Progress 06/01/17 to 05/31/20
Outputs
Target Audience:During the whole project period, we have reached to the following target audiences: Agricultural and Food Industries: The research findings were reported multiple times at the Institute of Technologists (IFT) Annual Meeting, Southern California IFT Section events, and the 2018 Annual Meeting of The Society of Flavor Chemists towards a wide range of food industry audiences. Specifically, collaborations with Spira Inc. and T. Hasegawa USA Inc. were established. Besides, we also reached out to agricultural industries related to rice production, such as the California Rice Experiment Station. Scientific Community and Researchers: The project-related research was presented three times by the project PI and five times by the participating student at various national and local conferences. The PI organized an IFT symposium on Flavors of Food Protein Ingredients and their Applications in Product Formulation in 2018. The PI also traveled to and met with various scientists at the University of California, Davis, to discuss the projects. The audience reached by these efforts include scientists in both academia and industry that work with and/or are interested in proteins and flavors. Particularly, collaborations with multiple scientists reached at these occasions are established in an effort to write a book on Flavour and Consumer Perception of Food Proteins, which is edited by the project PI and is currently under contract with the Royal Society of Chemistry. Besides, the project was performed with the involvement of two scientists at the University of Kentucky and one scientist at San Diego State University and their students. Government agencies and research centers: The project-related research was introduced during the 2018 Kika De La Garza Fellowship training to all the participants and the USDA leaders. The research progress was also communicated to scientists at the USDA Western Regional Research Center located inAlbany, CA during the PI's visit at the center. Changes/Problems:The major change in the experimental approach from the proposal is that the sensory evaluation was only performed informally within the PI's research group due to the low protein yields we were able to collect from laboratory extraction. After analyzing other properties, a limited amount of protein samples was available for sensory study. Also, because the overall odor intensity of the laboratory-prepared protein powders was very low, as confirmed by the results ofgas chromatography-mass spectrometry, the PI determined that a formal sensory evaluation would not be necessary or informative. What opportunities for training and professional development has the project provided?One master student who was partially supported by this project and eight undergraduate students at Cal State LA were trained and performed research activities related to this project. The master student worked on this project as her master thesis research. The undergraduate students were trained and participated in the activities supported by this project. Student training included basic laboratory and research skills, protein extraction and characterization, proximate analysis of foods, e.g., moisture, fat, and protein contents, EPR sample preparation, data analysis, and written and oral communication of research results. The master student and three undergraduate students presented research related to this project at various national and local meetings for a total of 6 times. How have the results been disseminated to communities of interest?Results from this project have been disseminated to stakeholders through three primary avenues. Through scientific publication(s) in peer-reviewed journals, presented at national meetings to interested parties including the annual meeting of the Institute of Food Technologists (where attendees from both industry and academia were present). Furthermore, where appropriate, results from this project have been disseminated to U.S. food companies via direct contact by methods such as presentations, telephone conversations and e-mails. The information disseminated directly to private companies is primarily the same information presented at annual meetings and in publications, but provide in advance by as much as 9 months. Specific dissemination activities are listed below: Dr. Zhao has been actively involved in the Southern California Institute of Food Technologists Section (SCIFTS). Connections with protein companies, e.g. Spira Inc., T. Hasegawa USA Inc., SPI group, RiceBran Technology, and Profood International, have been established. Research findings have been communicated orally and through emails with interested groups. Dr. Zhao organized and presented in a scientific symposium on Flavors of Food Protein Ingredients and their Applications in Product Formulation at 2018 IFT. The symposium reached a significant