Item No. 1 of 1

INVESTIGATOR: CHEN, G.; SANG, S.

PERFORMING INSTITUTION:
NORTH CAROLINA A&T STATE UNIV
1601 EAST MARKET STREET
GREENSBORO, NORTH CAROLINA 27411

MODIFICATION OF WHEAT AND CORN BRANS BY MICROFLUIDIZATION PROCESS

NON-TECHNICAL SUMMARY: In modern society, obesity constitutes a major public health issue with serious social and economic consequences worldwide. Numerous studies support that an increased intake of dietary fiber plays a protective role against obesity and some other chronic diseases. The reduced risk of obesity is of high importance since obesity is a risk factor for certain cancers. Although the healthy reputation of dietary fiber continues to grow, national data consistently shows that both children and adults consume less than one-half of the recommended daily intakes of dietary fiber. In reality, it is difficult for an individual consuming a typical Western diet to obtain an adequate quantity of fiber. Substantial dietary changes are thereby needed to meet the required needs, and one approach is to consume foods that are supplemented with high levels of fiber rich ingredients. However, formulating dietary fiber enriched foods still presents challenges since native fiber ingredients adversely affect color, texture, flavor and taste of the supplemented foods. This problem could be addressed by modifying physicochemical properties of fiber ingredients because their behavior in food processing and interaction with food matrices is relevant to these properties. In this project, wheat and corn brans, very important sources of dietary fiber and antioxidants in industrialized countries, will be modified using the microfluidization process in which aqueous streams containing bran particles will be driven through a microchannel at an extremely high speed. Upon completion of the project, a protocol for processing wheat and corn brans using microfluidization will be established for optimal process efficiency. Mathematical models that correlate the brans' physicochemical and nutritional properties with microfluidization processing parameters will be developed to optimize these properties. Corn cereals enriched with the modified brans will also be produced. These findings will allow us to further develop bran-enriched foods such as cereals and bakery products with good sensory properties. This should promote the intakes of dietary fiber in the United States and thus help prevent chronic diseases, especially obesity.

OBJECTIVES: Dietary fiber is an important component of healthy diets and has well documented health benefits. Wheat and corn brans are very important sources of dietary fiber and antioxidants in industrialized countries. The goal of the proposed project is to improve the brans' physicochemical and nutritional properties using the microfluidization process. This goal will be achieved through three specific objectives: 1) establishment of a microfluidization protocol for processing wheat and corn brans; 2) development of response surface models that correlate physicochemical and nutritional properties with microfluidization processing parameters; and 3) preliminary investigation of the effects of modified brans on product quality of extruded corn cereal. Expected outputs include a protocol for processing wheat and corn brans using microfluidization technology, response surface models that correlate physicochemical and nutritional properties of the brans with microfluidization processing parameters, palatable cereal products enriched with the modified brans, developing internal collaboration, training postdoctoral researchers and graduate students, and publishing journal papers and presenting at professional conferences.

APPROACH: Microfluidization process has been widely used to treat solutions, emulsions, and suspensions of fine particles. In this project, a protocol for treating suspensions of relatively large particles will be developed to treat wheat and corn brans. In this process, aqueous streams containing bran particles will be driven through a microchannel with a diameter of 200 microns at an extremely high speed. The generated high shear stress, impact force and hydrodynamic cavitation will substantially reduce the brans' particle size and loosen their microstructure, resulting in significant changes in their physicochemical and nutritional properties. Physicochemical properties to be investigated include microstructure of bran materials, particle size distribution, swelling capacity, water-holding capacity, oil-holding capacity, glucose-adsorption capacity, cation-exchange capacity, viscosity of aqueous suspension, effects on solvent retention capacity of wheat flour, and effects on expansion of extruded corn grits, and nutritional properties include antioxidant activity, bile acid binding capacity, and in vitro lower gastrointestinal fermentation. Since extents of microfluidization-induced changes of these properties are closely associated with processing conditions, response surface models will be developed to establish the relationships between them to obtain the optimal processing conditions. Evaluation of the results obtained will include: 1) reliability of the process protocol in terms of the success (without clogging) rate of processing; 2) percent improvement of physicochemical and nutritional properties of modified brans relative to the raw brans; 3) accuracy of response surface models in terms of percent error of the predicted property values relative to the observed values in independent experiments; and 4) percent improvement of overall quality of extruded cereals enriched with modified brans relative to raw brans at the same replacement level. Microfluidization process is a pure mechanical method which works in a continuous manner and thus has a high throughput. This process is more effective and energy efficient than existing mechanical methods for modifying fiber ingredients. Moreover, a laboratory microfluidization process is easy to scale up to pilot or production volumes. Therefore, it provides an effective and affordable way to modify fiber-rich ingredients.

