Progress 10/01/03 to 09/30/08
Outputs
OUTPUTS: The overall objective was to understand the internal morphology of biopolymer foams by utilizing non-invasive X-ray micro tomography (XMT) technology, identifying material properties critical for engineering desired structures, and comparing mechanisms of microstructure formation in processes such as conventional high shear and high temperature extrusion (HSTX), supercritical fluid extrusion (SCFX) and pellet milling. Brittle biopolymer foams with different structural and physico-chemical properties were produced by HSTX on a pilot-scale co-rotating twin screw extruder. A base formulation of normal corn starch was used along with 0-15% whey protein concentrate (WPC), 0-18 percent whey protein isolate (WPI) and 0-6 percent sucrose. Specific mechanical energy (SME) was directly controlled by varying the extruder screw speed (200-400 rpm) and in-barrel moisture content (23-34 percent wb). XMT was used for imaging internal morphology of foams, and facilitated accurate and hitherto impossible measurement of features like true cell size distribution, average cell diameter (0.79-6.32 mm), open wall area ratio (0.10-0.15), cell wall thickness (0.09-0.23 mm) and true void fraction (0.62-0.84). Material properties of formulations were measured, including glass transition temperature by DSC, and softening and flow temperatures by phase transition analyzer. Mechanical properties (including compression modulus and crushing stress) and acoustic features were measured using texture analyzer and sound acquisition apparatus. Expansion was directly correlated with specific mechanical energy, which in turn was positively correlated with screw speed and, in most cases, with Ts or Tf. The material properties, Ts and Tf, and the foaming action of protein-based ingredients such as WPI were identified as critical to controlling the internal morphology of the biopolymer foams. Good relationships were observed between structural features and mechanical properties, and also between acoustic-mechanical signals and sensory attributes. A variety of pregel corn starch-based brittle foams were produced using SCFX. Cell diameter and porosity of extrudates decreased with radial distance from the center of the extrudates, leading to a relatively non-porous skin that was absent in HSTX foams. Average cell diameter of SCFX foams was more than 10 times smaller than HSTX foams, and the cell density of the former was approximately 100-fold greater. SCFX foams also showed higher poly-dispersity indices, indicating more uniform cell size distribution. The differences in HSTX and SCXF foams were explained in terms of the phase-transition thermodynamics of their respective blowing agents - water and CO2. The HSTX foaming behavior of biopolymer systems consisting of normal or high amylose starch and soy protein concentrate was also studied. Additionally, the internal morphology and physico-chemical characteristics of floating and sinking aquatic feed pellets produced by HSTX was investigated, and compared to pellets produced using SCFX and pellet milling. Research was also directed towards developing a JAVA-based automated software for measurement of cellular features. PARTICIPANTS: S. Alavi (Kansas State University), K. Behnke (Kansas State University), A.M. Trater (Kansas State University), R.N. Agbisit (Kansas State University), E. Cheng (Kansas State University), N. J. de Mesa (Kansas State University), H. Dogan (Kansas State University), Y.C. Shi (Kansas State University), L. Zhu (Kansas State University), R. Shukri (Kansas State University), Y. Sang (Kansas State University), T. Herald (Kansas State University), T. Pearson (USDA-GMPRC), S.S.H. Rizvi (Cornell University), N. Singh (GNDU, India), O. Kaddour (AEnRI, Egypt) and M. Sorensen (AKVAFORSK, Norway). TARGET AUDIENCES: Overall scientific community engaged in research related to industrial and food foams, and extrusion processing. This audience was reached through by dissemination of project results via scientific meeting presentations and peer-reviewed journal publications. Food processing industry, especially companies engaged in production of snacks and breakfast cereal products. Apart from dissemination of project results via scientific meeting presentations and peer-reviewed journal publications, this target audience was also directly reached through various sponsored projects. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Agricultural products which utilize extrusion technology constitute approximately a $40 billion annual market in the U.S. alone. This includes breakfast cereal, snacks, pasta, pet food, aquatic feed, and bio-based industrial materials. Results from this research can be applied towards further improvement of extrusion processing technology, development of new, appealing food products, and enhancement in the value of agricultural commodities. This project has increased the capability of apriori design of biopolymer foams (both food and non-food) with desired cellular structure and physical properties such as strength, thermal conductivity and acoustic dampening, and would lead to better process control and higher quality grain-based food and industrial products. A significant outcome of this project is the development of a conceptual model for structure formation and microstructure-texture relationships in both steam-based extrusion and supercritical fluid extrusion processes, leading to an improvement over current knowledge in the area. Results from this study can be applied towards development of a new generation of cereal-based food products which are highly nutritious and have desired microstructure and texture characteristics. These results can also be utilized for improvement of the production process for biopolymer industrial foams. The new microstructure and material characterization techniques (XMT and PTA) explored in this project can be applied to a whole range of food and industrial products.