number of industry and academic professionals that are interested in food proteins. The symposium also brought more attention to protein flavors as a determining factor in protein applications. Dr. Zhao has given oral presentations on related topics to professionals and students at the Society of Flavor Chemists annual meeting in 2018 and the April SCIFTS monthly meeting in 2018. The presentations increased the awareness of the research activities supported by the project. We have reached and held discussions with scientists at California Rice Experiment Station and a few rice farmers to disseminate our findings and ask for their input. We also reached and organized individual meetings with scientists at the University of California, Davis, and USDA Agricultural Research Services at Albany, CA, to establish potential collaborations. The PI and the graduate student who works on this project presented research findings at national and local meetings, including the 2018 Institute of Food Technologists (IFT) Annual Meeting, Southern California IFT monthly meeting, and California State University, Los Angeles student symposium to reach a wide range of audiences. Certain research results from the project have been used in Dr. Zhao's lectures in various courses, e.g., food chemistry, sensory evaluation of food products, and food proteins, to increase the awareness and interests of students to these research activities. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
The importance of plant proteins as food ingredients is growing due to the need of high-quality dietary proteins and their potential role in improving food security. Rice is the second largest cereal crop in the world. Besides using rice as a staple food, rice protein extracted from rice and rice processing by-products, e.g., rice bran and rice dreg (by-product of rice syrup production), has been more and more commonly used a food ingredient to meet the dietary protein requirement of increased population. Rice protein is hypoallergic, gluten-free, and completely vegan. These properties make rice protein suitable for potential applications in infant formula, gluten-free foods, and as a protein-enhancing ingredient in various food products, e.g., nutritional drinks, cereal snack foods, baked foods, and meat products. However, application of isolated rice protein is limited by its objectionable flavor and low solubility. The long term goal of this project is to improve the sensory attributes of rice protein isolates, therefore, increase their applications as food ingredients. This project investigated the odorants formation in rice proteins affected by the start materials and extraction methods. Protein radicals were analyzed using electron paramagnetic resonance and chemiluminescence in order to reveal the relationship between metastable radical levels and odorants formation.The results obtained from this project led to an awarded grant of $150,000, funded by the California State University Agriculture Research Institute, to study the use of rice ingredients in gluten-free products. Objective 1. To study the factors affecting the formation of metastable radicals in rice protein isolates during processing and storage. Major activities completed/experiments conducted: Rice protein samples were extracted from rice bran and germinated brown rice flour. Alkaline, Alcalase-assisted, and amylase assisted extraction methods were performed. The proximate compositions and functionalities of the extracts were examined. Metastable radicals in extracted rice proteins were analyzed using electron paramagnetic resonance spectroscopy (EPR). Results and discussion: The physical and functional properties of the extracted rice proteins, e.g., protein solubility, protein composition by sodium dodecyl sulfate polyacrylamide gel electrophoresis, and protein oxidation were characterized. Solubility of the extracted rice proteins exhibited a U-shaped curve with the lowest solubility at pH 4 and the highest solubility at pH 6 for alkaline- and amylase-extracted samples and pH 7 for Alcalase-extracted sample. At pH 4, protein solubility of alkaline-extracted sample (6.9%) was significantly lower (P<0.05) than amylase- (38.1%) and Alcalase-extracted samples (32.8%). Amylase-assisted extraction resulted in the highest level of radicals in rice bran protein as detected by EPR followed while alkaline extraction isoelectric precipitation resulted in the lowest level of radicals accumulated in the rice bran protein. In germinated rice bran protein, Alcalase-assisted extraction resulted in the lowest radical level while amylase-assisted extraction showed similar radical levels as in alkaline-extracted proteins. Key outcomes or other accomplishments realized: Enzyme-assisted extraction, especially using protease Alcalase, significantly increases rice protein extraction yield and the solubility of the resulting proteins. On