Source: TEXAS A&M UNIVERSITY submitted to
EVALUATION OF FOOD, AGRICULTURAL AND BIOLOGICAL MATERIALS FOR IMPROVED CHARACTERIZATION AND VALUE-ADDED UTILIZATION
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0180224
Grant No.
(N/A)
Project No.
TEX08598
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Aug 12, 2010
Project End Date
Aug 11, 2015
Grant Year
(N/A)
Project Director
Castell-Perez, M, EL.
Recipient Organization
TEXAS A&M UNIVERSITY
750 AGRONOMY RD STE 2701
COLLEGE STATION,TX 77843-0001
Performing Department
Biological & Agricultural Engineering
Non Technical Summary
Complete characterization of rheological, physico-chemical and other engineering properties of food, agricultural and biological materials still remains a challenge to food process engineering and product development due to the complex nature of the materials. Many of these materials are complex in structure and in composition. Biopolymers polysaccharides and proteins) and/or colloidal particles (fat globules, water droplets, ice crystals, protein aggregates, sugar crystals) are typical examples of such systems. Properties of these materials which are important to consumers and manufacturers (appearance, shelf-life, quality and texture) depend on the structure, interactions and organization of the biopolymers and colloidal particles (Padua and Wang, 2000). Research is needed to understand the contribution that biopolymers and colloidal particles make to the overall physicochemical and mechanical properties of foods (natural and processed) and agricultural materials. This information is useful for the food and agricultural industries as it enables manufacturers to improve the properties of existing products, optimize processing conditions, develop new products and reduce manufacturing costs. Packaging of food is a challenging task because foods are complex and diverse. Unlike inert packaged commodities, foods are dynamic systems with limited shelf life and very specific packaging requirements. Also, since foods are consumed to maintain life, the safety aspect is a critical packaging parameter. U.S. consumers benefit from the most affordable, nutritious and safe food supply in the world. However, the safety and quality of food is profoundly affected by potential microbiological contamination that can occur during handling and processing. Consequently, efforts to develop, refine, and implement measures to enhance assurances of food safety are critically needed (CATT, 1997; Tauxe et al., 1997). Several preservation methods including antioxidant treatment, modified atmosphere packaging (MAP), refrigerated storage, washing with chlorinated water or ozone, have been applied to extend shelf-life and inhibit microbial spoilage of minimally processed fresh produce (Ahvenainen, 1996; Tapia de Daza et al., 1996; Fan et al., 2003). Studies have shown that ionizing radiation could eliminate food-borne pathogens in fresh fruits and vegetables (Wiley, 1994; Farkas et al., 1997; Fan et al., 2003). However, little is known about the potential synergistic effect of antimicrobial packaging and irradiation in the quality and safety of fresh produce (Han, 2000). These active films could control microbial contamination by reducing the growth rate and maximum growth population and extending the lag period of the target microorganism to prolong the product shelf life and maintain its safety. For example, they must reduce microbial growth of nosterile foods or maintain the stability of pasteurized foods without post-contamination. The project will provide a research-intensive learning environment for students in science and engineering in the area of biopolymers, bioactive materials, materials properties and characterization, and food safety.
Animal Health Component
(N/A)
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
5014099201010%
5015010202015%
5024099202020%
5025010201010%
5114099201010%
5115010202020%
7124099202015%
Goals / Objectives