PROGRESS: 2012/09 TO 2015/08
Target Audience:The target audience includesresearchers workingin the field of dietary fiber and food processors manufacturing high-fiber foods. This project is able to deliver the knowledge of processing fiber materials (corn bran and wheat bran) using microfluidization process. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?One undergraduate student, one graduate student, one research technician, and one research associatewere trained to process bran materials using the microfluidization process and to analyze physicochemical and nutritional properties of bran. How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

IMPACT: 2012/09 TO 2015/08
What was accomplished under these goals? Scientistshavecompleted the proposed project objectives withinthe originally proposed project period. 1. Establishment of a microfluidization protocol for processing wheat and corn brans and preparation of bran samples. The aqueous suspension of bran materials was prepared at different concentrations and microfluidized under different pressure using a 200 μm interaction chamber (IC200)of an M-110P Microfluidizer Processor (Microfluidics, Newton, MA, USA). The particle size of raw bran sample was the most important parameter determining the maximum concentration of bran that can be processed through the IC200. When the average particle size wasreduced below 500 μm, the maximum bran concentration could reach22%, which makes microfluidization economically feasible for large-scale production of dietary fiber ingredients from cereal bran. The processed bran samples were lyophilized and pulverized for storage, which maximally preserves the physicochemical and nutritional properties of processed bran. Analysis of particle size distribution was performed using a computer controlled Bluewave laser particle analyzer. Both light microscopy and confocal laser scanning microscopy were used to characterize the microstructure changes of bran material before and after microfluidization treatment. The results showed that microfluidization process could effectively reduce the particle size of corn bran and wheat bran, and loosen microstructure of the bran matrix. 2. Development of response surface models that correlate physicochemical and nutritional properties with microfluidization processing parameters. Nine percentaqueous suspensions of ground bran samples were processed through IC200 of a microfluidizer under various conditions determined from a second order central composite designwith two variables and five levels of each variable (Table 1). The independent variables were process pressure (P) and number of passes (N). The dependent variables include all the tested physicochemical and nutritional properties: swelling capacity (SC), water-holding capacity (WHC), viscosity of aqueous suspension (V), oil-holding capacity (OHC), solvent retention capacity (SRC), antioxidant activity (ABTS and DPPH radical scavenging activity), bile acid binding capacity (SCBC: sodium cholate binding capacity and SDBC: sodium deoxycholate binding capacity) and short chain fatty acid analysis after in vitro digestion and fermentation. Response surface models were obtained using Design-Expert 9 Software. Only the significant models (p<0.05) were listed in Table 2 for corn bran and in Table 3 for wheat bran. In each model, only those model terms with significant effect (p<0.05) were kept. Table 1 Experimental design for microfluidization experiment Experiment No. Coded levels Actual levels X1 X2 P (psi) N 1 1 -1 22,000 2 2 1 1 22,000 4 3 0 0 20,000 3 4 -1 -1 18,000 2 5 -1 1 18,000 4 6 -1.414 0 17,000 3 7 1.414 0 23,000 3 8 0 -1.414 20,000 1 9 0 1.414 20,000 5 10 0 0 20,000 3 11 0 0 20,000 3 12 0 0 20,000 3 13 0 0 20,000 3 Table 2. Response surface equationsfor physicochemical and nutritional properties of corn bran. P and N denote actual values of process pressure and number of passes, respectively. Corn