the other hand, enzyme-assisted extraction increases the metastable radicals in the extracted rice bran proteins. Alcalase-assisted extraction resulted in a lower radical level in germinated brown rice protein compared to the other two extraction method. Objective 2. To investigate the consequences of the oxidative burst resulting from the released metastable radicals and their influence on protein sensory attributes. Major activities completed/experiments conducted: The influences of metastable radical content and hydration conditions on chemical luminescence of commercial rice proteins were investigated. Soy, pea and egg albumin proteins were analyzed for comparison. Sensory evaluation of the odor and taste of the extracted rice proteins and commercial rice proteins was performed by the trained group members. The odor profiles of the laboratory-prepared rice protein samples were characterized using gas chromatography-olfactometry-mass spectrometry (GC-O-MS) during a storage period of 8 weeks. Besides, we continued investigating the influences of metastable radical content and hydration conditions on chemical luminescence of commercial rice proteins. Results and discussion: Upon hydration, all proteins examined (rice, soy, pea, egg albumin) generated a rapid burst of luminescence (350-650 nm) in the absence of any added enhancers/stimulates. Rice proteins exhibited the greatest amount of luminescence ranging from 3- to 10-times more intense than other types of protein. Luminescence intensities were standardized against luminescence from quinine sulfate/H2O2 mixture. Hydrating proteins with 25 mM hydrogen peroxide increased the luminescence intensities from all proteins by 4- to 5-times compared to the intrinsic levels. Levels of metastable radicals in the powdered proteins were most abundant in the rice protein products which contained 3.87 × 1016 - 61.69 × 1016 spins per gram. Based on peak shape, g-value (2.0050 ± 0.0003) and the power saturation (4-8 mW), these radicals were identified as carbon-centered radicals. The intrinsic luminescence is correlated to the amounts of metastable radicals (including all protein sources examined) with a R-value of 0.878. Overall, the amount of odor compounds in the laboratory-prepared rice protein samples was low and significantly lower compared to commercial samples, even though slight differences among the samples stored for different periods of time were detected. A major cause for the low levels of odor compounds in laboratory-prepared samples compared to commercial rice protein could be the difference in drying methods. In the industry, spray drying is the method of use while lab samples were all freeze-dried. The avoid of heat during drying process could be the major reason for the reduced odor formation. Intrinsic chemical luminescence, and the spectral characterization of the luminescence, from hydrated rice protein concentrates were investigated for the first time. Comparison between the levels of metastable radicals in the powdered rice proteins and oxidative bursts resulting from the release of metastable radicals (as measured by luminescence) exhibited a good correlation, which suggests that the metastable radicals in the protein powder could be the cause of chemical luminescence and related oxidation reactions. Key outcomes or other accomplishments realized: The metastable radicals in the protein powder could be the cause of chemical luminescence and related oxidation reactions. Drying method of protein samples may significantly affect their odor properties. Freeze-dried rice protein extracts had low off-odors.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Costa-Lima, B., Zhao, J., & Boatright, W. L. (2018). Chemically stimulated luminescence from food proteins. Cereal Chemistry, 95(6), 881-888.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Zhao J. (2018). Odor compounds and their formation in rice protein. Oral presentation in Flavors of Food Protein Ingredients and their Applications in Product Formulation symposium at the Annual Meeting of the Institute of Food Technologists, July 2018, Chicago, IL, USA.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Zhao, J. (2018). Flavor compounds and their formation in food proteins. Invited keynote talk at 2018 Society of Flavor Chemist Annual Meeting, January 18th, 2018, Los Angeles, CA, USA.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Salami E, Vanegas P, Liu C, & Zhao J. (2018). Solubility and antioxidant activities of rice bran proteins prepared from three extraction methods. Annual Meeting of the Institute of Food Technologists, July 2018, Chicago, IL, USA.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Salami, E., Zhao, J., & Liu, C. (2019). Functional properties of germinated brown rice protein extracted from three methods. Annual Meeting of the Institute of Food Technologists, June 25, 2019, New Orleans, LA, USA.