(1) Characterization of materials for better understanding of their processability and engineering functionality The goal of this research is to expand current knowledge on the behavior and properties of food, agricultural, and biological materials for new and improved utilization. Specific objectives of this research are to: (1) evaluate the physical, chemical, mechanical and functional properties of a wide range of potential food-substitute materials; and (2) obtain relevant dose distribution data in selected food targets for mathematical model benchmarking. Will conduct tests on e-beam and gamma to establish comparions regarding effectiveness and safety. The outcome from this research will be critical knowledge in the area of material properties, functionality, and utilization. (2) Feasibility of using current and new materials in alternative applications (such as food packaging). The main goal of this research is to design an effective biopolymeric antimicrobial carrier film for food packaging applications. Specific objectives of this research are: (1) develop film-forming processes for top-quality performance properties using biopolymers; (2) predict the antimicrobial mechanism/kinetics and the controlled-release profile of antimicrobial substances from the film into a food product using mathematical models of diffusion; and (3) optimize carrier film design by modifying the thickness of the control layer to alter the diffusivity of antimicrobial agents (controlled release-rate). The outcome from this research should be a series of antimicrobial delivery systems with tailor-made properties to achieve a given effect. These systems could be widely applied for clinical uses in hospitals (as wound dressings or drug delivery systems), biological labware, biotechnology equipment, as well as food packaging. Other major positive outcomes from this effort will be reduced packaging costs, reduced overwrapping and expanded utilization of newly developed biodegradable packaging materials, which also reduce the problem of excessive waste.
Project Methods
The experimental work to be carried out will, whenever possible, follow all the required testing standards and methodologies, such as AACC, AOAC and ASTM. Special attention will also be paid to make sure that the testing approach is scientifically sound. The results of testing and analyses will be documented and published in scientific journals. (1) Characterization of materials for better understanding of their processability and engineering functionality. Current efforts at our laboratory include testing of a wide series of materials. Our research plan is to: (1) identify an appropriate set of biopolymeric materials, blend biopolymers with greatly different viscosities, examine the effect of irradiation treatment on their properties, and understand polymer morphology and degradability; (2) characterize the shear behavior of starch-based ingredients for potential use in foods, energy and pacaging applications. Data Analysis: We will conduct steady shear and dynamic tests at a wide range of temperatures. Time-dependency will also be evaluated. 2) Feasibility of using current and new materials in alternative applications (such as food packaging). Current efforts at our laboratory include (1) modifying film barrier, structural, and mechanical properties by physical (UV, ultrasound, heat, e-beam irradiation), enzymatic, and chemical methods; (2) developing mechanical models of protein-matrix film structure to understand the relationship between structure and functionality; and more recently, (3) understanding the potential antimicrobial effects of natural active agents (proteins, natural oils, organic acids, flavors and nutraceuticals) on specific microorganisms, sensory properties, and quality of seasoned, precooked meats wrapped on films (this area is gaining considerable popularity as meat processors develop a variety of ready-to-heat products for quick meals with strict safety requirements) (Han, 2001). Our research plan is to: (1) investigate the effect of ionizing radiation on antimicrobial agent release rates; (2) determine whether the irradiation treatment functions as a release (anti-stick) factor or an anti-release factor into the foodstuff (Fan and Singh, 1989; Han, 2000); (3) establish whether irradiation can be the controlling factor for antimicrobial release; (4) carry out tests to predict performance of films; and (5) formulate a predictive model and a set of procedures for performance predictions. Data Analysis: Empirical/fundamental models or testing methodology will be used as a basis to predict film performance. Studies on these problems will provide information on the exact amount of antimicrobial agent and release rate of the antimicrobial substances required to achieve a given effect. Results from these studies will be expanded to other applications such as utensils.