Bran Models R2 P value SC = 5.65-1.65E-004*P+0.603*N-0.0752*N2 0.9153 <0.0001 WHC = 4.67-9.07E-005*P+0.435*N-0.0429*N2 0.9417 <0.0001 V = 0.0780+6.20E-004*N2 0.5068 0.0004 OHC = -3.35+4.45E-004*P+1.67*N-4.65E-005*P*N-0.0793*N2 0.9487 <0.0001 SRCwater = 36.0+2.53E-003*P+18.3*N-1.17*N2 0.9623 <0.0001 SRCsucrose = 67.1+3.25E-003*P+26.2*N-2.10*N2 0.9873 <0.0001 SRCNa2CO3 = 59.6+2.61E-003*P+14.8*N-1.66*N2 0.9865 <0.0001 SRClactic acid = 67.2+2.55E-003*P+2.51*N-6.12E-008*P2-0.312*N2 0.9432 <0.0001 ABTS = -67.2+9.61E-003*P+4.51*N-2.39E-007*P2-0.871*N2 0.7326 <0.0001 DPPH = 24.9+5.33E-004*P+4.41*N 0.5580 <0.0001 Table 3. Response surface equationsfor physicochemical and nutritional properties ofwheat bran. P and N denote actual values of process pressure and number of passes, respectively. Wheat Bran Models R2 P value SC = 4.35+0.504*N 0.8002 <0.0001 WHC = 4.43-8.19E-005*P-0.455*N+3.76E-005P*N 0.8828 <0.0001 V = 0.0933-0.0117*P+6.43E-007*P*N 0.4315 0.0003 OHC = 7.30-5.80E-004*P-3.66E-005*P*N+1.82E-008*P2 0.7757 <0.0001 SRC-water = 66.2+1.19E-003*P+2.38*N-0.311N2 0.6225 <0.0001 SRC-sucrose = -2.36*N+4.37E-004*P*N-0.669*N2 0.8156 <0.0001 SRC-Na2CO3 = 97.3+3.93*N-0.345*N2 0.7367 <0.0001 SRC-lactic acid = 79.1+2.67E-004*P+0.946*N 0.6798 <0.0001 DPPH = -19.6-5.19E-004*P*N 0.6399 0.0219 Microfluidization process improved the physicochemical and nutritional properties of corn bran and wheat bran. The extent of the improvement depended on the processing pressure and number of passes. Response surface models were established significantly for all the tested physicochemical properties, including SC, WHC, viscosity of aqueous suspension, OHC, SRCsand the antioxidant activitiesof both corn bran and wheat bran,except for the ABTS radical scavenging activity of wheat bran. For short chain fatty acid profilesand bile acid binding capacities of bran materials, significant response surface models were not obtained due toasharpdecrease in valuesof the examined properties for bran processed at 23,000 psi and 3 passes. The reason for this sharp decrease might be because very high pressure substantially disrupted microstructure of the bran materials, leading to noncontinuous changes in the properties examined. Further investigation is needed to find the real reason. 3. Preliminary investigation of the effects of modified brans on product quality of extruded corn cereal. Blends of corn grits (70%) and brans (30%) microfluidized under each set of conditions (Table 1) were extruded through a laboratory co-rotating twin-screw extruder (Brabender MARK III, CTSE-V) with barrel diameter 32 mm, screw length 13 times its diameter. Extrusion conditions used were sample moisture content (16%, wet basis), extruder speed (180 rpm), extruder temperature (30, 80, 110, 120, 120 ºC for zone 1-5, respectively), feed rate (110 g min-1), and rod die (3.2 mm in diameter). The expansion ratio (ER),sectional expansion index (SEI), bulk density, hardness (H), breaking strength and total color change were measuredto evaluate the quality of extrudates.Overall, the quality of corn cereal extrudates were acceptable when 30% (wt/wt) of corn grits was replaced by microfluidized corn bran and wheat bran based on these quality factors. However, the second order polynomial response surfacemodels developed were only statistically significant for ER and bulk density of extruded corn cereal blended with microfluidized corn bran (Table 4), but not for other properties. Thereis no statistically significant relationship between quality factors of extrudates of corn grits blended with wheat bran and microfluidization parameters. Table 4Response surface equations for selected quality factorsof extruded blends of corn grits and microfluidized corn bran Parameter Equations in terms of actual factors R2 p Value Expansion ratio =4.09-5.31E-005*P*N+1.29E-008*P2-0.017*N2 0.9187 0.0011 Bulk Density =-0.0365-1.86E-005*P*N-3.80E-009*P2 0.8901 0.0030