Publications
- Zhu, L., de Mesa N., Alavi, S., Shi, Y., Dogan, H., and Shukri, S. 2008. Physical and biochemical properties of high amylose-soy protein concentrate extrudates. AACC Annual Meeting, Sept. 21-24, Honolulu, HI. Cereal Foods World, 53: A45.
- De Mesa, N.J.E., Alavi, S., Singh, N., Shi, Y-C, Dogan, H. and Sang, Y. 2009. Soy protein fortified expanded extrudates: Baseline study using normal corn starch. Journal of Food Engineering. 90(2): 262-270.
- Cheng, E., Alavi, S., Pearson, T., and Agbisit, R. 2007. Mechanical-acoustic and sensory evaluations of corn starch-whey protein isolate extrudates. Journal of Texture Studies. 38: 473-498.
- Kaddour, O., Alavi, S., Dogan, H., Behnke, K., Sorensen, M., and Rizvi, S.S.H. 2007. Effect of different process technologies on microstructure, starch gelatinization and quality of floating and sinking aquatic feed pellets. AACC Annual Meeting, Oct. 07-10, San Antonio, TX. Cereal Foods World, 52(4), Suppl.
- Cho, K. Y., De Mesa, N.J., Rizvi, S. S. H., and Alavi, S. 2007. Melt rheology and 3-D microstructures of steam-expanded and supercritical fluid extrudates. Institute of Food Technologists Annual Meeting, July 28-Aug 1, Chicago, IL. Book of Abstracts.
- Agbisit, R., Alavi, S., Cheng, E., Herald, T.J., and Trater, A.M. 2007. Relationships between microstructure and mechanical properties of cellular corn starch extrudates. Journal of Texture Studies. 38:199 to 219.
- Agbisit, R.N., Cheng, E. M., and Alavi, S. 2006. Interrelationships among physical, thermal flow, microstructure and mechanical properties of extruded corn starch-whey protein foams. Institute of Food Technologists Annual Meeting, June 23-28, Orlando, FL. Book of Abstracts.
- Cho, K. Y., Alavi, S., and Rizvi, S. S. H. 2006. Microstructures of steam-expanded and SCFX extrudates using 3-D non-invasive image analysis. 2006 Institute of Food Technologists Annual Meeting, June 23-28, Orlando, FL. Book of Abstracts.
- Trater, A.M., Alavi, S, and Rizvi, S.S.H. 2005. Use of non-invasive X-ray microtomography for characterizing microstructure of extruded biopolymer foams. Food Research International. 38: 709-719.
|
Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: Research was focused on using non-invasive X-ray microtomography (XMT) technique to characterize the internal structure of floating and sinking aquatic feed and understand the dynamics of three distinct processing technologies. Conventional high shear and temperature extrusion processing and pellet milling are two primary technologies for producing aquatic feed. In recent years, a promising new technology, supercritical fluid extrusion (SCFX), has been developed and utilized for producing products such as expanded snack and breakfast cereal, and continuously leavened bread. The primary objective of this study was to characterize the internal microstructure of floating and sinking aquatic feed pellets produced by these three processes, and to relate that to process and product quality parameters such as specific mechanical energy (SME) input, degree of starch gelatinization, water stability and durability. Pilot-scale single screw extruder, pellet mill and twin-screw extruder
configured for SCFX operation were used to produce floating and sinking extruded aquatic feed with a wide range of morphologies. High-resolution X-ray micro-tomography (XMT) was used for studying the internal microstructure of the aquatic feed pellets. For conventionally extruded floating feed, time of floating decreased with reduction in average pore size and void fraction; and pellets extruded with water injection at both preconditioner (9 per-cent) and extruder barrel (5 per-cent) resulted in large average pore size and void fraction, and 100 per-cent floating percentage up to 48 hours. For sinking feed produced by SCFX, 37 per-cent in-barrel moisture, 5 per-cent steam injection in the preconditioner and 0.5 per-cent carbon dioxide injection in the barrel led to best quality sinking feed product.