Progress 08/12/10 to 08/11/15

Outputs
Target Audience:Scientists, professionals and students in the field of foor process technology and engineering and materials science. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?presentations at professional societies and training of graduate students How have the results been disseminated to communities of interest?IFT (Institute of Food Technologists) annual meetings and publications in several journals What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Developed a methodology to use rheology to characterize food matrices from biopolymers. Maximized the encapsulation and bioavailability of water-soluble flavonoids by (1) identifying the influence of the matrix (e.g., protein) intrinsic characteristic and the conditions of the surrounding media (e.g. temperature, pH, ionic strength, shear rate) during their encapsulation and isolation, to enhance entrapment efficiency and stability; and (2) characterizing their stability and bioavailability at different gastro-duodenal conditions. Assessed the effectiveness of washing treatments as a postharvest practice to minimize the growth of Listeria spp. on fresh-cut cantaloupe and romaine lettuce leaves under different storage temperatures. These dynamic models can be useful for manufacturers to evaluate the impact of handling practices (storage temperature and washing treatments) on the growth of Listeria in the selected fresh produce. Growth models were used to develop quantitative risk assessment models.

Publications

  • Type: Journal Articles Status: Accepted Year Published: 2015 Citation: Ruengvisesh, S., Loquercio, A., Castell-Perez, E., Taylor, M.T. (2015). Inhibition of Bacterial Pathogens in Medium and on Spinach Leaf Surfaces using Plant-Derived Antimicrobials Loaded in Surfactant Micelles. Journal of Food Science. Food Microbiology and Safety Section.
  • Type: Journal Articles Status: Accepted Year Published: 2015 Citation: Loquercio, A., Castell-Perez, M. E., Gomes, C. and Moreira, R.G. (2015). Preparation of Chitosan-Alginate Nanoparticles for Trans-cinnamaldehyde Entrapment. Journal of Food Science. Nanoscale Food Science Section, 80(10): N2305-N2315.
  • Type: Journal Articles Status: Accepted Year Published: 2015 Citation: Puerta-Gomez, A.F. and Castell-Perez, M.E. (2015). Physical stability of octenyl-succinate-modified polysaccharides and whey proteins for potential use as bioactive carriers in food systems. Journal of Food Science 80 (6): E1209-E1217.
  • Type: Journal Articles Status: Accepted Year Published: 2015 Citation: Kim, K., Moreira, R.G., Castell-Perez, M.E. (2015). Improving phytosanitary irradiation treatment of mangoes using Monte Carlo simulation. Journal of Food Engineering, 149: 137-143.


Progress 10/01/13 to 09/30/14

Outputs
Target Audience: Fresh produce producers and processors, consumers, food technology and engineering professionals, students. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Graduate student training (total of 5, 1 PhD, 4 MS) How have the results been disseminated to communities of interest? yes, at professional societies - IFT What do you plan to do during the next reporting period to accomplish the goals? 1. Continue work on development of methods to understand structure formation of biopolymeric matrices for purposes of encapsulation. 2. Continue work on identification of green biopolymeric materials

Impacts
What was accomplished under these goals? 1. Conti9nuted devlopment of methods to characterize biopolymers using rheological principles. It is cheaper, afster and accurate. 2. Tested several combinations of natural biopolymers suitable for encapsulation of antimicrobials.

Publications

  • Type: Journal Articles Status: Under Review Year Published: 2015 Citation: Puerta-Gomez, A.F. and Castell-Perez. M.E. Characterization of Biopolymers for use as Matrices for Encapsulation of Hydrophobic Compounds. Journal of Food Science.
  • Type: Journal Articles Status: Under Review Year Published: 2015 Citation: Booren, Castell-Perez, Miller. Characterization of Hydroxypropyl Methylcellulose and Konjac Flour in Meat Enhancement Solutions to Improve Pale, Soft, and Exudative Pork. Journal of Food Science,


Progress 01/01/13 to 09/30/13

Outputs
Target Audience: Target audiences: Students and faculty at land-grant universities focusing on postharvest and value-added processes of food, agricultural and biological materials. Fresh produce processors and consumers. Efforts: Teaching in classroom and laboratory activities, presentations at scientific meetings, workshops, publication of research activities. Changes/Problems: No major changes. Research goals continue as planned. New emphasis on rheological methods to characterize physical stability of biopolymers. What opportunities for training and professional development has the project provided? Training of 3 graduate students (1 PhD, 2 MS) How have the results been disseminated to communities of interest? 1. Publications in scholarly journals (peer-reviewed) 2. Presentations at professional society meetings What do you plan to do during the next reporting period to accomplish the goals? 1. Continue refining of methods to characterize the biopolymers 2. Debvelop films and matrices for encapsulations and test them on a varity of food materials

