Progress 10/01/09 to 09/30/14
Outputs
Target Audience: Academic researchers, students, and industrial personnel in the food and related area. In addition, the PI joined the Center for Pharmaceutical Processing Research (CPPR) in Pharmacy College of Purdue University, which allowed for additional communications with researchers, students, and industrial representatives in the pharmaceutical area. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? (1) Mentored 5 Ph.D. students (2 graduated), 4 visiting scholars (2) Co-instructed the class of Carbohydrates (FS 63000, 3 credits, graduate) (3) Instructed the class of Case Study (FS 55500, 1 credit, graduate) (4) Provided lecture for the class of Food Ingredients (FS 53000) (5) Co-lectured for the industrial short course hosted by the Whistler Center for Carbohydrate Research How have the results been disseminated to communities of interest? (1) Through the Whistler Center for Carbohydrate Research: (1) attended two meetings (board meeting and focus meeting) to report research outcomes and discuss research directions, (2) joined industrial short course to lecture on specific topics (polyols, sweeteners, and modified starch) (2) Through the Center for Pharmaceutical Processing Research (CPPR): proposal presentation to industry representatives (3) Through 2014 IFT annual meeting: invited talk for a symposium What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
(1) Progress has been made with a high-risk, high-return project of high throughput screening of cereal grains for new carbohydrates and enhanced nutrients. The long-term goal is to identify, from thousands of potential mutations, the genetic traits that may provide enhanced value for food and health. (2) Substantial progress has been made to use carbohydrate-based colloidal systems to deliver antimicrobial compounds for improved food safety. (3) Substantial progress has been made to use sustainable biomaterials to stabilize and deliver bioactive ingredients including food nutrients and pharmaceutical ingredients.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
Bordenave N, Janaswamy S, Yao Y. 2013. Influence of glucan structure on the swelling and leaching properties of starch microparticles. Carbohydrate Polymers, 103: 234-243
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Progress 10/01/12 to 09/30/13
Outputs
Target Audience: In the year of 2012-2013, the target audiences of this project included researchers, students and industrial personnel in the food area. In addition, the PI joined the Center for Pharmaceutical Processing Research (CPPR) in Pharmacy College of Purdue University, which allowed for additional communications with researchers, students, and industrial representatives in the pharmaceutical area. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? (1) Mentoring 4 graduate students (3 Ph.D., 1 MS), 3 undergraduate students, and 1 visiting scholar; (2) Co-instructed classes of Carbohydrates (FS 63000, 3 credits, graduate) and Case Study (FS 55500, 1 credit, graduate); (3) Provided invited lecture for the class of Food Ingredients FS 53000; (4) Co-lectured for the industrial short course hosted by the Whistler Center for Carbohydrate Research. One of the PI’s Ph.D. students, Preetam Sarkar, was awarded the 3rd position in the Carbohydrate Division competition in the 2013 IFT annual meeting (July 2013) with his poster presentation “Starch octenyl succinate stabilized emulsion for the protection of nisin activity in a cantaloupe juice food model”. How have the results been disseminated to communities of interest? Through the Whistler Center for Carbohydrate Research: (1) attended two meetings (board meeting and focus meeting) to report research outcomes and discuss research directions, (2) joined industrial short course to lecture on specific topics (polyols, sweeteners); Through the Center for Pharmaceutical Processing Research: proposal presentation to industry representatives; Through 2013 IFT annual meeting: poster presentation. What do you plan to do during the next reporting period to accomplish the goals? There are several activities in plan for the next reporting period: (1) submitting research manuscripts, (2) submitting proposals to federal agencies (NIFA, NSF, or NIH), (3) graduating 2 Ph.D. students, (4) recruiting 2 Ph.D. students, and (5) accepting 2-3 visiting scholars.
Impacts
What was accomplished under these goals?