PARTICIPANTS: Principal Investigators: Sajid Alavi, Hulya Dogan and Keith Behnke (Grain Science and Industry); Syed Rizvi (Cornell University); Osama Kaddour (Agricultural Engineering Research Institute, Egypt); Mette Sorensen (AKVAFORSK, Norway)
TARGET AUDIENCES: Kansas process equipment manufacturers; soybean and wheat growers
Impacts
This research was a first in terms of application of XMT to study aquatic feed internal microstructure. The non-invasive microstructure data obtained by high-resolution X-ray micro-tomography (XMT) were very useful in understanding differences in pellet quality. For both floating and sinking feed, the internal morphology was substantially different depending on the process conditions and technology (pellet mill, conventional extrusion and SCFX). SME played a significant role in controlling microstructure and pellet quality. A novel outcome was the development of the ability of gray scale comparison of cell wall material for feed processed at different operating conditions. This led to significant insights into the processing and also the state of the cell wall material. Agricultural products that utilize extrusion technology constitute approximately a $40 billion annual market in the U.S. alone, and aquatic feed comprises of a fast growing segment. This research can be
applied towards further improvement of extrusion technology towards development of better aquatic feed targeted to specific species and their feeding requirements. Results from this study have the potential for increasing the competitiveness of Kansas-based process equipment manufacturers and also will lead to enhancement in the value of Kansas agricultural commodities, such as soybean.
Publications
- Kaddour, O., Alavi, S., Dogan, H., Behnke, K., Sorensen, M., and Rizvi, S.S.H. (2007). Effect of different process technologies on microstructure, starch gelatinization and quality of floating and sinking aquatic feed pellets. AACC Annual Meeting, Oct. 07-10, San Antonio, TX. Cereal Foods World, 52(4), Suppl.
|
Progress 01/01/06 to 12/31/06
Outputs
Research was focused using non-invasive X-ray microtomography (XMT) technique to characterize the internal structure of biopolymer-based extruded foams and understand the foaming process during extrusion. The first objective was to understand the effect of different formulations and in-barrel moistures on the foaming process and resultant cellular structure of brittle foams produced by steam-based extrusion (SBX). A pilot-scale twin screw extruder was used to process corn starch with various combinations of whey protein isolate or WPI (0-18%), sucrose (0-6%) and in-barrel moisture (22 and 26% wet basis) in a factorial experimental design. Average cell diameter (1.00 - 3.56 mm), cell wall thickness (0.04 - 0.27 mm) and cell number density (1-193 cells/cm3) were obtained using XMT. As WPI content increased, cell diameter decreased and cell number density increased. WPI possibly induced greater nucleation due to its foaming action. As sucrose content increased, cell
diameter decreased while cell number density remained unchanged in general. The plasticizing effect of sucrose lead to lower specific mechanical energy input and less expansion. Lower cell wall thickness was observed for samples processed at lower in-barrel moisture, because of more cell expansion and consequently greater stretching of cell walls. The second objective was to understand the effect of SC-CO2 injection rates (0.25-0.74%) on the foaming process and resultant cellular structure of pregel corn starch - based brittle foams produced by supercritical fluid extrusion (SCFX). Cell diameter and porosity from transverse cross-sections of SCFX extrudates decreased with radial distance from the center indicating presence of a relatively non-porous skin, which was absent in SBX extrudates. This skin-effect was more prominent for less CO2 injection rates. Cell diameter (0.34-0.40 mm) increased with CO2 injection rate, and was more than 10 times smaller than that for SBX foams. Cell
wall thickness (0.13-0.16 mm) was lower than that for SBX foams. Cell density was approximately 100-fold greater than that for SBX extrudates. SCFX extrudates showed higher polydispersity indices, indicating more uniform cell size distribution. The last objective was to investigate the feasibility of using stereological methodology to obtain 3-D cell diameter distributions from 2-D images. Corn starch - based brittle foams of varying structures were produced using SBX at two moisture contents (24.8 and 28.8% wet basis) and two screw speeds (200 and 400 RPM). Microstructure of foams was imaged by XMT. Saltykov's stereological method was applied to obtain 3-D bubble size distributions using structural data from several non-invasive 2-D slices of the same sample. Actual 3-D cell-diameter distributions were also obtained by integrating 2-D structural information from the slices. Saltykov's stereological method could be used to obtain 3-D cell-diameter distribution data that were
reasonably close to data obtained from the more time consuming but accurate integration method. For future study, more slice images will be used to eliminate the error caused by large slice thickness.