Impacts
What was accomplished under these goals? 1. Developed a method to characterize natural, biodegradable polymers for useas encapsulation matrices for nutrients and/or antimicrobials in foods. 2. Proposed biopolymers are green, cheaper and non-toxic

Publications

  • Type: Journal Articles Status: Accepted Year Published: 2013 Citation: Chimbombi, Castell-Perez, M.E, Moreira, R.G., and A.F. Puerta-Gomez, 2013. M. Assessing accumulation (growth and internal mobility) of Salmonella Typhimurium LT2 in fresh-cut cantaloupe (Cucumis melo L.) for optimization of decontamination strategies. Food Control 32, 574-581. http://dx.doi.org/10.1016/j.foodcont.2013.01.042


Progress 01/01/12 to 12/31/12

Outputs
OUTPUTS: Continued training of graduate students on several aspects of properties and behavior of biological materials. Continued fine-tuning of a quantitative risk assessment tool to predict the potential of foodborne outbreaks in leafy greens. Presented five posters at the International Annual Meeting of the Institute of Food Technologists in June 2012. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Producers and processors of fresh leafy greens. Students, academics, scientists and industry personnel in food safety and engineering. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Analysis of potential scenarios leading to a foodborne outbreak in fresh produce has provided several practical recommendations for producers in Texas and nationwide.

Publications

  • Sipahi, R., N., Castell-Perez, M.E., Moreira, R.G. Gomes, C. and Castillo, A, 2012. Improved multilayered antimicrobial alginate-based edible coating extends the shelf life of fresh-cut watermelon (Citrullus lanatus)". LWT- Food Science and Technology. Accepted November 9, 2012.
  • Puerta-Gomez, A., Kim, J., Moreira, R.G., Klutke, G.-A., Castell-Perez, M.E. 2012. Quantitative assessment of the effectiveness of intervention steps to reduce the risk of contamination of ready-to-eat baby spinach with Salmonella. Food Control, Available online October 24, 2012. http://dx.doi.org/10.1016/j.foodcont.2012.10.022.
  • Mantilla, N., Castell-Perez, M.E., Gomes, C. and Moreira, R.G. 2012. Multilayered antimicrobial edible coating and its effect on quality and shelf-life of fresh-cut pineapple (Ananas comosus). LWT- Food Science and Technology. Available online. 31-OCT-2012 DOI information: 10.1016/j.lwt.2012.10.010.
  • Puerta-Gomez, A.F, Moreira, R.G., Kim J., and Castell-Perez, M.E. 2012. Comparison of growth rates of Escherichia Coli spp. and Salmonella Typhimurium LT2 in baby spinach leaves under slow cooling. Food Control, accepted May 2012. http://dx.doi.org/10.1016/j.foodcont.2012.05.070.
  • R.G. Moreira, A. F. Puerta-Gomez, J. Kim, and E. Castell-Perez. 2012. Factors affecting radiation D-values (D10) of an Escherichia coli cocktail and Salmonella typhimurium LT2 inoculated in fresh produce. Journal of Food Science. doi: 10.1111/j.1750-3841.2011.02603
  • Brasil, I.M, Gomes, C., Puerta-Gomez, A, Castell-Perez, M.E, Moreira, R.G. 2012. Polysaccharide-based multilayered antimicrobial edible coating enhances quality of fresh-cut papaya, LWT - Food Science and Technology (2012), doi: 10.1016/j.lwt.2012.01.005
  • Gomes, C.; Castell-Perez, M. E.; Chimbombi, E.; Karagoz, I.; Hare, B.; Liang, Y-L; Sue, H-J.; Sherman, P.; Dunne, P.; Wright, A. O.; Yang, T. 2012. Quality of olive-oil reformulated MRE entree. Lebensmittel-Wissenschaft und-Technologie/Food Science and Technology. Volume 45, Issue 2, 191-197. ttp://dx.doi.org/10.1016/j.lwt.2011.09.005