(1) Under the support of the Whistler Center for Carbohydrate Research, a new project is being initiated to create, screen, and characterize cereal mutants for carbohydrate polymers (e.g. starch) with altered structure and properties. With current plan, this will be a 3-year project with cereal grains containing new genetic traits as deliverables. (2) Progress has been made to use carbohydrate-based colloidal systems to deliver antimicrobial compounds for improved food safety. A NIFA grant with Food Safety program was awarded on reducing the bacterial load of fresh and fresh-cut produce, using cantaloupe as a model system. (3) Progress has been made to use carbohydrate-based biomaterials to stabilize and deliver bioactive ingredients. An NSF grant has been awarded to study the structure and functions of these biomaterials for drug delivery.
Publications
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Progress 10/01/11 to 09/30/12
Outputs
OUTPUTS: This project has contributed to several research activities: (1) application of carbohydrates to stabilize and protect bioactive ingredients, such as food nutrients, nutraceuticals, or drugs, (2) delivery of antimicrobial compounds against food pathogens in food systems, such as fresh and fresh-cut produce, and (3) advanced characterization of phytoglycogen structure. During this period of time, intellectual property has been a primary form of research output, with research publications planned to follow. A collaborative work on switchgrass, an energy crop has led to research publication. PARTICIPANTS: Yuan Yao, PI, Department of Food Science, Purdue University. His role was to supervise the project and direct the work on the preparation and characterization of carbohydrate-based, functional materials. Arun Bhunia, Co-PI, Department of Food Science, Purdue University. His role was to direct the work related to microbiological tests. Ganesan Narsimhan, Co-PI, Department of Agricultural and Biological Engineering. His role was to advise the work related to the analysis of nanoparticles. Yiwei Jiang, Co-PI, Department of Agronomy. His was the collaborator in a research related to switchgrass. Hua Chen, graduate student of the Department of Food Science. Her role was to study the branching structure of carbohydrate nanoparticles, and the interaction between carbohydrates and polyphenols. Preetam Sarkar, graduate student of the Department of Food Science. His role was to study the protection and delivery of antimicrobial compounds. Ying Xie, graduate student of the Department of Food Science. Her role was to study the stabilization and delivery of nutraceuticals and drugs. Randol Rodriguez, graduate student of the Department of Food Science. His role was to study the complexation between bioactive ingredients and carbohydrates. TARGET AUDIENCES: The audiences include academic researchers such as faculty members and students in the areas of food safety, nanotechnology, biomaterials, food chemistry, and pharmacy. The audiences also include personnel from the food and pharmaceutical industries and agencies related to food safety. The efforts include meeting presentations, Whistler Center reports, and patent application. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
One of the major causes of food borne illnesses has been the fresh produce. The year 2011-12 has seen a number of outbreaks and recalls in the fresh produce category. These included E. coli O157: H7 in strawberries in Oregon, Listeria monocytogenes in chopped lettuce in California, Listeria monocytogenes outbreak with cantaloupes in 26 states, and Salmonella outbreak with cantaloupes in 24 states. An effective strategy to reduce the risk of food pathogens would have profound impact on the society. Antimicrobial peptide nisin is effective to inhibit Gram-positive pathogens such as Listeria monocytogenes and in the presence of other antimicrobial compounds, also effective against Gram-negative pathogens such as Salmonella. However, nisin can be quickly degraded by the components in food, such as proteases in fresh produce. To address this problem, we have started a study on cost-effective and functional antimicrobial formulations for prolonged efficacy against both Gram-positive and negative bacteria. In the area of food quality and nutrition, we are developing carbohydrate-based systems to stabilize and deliver nutrients such as polyphenols. These bioactive compounds are highly important to the diet and food supplements. However, their bioavailability is limited by their instability in aqueous systems. The systems we have developed have shown substantial protecting effects on these compounds.
