Progress 01/01/09 to 12/31/12
Outputs
OUTPUTS: The results of this project were presented as technical talks and posters at the annual meetings of Institute of Food Technologists (2009, 2010, and 2012). Talks on this topic were given at the International Conference on Engineering and Food, Athens, Greece (May, 2011) and Riddet Conference on Food Structures, Digestion and Health, Palmerston North, New Zealand (March, 2012), and Annual Conference of American Society of Nutrition, San Diego (April 2012). Results were also shared with the Research Committee of California Almond Board. In addition, papers and book chapters were written based on the results of this project. The most significant outputs of this project were the presentation of results to peers at national and international meetings throughout the entire duration of this project. PARTICIPANTS: Fanbin Kong, Post doctoral Scholar, Gail Bornhorst, Graduate Research Assistant and Post Doctoral Scholar, Maxine Roman, Graduate Research Assistant, Zhengjun Xue, Post Doctoral Scholar, Maria Ferrua, Post Doctoral Scholar. Partner Collaborators: Distinguished Professor Paul Moughan, and Professor Harjinder Singh, Dr. Maria Ferrua, Riddet Institute, Massey University, Palmerston North. As for Professional Development, Bornhorst and Roman received graduate degrees (Ph.D. and M.S., respectively) and Xue, Ferrua, and Bornhorst received post-doctoral training. TARGET AUDIENCES: Target audiences are peers working in the area of Food Science and Health in academia and industry. Efforts designed to cause a change in knowledge included technical presentations at annual national meetings of professional societies, and international conferences on engineering, food and nutrition. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
A human gastric simulator (HGS) was constructed as an in vitro system to accurately reproduce in vivo gastric digestion conditions. The HGS consists of a flexible-walled vessel and a series of rollers to create continuous contractions from all sides. Gastric juice is injected at predetermined rates to adjust the pH and enzyme concentration. The HGS was tested with apple, pear, rice, bread, and ham. The final digested samples resembling chyme were tested for particle size distribution and viscosity. The result showed that HGS was more effective in reducing the size of the food particles and the mixture viscosity increased as compared to the shaking bath method. Disintegration kinetics of bread boluses during static and agitated soaking were measured for six types of bread. Disintegration kinetics followed three distinct profiles: exponential, sigmoidal, and delayed sigmoidal, depending on the bolus bread type. These differences in profiles were attributed by varying levels of water absorption in the different bread types, caused by the variations of bread structure, water holding capacity, and moisture content. A 3-D computational fluid dynamics (CFD) model was developed to characterize the fluid dynamics of gastric contents of different viscosities. The flow field within the model strongly depended on the viscosity of gastric contents. By increasing the viscosity, the formation of the retropulsive jet and eddy structures were diminished, while an increase of the pressure field was predicted. These results were in good agreement with previously reported experimental data, and suggest that gastric contents associated with high viscous meals are poorly mixed. An in vivo study was undertaken to determine the gastric emptying, rice physical breakdown, and meal mixing of cooked brown and white rice using the growing pig as a model for the adult human. Brown and white rice did not show significantly different gastric emptying rates. Rice gastric chyme behaved as a Herschel-Bulkely fluid, with the shear stress values showing significant differences as a result of rice type, stomach region, and digestion time. Rice grain firmness and hardness showed differences as a result of rice type and decreased over the 8 hr digestion period. A mixing rate constant was determined for the brown and white rice meals that demonstrated that white rice had a faster rate of mixing compared to brown rice. Overall, we have constructed an in vitro system, capable of reproducing the physical and chemical aspects of gastric digestion and this system has been used to study the breakdown of various foods. The influence of food texture and structure has been determined on bread bolus disintegration kinetics during in vitro gastric digestion. The flow field in the human stomach has been predicted using a 3-D computational fluid dynamic model, and the impact of meal viscosity on the flow field has been demonstrated. Finally, an in vivo study was undertaken to determine the breakdown and mixing during gastric digestion of rice in pigs. These studies have demonstrated the importance of food material properties and their behavior and breakdown during gastric digestion.
Publications
- Ferrua, M. and R. P. Singh. 2010. Modeling the Fluid Dynamics in a Human Stomach to Gain Insight of Food Digestion. Journal of Food Science 75(7): R151-R162
- Ferrua, M., F. Kong and R. P. Singh. 2011. Computational modeling of gastric digestion and the role of food material properties. Trends in Food Science and Technology. doi:10.1016/j.fifs.2011.04.
- Bornhorst, G.M. and R. P. Singh. 2012. Food bolus formation and disintegration for starch-based foods. Comprehensive Reviews of Food Science and Food Safety 11(2):101-118.
- Bornhorst, G.M., Strobinger, N., Rutherfurd, S.M., Singh, R.P., Moughan, P.J. 2012. Properties of gastric chyme for pigs fed cooked brown or white rice. Food Biophysics. DOI: 10.1007/s11483-012-9277-9.