Progress 01/01/11 to 12/31/11

Outputs
OUTPUTS: Completed rheological characterization of lapping of Polycrystalline Diamond Compact (PDC). Steady-shear and dynamic oscillatory tests revealed that the material exhibits highly shear-thinning behavior at high shear rates ( > 6,000 rmp) at room temperature. Studies on selection of "natural" and "green" materials was initiated. Materials evaluated included several food gums and starches, and their combinations. Studies on characterization of natural biopolymers for use as encapsulation matrices was initiated. Native starches and other biopolymeric materials were evaluated in terms of their functionality (glass transition temperature) and their ability to remain stable under high relative humidity conditions. Studies on feasibility of edible coatings for use in fresh-cut pineapple and watermelon were completed. The coatings extend the shelf life of the fruits (~ 12 days vs. 7 days for the uncoated fruits) and maintain their quality attributes. These results will be published in 2012. The feasibility of nanoencapsulated antimicrobials was evaluated as a means to reduce the dose required to irradiate fresh-produce. Results from these studies were published in 2011. The feasibility of an oxygen-absorbing packaging material was evaluated for packaging of MRE items containing olive oil. Accelerated shelf life testing confirmed that the product (chicken with noddles) meets the required shelf-life of 3 years at room temperature. Physical, chemical, sensory and microbiological data showed that reformulation of the retorted chicken item with olive oil was feasible. PARTICIPANTS: Dr. Elena Castell-Perez, Professor of Food Engineering, Department of Biological and Agricultural Engineering, Texas A&M University. Emphasis on characterization of material properties. Dr. Rosana G. Moreira, Professor of Food Engineering, Department of Biological and Agricultural Engineering, Texas A&M University. Emphasis on food irradiation optimization. Dr. Carmen Gomes, Assistant Professor of Food Engineering, Department of Biological and Agricultural Engineering, Texas A&M University. Emphasis on development of encapsulating materials. Dr. Hung-Jue, Sue, Professor of mechanical Engineering, Texas A&M University. Emphasis on polymers properties and development. Training of ten graduate students has been possible, in the areas of material properties, rheology, irradiation, nanotechology, and food safety engineering. TARGET AUDIENCES: Classroom instruction to undergraduate and graduate students in the area of food technology and engineering. Aspects of this project are covered in courses such as Food Irradiation, Engineering Properties of Biological materials, Engineering Aspects of Packaging, and Unit Operations in Food Engineering. Several workshops were conducted for intorduction of the topics to high-school students interested in the science and technology fields. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Several carbohydrates and combinations of modified starches were characterized in terms of their physical properties. Gelatinization temperatures and moisture isotherms are some of the properties measured which will help elucidate the behavior of these materials as potential matrices for encapsulation of antimicrobials. The rheological behavior of polymeric materials was evaluated for potential uses as lubricants. Reformulation of certain MRE retorted items with olive oil is feasible. This provides a healthy alternative to consumers. Interest in the oxygen-absorbing packaging technology has surged. Irradiation treatment of fresh produce can be optimized by accurate calculation of absorbed dose using Monte Carlo simulation and CT-scan technology. the application of edible coatings with encapsulated antimicrobials is another means to reduce absorbed dose and diminish produce quality losses.