Publications
- Jiang Y, Yao Y, Wang Y. 2012. Physiological response, cell wall components, and gene expression of switchgrass under short-term drought stress and recovery. Crop Science, 52: 2718-2727
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Progress 10/01/10 to 09/30/11
Outputs
OUTPUTS: This project has contributed to several activities and initiatives: (1) the study of using carbohydrate-based nanomaterials to stabilize antimicrobial peptides, (2) better understanding of phytoglycogen molecular structure, and (3) Food Nanotechnology workshop. Research publications, meeting presentations, and a workshop have been used to communicate and disseminate the research outcome to the scientific community and general public. Two symposiums were organized by the PI in the 2011 IFT annual meeting to focus on carbohydrate and nanotechnologies. Particularly, a workshop on Food Nanotechnology (Oct. 25-26, 2011, Purdue) was organized by the PI with nearly 40 participants from academia, governmental agencies (USDA, FDA), non-profit organization (IFT), and the industry (food and related companies). PARTICIPANTS: Yuan Yao, PI, Department of Food Science, Purdue University. His role was to supervise the project and direct the work on the preparation and characterization of carbohydrate-based nanomaterials. Arun Bhunia, Co-PI, Department of Food Science, Purdue University. His role was to direct the work related to microbiological tests. Ganesan Narsimhan, Co-PI, Department of Agricultural and Biological Engineering. His role was to advise the work related to analysis of nanoparticles. Lin Bi, graduate student of the Department of Food Science. Her role was to prepare carbohydrate nanoparticles and conduct microbiological tests. Hua Chen, graduate student of the Department of Food Science. Her role was to study the branching structure of phytoglycogen nanoparticles. Preetam Sarkar, graduate student of the Department of Food Science. His role was to study the mechanism of peptide-nanoparticle interactions. TARGET AUDIENCES: The audiences include academic researchers such as faculty members and students in the areas of food safety and microbiology, bionanotechnology, and food chemistry. The audiences also include personnel from the food industry and agencies related to food safety and nutrition. The efforts include meeting presentations, papers, workshops, and Whistler Center reports. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
In the US, 48 million people get sick due to foodborne illness with 128,000 hospitalizations and 3,000 deaths (CDC, 2011), leading to an economic loss of $152 billion. An effective strategy to reduce the risk of food pathogens will have profound impact to the society and help to save lives. Antimicrobial peptides such as nisin and epsilon-polylysine (EPL) are effective to inhibit foodborne pathogens including Listeria monocytogenes and E. coli O157:H7; however, these peptides are often subjected to rapid depletion and lose their activities quickly. To address this problem, we have developed several systems to stabilize antimicrobial peptides: (1) nanoparticle-nisin system against Listeria (as a model of Gram-positive bacteria), (2) nanoparticle-stabilized emulsion-nisin system against Listeria, and (3) nanoparticle-stabilized emulsion-EPL system against E. coli (as a model of Gram-negative bacteria). The first two systems have been studied earlier and shown superior properties to enhance antimicrobial efficacies. For the third system, the emulsion-EPL system also showed exciting effect to substantially enhance the efficacy of EPL against E. coli O157:H7. In addition, we have probed the molecular branch structure of phytoglycogen using beta-amylolysis. It was found that phytoglycogen shares some similarity to amylopectin on their placement of branch points. However, the lack of internal long chains and related cluster structure with phytoglycogen make beta-amylolysis more difficult than that for amylopectin. Particularly, it seems rather difficult to trim the DP4 stub to DP2 with exhaustive beta-amylolysis. This unique feature can be closely related to the highly dense structure of phytoglycogen.
