Progress 01/01/14 to 12/31/17
Outputs
Target Audience:During the course of the project, we have reached companies (e.g. BASF) that produce products to improve food quality by incorporating lipophilic bioactives into foods. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?This project graduated one PhD student, who was recently successful in obtaining a USDA post-doctoral fellowship by proposing continuing work in stabilizing lipophilic bioactives-loaded CLAMs. Several undergraduate students have also benefitted from traiing on this project. How have the results been disseminated to communities of interest?Results from this project have been disseminated primarily by presentations at conferences (ACS, ASABE and Controlled Release Society)and our peer-reviewed paper. We havemore manuscripts in preparation from this project that will be submitted in the near future. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
This project established the UC Davis Cross-Linked Alginate Mircrocapsule (CLAMs) technology as an industrially-scalable technology for stabilizing and enteric delivery of lipophilic bioactives. Through this project, CLAMs formulation was improved and optimized to form 10-15 micrometer powder particles containing up to 35% (d.b.) oil. We found and demonstrated that the surfactant type (e.g. Tween80 or Whey Protein Isolate) plays a significant role in the oxidative stability of the lipophilic cargo over time. Shelf-life studies show that microencapsulation of omega-3 fatty acids in CLAMs extends shelf life, and parameters such as matrix composition and surfactants impact shelf-life. Preliminary techneconomic analyses show that as expected, the CLAMs process has a higher throughput and lower production cost of the final product. One reason is the streamlined CLAMs process that requires only two unit operations (emulsification and spray drying) while conventional processes require several unit operations(emulsification, extrusion with curing time, separation, drying). Another reason is the minimization of water usage in the CLAMs process. The technoeconomic analyses, recently completed using a commercial software (SuperPro designer), is currently being written up to be submitted for publication.
Publications
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2017
Citation:
Strobel, S., Arbaugh, B., Hudnall, K., Scher, H., Nitin, N., Jeoh, T. Stability of fish oil in cross-linked alginate microcapsules prepared by spray-drying. August 20, 2017. 254th ACS National Meeting, Washington, D.C. Oral Presentation.
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Progress 01/01/17 to 12/31/17
Outputs
Target Audience:
Nothing Reported
Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?During this period, one graduate student completed his PhD dissertation that was based on this project. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Nutrients such as omega-3 fatty acids, vitamin E, or even essential oils are hydrophobic bioactive compounds that can confer health benefits when integrated into foods. These compounds, however, degrade easily and rapidly on the shelf ifnot protected. Microencapsulation of bioactive compounds has been widely demonstrated to be effective at extending the shelf-life of sensitive ingredients; however, there has been an unmet need to develop industrially-scalable and econcomically viable processes to encapusulate bioactive compounds. The UC Davis patented process to encapsulate bioactives in cross-linked alginate microcapsules (CLAMs) by spray drying is promising in its industrial scalability and favorable microcapsule properties. This research specifically investigates the technical and cost effectivenessof this process to encapsulate and stabilizehydrophobic bioactives in CLAMs. This project was carried out at UC Davis under the direction of Prof. Tina Jeoh and Dr.Herb Scher. The project involved graduate and undergraduate students and a post-doctoral researcher. We have demonstrated that the UC Davis CLAMs process has the advantage of being a simple, one step process that achieves in excess of 35% oil loading (on a dry microcapsule mass basis) by spray drying, a unit operation that is ubiquitous in the food industry. The particles loaded with oil are generally round and small, with average diameters of about 10 micrometers.In contrast, conventional processes require multiple process steps