Publications

  • Fang, A., Castell-Perez, E, Puerta-Gomez, A, Zhou, S. and Sowers, J. 2010. Lapping of Polycrystalline Diamond Compact (PDC). Advanced Materials Research Vols. 126-128 (2010) pp 469-474.
  • Gomes, C.; Moreira, R. G.; Castell-Perez, E. 2011. Microencapsulated antimicrobial compounds as a means to enhance electron beam irradiation treatment of fresh produce. Journal of Food Science. 76,6, E479-E488.
  • Gomes, C., Moreira, R.G., Castell-Perez, M.E 2011. Poly (DL-lactide-co-glycolide) (PLGA) nanoparticles with entrapped trans-cinnamaldehyde and eugenol for antimicrobial delivery applications. Journal of Food science. 76(2), N16-N24.
  • Gomes, C.; Castell-Perez, M. E.; Chimbombi, E.; Karagoz, I.; Hare, B.; Liang, Y-L; Sue, H-J.; Sherman, P.; Dunne, P.; Wright, A. O.; Yang, T. 2011. Quality of olive-oil 1 reformulated MRE entree. Lebensmittel-Wissenschaft und-Technologie/Food Science and Technology. Volume 45, Issue 2, 191-197.
  • Moreira, R.G. and Castell-Perez, M.E. 2011. Irradiation applications in fruit and other fresh produce processing. Chapter 7 in Advances in Fruit Processing Technologies (a volume in the Contemporary Food Engineering Series). Edited by Sueli Rodrigues and Fabiano Andre Narciso Fernandes.


Progress 01/01/10 to 12/31/10

Outputs
OUTPUTS: OUTPUTS: Continued analysis and evaluation of food materials under different processing conditions, including vacuum frying and irradiation. Specific food materials include leafy vegetables (lettuce and spinach), cantaloupes, papaya, potatoes, blueberries, watermelon, and mangoes. Presented results from evaluation at the IFT Annual meeting in Chicago, July 2010. Continued training of graduate students (3) in areas related to the project, including irradiation, product shelf-life, characterization of packaging films, and dosimetry. Published several articles about the research conducted. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: No major changes were made. Research objectives remain the same.

Impacts
Findings on irradiation of fresh produce demonstrated that the technology is reliable to ensure safety of the produce -- only when accurately done. This means that dosimetry is still an area that needs to be prefected since wrong dose measurement leads to produce quality problems. Results illustrate that pathogens such as Salmonella and E. Coli have the ability to penetrate fresh produce (ie, cantaloupe and lettuce) and therefore surface treatments (washing and chlorination) are not sufficient. Electron beam irradiation effectively penetrates and eliminates the pathogens. Methods to reduce the radiation dose were tested in combination with irradiation treatment. Findings show that it is possible to reduce required dose using antimicrobial films, modified packaging atmosphere, and a combination of both technologies.

Publications

  • Gomes, C., Moreira, R.G., Castell-Perez, M.E. 2010. Radiosensitization of Salmonella spp. and Listeria spp. in ready-to-eat baby spinach leaves. Journal of Food Science. Published online November 18 2010.
  • Kim, J., Moreira, R.G., Castell-Perez, M.E. 2010. Simulation of pathogen inactivation in whole and fresh-cut cantaloupe (Cucumis melo) using electron beam treatment. Journal of Food Engineering, 97(3), 425-433.
  • Kim, J., Moreira, R.G., Castell-Perez, M.E. 2010. Optimizing irradiation treatment of shell eggs using simulation. Journal of Food Science. Published online December 1 2010.
  • Chimbombi, E., Kim, J., Moreira, R.G., Castell-Perez, M.E. 2010. Prediction of targeted Salmonella enterica serovar Typhimurium inactivation in fresh-cut cantaloupe (Cucumis melo L.) using electron beam irradiation. Journal of Food Engineering. In PRess, Corrected Proof. Available online November 24 2010.


Progress 01/01/09 to 12/31/09

Outputs
OUTPUTS: Continued analysis and evaluation of food materials under different processing conditions, including vacuum frying and irradiation. Specific food materials include leafy vegetables, cantaloupes, papaya, potatoes, and mangoes. Presented results from evaluation at the IFT Annual meeting in New Orleans, 2009. continued training of graduate students (4) in areas related to the project, including irradiation, product shelf-life, characterization of packaging films, and dosimetry. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Findings on irradiation of fresh produce demonstrated that the technology is reliable to ensure safety of the produce -- only when properly done. Results illustrate that pathogens such as Salmonella have the ability to penetrate fresh produce (ie, cantaloupe and lettuce) and therefore surface treatments (chlorination) are not sufficient. Electron beam irradiation effectively penetrates and eliminates the pathogens. Methods to reduce the radiation dose were tested in combination with irradiation treatment. Findings show that it is possible to reduce required dose using antimicrobial films, modified packaging atmosphere, and a combination of both technologies.

