an output signal during dough mixing, to evaluate potential mixing stop points. Computer controlled logic need supporting data to provide reasonable guidelines for selecting the automatic mixer stop points. One of the objectives of the study was to see the effect of varied mixing time on the baked loaf volume. Three flours with distinctly different protein contents were used. Dough samples were under-mixed and over-mixed and then baked. The bread loaf volume varied with mixing time and mixing speed. The results from this study should help provide guideline for writing software to automatically shut-off the mixer. This should help produce more consistent experimental baking results. A second objective was to compare a smaller mixer, 35g mixograph, with the multi-speed 200g mixer. Smaller samples of flour are commonly tested with 35g mixograph to help determine flour and mixing characteristics such as mixing peak time and water requirements. When testing with only flour and water, the multi-speed 200g mixer produced different mixing times. However, when the 200g mixer operated at 90rpm and included sugar and salt baking ingredients, mixing times were similar to the 35g mixograph mixing times for many samples.

Technical Abstract: Under mixing or over mixing the dough results in varied experimental loaf volumes. Bread preparation requires a trained baker to evaluate dough development and determine stop points of mixer. Instrumentation and electronic control of the dough mixer would allow for automatic mixing. This study used a 200g mixer, which provided an output signal during dough mixing, to evaluate potential mixing stop points. 200g of flour is mixed with water and ingredients such as sugar and salt. After mixing, the dough is divided into two equal portions and baked. The 200g mixer motor provided an output signal indicating peak mixing time. The motor signal was digitized and data were collected using MixSmart software and used to mix dough samples to various mixing times. Computer controlled logic need supporting data to provide reasonable guidelines for selecting the automatic mixer stop points. One of the objectives of the study was to see the effect of varied mixing time on the baked loaf volume. Three flours were used with protein contents; 10.6%, 12.4%, and 13.8%. Dough samples were under-mixed, mixed to peak, and over-mixed. Over-mixing by 0.6 minutes reduced the loaf volume in all flours tested, by 16-50 cc at 90 rpm and by 29-68 cc at 118 rpm. When the high-protein flour sample was under-mixed, the largest baked loaves were produced, with an average volume of 922 cc. Its bread grain contained more large cells as determined with image analysis. The lowest protein flour sample (10.6% protein) mixed at 90 rpm, demonstrated mixing tolerance and produced bread with statistically similar bread volumes at all mixing times, 708cc -733cc. A second objective was to study the similarities and differences between a 35g Mixograph and the multi-speed 200g mixer. Smaller samples of flour are commonly tested with a Mixograph to help determine flour and mixing characteristics such as mixing peak time and water absorption. The same flours were mixed on both the 200g mixer and a 35g Mixograph. The multi-speed 200g mixer was operated at 90, 104, and 118 rpm. The mixing peak values for the 200g mixer were normalized to the 35g Mixograph peaks. The mixing times with the 200g mixer averaged 0.7, 1.2, and 1.6 minutes shorter than the 35g Mixograph, respective to 90, 104, and 118 rpm, when mixing only flour and water. However, when the other baking ingredients like sugar and salt were added to the 200g at 90rpm, mixing times were within 0.2 minutes of the 35g Mixograph peak times for three of the four flours.