|
Progress 06/01/18 to 05/31/19
Outputs
Target Audience:The main target audience of the project are agricultural and food industries related to rice products production. Other target audiences include researchers, government agencies, and the public who consume rice protein-containing products. During this reporting period, we have reached to and held individual meetings with scientists at California Rice Experiment Station, University of California, Davis, and USDA Agricultural Research Services at Albany, CA. We have also connected and met with scientists who work in the industry that use rice protein ingredients. The PI and the graduate student who works on this project presented research findings at national and local meetings, including 2018 Institute of Food Technologists (IFT) Annual Meeting, Southern California IFT monthly meeting, and California State University, Los Angeles student symposium to reach a wide range of audiences. Changes/Problems:No changes in the objectives of the project was made or will be made. The drying method of rice protein samples will be changed from freeze-drying to a drying method involving heat to mimic industry practices using spray dryingdue to low levels of odorants detected in the current samples. What opportunities for training and professional development has the project provided?One master student who is partially supported by this project and five undergraduate students at Cal State LA have been trained by Dr. Zhao and are involved in the activities supported by the project. The students have been trained in basic laboratory and research skills, protein extraction and characterization, proximate analysis of foods, e.g., moisture, fat, and protein contents, data analysis, and written and oral communication of research results. Two of the students, one master and one undergraduate student, have presented their research findings related to this project at the Cal State LA Annual Research, Scholarship, and Creative Activities Student Symposium. Their research abstract has been accepted to be presented at the Institute of Food Technologists (IFT) Annual Meeting in Chicago in both 2018 and 2019. How have the results been disseminated to communities of interest?1. Dr. Zhao has been actively involved in Southern California Institute of Food Technologists Section (SCIFTS). Connections with protein companies, e.g., SPI group, RiceBran Technology, and Profood International, have been established at the monthly meetings. Research findings have been communicated orally with interested groups. 2. We have reached to and held discussions with scientists at California Rice Experiment Station and a few rice farmers to disseminate our findings and ask for their input. 3. We also reached to and organized individual meetings with scientists at University of California, Davis, and USDA Agricultural Research Services at Albany, CA, to establish potential collaborations. 4. The PI and the graduate student who works on this project presented research findings at national and local meetings, including 2018 Institute of Food Technologists (IFT) Annual Meeting, Southern California IFT monthly meeting, and California State University, Los Angeles student symposium to reach a wide range of audiences. 5. Certain research results from the project have been used in Dr. Zhao's lectures in various courses, e.g., food chemistry, sensory evaluation of food products, and food proteins, to increase the awareness and interests of students to these research activities. What do you plan to do during the next reporting period to accomplish the goals?We plan to change the drying method of the laboratory-prepared rice protein samples to mimic the industry practice and therefore making the results more relevant to commercial rice protein products. Besides, we will continue to the sensory evaluation study proposed in the project after the instrumental analyses portion is completed.
Impacts
What was accomplished under these goals?
Objective 1. To study the factors affecting the formation of metastable radicals in rice protein isolates during processing and storage. 1) Major activities completed/experiments conducted: Rice protein samples are extracted in Dr. Zhao's laboratory at Cal State LA using rice bran and germinated brown rice flour. Alkaline, Alcalase-assisted, and amylase assisted extraction methods were performed. The proximate compositions and functionalities of the extracts were examined. Metastable radicals in extracted rice proteins were analyzed using electron paramagnetic resonance spectroscopy (EPR). 