Publications

  • Carmen Gomes, Paulo Da Silva, Rosana G. Moreira, Elena Castell-Perez, E. Ann Ellis, Michael Pendleton. (2009). Understanding E. coli internalization in lettuce leaves for optimization of irradiation treatment. International Journal of Food Microbiology 135,238-247.


Progress 01/01/08 to 12/31/08

Outputs
OUTPUTS: Taught courses on material properties and food rheology. Presented research results on several aspects of material properties at the Institute of Food Technologists Conference in New Orleans, July 2008. Acquired new rheometer for collection of fundamental rheological properties. Advised four graduate students in this area. PARTICIPANTS: PI: Dr. Rosana Moreira. responsible for design of irradiation treatment plans. Collaborator: Dr. Jongsoon Kim, responsible for irradiation trials. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Results from research aid in understanding of applications of new technology to insure safety of fresh produce without impact on quality.

Publications

  • Gomes, C., Da Silva, P., Chimbombi, E., Kim, J., Castell-Perez, M.E. and Moreira, R.G. 2008. Electron-Beam Irradiation of Fresh Broccoli Heads Brassica oleracea L. Italica).Lebensmittel Wissenschaft und Technologie Food Science and Technology,41, 1828-1833.
  • Kim, J.,Moreira,R.G.and Castell-Perez,M.E. 2008. alidation of Irradiation of Broccoli with a 10 MeV electron beam accelerator. Journal of Food Engineering 86(4),595-603.
  • Moreno, M.A.,Castell-Perez,M.E.,Gomes,C.,Da Silva,P.F.,Kim,J.and Moreira, R.G. 2008. Treatment of cultivated highbush blueberries (Vaccinium corymbosum L.)with electron beam irradiation: Dosimetry and product quality. Journal of Food Process Engineering 31, 155-172.


Progress 01/01/07 to 12/31/07

Outputs
OUTPUTS: Products: (1) Students graduating in the graduate program of Biological and Agricultural Engineering with emphasis on Food Engineering: (a) Kim, J. 2007. PhD. Dissertation topic: Beam Delivery Strategies for Low-Energy Irradiation of Foods. August 2007. (b) Continued supervision of 4 graduate students in the area of food process engineering with emphasis on material properties, packaging, and food safety. (2) Courses taught: (a) Food Rheology, BAEN 620, January-March 2007. Graduate students in food engineering and related fields. (b) Engineering properties of Biological Materials, BAEN 354, September-December 2007. Undergraduate students in Biological and Agricultural Engineering. Dissemination: (1) Workshop entitled "Engineering Applications to Food Safety", June 2007. Audience: high school science teachers participating in the NSF E3 program. Emphasis on use and measurement of material properties and their effect on process and quality. (2) Participated in workshop entitled "Poultry 101". Presentation to producers and processors from several areas of Latin America on the effect of non-thermal treatments on poultry physical properties and shelf-life. College Station, September 2007. PARTICIPANTS: Co-Project Director: Dr. Rosana G. Moreira, BAEN, TAMU. Graduate students: Jongsoon Kim (PhD in BAEN), Carmen Gomes (PhD in BAEN), Paulo da Silva (PhD in BAEN), Ezekiel Chimbombi (PhD in BAEN), Maria Moreno (MS in BAEN). Training of one undergraduate student in BAEN and one international graduate student in Food Science and Technology (Zamorano University, Honduras). TARGET AUDIENCES: Classroom instruction: graduate and under graduate students in biological engineering, food science and technology and related fields. Workshop for high school science teachers.