PUBLICATIONS (not previously reported): 2012/09 TO 2015/08
1. Type: Journal Articles Status: Other Year Published: 2016 Citation: He, F., Wang, T., Zhu, S., & Chen, G. (2016). In vitro bile acid binding and short-chain fatty acid profile of microfluidized wheat bran. (In preparation) He, F., Wang, T., Zhu, S., & Chen, G. (2016). Developing extruded high-fiber corn cereal using microfludized corn bran. (In preparation)
2. Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Wang, T., Zhu, Y., Raddatz, J., & Chen, G. Improving antioxidant activity of corn bran using the microfluidization process. Poster presented in 2013 IFT Annual Meeting, Chicago. Wang, T., Sun, X., Raddatz, J., & Chen, G. Effect of microfluidization on microstructure and physicochemical properties of corn bran. Poster presented in 2013 IFT Annual Meeting, Chicago.
3. Type: Journal Articles Status: Published Year Published: 2013 Citation: Wang, T., Sun, X., Raddatz, J., & Chen, G. (2013). Effects of microfluidization on microstructure and physicochemical properties of corn bran. Journal of Cereal Science, 58, 355-361. Wang, T., Sun, X., Raddatz, J., & Chen, G. (2013). Effect of microfluidization on antioxidant properties of wheat bran. Journal of Cereal Science, 58, 380-386
4. Type: Journal Articles Status: Published Year Published: 2014 Citation: Wang, T., Zhu, Y., Sun, X., Raddatz, J., & Chen, G. (2014). Effect of microfluidization on antioxidant properties of corn bran. Food Chemistry, 152, 37-45.
5. Type: Journal Articles Status: Under Review Year Published: 2015 Citation: He, F., Zhu, S., Wang, T., & Chen, G. (2015). Modeling the effects of microfluidization conditions on properties of corn bran. Journal of Cereal Science.
6. Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Wang, T., He, F., & Chen, G. Developing extruded high-fiber corn cereal using microfludized corn bran. Poster presented in 2014 IFT Annual Meeting, New Orleans.
7. Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: He, F., Zhu, S., Wang, T., & Chen, G. Modeling the effects of microfluidization condition on properties of corn bran. Poster presented in 2015 IFT Annual Meeting, Chicago.

PROGRESS: 2013/09/01 TO 2014/08/31
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? - To complete the measurement of physiochemical properties and antioxidant activity of microfluidized wheat bran - To complete the measurement of bile acid binding capacity and invitrolower gastrointestinal fermentation of modified corn bran and wheat bran - To establishresponse surface models for measured physicochemical and nutritional properties against microfluidization processing parameters