Publications
- Bi, L., Yang, L., Bhunia, A., Yao, Y. 2011. Carbohydrate nanoparticle-mediated colloidal assembly for prolonged efficacy of bacteriocin against food pathogen. Biotechnology and Bioengineering, 108: 1529-1536
- Bi, L., Yang, L. Narsimhan, G., Bhunia, A., Yao, Y. 2011. Designing carbohydrate nanoparticles for prolonged efficacy of antimicrobial peptide. Journal of Controlled Release, 150: 150-156
- Huang, L., Yao, Y. 2011. Particulate structure of phytoglycogen nanoparticles probed using amyloglucosidase. Carbohydrate Polymers, 83, 1665-1671
- Yao, Y., Janaswamy, S. 2011. Gene dosage effect on starch structure studied using maize polygenic model containing ae and su1 mutant alleles. Food Chemistry, 125, 1153-1159
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Progress 10/01/09 to 09/30/10
Outputs
OUTPUTS: Five research papers were published (or accepted) and another two manuscripts in review, an additional three-year grant awarded by the National Science Foundation, a license being negotiated with a major food ingredient company for one of intellectual properties we have developed, and a news release in Dec. 2009 ("Nanoparticle Protects Oil in Foods from Oxidation, Spoilage") to introduce our work on food nanotechnology to the public. PARTICIPANTS: Dr. Arun Bhunia, Department of Food Science, 745 Agriculture Mall Drive, West Lafayette, IN 47907-2009, Phone: (765) 494-5443 Dr. Fernanda San Martin, Department of Food Science, 745 Agriculture Mall Drive, West Lafayette, IN 47907-2009, Phone: (765) 496-1140 Dr. Ganesan Narsimhan, Department of Agricultural and Biological Engineering, 745 Agriculture Mall Drive, West Lafayette, IN 47907-2009, Phone: (765) 494-1199 Training or professional development includes graduate students, an undergraduate student, and visiting scholars TARGET AUDIENCES: University faculty members, researchers, and students Industry personnel in the research and development PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
In the area of food nanotechnology, we are developing carbohydrate-based nano-materials which are food-based, economical, and with functional effectiveness. For example, we have transformed phytoglycogen, an alpha-D-glucan abundant in mutant maize, into amphiphilic and partially digestible carbohydrate nanoparticles, such as phytoglycogen octenyl succinate (PG-OS). Our work has shown that PG-OS has outstanding capabilities to prolong the efficacy of antimicrobial peptide and to protect polyunsaturated fatty acids from oxidation. These accomplishments have significant implications for enhanced food safety and quality. At the fundamental level, we have successfully elucidated the particulate structure of phytoglycogen, which not only helps to reveal the mechanism of starch genesis but also provides guidance for engineering phytoglycogen-based functional nanoparticles. In addition, we have made substantial progress in starch modifications for enhanced nutrition benefit. A combined enzymatic and physical modification was used to prepare resistant starch from normal corn starch, which may lead to reduced cost for preparing carbohydrates with modulated digestibility.
Publications
- Song, W., Janaswamy, S., Yao, Y. 2010. Structure and in vitro digestibility of normal corn starch: effect of acid treatment, autoclave, and β-amylolysis. Journal of Agricultural and Food Chemistry, 58: 9753-9758
- Scheffler, S.L., Huang, L., Bi, L., Yao, Y. 2010. In vitro digestibility and emulsification properties of phytoglycogen octenyl succinate. Journal of Agricultural and Food Chemistry, 58: 5140-5146
- Scheffler, S.L., Wang, X., Huang, L., San-Martin Gonzalez, F., Yao, Y. 2010. Phytoglycogen octenyl succinate, an amphiphilic carbohydrate nanoparticle, and epsilon-polylysine to improve lipid oxidative stability of emulsions. Journal of Agricultural and Food Chemistry, 58: 660-667
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Progress 10/01/08 to 09/30/09
Outputs
OUTPUTS: The past year has seen significant progresses in our research program. (1) Carbohydrate nanoparticles have been prepared and used to prolong the efficacy of bacteriocin (nisin) against food pathogen (Listeria monocytogenes). (2) Carbohydrate nanoparticles have been used to substantially enhance the oxidative stability of lipids, such as omega-3 fish oil in emulsion systems. (3) Starch has been treated by novel technologies to offer drastically increased resistant starch, a functional dietary fiber with outstanding health benefits. We have filed provisional patent applications, published 3 papers and have one NSF grant awarded. In addition, a number of projects are supported by industrial partners. PARTICIPANTS: Dr. Arun Bhunia, Department of Food Science, 745 Agriculture Mall Drive, West Lafayette, IN 47907-2009, Phone: (765) 494-5443 Dr. Ganesan Narsimhan, Department of Agricultural and Biological Engineering, 745 Agriculture Mall Drive, West Lafayette, IN 47907-2009, Phone: (765) 494-1199 Senay Simsek, Department of Plant Sciences, North Dakota State University, Fargo, ND 58108-6050, Phone: (701) 231-7737 TARGET AUDIENCES: University faculty members, researchers, and students Industry personnel in the research and development PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The impact of our research can be addressed from three aspects. (1) To prolong the release of antibacterial compounds is very important for enhanced food safety and extended shelf life of food. The strategy of using carbohydrate nanoparticles to complex antibacterial compounds may complement with regular active packaging approaches in a number of food products, such as deli meats. (2) Lipid oxidation is a major food quality problem due to the rancidity and even toxicity resulted. To use food-based ingredients to realize a much enhanced oxidative stability of lipid will have enormous benefits to the food industry, as well as other areas where lipid oxidation is a concern. (3) To produce functional food ingredients, such as resistant starch, in a cost-effective way is important to benefit more consumers. The methodology and technology developed in our lab has the potential to substantially reduce the cost of resistant starch by using regular starch instead of high-cost starting materials such as high amylose starch.