- Ferruzzi, M.G., Peterson, D.G., Singh, R.P., Schwartz, S.J. and Freedman, M.J. 2012. Nutritional Translation Blended With Food Science: 21st Century Applications. American Society of Nutrition, Advances in Nutrition 3: 813-819, 2012; doi:10.3945/an.112.003202.
- Bornhorst, G.M. and R.P. Singh. 2013. Kinetics of bread bolus digestion with varying in vitro oral and gastric parameters. Food Biophysics. DOI:10.1007/s11483-013-9283-6.
- Kong, F., Oztop, M.H., Singh, R. P. and M.J. McCarthy. 2013. Effect of boiling, roasting and frying on disintegration of peanuts in simulated gastric environment. LWT- Food Science and Technology. 50(1):32-38.
|
Progress 01/01/11 to 12/31/11
Outputs
OUTPUTS: Results from this research were presented at the annual meeting of Institute of Food Technologists. PARTICIPANTS: R. Paul Singh, Principal Investigator. Directed the research, data analysis and publication of results. Gail Bornhorst PhD student conducted research, data analysis and prepared results for publication. TARGET AUDIENCES: Target audience of this research involves peers working in this field. Results from this research were reported at the annual conference of Institute of Food Technologists. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Processed foods have been shown to elicit a higher post-consumption glucose response and faster gastric emptying compared to their non-processed counterparts. These differences have been hypothesized to be due to differences in food structure and physical properties caused by processing, however, the specific physical properties and structure in relation to in vivo digestion have not been studied. The objective of this study was to compare the physical properties of brown and white rice digesta in both the proximal and distal regions of the stomach over a two hour time period in order to determine the effect of processing on the breakdown and emptying of rice during gastric digestion. Thirty six male pigs were used to examine the effect of brown and white rice on the properties of gastric digesta. Sampling of digesta was performed 20, 60, or 120 min after consumption of a rice meal and samples were taken from both the proximal and distal regions of the stomach. Stomach mass was measured before samples were removed. Moisture content, pH, and particle size analyses were conducted. Gastric secretions were observed more prominently in the distal regions than the proximal regions. The distal region (for all treatments) had higher moisture content and lower pH, suggesting there was more gastric acid in this region. Although gastric emptying was not explicitly measured in this study, the results suggest that white rice has a faster rate of emptying compared to brown rice. The stomach masses for those pigs that consumed white rice decreased faster over time (143% of food mass consumed to 41%) in comparison to brown rice (112% to 78%). The change in mass of digesta is an approximate measure of how much of the meal has emptied. Particle size analysis demonstrated that the mixing and emptying patterns for large (>0.28 mm^2) and small (<5x10^(-5) mm^2) particles are different for each rice type, with white rice small particles emptying faster than brown rice, and white rice large particles being broken down at a faster rate than brown rice. Both rice types, digestion time, and stomach region have an effect on the physical properties of gastric digesta in pigs. This suggests that food structure play an important role in the digestion process, dictating digesta properties such as stomach mass and particle size.
Publications
- Singh, S.K. and R. P. Singh. 2011. Gastric digestion of foods; Mathematical modeling of flow filed in a human stomach. In Food Engineering Interfaces. Ed. Aguilera, J.M. Barbosa-Canovas, G.V., Simpson, R. Welti-Chenas, J. and Bermudez-Aguirre, D. p 99-117. Springer, New York.
- Kong, F. and R.P.Singh. 2011. Chemical deterioration and physical instability of foods and beverages. In Food and Beverage Stability and Shelf Life. Ed. Kilcast, D. and Subaramaniam, P. p 29-62. Woodhead Publishing Ltd, Cambridge, UK.
- Kong, F. and R.P.Singh. 2011. Advances in instrumental methods to determine food quality deterioration. In Food and Beverage Stability and Shelf Life. Ed. Kilcast, D. and Subaramaniam, P. p 381-404. Woodhead Publishing Ltd, Cambridge, UK.
- Kong, F., Oztop, M.H., Singh, R.P. and M.J. McCarthy. 2011. Physical changes in white and brown rice during simulated gastric digestion. Journal of Food Science 76(6) ppE450-E457.