IMPACT: 2013/09/01 TO 2014/08/31
What was accomplished under these goals? Most Americans including both children and adults greatly under-consume dietary fiber, and usual intake is about half of the recommended daily intake . This has been demonstrated to be partially responsible for the growing incidence of obesity. Therefore, increasing consumption of dietary fiber is a critical step in stemming the epidemic of obesity found in the United States. However,the majorobstacle for consuming fiber-enriched foods is their poor sensory properties.Ourstudieshave demonstrated thathigh-fiber extruded corn cereals with good tastes could be manufactured using microfluidized corn bran. In addition, the process can also produce more powerful dietary fiber ingredients with substantially enhanced nutritional value. Using mathematical optimization, we designed high-fiber extruded cereals with the optimal nutrion values and sensory properties.As a result, ourfindings are helpful for combating the mentioned health issue. Experimental results were shown in the following. 1. Measurement of physical properties for extruded cereals The quality of the extrudates from blends of corn grits and modified brans was acceptable as indicated by the measured quality factors shown in previous report and Table 1 and Table 2 in this report. Table 1 Effects of microfluidization parameters on physical properties of extruded blends of corn grits and corn bran Processing Pressure (psi) Passes Diamete (mm) Bulk Density (g/cm3) Hardness (N) Color ΔE 22,000 2 6.95 0.358 22.5 37.7 22,000 4 6.50 0.415 21.8 38.7 20,000 3 6.81 0.386 22.5 36.6 18,000 2 6.52 0.404 22.5 36.9 18,000 4 7.41 0.312 24.7 37.8 17,000 3 7.15 0.341 26.4 38.0 23,000 3 7.09 0.353 26.7 37.4 20,000 1 6.45 0.412 21.8 36.9 20,000 5 6.61 0.402 22.9 36.4 20,000 3 6.68 0.391 24.9 37.2 20,000 3 6.64 0.398 24.0 37.2 20,000 3 6.90 0.360 26.7 36.7 20,000 3 6.70 0.372 27.2 36.6 Table 2 Effects of microfluidization parameters on physical properties of extruded blends of corn grits and wheat bran Processing Pressure (psi) Passes Diamete (mm) Bulk Density (g/cm3) Hardness (N) Color ΔE 22,000 2 7.25 0.295 24.3 45.5 22,000 4 7.01 0.320 23.2 44.6 20,000 3 7.19 0.290 19.5 44.4 18,000 2 6.90 0.308 20.3 44.1 18,000 4 7.25 0.283 20.9 44.1 17,000 3 7.21 0.287 24.5 44.4 23,000 3 7.14 0.290 22.7 45.3 20,000 1 7.35 0.266 19.2 45.0 20,000 5 7.26 0.288 23.3 47.1 20,000 3 7.38 0.271 24.0 45.0 20,000 3 7.29 0.283 23.8 45.0 20,000 3 7.36 0.277 23.1 45.6 20,000 3 7.49 0.265 21.2 44.1 2. Response surface models for selected quality factors of extruded corn cereal with addition of microfluidized bran Design Expert 9.0.3.1 (State Ease, USA) was used to establish the second order polynomial response surface models. The models developed were statistically significant for expansion ratio and bulk density of extruded corn cereal blended with microfluidized corn bran (Table 3), but not for other properties. However, there is no statistically significant relationship between quality factors of extrudates of corn grits blended with wheat bran and microfluidization parameters. Table 3 Response surface equations for selected physical properties of extruded blends of corn grits and microfluidized corn bran Parameter Equations in terms of actual factors R2 p Value Expansion ratio =4.09-5.31E-005*P*N+1.29E-008*P2-0.017*N2 0.9187 0.0011 Bulk Density =-0.0365-1.86E-005*P*N-3.80E-009*P2 0.8901 0.0030 Note: P - processing pressure; N - number of passes 3. Measurement of particle size distribution and physicochemical properties of microfluidized corn bran Hydration properties (swelling capacity and water-holding capacity) and oil-holding capacity of cereal bran are determined by its chemical composition, microstructure and particle size.Table 4 shows these properties as affected by microfluidization conditions. Table 4 Effect of microfluidization processing pressure and passes on hydration properties and oil-holding capacity of microfluidized corn bran Processing Pressure (psi) Passes MV (µm) SC (ml/g d.w) WHC (g water/g d.w) OHC (g oil/g d.w) 22,000 2 65.85 5.555 4.939 4.103 22,000 4 51.55 6.611 5.392 4.357 20,000 3 55.48 5.927 5.077 4.276 18,000 2 77.18 5.608 4.831 3.748 18,000 4 54.63 6.540 5.254 4.374 17,000 3 56.34 5.779 5.038 4.220 23,000 3 56.68 6.307 5.247 4.324 20,000 1 100.9 4.842 4.411 3.425 20,000 5 50.72 6.621 5.488 4.574 20,000 3 56.14 6.157 5.081 4.341 20,000 3 59.37 6.015 5.167 4.310 20,000 3 57.99 5.964 5.086 4.269 20,000 3 60.19 6.190 5.207 4.334 Note: SC- Swelling capacity; WHC-Water-holding capacity; OHC-Oil-holding capacity 5. Response surface models for the effect of microfluidization parameters on the physiochemical properties, phenolic compound contents and antioxidant activities of microfluidized corn bran Table5 shows response surface equations for the measured properties of microfluidized corn bran (all p <0.0001). As indicated by these equations, within the experimental range, mean particle size was only affected by the number of passes and decreased with increase in the number of passes, probably due to the small range of processing pressure. Differently, other properties including SC, WHC, OHC, SRCs, SR-PC, DPPH and ABTS were affected by both the number of passes and processing pressure, the former being more significant. Table5Response surface equations Parameter Equations in terms of actual factors R2 CB-MV =+162-59.2*N+4.52*N2 0.9656 SC =+5.65-1.65E-004*P+0.603*N-0.0752*N2 0.9153 WHC =+4.67-9.07E-005*P+0.435*N-0.0429*N2 0.9417 OHC =-3.35+4.45E-004*P+1.67*N-4.65E-005*P*N-0.0793*N2 0.9487 SRC-Water =+36.0+2.53E-003*P+18.3*N-1.17*N2 0.9623 SRC-Sucrose =+67.1+3.25E-003*P+26.2*N-2.10*N2 0.9873 SRC-Na2CO3 =+59.6+2.61E-003*P+14.8*N-1.66*N2 0.9865 SRC-LA =+67.2+2.55E-003*P+2.51*N-6.12E-008*P2-0.312*N2 0.9432 SR-PC =+175-9.92E-003*P+11.5*N-1.92*N2 0.9342 DPPH =+24.9+5.33E-004*P+4.41*N 0.5580 ABTS =-67.2+9.61E-003*P+4.51*N-2.39E-007*P2-0.871*N2 0.7326