Publications
- Hickman, B.E., Janaswamy, S., and Yao, Y. Properties of starch subjected to partial gelatinization and beta-amylolysis. 2009, Journal of Agricultural and Food Chemistry, 57: 666-674
- Simsek, S., M.C. Tulbek, Y. Yao, and B. Schatz. Starch characteristics of dry peas (Pisum sativum L.) grown in the USA. 2009, Food Chemistry, 115, 832-838
- Hickman, B.E., Janaswamy, S., and Yao, Y. Autoclave and beta-amylolysis lead to reduced in vitro digestibility of starch. 2009, Journal of Agricultural and Food Chemistry, 57: 7005-7012
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Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: The past year has been very productive towards our goal of studying the biosynthesis, degradation, and modification of starch for food and non-food utilizations. A number of external grants (including industry and federal funding) were awarded. These projects are related to the modifications of starch and starch-related materials, and their applications in food and non-food areas. Particularly, we have made significant progress in the area of food nanotechnology. A group of novel materials, "dendritic carbohydrate polymers" have been designed and constructed, and their superior properties have been identified for nano-carriers of functional food compounds. These materials are prepared from mutant maize, in which the starch biosynthetic pathway was altered to generate nano-scale glucan particles with extremely high molecular density. After modifications, these nanoparticles were used to complex nisin for prolonged inhibition against Listeria monocytogenes and to form emulsion with superior stability against coalescence and oxidation. The outcomes have been very promising. One USDA funding was awarded in this area. Meanwhile, several manuscripts are being prepared. In addition, studies on starch structure and function have been very fruitful. Physical and enzymatic starch modifications have been applied on corn starch and wheat starch to prepare starch materials with modulated digestibility. This methodology will allow us to find a new way to generate resistant starch using low-cost starches. Beside this, the pasting behavior can be stabilized by a combined physical and enzymatic modification as well. Two papers will be submitted on this work. Associated with industrial applications, a number of projects are being conducted to use different types of modification to improve starch functionalities. PARTICIPANTS: Dr. Arun Bhunia, Department of Food Science, 745 Agriculture Mall Drive, West Lafayette, IN 47907-2009, Phone: (765) 494-5443 Dr. Ganesan Narsimhan, Department of Agricultural and Biological Engineering, 745 Agriculture Mall Drive, West Lafayette, IN 47907-2009, Phone: (765) 494-1199 TARGET AUDIENCES: University faculty members, researchers, and students Industry personnel in the research and development PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
In the food and food-related industries, there is high demand for nanotechnologies that can enhance the food safety, nutrition, and quality. Particularly, to design effective nano-constructs to deliver functional or bioactive compounds is of essential importance. Thus far, very few functional nano-constructs have been developed for food due to the high cost and non-food status of most materials designed for the non-food areas such as drug delivery. In our labs, exciting progress has been made in the research on the structure and functionalities of nanoparticles prepared from food-based dendritic carbohydrate polymers. Using different modifications, structural characteristics of nanoparticles can be manipulated. Several key applications are investigated. One application is to use nano-carriers for controlled release of nisin, with an aim to prolong the release of this anti-bacterial peptide against pathogen Listeria monocytogenes on food surface. This work may help to save lives from Listeria contaminations. Another application is to prepare nanoparticle-based emulsifiers that have superior capability to stabilize oil-in-water emulsions. These emulsifiers can be used to protect lipophilic compound such as omega-3 fatty acids. Resistant starch has the benefit of dietary fiber and offers prebiotic functionalities. Currently most resistant starches are prepared from the high-cost starch material: high amylose starch. Using normal corn starch or wheat starch to make resistant starch has the potential to reduce the cost and thus enhance the applications and benefits of resistant starch in foods.
