Source: UNIV OF WISCONSIN submitted to
INVESTIGATION OF THE EFFECT OF MIXING INTENSITY ON DOUGH DEVELOPMENT AND RHEOLOGICAL PROPERTY MEASUREMENT
 
PROJECT DIRECTOR: Connelly, R. K.
 
PERFORMING ORGANIZATION
FOOD SCIENCE
UNIV OF WISCONSIN
MADISON,WI 53706
 
NON TECHNICAL SUMMARY: The two most common mixing flour testing instruments, the Farinograph and the Mixograph, do not always give the same information because they use completely different speeds, geometry and mixing actions, with resulting differences in the mixing intensity. The main purpose of this work will be to explore the links of rate and type of strain to dough development for Wisconsin grown hard and soft winter wheat flour in both the Mixograph and Farinograph.
 
OBJECTIVES: The main use of wheat is the production of flour for bread, baked goods and snacks foods. The strength of wheat flour is a critical property related to its ability to develop and retain desirable product properties during processing and is a function of the variety and growing conditions. It must be considered by breeders, growers, millers and processors alike in order to insure proper flour selection and a consistent final product quality for consumers. Mixing is a universal processing operation that must take into account the flour strength and can be used to demonstrate it. However, the two most common mixing flour testing instruments, the Farinograph and the Mixograph, do not always give the same information, especially when used with hard flours, which can lead to costly problems when the data is used to choose cultivars for development or use for specific products or to modify product formulations and processing parameters. A source of the difference in the results of these two instruments is that they use completely different speeds, geometry and mixing actions, with resulting differences in the intensity or strain rate as well as the type and amount of strain. What is needed to better understand and evaluate the results generated by these two mixers is a more thorough understanding of the rate, type and range of strain experienced by material as it is tested. A modern tool that is ideally suited for this purpose is 3D numerical simulation combined with particle tracking. Computer hardware and computational fluid dynamics software have evolved to the point where they can calculate in 3D the velocity, pressure and stresses generated during mixing as they change with the movement of the mixing blades, and then use that information to track the position and mixing environment experienced by thousands of material points in order to get a picture of the mixing capability and efficiency of a given mixer as shown by Connelly (2004) for the Farinograph. However, in order to verify that the results generated using numerical simulations are accurate, it is necessary that they be experimentally validated. The main objective of the work proposed here will be to explore the links of rate and type of strain to dough development for Wisconsin grown hard and soft winter wheat flour in both the Mixograph and Farinograph. An additional objective will be to obtain data that can be used for experimental validation of simulation results in the Mixograph that will be generated in a separate project. Once the mixing environment is better understood, then the relationship of the flour properties to the results can be better determined and the differences between results in the two instruments can be explained, leading to more reliable information for use in the selection of appropriate flours, formulation and processing parameters for a given product.
 
APPROACH: In order to increase our the understanding of dough development and the effect of the type of mixing motion on it, the work proposed here will first characterize the rheological, baking performance and compositional properties of flours from Wisconsin grown hard red winter wheat and soft red winter wheat using AACC methods. Then dough from both flours will be mixed to peak development using a wide range of mixing speeds in both the twin sigma blade Farinograph and the pin mixing Mixograph. The resulting developed dough will be examined using a range of available methods, including small and large strain fundamental rheological methods as well as functionality tests, in order to determine if there are any discernable differences between dough developed at different speeds in different mixers. Mixing parameters will be calculated at peak development at each speed that include energy input, strain, average shear rate, etc. Finally, mixing curves will be developed for each flour and each mixer that relate rpm to the calculated mixing parameters. The mixing speeds for both flours in both the Farinograph and the Mixograph below which complete dough development no longer occurs and above which dough development is independent of the mixing speed will be determined, if they exist. The mixing speeds in each mixer that provide similar results will then be determined. The results of this work will bring together the many pieces of understanding of dough development into a unifying theory that can be used to explain differences in results between different methods of measuring and developing dough rheological character. It will also provide necessary background information, bulk-average data and validation data that can be used with numerical simulation in a separate study to explore the effects of flow type distribution and distribution history on mixer efficiency and effectiveness.
 