PUBLICATIONS: 2013/09/01 TO 2014/08/31
1. Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Wang, T., F. He, and G. Chen, Developing extruded high-fiber corn cereal using microfludized corn bran. IFT Meeting 2014, New Orleans.
2. Type: Journal Articles Status: Published Year Published: 2014 Citation: Wang, T., Zhu, Y., Sun, X., Raddatz, J., and Chen, G*. (2014). Effect of microfluidization on antioxidant properties of corn bran. Food Chemistry, 152, 37-45.

PROGRESS: 2012/09/01 TO 2013/08/31
Target Audience: Researchers working in the field of dietary fiber. Food processors manufacturing high-fiber foods. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? 1. Complete half of the physicochemical and nutritional property measurements for microfluidized wheat and corn bran samples (totally 26) and the corresponding response surface models as described in Objective 2. 2. Complete preliminary investigation of the effects of modified brans on the qualities of extruded corn cereal as described in Objective 3. Preparation of extrudates: Modified brans that lead to the largest radial expansion ratio determined from Objective 2 will be chosen for extrusion tests following the same extrusion conditions as used in Objective 2. Four bran replacement levels which are 25%, 30%, 35%, and 40% (wet basis) will be tested. Measurement of extrudate properties including moisture, color, radial expansion ratio, product volume, product bulk density, hardness and crispiness, and microstructure.