Publications
- Shin J, Simsek S, Reuhs B, Yao Y. Glucose release of water-soluble starch-related alpha-glucans by pancreatin and amyloglucosidase is affected by the abundance of alpha-1,6 glucosidic linkages. 2008, Journal of Agricultural and Food Chemistry, online ASAP publication
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Progress 10/01/06 to 09/30/07
Outputs
OUTPUTS: Maize starch mutants were planted in the greenhouse for cross studies. The goal is to produce an array of genotypes in which the starch biosynthetic pathway is impacted, thus generating mutant starches with altered molecular structure and functions. This program is our primary effort of ongoing "Rational Design of Starch" strategy that incorporates the studies of starch biosynthesis, structure, and function. In the past year, we have constructed a full set of 16 combinations of ae and su1 allelic doses. With regard to their functions, ae and su1 mutations are two opposite extremes. Mutant ae leads to drastically reduced starch branching enzyme (SBE) activity and amylopectin branching. In contrast, su1 leads to reduced starch debranching enzyme (DBE) activity, enhanced amylopectin branching, and production of highly branched phytoglycogen. Therefore, ae and su1 constitute an excellent pair of alleles for engineering starch structure. Our results indicated that both starch
structure and granular morphology are affected by the ae and su1 doses in maize endosperm. Starches of homozygous ae, su1, and ae su1 show drastic differences from non-mutant starch. Starches of several other ae and su1 dosage combinations also show differences from non-mutant and homozygous mutants. For example, starch granule morphology (granular size, shape, and compound starch granules) from genotypes containing 3 doses of ae or su1 shows substantial differences from that of non-mutant. At 3 doses of su1, the ae dose (0, 1, 2, and 3) affects the amount of short branch chains. With an increase of ae dose, the amount of short chains is reduced. Paralleling with this progress, we have generated a number of segregating corn ears containing dosage combinations of ae, su1, and wx alleles. From these ears, kernels of specific genotypes will be identified to construct dosage combinations of ae, su1, and wx mutant alleles. In the past year, exciting progress has been made to create
rigorous micro-encapsulation systems using modified starch. Currently, encapsulation system with oil (lipophilic compound) as core material is resistant to water and hexane treatment, indicating the potential to use this type of micro-encapsulation system in food formulation and processing. The particle size of micro-capsules ranges from 10 to 100 microns. In this research, the development of a number of genetically, enzymatically, and chemically modified starches has been essential.
TARGET AUDIENCES: Starch chemists and maize breeders
Impacts
Our research in the area of rational design of starch is to establish a platform that guides the genetic manipulations of starch and related alpha-glucans. By understanding the relationship between branching and debranching during glucan assembling, the structure of starch can be tailored using mutant crosses (among ae, su1, and wx in our research) to achieve a wide spectrum of functionalities. Currently, among the functionalities of mutant starches we focus on the digestibility, i.e., the rate and extent of glucose release from starch when subjected to enzymatic hydrolyzation. Digestibility is a measure of carbohydrate nutrition, since it governs the glucose release in the gastrointestinal tract. Processing stability and targeted delivery of lipophilic nutrients, e.g. omega-3 fatty acids, are essential for their bioavailability and health benefit. In our research, we are developing a novel micro-encapsulation system that can protect lipophilic compounds. We expect
that micro-capsules thus prepared are resistant to heat, moisture, shear, and acidity, and that the nutrient release is triggered by enzyme erosion of shell that occurs in lower GI tract. The knowledge and technology established in this research will profoundly impact the delivery strategy and practice of lipophilic nutrients and other bioactive compounds. This research will create new opportunities in the food industry for incorporating valuable whereas unstable compounds into food formulation and processing and maintaining their bioavailability.