that are costly to scale and are limited to larger particles greater than 100 micrometers in diameter under the best case scenario. These particle sizes are sufficiently large such that their texture are noticeablein (e.g.) beverages. The major accomplishment in this final period of the project was for the 4th goal - to evaluate the economics of the microencapsulation process. We developed process models were developed using a commercial software, SuperPro, to evaluate the process econcomics of the 'UC Davis CLAMs process'. With these process models, we demonstrate that the cost of microencapuslation using the UC Davis CLAMs process is at least half the cost of a comparable conventional process. Moreover, that increasing processing scales improve the economics of the UC Davis CLAMs process. This project focused on encapsulating hydrophobic food ingredients as one advantage of CLAMs (as shown as part of the third goal of the project) is the controlled release through the gastrointestinal tract. CLAMs retain cargo in the acidic stomach environment but fully release in the intestinal environment where the nutrients are most effectively taken up by the body. This technology, however, has broader implications in agricultural and industrial applications. Major accomplishments for each goal in this period: 1) to optimize the formulation to maximize lipid loading in the particles, maximize spray-drying yields, minimize oxidation and optimize particle sizes and morphology; None in this period. 2) to evaluate the stability of the encapsulated lipid phase to oxidation at varying storage times and conditions and characterize the kinetics of oxygen transport in the alginate particles. Shelf-life of omega-3 fatty acids encapsulated in CLAMs with varying formulations have been completed. Results demonstrate that the protein surfactant Whey Protein Isolate (WPI) improves the shelf-stability of omega-3 fatty acids over that of a small molecular surfactant Tween80. Further analyses of the results are on-going. 3) to evaluate the release kinetics of lipophiles in simulated gastrointestinal fluids The release of omega-3 fatty acids from CLAMs with WPI as an emulsifier appears to show increased protection in the gastric fluid. Further analyses of the resutls are on-going. 4) to evaluate the eoncomics of the microencapsulation process. We developed process models were developed using a commercial software, SuperPro, to evaluate the process econcomics of the 'UC Davis CLAMs process'. With these process models, we demonstrate that the cost of microencapuslation using the UC Davis CLAMs process is at least half the cost of a comparable conventional process. Moreover, that increasing processing scales improve the economics of the UC Davis CLAMs process.
Publications
- Type:
Theses/Dissertations
Status:
Accepted
Year Published:
2017
Citation:
Strobel, S. A. (2017). Microencapsulation of Actives in Cross-linked Alginates Prepared by Spray-Drying. Ph. D., University of California, Davis.
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Progress 01/01/16 to 12/31/16
Outputs
Target Audience:
Nothing Reported
Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?PhD candidate, Scott Strobel continues to hone his research skills with this project. During this period, Scott was able to complete a 3 month internship at BASF working on microencapsulation projects. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?In the final year of the project, our focus is on completing Objectives 2 and 4, to study the kinetics of oxidation of the lipophilic cargo in the CLAMs and to study the process economics of the CLAMs formation process as compared to conventional processes to produce cross-linked alginate microcapsules.
Impacts
What was accomplished under these goals?