2) Results and discussion: The physical and functional properties of the extracted rice proteins, e.g., protein solubility, protein composition by sodium dodecyl sulfate polyacrylamide gel electrophoresis, and protein oxidation have been characterized. Solubility of the extracted rice proteins exhibited a U-shaped curve with the lowest solubility at pH 4 and the highest solubility at pH 6 for alkaline- and amylase-extracted samples and pH 7 for Alcalase-extracted sample. At pH 4, protein solubility of alkaline-extracted sample (6.9%) was significantly lower (P<0.05) than amylase- (38.1%) and Alcalase-extracted samples (32.8%). Amylase-assisted extraction resulted in the highest level of radicals in rice bran protein as detected by EPR followed while alkaline extraction isoelectric precipitation resulted in the lowest level of radicals accumulated in the rice bran protein. In germinated rice bran protein, Alcalase-assisted extraction resulted in the lowest radical level while amylase-assisted extraction showed similar radical levels as in alkaline-extracted proteins. 3) Key outcomes or other accomplishments realized: Enzyme-assisted extraction, especially using protease Alcalase, significantly increases rice protein extraction yield and the solubility of the resulting proteins. On the other hand, enzyme-assisted extraction increases the metastable radicals in the extracted rice bran proteins. Alcalase-assisted extraction resulted in a lower radical level in germinated brown rice protein compared to the other two extraction method. Objective 2. To investigate the consequences of the oxidative burst resulting from the released metastable radicals and their influence on protein sensory attributes. 1) Major activities completed/experiments conducted: The odor profiles of the laboratory-prepared rice protein samples were characterized using gas chromatography-olfactometry-mass spectrometry (GC-O-MS) during a storage period of 8 weeks. Besides, we continued investigating the influences of metastable radical content and hydration conditions on chemical luminescence of commercial rice proteins. 2) Results and discussion: Overall, the amount of odor compounds in the laboratory-prepared rice protein samples was low and significantly lower compared to commercial samples, even though slight differences among the samples stored for different periods of time were detected. A major cause for the low levels of odor compounds in laboratory-prepared samples compared to commercial rice protein could be the difference in drying methods. In the industry, spray drying is the method of use while lab samples were all freeze-dried. The avoid of heat during drying process could be the major reason for the reduced odor formation. Intrinsic chemical luminescence, and the spectral characterization of the luminescence, from hydrated rice protein concentrates were investigated for the first time. Comparison between the levels of metastable radicals in the powdered rice proteins and oxidative bursts resulting from the release of metastable radicals (as measured by luminescence) exhibited a good correlation, which suggests that the metastable radicals in the protein powder could be the cause of chemical luminescence and related oxidation reactions. 3) Key outcomes or other accomplishments realized: Drying method of protein samples may significantly affect their odor properties. Further study is needed to understand the impact of different drying methods.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Costa?Lima, B., Zhao, J., & Boatright, W. L. (2018). Chemically stimulated luminescence from food proteins. Cereal Chemistry, 95(6), 881-888.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2019
Citation:
Salami, E.; Zhao, J.; Liu, C. Functional properties of germinated brown rice protein extracted from three methods. Poster presentation accepted for presentation at IFT19 in New Orleans, LA, USA from June 25, 2019.
|
Progress 06/01/17 to 05/31/18
Outputs
Target Audience:The main target audiences of the project are agricultural and food industries related to rice products production. Other target audiences include researchers, government agencies, and the public who consume rice protein containing products. Food industries that focus on protein products or utilize protein ingredients in their products can use the results obtained from this study to improve their processing technology and storage conditions to achieve improved product quality. Researchers and government agencies could use the information for research or education related activities as well as for policy making. Consumers will be involved in the sensory evaluation study in this project. Their opinions are important and determine the targets of flavor modification. Changes/Problems:A few difficulties have been encountered during the first year of the project. The problems and the corresponding actions we plan to take in the following year are listed below: We proposed to use rice dreg, a product from rice syrup production, as a start material in this project. However, we have not been able to get the rice dreg materials either from the market or rice syrup producers. Rice dreg will be dropped out of the project due to unavailability. The subcontract between the PI and Co-PI's institutions was not agreed on until February 2018, eight months after the project's start date, which impacted the rate of expenditure from Co-PI's laboratory. The project progress was not affected by this delay since majority of the research in the first year of the project was scheduled to be done at Cal State LA. And we have a submitted journal article