CRIS NUMBER: 0199155 SUBFILE: CRIS
PROJECT NUMBER: WIS04829 SPONSOR AGENCY: NIFA
PROJECT TYPE: HATCH PROJECT STATUS: TERMINATED MULTI-STATE PROJECT NUMBER: (N/A)
START DATE: Feb 1, 2004 TERMINATION DATE: Sep 30, 2006

GRANT PROGRAM: (N/A)
GRANT PROGRAM AREA: (N/A)

CLASSIFICATION
Knowledge Area (KA)Subject (S)Science (F)Objective (G)Percent
402154020202.125%
402154220202.125%
501154020202.125%
501154220202.125%

CLASSIFICATION HEADINGS
KA501 - New and Improved Food Processing Technologies
KA402 - Engineering Systems and Equipment
S1542 - Soft red wheat
S1540 - Hard red winter wheat
F2020 - Engineering
G2.1 - Expand Domestic Market Opportunities


RESEARCH EFFORT CATEGORIES
BASIC 50%
APPLIED 50%
DEVELOPMENTAL (N/A)%

KEYWORDS: mixing; strain; dough; food processing; rheological properties; winter wheat; flour; soft wheat; hard wheat; food processing equipment; speed; flow; shear strength; time; food engineering; research equipment; cultivars; food quality; food properties; formulations; instrumentation; validation

PROGRESS: Jan 1, 2005 TO Dec 31, 2005
The final results of the initial phase of the work were presented as a poster at the 2005 IFT Annual Meeting entitled: Comparison of dough development between two mixers with different geometries. They confirmed the expected dependence of dough development of flour/water dough on mixing speed at low speeds in the Farinograph, while dough development at high speeds was attributable solely to energy input with hard and all purpose strength flours in both mixers. Soft flours broke down too quickly to be conclusive. There was also visually apparent evidence of a lack of dough development at very low speeds in the Farinograph mixer with the hard flour. Since the Reomixer mixer did not provide a direct measurement of torque needed to calculate energy input, modifications were designed to allow both a lower speed range where dough mixing is expected to be speed dependant, as well as to directly measure energy input. An additional finding was that dough that was prepared using a premix of frozen powdered water & flour under freezing conditions that was allowed to warm to mixing temperature during a prescribed waiting time before mixing did not develop to the same level of torque as was the case when using a standard mixing method or a slow premix of room temperature ingredients that were mixed after a prescribed waiting period. This result was unexpected since the ice method is frequently used in dough rheology research to create undeveloped dough that is then compared with normally developed dough. Further work is proceeding to investigate the source and effect of this difference. A final experimental approach has been designed with the aid of CALS statistical service in order to investigate four questions for a given flour in full formula bread dough: 1. At different levels of dough development, can the various available tests of dough functionality detect differences? 2. Are there differences in dough mixed to the same level of dough development at different speeds in a given mixer? 3. Are there differences in dough mixed to the same level of development in the two mixers? 4. What is the speed where peak dough development becomes a function of energy input that is independent of speed in each mixer? Results for this phase of the work are expected to be presented at the 2006 IFT annual meeting and will be used to compare the two mixers and determine where they provide equivalent mixing intensity.

IMPACT: 2005-01-01 TO 2005-12-31 Mixing flour/water dough with a range of flours has demonstrated that the ability of a mixer to develop dough depends on the mixing rate until a critical rate, after which it is a function of energy input. This helps to explain why energy input is an effective controlling mechanism in high speed dough mixers, but is not used with slower, less intense dough mixers. The finding that ice dough does not develop in the same way as normally prepared dough brings into question the common practice of using dough prepared with that technique as an undeveloped dough for comparison with normally developed dough in dough rheology studies.

PUBLICATION INFORMATION: 2005-01-01 TO 2005-12-31
No publications reported this period

PROJECT CONTACT INFORMATION
NAME: Connelly, R. K.
PHONE: 608-262-8033
FAX: 608-262-6872