Progress 12/15/08 to 12/14/12
Outputs
OUTPUTS: Now that prebiotics are being added to many processed food, assessing their stability has become an important issue to the food industry. This research provides a basis for predicting how prebiotics will behave in foods exposed to high temperature, low pH, extrusion, and other conditions common to food processing. This research also provides insights into the effects of food matrices as well as processing on stability of prebiotics. The results from this research have been presented at several regional, national, and international conferences and manuscripts have been prepared submitted for publication in journals. PARTICIPANTS: Project Participants included: Robert Hutkins, PI, Professor, University of Nebraska Randy Wehling, Co-PI, Professor, University of Nebraska Vicki Schlegel, Co-PI, Associate Professor, University of Nebraska Richard Zbasnik, Research Scientist, University of Nebraska Rebeca Duar, Graduate Student, University of Nebraska Kristina Moore, Graduate Student, University of Nebraska Emily Ang, Graduate Student, University of Nebraska TARGET AUDIENCES: The Target Audiences included researchers and product development scientists in industry and academia. Efforts included presentation at national meetings. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
The goal of this proposal was to assess the chemical and biological stability of commercial prebiotics in processed foods. Included were fructooligosaccharides (FOS), galactooligosaccharides (GOS), inulin, polydextrose (PDX), and resistant starch. Nine prototype products were developed to represent typical foods to which prebiotics could be adeed. These included baked foods (muffins, bread, cookies), acidified foods (two types of sports beverages), two types of nutrition bars, and an extruded breakfast cereal. Prebiotics were added at 1%; controls were also produced. The effects of the prebiotics on various physical properties (color, rate of staling, internal structure) were determined. In general, significant differences were observed browning for GOS in the cookies and cereal, for gas formation in the FOS bread, and for tackiness in the nutrition bars for FOS, GOS, and PDX. For chemical analysis of prebiotic stability, methods to measure prebiotics in complex food materials were developed and validated. These methods were based on the recovery of prebiotic spiked samples and measurement by HPLC and comparison to the prebiotic incorporated in the food samples. Recovery rates for ranged from 81 to 100%. For some products, the matrix consistently affected recovery. For biological analysis of prebiotic stability, a prebiotic activity assay was used. The output of this bioassay is a score that is based on the change in growth of a test strain of bacteria relative to growth of a control strain using the food as a substrate. Assays were performed before and after processing. Reductions in the activity score means that the prebiotic lost activity and was no longer prebiotic. Initial results revealed that all of the scores were low (< 0.1), indicating that at 1% prebiotic concentrations, the chemical methods were more sensitive than biological methods. However, when the prebiotic concentration was increased, the prebiotic activity assay could be used to assess the effects of processing. These results showed that the fructans, FOS and inulin, were stable when exposed to moderate heating, but were degraded when exposed to an acidic environment and moderate heat. In contrast, GOS was stable when exposed to heat, low pH, and a combination of moderate heat at low pH. For all of the products tested, resistant starch and PDX had low prebiotic activities. Matrix effects also existed for some products.
Publications
- Duar, R.M., R. Wehling, R. Hutkins, and V. Schlegel. 2011. Adaptation and validation of existing analytical methods capable of monitoring prebiotics present in extruded ready-to-eat breakfast cereal. Presented at the American Association of Cereal Chemists Annual Meeting.
- Duar, R.M., R. Wehling, R. Hutkins, and V. Schlegel. 2011. Adaptation and validation of food-specific analytical methods capable of monitoring prebiotics present in different types of processed food matrices. Presented at the Institute of Food Technologists Annual Meeting.
- Duar, R.M. 2011. Adaptation and validation of food-specific analytical methods capable of monitoring prebiotics present in different types of processed food matrices. M.S. Thesis, University of Nebraska-Lincoln.
- Duar, R.M, R. Wehling, R. Hutkins, and V. Schlegel. 2013. Adaptation and validation of food-specific analytical methods capable of monitoring prebiotics present in different types of processed food matrices. Presented at the American Association of Hispanics-USDA-NIFA- Annual Meeting.
- Moore, K. 2011. Biological analysis of prebiotics in various processed food matrices. M.S. Thesis, University of Nebraska-Lincoln.
- Moore, K., R. Duar, P.T. Ang, R. Wehling, V. Schlegel, and R. Hutkins. 2011. Chemical and biological stability of prebiotics in processed foods. Presented at the Institute of Food Technologists Annual Meeting.
- Ang, P.T. 2011. Adaptation and validation of existing analytical methods for monitoring prebiotics present in different types of processed food matrices. M.S. Thesis, University of Nebraska-Lincoln.
- Duar, R., R. Wehling, R. Hutkins, and V. Schlegel. 2013. Chemical stability of prebiotic carbohydrates in different types of processed food matrices. Journal of Food Science. Submitted.