|
Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: The results of this work were presented at the Annual meetings of the Institute of Food Technologists. PARTICIPANTS: R. Paul Singh, Principal Investigator. Directed the research, data analysis and publication of results. Fanbin Kong, Postdoctoral Scholar. Conducted experiments, data analysis and prepared results for publication and dissemination. TARGET AUDIENCES: Target audience of this research at this stage involves peers working in this field. Research results were reported at the annual conference of Institute of Food Technologists. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
An in vitro system that can accurately reproduce the gastric conditions in a human stomach is necessary for studies on digestion of foods. Although some in vitro systems of the Gastro-Intestinal tract have been recently reported, there is a need of a reactor that can truly mimic the gastric environment. The objectives of this research were 1) to design and construct a human gastric simulator (HGS) with flexible walls that can reproduce continuous peristaltic contractions, and 2) to use the HGS to study the disintegration kinetics of selected foods. Based on these objectives, an HGS was constructed in our workshop. The HGS consists of a 1 liter vessel with walls made of latex, a series of rollers secured on belts driven by a motor to create continuous contractions of the flexible walls from all sides, and temperature of the system maintained at 37 C. The wall contractions are adjustable to provide similar amplitude and frequency of the peristaltic waves as measured in a human stomach. Gastric juice is injected along the walls of HGS at predetermined rates to adjust the pH and concentration of gastric enzymes. The HGS was tested with particulates of apple, pear, rice, bread, and ham. About 100-150 g samples were transferred to the HGS and 70-105 mL simulated gastric juice was added. The peristalsis was initiated, and the trials continued for 1-2 hours. Samples were also tested in a shaking water bath under same conditions. The final samples of mixture resembling chyme, from both methods, were tested for particle size distribution and viscosity. The result showed that HGS was more effective in reducing the size of the food particles and the mixture viscosity increased as compared to the shaking bath method. Based on data available on solid breakdown in the literature, the HGS appears to be more suitable as a test method for studies involving food digestion than other procedures used for this purpose. Several studies are now underway to compare results of HGS with animal trials. These studies will provide the required validation data for the use of HGS in routine digestion studies.
Publications
- Kong, F. and Singh, R.P. 2010. A human gastric simulator (HGS) to study food digestion in human stomach. Journal of Food Science. 75 (9). pp E627-E635
|
Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: The results of this work were presented at the Annual meetings of the Institute of Food Technologists. PARTICIPANTS: R. Paul Singh, Principal Investigator. Directed the research, data analysis and publication of results. Fanbin Kong, Postdoctoral Scholar. Conducted experiments, data analysis and prepared results for publication and dissemination. Maria Ferrua, Postdoctoral Scholar. Conducted experiments, data analysis and prepared results for publication and dissemination. TARGET AUDIENCES: Target audience of this research at this stage involves peers working in this field. Research results were reported at the annual conference of Institute of Food Technologists. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Ultrasonography and magnetic resonance imaging have successfully identified the mechanical processes promoting digestion of solid foods in the stomach. However, these techniques are unable to characterize the fluid dynamics of the luminal contents. The goal of this work was to develop an improved understanding of the flow that develops within a human stomach due to peristalsis during digestion. A non-intrusive flow measurement technique, Particle Image Velocimetry (PIV), was used to characterize the flow within a custom-built chamber due to the peristaltic deformation of one of its walls. The physical model consisted of an acrylic chamber (20.3 x 20.3 x 2.3 cm) filled with water, one of its walls was substituted by a neoprene sheet 0.15 cm thick. The flow within the chamber was developed by periodically moving a cycloid-shaped object (4.8 cm long and 1.0 cm high) along the neoprene sheet, thus creating a longitudinal hump (1.15 cm high or 50% of the chamber height) in the fluid cross-section moving at a speed of 6.1+- 0.2 mm/s. PIV velocity fields were used to compute the shear stresses and vorticity of the flow. Measurements showed that the velocity field was mainly developed in the proximity of the deforming wall (maximum velocity region located at the center of the hump). The direction of the peristaltic movement significantly affected the flow. When the hump moved away from the bottom of the chamber, flow reversals developed at the center of the hump, displacing the region of maximum velocity away from the deforming wall. The distribution of the shear stresses and vorticity confirmed that the higher stretching and folding of the fluid (essential for mixing) occurs in the vicinity of the hump. This study provides valuable information to validate mathematical models of peristaltic flows within closed containers. Gastric digestion of foods may significantly influence the rheological properties of stomach contents, and subsequently affect stomach wall movement as well as stomach emptying. We investigated how digestion of pudding affects rheological behaviour of gastric mixture with an in vitro experiment. Samples of 5.5mL vanilla flavored ready-to-eat pudding was mixed with 0.9 mL of simulated saliva in a shaking water bath at 37C for 30 seconds. Then, 17 mL of simulated gastric juice was added and mixed for different time periods from 0 to 55 minutes, to simulate gastric digestion. The treated mixture was then evaluated for rheological properties. Shear stress - shear rate curves were obtained using a cylindrical sensor in controlled rate mode for shear rates from 0 to 100/s. The digested mixture was a Non-Newtonian time independent fluid and the shear stress-shear rate data fitted well with the power law flow equation. The viscosity increased within first 5 min of digestion followed by a continual decrease. Changes in the starch structure during digestion played a major role in the initial increase of viscosity. The results provided quantitative data on rheological properties of the stomach contents during in vitro digestion of a semi-solid food. This information is useful for understanding physical mechanisms important in food digestion.
Publications
- Ferrua, MJ, Marra, F, Singh, RP. 2009 PIV analysis of the flow field within a closed system that simulates the peristaltic movement of the stomach wall. IFT Abstract Book 202-23
|