Publications
- No publications reported this period
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Progress 10/01/05 to 09/30/06
Outputs
Maize starch mutants were planted in the greenhouse for crossing studies. The goal is to produce an array of genotypes in which the starch biosynthetic pathway is impacted, thus generating mutant starches with altered molecular structure and functions. A comprehensive system that extracts, isolates, and characterizes starch branching enzymes (SBE), starch debranching enzymes (DBE), and starch synthases (SS) has been established. This system includes a preparative electrophoresis system by which enzyme isoforms can be isolated with high resolution, a high throughput microplate enzyme identification system to identify enzyme activities, and a native-PAGE-zymogram system to compare enzyme activity profiles from different maize genotypes. In addition, a systematic protocol has been established for quantitative enzyme profiling of SBE, DBE, SS, and alpha- and beta-amylases. Progress has been made to degrade starch using a novel high solid processing, which may lead to
reduced energy cost for ethanol production and other industries. We use high shear force, e.g., an extrusion process, to facilitate starch degradation under low moisture content (<30%) and low temperature (<80 degree C). Using the capillary rheometer as the model system of high shear controlling, synergistic effect was found among the shear rate and alpha-amylase during the degradation of starch with 30% moisture content. It was evident that, first, high shear rate allows for a significantly greater starch degradation at low temperatures (e.g., 70 degree C), and second, the glucose yield after amyloglucosidase treatment may be substantially improved by high shear treatment. This finding is important since high solid low temperature starch conversion can be used in an ethanol or corn refining plant to reduce the energy required for heating water. In addition, low temperature processing may improve the quality of co-products from corn meal. Research on starch modification has been very
fruitful. Two papers are in preparation, and one poster and one oral presentation were given in the AACC 2006 conference. In addition, a provisional patent application was filed. Briefly, our group has discovered that glucans with enhanced branching leads to reduced digestibility, no mater if the starch materials are genetically modified, like phytoglycogens, or enzymatically modified, like highly branched malto-oligosaccharides extracted from regular starches. To establish the enzyme digestibility of phytoglycogen, a variety of commercial sweet corns were collected, and those containing su1 gene were used to extract phytoglycogen, a type of soluble highly branched alpha-glucan found in starch-deficient maize genotypes. In vitro enzyme digestibility of phytoglycogen was found to be significantly lower than that of starch. Meanwhile, using a proprietary process, highly branched malto-oligosaccharides were extracted. Their molecular weight distribution, branch density, and digestibility
were measured. The results showed that their digestibility is negatively correlated with branch density.
Impacts
Generally, our research is to establish a platform that guides the genetic and chemical manipulations of starch and related alpha-glucans. By understanding the relationship between branching and debranching during glucan assembling, the structure of starch can be tailored using mutant crossing (between ae and su1 in our research) to achieve a wide spectrum of functionalities. Currently, among the functionalities of mutant starches we focus on the digestibility, i.e., the rate and extent of glucose release from starch when subjected to enzymatic hydrolyzation. Digestibility is a measure of carbohydrate nutrition, since it governs the glucose release in the gastrointestinal track. In an effort to manipulate glucan digestibility, we also identified a group of commercial sweet corns that produce glucans of reduced digestibility. We are exploring an efficient strategy to reduce energy consumption required by starch-to-glucose conversion. Our current progress of high solid,
low temperature starch processing is very important, since it proves the concept of reducing the amount of water needed to cook starch, and minimizing the energy needed to heat water. An industrial application of this concept will possibly reduce the energy consumption of an ethanol plant by 10%. In addition, it may provide an approach to improve the quality of co-product from corn meal residuals, thus enhance the entire economy of ethanol industry.
Publications
- Patent Application US60/798,576. Y. Yao. Process and carbohydrate product having controlled digestibility. 2006
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