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Progress 12/15/10 to 12/14/11
Outputs
OUTPUTS: The overall goal of this proposal was to assess the prebiotic stability, chemically and biologically, of five commercial prebiotics, fructooligosaccharides (FOS), galactooligosaccharides (GOS), inulin, polydextrose (PDX), and resistant starch, in processed foods. These prebiotics were formulated into nine prototype products (two types of muffins, bread, cookies, two types of sports beverages, two types of nutrition bars, and breakfast cereal) using standard formulas. The effects of the prebiotics on physical properties (color, rate of staling, internal structure) were determined. Significant differences were observed for cookie and cereal browning for GOS, gas formation for FOS in bread, and for tackiness in the nutrition bars for FOS, GOS, and PDX. Analytical HPLC methods capable of measuring prebiotics were developed and validated using customized extraction methods. These methods were based on the recovery of a sample spiked with 1% prebiotic. The recovery of prebiotic in the food samples was compared with the recovery of the spiked samples to determine the fate of prebiotic. Recovery rates for FOS products tested range from 81 to 100% based on severity of matrix effects. Next, a previously developed prebiotic bioassay was used to measure residual prebiotic activity in these products. The assay generates a prebiotic activity score based on the change in growth of a test strain of bacteria relative to growth of a control strain using the food as a substrate. For products that contained 1% prebiotic, scores were low (< 0.1), indicating that at these low prebiotic concentrations , chemical methods are more sensitive than biological methods. However, for foods that contained higher concentrations (10%) and limiting background sugars, prebiotic activity scores were appreciably higher (>0.4). The results showed that FOS and inulin were stable when exposed to mild to moderate heating, but were biologically degraded when exposed to an acidic environment and moderate heat. GOS was stable when exposed to mild to moderate heat as well as when exposed to an acidic environment that was processed with moderate heat. Resistant starch had a low standard prebiotic activity and low scores when tested in food products. In addition, there were still food matrix effects for some products. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
The methods we have developed and validated for assessing stability of prebiotics in foods should be of considerable value to the food industry. Our research group has been approached by several food companies regarding this project. Overall, this research has been able to provide insight of the effects of food matrices as well as processing on stability of prebiotics. The data generated from this research is generally in agreement with previously published data using both chemical and biological methods to test for prebiotic activity.
Publications
- No publications reported this period
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Progress 12/15/09 to 12/14/10
Outputs
OUTPUTS: Prebiotic carbohydrates are now added to many foods, including nutritional bars, breakfast cereals, and beverages. Manufacture of these foods exposes prebiotics to processing conditions which may cause them to degrade or lose prebiotic activity. The overall goal of this proposal, therefore, was to assess the prebiotic stability, both chemically and biologically, of five commercial prebiotics, fructooligosaccharides (FOS), galactooligosaccharides (GOS), inulin, polydextrose (PDX), and resistant starch, in processed foods. These prebiotics were formulated into six prototype products (muffins, bread, cookies, sports beverage, nutrition bar, and breakfast cereal) using standard formulas. The effects of the prebiotics on physical properties (color, rate of staling, internal structure) were determined. Significant differences were observed for cookie and cereal browning for GOS, gas formation for FOS in bread, and for tackiness in the nutrition bars for FOS, GOS, and PDX. Analytical HPLC methods capable of measuring prebiotics were developed and validated using customized extraction methods. These methods were based on the recovery of a sample spiked with 1% prebiotic. The recovery of prebiotic in the food samples was compared with the recovery of the spiked samples to determine the fate of prebiotic. Recovery rates for FOS products tested range from 81 to 100% based on severity of matrix effects. Next, a previously developed prebiotic bioassay was used to measure residual prebiotic activity in these products. The assay generates a prebiotic activity score based on the change in growth of a test strain of bacteria relative to growth of a control strain using the food as a substrate. In general, scores were low (< 0.3) for all products, indicating that at low prebiotic concentrations (1%), chemical methods are more sensitive than biological methods. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
The methods we have developed and are now validating for assessing stability of prebiotics in foods should be of considerable value to the food industry. Our research group has been approached by several food companies regarding this project.
Publications
- Abstract at IFT, 2010 Assessing and enhancing stability of prebiotic oligosaccharides in foods R. Hutkins, M. Hoffman, E. Ang, R. Duar, K. Moore, R. Zbasnik, R. Wehling, and V.Schlegl.
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Progress 12/15/08 to 12/14/09
Outputs
OUTPUTS: The results from the first year of this study have been submitted as an IFT Abstract to be presented in July at the IFT Annual Meeting. PARTICIPANTS: Dr. Roberet Hutkins, PI, responsible for coordinating the project and specifically for conducting the microbiological analyses. Dr. Vicki Schlegel, Co-PI, responsible for conducting the chemical analyses. Dr. Randy Wehling, Co-PI, responsible for developing food prototypes. Three graduate students (all M.S. in food science) are working on this project. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Prebiotic carbohydrates are now added to many foods, including nutritional bars, breakfast cereals, and beverages. Manufacture of these foods exposes prebiotics to processing conditions which may cause them to degrade or lose prebiotic activity. The overall goal of this proposal, therefore, was to assess the prebiotic stability of five commercial prebiotics, fructooligosaccharides (FOS), galactooligosaccharides (GOS), inulin, polydextrose (PDX), and resistant starch, in processed foods. These prebiotics were formulated into six prototype products (muffins, bread, cookies, sports beverage, nutrition bar, and breakfast cereal) using standard formulas. The effects of the prebiotics on physical properties (color, rate of staling, internal structure) were determined. Differences were observed for cookie and cereal browning for GOS, gas formation for FOS in bread, and for tackiness in the nutrition bars for FOS, GOS, and PDX. Analytical methods based on existing assays were also established. However, application of these tests to the processed foods showed matrix affects that compromised accuracy. Therefore, we are developing sample handling procedures and modifying the testing procedures to increase the accuracy for each system. Next, we validated that a prebiotic bioassay could be used to measure residual prebiotic activity in these products. The assay generates a prebiotic activity score based on the change in growth of a test strain of bacteria relative to growth of a control strain using the food as a substrate. For each prebiotic, suitable test and control strains were identified. Prebiotic activities for extruded breakfast cereal and the nutrition bar containing FOS were determined, giving scores within an expected range. The results obtained during this first year indicate that prebiotics can be incorporated into processed foods, but that color and texture may be affected. Prebiotic activity appears to be stable to the processing conditions we have evaluated, although more assays are now in progress.
Publications
- No publications reported this period
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