IMPACT: 2012/09/01 TO 2013/08/31
What was accomplished under these goals? 1. Establishment of a microfluidization protocol for wheat and corn bran Coarse bran was washed extensively using cold distilled water to remove flour residues and other floating impurities. The washed bran was air dried at 32 °C for 48 h. The dry bran was repeatedly ground and passed through sieves with different pore sizes. Bran samples in the particle size range of 500-600 µm, 425-500 µm, 300-425 µm, and 225-300 µm, respectively, were prepared, each having a mass of 100 g. Each sample was dispersed in deionized water to prepare dispersions at different solid concentrations (wt/wt). Each of the dispersions was then processed through a 200 µm interaction chamber of an M-110P Microfluidizer Processor (Microfluidics, Newton, MA, USA) at room temperature. The processing pressure started at 24,000 psi and decreased by 1,000 psi until 17,000 psi or the machine was clogged. In this way, for a given processing pressure, the maximum concentration of bran in each particle size range was determined. When particle size was in the range of 500-600 µm, a 7% aqueous suspension of corn bran clogged the machine at 24,000 psi but 5% suspensions could be processed in the pressure range tested. For wheat bran, a 15% bran suspension clogged the machine at 24,000 psi and a 12% bran suspension clogged at 20,000 psi, whereas 9% bran suspensions could be processed in the pressure range tested. When particle size was in the range of 425-500 µm or below, suspensions containing up to 22% bran could be processed without clogging. A suspension containing more than 22% bran was so thick that the machine could not take samples from the inlet reservoir. The results showed that the maximum concentration of bran that can be processed through the 200 µm interaction chamber depends on the particle size. When the maximum particle size is reduced below 500 µm, the maximum bran concentration is 22%, which makes microfluidization economically feasible for producing dietary fiber ingredients from cereal bran. 2. Preparation of microfluidized wheat and corn bran samples under different conditions Coarse bran was washed extensively using cold distilled water and air dried at 32 °C for 48 h. The dry bran was repeatedly ground and passed through a US standard No. 35 sieve with a nominal opening of 500 µm (Fisher Scientific Co., TX, USA). The ground bran was dispersed in distilled water (bran: water = 9:91, wt/wt) and then processed through a 200 µm interaction chamber of an M-110P Microfluidizer Processor (Microfluidics, Newton, MA, USA) under various conditions determined from a second order central composite design (CCD) with two variables and five levels of each variable. The independent variables were process pressure (X1) and number of passes (X2) which along with variation levels are shown in Table 1. The center point in the design was repeated five times to calculate the repeatability of the method. Experiments were randomized in order to minimize the effects of unexplained variability in the observed responses due to extraneous factors. The processed bran samples were collected by centrifugation and freeze dried. Thirteen 150-g dry samples from each set of the microfluidization conditions were obtained. Dry samples were sealed in sample bottles and stored at -20 oC for future analysis. Table1 Experimental design for microfluidization experiment Experiment number Coded levels Actual levels X1 X2 Process pressure (psi) Number of passes 1 -1 -1 18,000 2 2-1 1 18,000 4 3 1 -1 22,000 2 4 1 1 22,000 4 5 -1.414 0 17,000 3 6 1.414 0 23,000 3 7 0 -1.414 20,000 1 8 0 1.414 20,000 5 9×5 0 0 20,000 3 3. Expansion tests of extruded blends of corn grits and microfluidized bran The expansion ratio (extrudate diameter/die diameter) is one of the most important quality factors for extruded cereal products. In order to determine the microfulidized bran which results in the largest expansion ratio, blends of corn grits (70%, wet basis) and brans (30%, wet basis) microfluidized under each set of conditions (Table 1) were extruded through a laboratory co-rotating twin-screw extruder (Brabender MARK III, CTSE-V) with barrel diameter 32 mm, screw length 13 times its diameter. Extrusion conditions used were sample moisture content (16%, wet basis), extruder speed (180 rpm), extruder temperature (30, 80, 110, 120, 120 ºC for zone 1-5, respectively), feed rate (110 g min-1), and rod die (3.2 mm in diameter). The expansion test results are illustrated in Table 2. The second order polynomial response surface model will be fitted to expansion ratio with the independent variables (X1 and X2). Regression analysis and analysis of variance (ANOVA) will be conducted using the Matlab Statistics Toolbox for fitting the model and to examine the statistical significance of the model terms. Matlab Optimization Toolbox will then be used to find a point that maximizes the expansion ratio. Table2 Expansion ratios of extrudates from blends of corn grits (CG) and microfluidized wheat bran (WB) and corn bran (CB), respectively Processing pressure (psi) Passes Expansion ratio of CB and CG Expansion ratio of WB and CG 22,000 2 2.17 2.26 22,000 4 2.03 2.19 20,000 3 2.13 2.25 18,000 2 2.04 2.16 18,000 4 2.32 2.26 17,000 3 2.24 2.25 23,000 3 2.22 2.23 20,000 1 2.02 2.30 20,000 5 2.07 2.27 20,000 3 2.09 2.31 20,000 3 2.08 2.28 20,000 3 2.16 2.30 20,000 3 2.09 2.34 4. Effects of microfluidization on microstructure and physicochemical properties of corn bran Wang, T., Sun, X., Raddatz, J. & Chen, G. (2013). Effects of microfluidization on microstructure and physicochemical properties of corn bran. Journal of Cereal Science, 58, 355-361. 5. Effects of microfluidization on antioxidant properties of wheat bran Wang, T., Sun, X., Raddatz, J. & Chen, G. (2013). Effect of microfluidization on antioxidant properties of wheat bran. Journal of Cereal Science, 58, 380-386.

PUBLICATIONS: 2012/09/01 TO 2013/08/31
1. Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Wang, T., Zhu, Y., Raddatz, J., & Chen, G. Improving antioxidant activity of corn bran using the microfluidization process. Poster in IFT Annual Meeting, Chicago, July 13-16, 2013. Wang, T., Sun, X., Raddatz, J., & Chen, G. Effect of microfluidization on microstructure and physicochemical properties of corn bran. Poster in IFT Annual Meeting, Chicago, July 13-16, 2013.
2. Type: Journal Articles Status: Published Year Published: 2013 Citation: Wang, T., Sun, X., Raddatz, J. & Chen, G. (2013). Effects of microfluidization on microstructure and physicochemical properties of corn bran. Journal of Cereal Science, 58, 355-361. Wang, T., Sun, X., Raddatz, J. & Chen, G. (2013). Effect of microfluidization on antioxidant properties of wheat bran. Journal of Cereal Science, 58, 380-386.