from the work done at the University of Kentucky. What opportunities for training and professional development has the project provided?One master student who is partially supported by this project and five undergraduate students at Cal State LA have been trained by Dr. Zhao and are involved in the activities supported by the project. The students have been trained in basic laboratory and research skills, protein extraction and characterization, proximate analysis of foods, e.g., moisture, fat, and protein contents, data analysis, and written and oral communication of research results. Two of the students, one master and one undergraduate student, have presented their research findings related to this project at the Cal State LA Annual Research, Scholarship, and Creative Activities Student Symposium. Their research abstract has been accepted to be presented at the Institute of Food Technologists (IFT) Annual Meeting in Chicago in July, 2018. How have the results been disseminated to communities of interest? Dr. Zhao has been actively involved in Southern California Institute of Food Technologists Section (SCIFTS). Connections with protein companies, e.g., SPI group, RiceBran Technology, and Profood International, have been established at the monthly meetings. Research findings have been communicated orally with interested groups. Dr. Zhao has given oral presentations on related topics to professionals and students at the Society of Flavor Chemists annual meeting in Jan., 2018 and the April SCIFTS monthly meeting in 2018. The presentations increased the awareness of the research activities supported by the project. Certain research results from the project have been used in Dr. Zhao's lectures in various courses, e.g., food chemistry, sensory evaluation of food products, and food proteins, to increase the awareness and interests of students to these research activities. What do you plan to do during the next reporting period to accomplish the goals?In the next project year, the following activities will be continued or initiated to accomplish the goals and objectives of the project: GC-MS analysis of odorants in commercial and laboratory extracted rice proteins; Radical characterization and quantificationusing EPR; Oxidation characteristics, e.g., chemiluminescence emitted during hydration, carbonyl formation during storage, and other oxidative indicators of thelaboratory preparedrice proteins. Sensory evaluation ofcommercial and laboratory extracted rice proteins using a trained sensory panel.
Impacts
What was accomplished under these goals?
The importance of plant proteins as food ingredients is growing due to the need of high-quality dietary proteins and their potential role in improving food security. Rice is the second largest cereal crop in the world. Besides using rice as a staple food, rice protein extracted from rice and rice processing by-products, e.g., rice bran and rice dreg (by-product of rice syrup production), has been more and more commonly used a food ingredient to meet the dietary protein requirement of increased population. Rice protein is hypoallergic, gluten-free, and completely vegan. These properties make rice protein suitable for potential applications in infant formula, gluten-free foods, and as a protein-enhancing ingredient in various food products, e.g., nutritional drinks, cereal snack foods, baked foods, and meat products. However, application of isolated rice protein is limited by its objectionable flavor and low solubility. The long term goal of this project is to improve the sensory attributes of rice protein isolates, therefore, increase their applications as food ingredients. We hypothesized that the odorants formation in rice proteins is affected by the start materials (e.g., rice bran, germinated brown rice, or rice dreg) and the extraction methods (alkaline extraction which is the standard method and enzyme-assisted methods) of the rice protein. The start materials and the extraction methods determines the rice protein purity, residual lipid content, and mineral contents, which in turn affect the formation and stabilization of metastable radicals in the protein powder. When protein powder is hydrated, the metastable radicals would be released and catalyzes oxidative reactions that generate the odor compounds. In the first part of the project, rice protein samples are extracted in Dr. Zhao's laboratory at Cal State LA using rice bran and germinated brown rice flour. Alkaline, Alcalase-assisted, and amylase assisted extraction methods were performed. The physical and functional properties of the extracted rice proteins, e.g., protein solubility, protein composition by sodium dodecyl sulfate polyacrylamide gel electrophoresis, and protein oxidation have been characterized. The metastable radical levels in the extracted rice protein samples during storage are under analysis. The relationship between metastable radical contents and chemical luminescence in commercial rice proteins are investigated under the supervision of Dr. Boatright (Co-PD) at the University of Kentucky. By revealing the relationship