Objective 1: To produce and characterize the cross-linked alginate-lipophile microcapsules, Towards this first objective, a major accomplishment was a better understanding the role of calcium content in the spray-drying feed on the extent of alginate cross-linking affecting microcapsule properties. Several assays were developed to measure the extent of cross-linking in the microcapsules, to measure the rate of hydration of dry microcapsules and to measure the rate of erosion of the microcapsules in an aqueous suspension. The 'extent of cross-linking' was determined from a measure of the soluble/insoluble alginate content of the sample of microcapsules in an aqueous suspension. The assay was conducted by a perioidic shift assay to measure alginate concentration in the supernatant when the microcapsules were suspended in water. Lower soluble/insoluble alginate ratio of a sample indicated greater extent of cross-linking within the microcapsules (thereby preventing solubilization of the alginates). We found that higher concentrations of calcium hydrogen phosphate in the spray dryer inlet suspension generally resulted in higher 'extents of cross-linking' with a saturation effect at higher calcium contents. Different commercial sources of alginates responded differently to varying calcium content, thus we are conducting a study now to characterize the composition of commercial alginates for better understanding of alginate properties influencing cross-linking. Comparing samples with low extents (~65-70% soluble alginates) to samples with higher extents of crosslinking (~15-20% soluble alginates), we found that particle hydration rates were not significantly influenced by crosslinking. Erosion rates, as quantified by the rate of soluble alginate release in aqueous suspensions, however, were significantly slower for particles with greater extents of cross-linking. Greater extent of cross-linking also appear to increase particle sizes of the microcapsules. SEM images corroborated sizing data and further revealed the presence of calcium hydrogen phosphate particles in samples formed with an excess of the salt. This observation was consistent with XRD measurements of these samples indicating the presence of crystalline CaHPO4 in the samples. Objective 2: To study the kinetics of oxidation in the microcapsules. These studies are still on-going. We have been developing a plate-reader based, fluorescence assay to measure oxygen diffusivity in dry powder particles. This assay, based on a published assay of a similar nature in emulsions turns out to have additional challenges for powder samples. The assay is based on measuring the fluorescence intensity of oxygen-responsive fluorophores incorporated into the CLAMs. We have found that hydrophilic oxygen-responsive fluorophores are inactive in the dry state, thus we will be unable to measure rate of oxygen uptake into the matrix. We can, however, measure the oxygen uptake rate into the oil bodies encapsulated in the CLAMs using hydrophobic oxygen-responsive fluorophores. The dry powder assay, however, is also highly sensitive to environmental conditions including temperature and particularly relative humidity. We have been developing engineering controls to manage these external factors and the studies are on-going. We have formulated CLAMs with different surfactants, Tween80, casein and whey protein isolate (WPI) to understand the role of surfactants in determining the oxygen barrier properties of CLAMs. Shelf-stability studies of lipids encapsulated in CLAMs with these surfactants are also on-going.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Strobel, S. A., H. B. Scher, N. Nitin and T. Jeoh (2016). "In situ cross-linking of alginate during spray-drying to microencapsulate lipids in powder." Food Hydrocolloids 58: 141-149. DOI: http://dx.doi.org/10.1016/j.foodhyd.2016.02.031.
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Progress 01/01/15 to 12/31/15
Outputs
Target Audience:Chemical or food companies interested in encapsulating lipophilic bioactives for incorporation into functional foods. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?PhD student, Scott Strobel continues to receivetraining on this project. Scott presented a poster with recent results from this projectat the 2015 IFT. How have the results been disseminated to communities of interest?Presentations at the AFRI PD meeting and the International Food Technologist (IFT) meeting were made this past year (2015). Additionally, a manuscript on this work is currently in review with the journal Food Hydrocolloids. Three separate CDAs have been placed with industry partners interested in pursuing this technology. What do you plan to do during the next reporting period to accomplish the goals?Our current focus is on successfully characterizing the oxygen barrier properties of the CLAMs and assessing shelf-stability of model hydrophobic compounds encapsulated in the CLAMs.
Impacts
What was accomplished under these goals?