Impacts
Agricultural products which utilize extrusion technology constitute approximately a $40 billion annual market in the U.S. alone. This includes breakfast cereal, snacks, pasta, pet food, aquatic feed, and bio-based industrial materials. Results from this research can be applied towards further improvement of extrusion processing technology, development of new, appealing food products, and enhancement in the value of Kansas agricultural commodities. This project has increased the capability of apriori design of biopolymer foams (both food and non-food) with desired cellular structure and physical properties such as strength, thermal conductivity and acoustic dampening, and would lead to better process control and higher quality grain-based food and industrial products. A new, much simpler stereological methodology was also evaluated for obtaining microstructure information from two-dimensional data.
Publications
- Agbisit, R. Alavi, S., Trater. A.M., Cheng, E., and Herald, T.J. 2006. Relationships between microstructure and mechanical properties of cellular corn starch extrudates. Journal of Texture Studies. Accepted for publication.
- Cheng, E., Alavi, S., Pearson, T., and Agbisit, R. 2006. Mechanical-acoustic and sensory evaluations of corn starch-whey protein isolate extrudates. Journal of Texture Studies. Accepted for publication.
- Agbisit, R.N., Cheng, E. M., and Alavi, S. Interrelationships among physical, thermal flow, microstructure and mechanical properties of extruded corn starch-whey protein foams. 2006 Institute of Food Technologists Annual Meeting, June 23-28, Orlando, FL. Book of Abstracts.
- Cho, K. Y., Alavi, S., and Rizvi, S. S. H. 2006. Microstructures of steam-expanded and SCFX extrudates using 3-D non-invasive image analysis. 2006 Institute of Food Technologists Annual Meeting, June 23-28, Orlando, FL. Book of Abstracts.
|
Progress 01/01/04 to 12/31/04
Outputs
The purpose of this research is to discover new and improved uses for Kansas agricultural products and equipment through the development of extruded aquatic feeds. However, the results may pertain to other extruded feeds made in Kansas as well. Product density is the primary factor affecting sinking rate of feed particles. Several processing conditions and formulations were investigated in an attempt to gain an understanding of how these factors affect product density and sinking rate. To produce a feed that had different sinking rates and maintained excellent pellet quality, the effects of extruder screw speed, in-barrel moisture and special coatings were studied. Screw speeds were chosen at 300 and 400 rpm, and in-barrel moisture levels at 28.4% for both speed and 31.9% for 400 rpm. As screw speed increased, product bulk density decreased (610 and 530 g/L for 300 and 400 rpm, respectively), the specific mechanical energy (SME) increased (300 and 403.2 KJ/Kg for 300
and 400 rpm, respectively). However, the sinking rate of the feed increased as the screw speed increased (0.20 and 0.216 ft/s for 300 and 400 rpm, respectively). With the higher moisture level and the same screw speed, the opposite happened. The bulk density increased (530 and 578 g/L for 300 and 400 rpm, respectively), SME decreased (403.2 and 322.56 KJ/Kg for 300 and 400 rpm, respectively), and the sinking rate increased (0.216 and 0.34 ft/s for 300 and 400 rpm, respectively). The second stage of this experiment focused on creating a post coating application that will allow the feed to stop at a given depth. The coating was a soybean oil mix with 40% of sodium bicarbonate and 20, 40, 60% of propionic acid concentrations. As the level of propionic acid increased, the pellets began to float. To summarize effects of screw speed, in-barrel moisture levels, and coating on density, pellet durability and sinking rate of extruded aquatic feed were investigated, In the remaining duration for
this project, studies will focus on palatability of these novel feed products for various aquatic species. One patent disclosure and one manuscript are in process.
Impacts
As product quality is enhanced by the addition of corn/soybean oil and starch to the formulation, Kansas farmers may benefit from the increased value of crops high in oil or starch content. By illuminating the effects of some process variables (i.e. fat and starch content), producers of aquatic feeds may now be better able to manipulate their products to meet customer demands, possibly leading to increased sales of extruded feeds manufactured in Kansas.
Publications
- No publications reported this period
|