between metastable radical levels, odorants formation, and rice processing conditions, potentialsolutions can be provided to improve the flavor properties of rice protein products. Objective 1. To study the factors affecting the formation of metastable radicals in rice protein isolates during processing and storage. Major activities completed/experiments conducted: Rice protein samples are extracted in Dr. Zhao's laboratory at Cal State LA using rice bran and germinated brown rice flour. Alkaline, Alcalase-assisted, and amylase assisted extraction methods were performed. Metastable radicals in extracted rice proteins are analyzed using electron paramagnetic resonance spectroscopy (EPR) during storage of up to 8 weeks. Results and discussion: Enzyme assisted methods significantly increased the yield of rice bran protein extraction from 3.7% (alkaline extraction) to 4.8% by amylase-assisted extraction and 13.5% by Alcalase-assisted extraction. Similarly results were found in germinated brown rice protein. The physical and functional properties of the extracted rice proteins, e.g., protein solubility, protein composition by sodium dodecyl sulfate polyacrylamide gel electrophoresis, and protein oxidation have been characterized. Solubility of the extracted rice proteins exhibited a U-shaped curve with the lowest solubility at pH 4 and the highest solubility at pH 6 for alkaline- and amylase-extracted samples and pH 7 for Alcalase-extracted sample. At pH 4, protein solubility of alkaline-extracted sample (6.9%) was significantly lower (P<0.05) than amylase- (38.1%) and Alcalase-extracted samples (32.8%). The EPR results are still under collection and analysis. Key outcomes or other accomplishments realized: Enzyme-assisted extraction, especially using protease Alcalase, significantly increases rice protein extraction yield and the solubility of the resulting proteins. Objective 2. To investigate the consequences of the oxidative burst resulting from the released metastable radicals and their influence on protein sensory attributes. Major activities completed/experiments conducted: The influences of metastable radical content and hydration conditions on chemical luminescence of commercial rice proteins were investigated. Soy, pea and egg albumin proteins were also analyzed as comparisons. Besides, preliminary testing has been performed on the sensory (odor and taste) properties of the laboratory extracted rice proteins. Rice protein samples have been prepared for gas chromatography-mass spectrometry (GC-MS) analysis of the odorants. The GC-MS experiments are scheduled to be done in July and August, 2018 after timed storage. Results and discussion Upon hydration, all proteins examined (rice, soy, pea, egg albumin) generated a rapid burst of luminescence (350-650 nm) in the absence of any added enhancers/stimulates. Rice proteins exhibited the greatest amount of luminescence ranging from 3- to 10-times more intense than other types of protein. Luminescence intensities were standardized against luminescence from quinine sulfate/H2O2 mixture. Hydrating proteins with 25 mM hydrogen peroxide increased the luminescence intensities from all proteins by 4- to 5-times compared to the intrinsic levels. Levels of metastable radicals in the powdered proteins were most abundant in the rice protein products which contained 3.87 × 1016 - 61.69 × 1016 spins per gram. Based on peak shape, g-value (2.0050 ± 0.0003) and the power saturation (4-8 mW), these radicals were identified as carbon-centered radicals. The intrinsic luminescence is correlated to the amounts of metastable radicals (including all protein sources examined) with a R-value of 0.878. Key outcomes or other accomplishments realized: Intrinsic chemical luminescence, and the spectral characterization of the luminescence, from hydrated rice protein concentrates were investigated for the first time. Comparison between the levels of metastable radicals in the powdered rice proteins and oxidative bursts resulting from the release of metastable radicals (as measured by luminescence) exhibited a good correlation, which suggests that the metastable radicals in the protein powder could be the cause of chemical luminescence and related oxidation reactions.
Publications
- Type:
Journal Articles
Status:
Submitted
Year Published:
2018
Citation:
Costa-Lima B, Zhao J, Boatright WL. Chemically stimulated luminescence from food proteins. Manuscript submitted to Cereal Chemistry on 5/16/2018.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2018
Citation:
Zhao J. 2018. Odor compounds and their formation in rice protein. Oral presentation in Flavors of Food Protein Ingredients and their Applications in Product Formulation symposium at the Annual Meeting of the Institute of Food Technologists, July 2018, Chicago, IL, USA.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2018
Citation:
Salami E, Vanegas P, Liu C, Zhao J. 2018. Solubility and antioxidant activities of rice bran proteins prepared from three extraction methods. Annual Meeting of the Institute of Food Technologists, July 2018, Chicago, IL, USA.
|
|