1) We achieved up to 35% (d.b.) loading of oil in the cross-linked alginate microcapsules (CLAMs) where oil is now a dominant component of the CLAMs. Oil-loaded CLAM morphology was spherical with 200-300 micron sized oil droplets homogeneously dispersed within the volume of the CLAMs. The morphology of empty CLAMs (identical composition but without oil) exhibited a 'collapsed beach ball' appearance. We speculate that shortly after atomization at the spray dryer nozzle, alginate cross-linking occurs rapidly at the surface of spherical droplets. Without occlusion bodies (i.e. oil droplets) within the volume of the droplet, evaporation of water making up the bulk of the mass of the droplet causes the deflated appearance. The absence of 'blow holes' or evidence of rupture of the particles has been hailed as a positive physical trait by industry. An assay to measure the extent of cross-linking was developed based on quantifying thesolubilization of un-crosslinked alginates into the supernatant of an aqueous suspension of CLAMs. The base CLAM formulation was found to exhibit ~50% extent of cross-linking (i.e. ~50% of alginates in the CLAMs are released into the supernatant). Based on this finding, we have shown that we can tune the extent of cross-linking in the CLAMs by changing the insoluble calcium content in the feed. We are currently looking into how the extent of crosslinking impacts CLAM properties including release rates and oxygen permeability. 2) We are adapting a fluorescence-based microtiter plate assay to measure diffusivity of oxygen into emulsions to measuring diffusivity of oxygen into the powder CLAM particles. In this assay, the rate of fluroescence signal decay from an oxygen-sensitive fluorescence dye in the sample wellis used to estimate oxygen diffusivity in the sample. Some challenges encountered in applying this assay to powder samples is the sensitivity of the fluorophores to sample moisture content. We have adapted our experimental setups to maintain control of the ambient humidity as well as ambient oxygen content. Preliminary data suggest that oxygen diffusivity within CLAMs are on the order of 10-16m2/s (within the order of gas diffusion in solids), and that the extent of cross-linking may have measurable impact of the apparent diffusivity of oxygen in CLAMs. These measurements are on-going. A manuscript describing oil-loadedCLAM formation and characterization is currently under review with the journal Food Hydrocolloids. 3) The evaluation of release of oil from CLAMS in simulated gastric fluids (SGF) and simulated intestinal fluids (SIF) supported our expectation that the majority of the oil release would be in the SIF with only a small extent of release in the SGF. The extent of oil release from the CLAMs was observed to be strongly dependent on the fluid pH and also influenced by the ionic content of the fluids. 4) The economic evaluation will be conducted in this project year.
Publications
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2015
Citation:
Investigating a New Strategy for Effective and Inexpensive Delivery of Lipophilic Bioactives in Foods, NRI/AFRI Project Director Meeting at the IFT, Chcago, IL; July 10, 2015.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2015
Citation:
Microencapsulation of Lipids in Cross-Linked Alginate by Spray-Drying. Scott Strobel, Herb Scher, Nitin Nitin and Tina Jeoh. Poster at IFT 2015.
- Type:
Journal Articles
Status:
Under Review
Year Published:
2016
Citation:
In situ cross-linking of alginate during spray-drying to microencapsulate lipids in powder. 2016. Scott Strobel, Herbert Scher, Nitin Nitin and Tina Jeoh. Food Hydrocolloids.
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Progress 01/01/14 to 12/31/14
Outputs
Target Audience:
Nothing Reported
Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? Graduate student, Scott Strobel passed his Ph.D. qualifying exam in November 2014. Scott is funded on this project and is focusing his Ph.D. work on assessing oxygen diffusion barrier properties of CLAMs. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals? In this next reporting period, we are measuring the oxygen barrier properties of the CLAMs. If necessary, we also plan to explore changes to the formulation to improve oxygen barrier properties, such as by using different surfactants in the emulsified feed stream.
Impacts
What was accomplished under these goals?
We have achieved our goal of demonstrating > 20% core loading in the Cross-Linked Alginate Microcapsules (CLAMs) prepared by our novel spray-drying technology. These microcapsules and corresponding Spray-Dried Cross-linked Alginate (SDCA) microparticles (control particles with no oil) have been thoroughly characterized in this past year.
Publications
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2014
Citation:
Investigating the role of surfactant in encapsulating oil-in-water emulsions in a novel spray-dried alginate matrix. Scott Strobel, Amol Chaudhari, Herb Scher, Nitin, Nitin and Tina Jeoh. Poster Presentation. USDA-AFRI PD Meeting, 2014.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2014
Citation:
nvestigating the role of surfactant in encapsulating oil-in-water emulsions in a novel spray-dried alginate matrix. Scott Strobel, Amol Chaudhari, Herb Scher, Nitin, Nitin and Tina Jeoh. Poster Presentation. UC Davis, Integrated Graduate and Professional Symposium (IGPS); April, 2014.
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