Impacts
Studies conducted in packaging development, food quality and shelf-life, and material properties characterization have resulted in new fundamental knowledge that will be applied in the near future as a new intervention technology to minimize quality deterioration in minimally processed foods.

Publications

  • Refereed publications: Moreno,M., Castell-Perez,M.E., Gomes,C., Da Silva, P., Kim, J., and Moreira,R.G. 2007.Optimizing electron beam irradiation of "Tommy Atkins" mangoes (mangifera indica L.). Journal of Food Processing Engineering, 30(4), 436-457.
  • Kim,J., Moreira,R.G.,Huang,Y. and Castell-Perez, M.E. 2007. 3-D dose distributions for optimum radiation treatment planning of complex foods. Journal of Food Engineering, 79(1), 312-321.
  • Abstracts: Da Silva,P., Gomes, C., Chimbombi,E., Barros, F., Negi,S., Kim, J., Castell-Perez,E., and Moreira,R.G. 2007. Effects of low-dose electron beam irradiation and storage on quality of broccoli heads (Brassica oleracea Lvar Italica),Institute of Food Technologists Annual Meeting, Chicago, July.
  • Kim,J., Huang,Y., Moreira,R.G., and Castell-Perez, M.E. 2007. Image-processing scheme to quantify color of irradiated fresh produce, Institute of Food Technologists Annual Meeting, Chicago, July.
  • Gomes,C., Da Silva,P., Kim, J., Castell-Perez,E., and Moreira, R.G. 2007. Quality of baby spinach (Spinacia oleracea L.) exposed to low-dose electron beam irradiation,Institute of Food Technologists Annual Meeting, Chicago, July.


Progress 01/01/06 to 12/31/06

Outputs
Work on characterization of food, agricultural and biological materials continued. Significant progress has been made in the area of dose distribution data calculation and measurement for selected food targets. Experiments using both a 2.0 MeV Van der Graaf accelerator and a 10.0 MeV (19 kW) linear electron beam accelerator provided input for the radiation transfer code to simulate dose inside complex-shaped products such as a chicken carcass, packaged blueberries, and a head of broccoli. These results provided guidance into determining proper electron beam configuration to achieve optimum dose uniformity ratio. Tests on the quality and microbial characteristics of the food products were performed to help optimize irradiation treatment planning of such produce. Other studies included establishment of a series of guidelines for further work in the area of antimicrobial packaging for radiosensitization purposes. Several peer-reviewed articles were published in these areas in professional journals. A new study will be initiated in January 2007 to optimize release rate of active compounds using kinetic concepts and nanotechnology. Work continued in the area of rheological characterization of hydrocolloids and egg proteins for use as ingredients in meat-based products.

Impacts
When fully developed, results from this research program will help alleviate the current problem with food-borne illnesses due to consumption of fresh fruits and vegetables. The impact of the radiosensitization studies will be a higher quality irradiated produce with the assurance of safety. The work on ingredient characterization will directly impact the quality problems of pork and poultry-based products.

Publications

  • J. Han, M. E. Castell-Perez and R. G. Moreira. 2006. The Influence of Electron Beam Irradiation of Antimicrobial-Coated LDPE/Polyamide Films on Antimicrobial Activity and Film Properties. Lebensmittel-Wissenschaft und-Technologie/Food Science and Technology. Accepted, Nov. 2006.
  • Moreno, M.A., Castell-Perez, M.E., Gomes, C. Da Silva, P., and Moreira, R.G.. 2006. Quality of Electron Beam Irradiation of Blueberries (Vaccinium corymbosum L.) at Medium Dose Levels (1.0-3.2 kGy). Lebensmittel-Wissenschaft und-Technologie/Food Science and Technology. In press.
  • Rivadeneira, R., Moreira, R., Kim, J., and Castell-Perez, M.E. 2006. Dose Mapping of Complex-Shaped Foods using Electron-Beam Accelerators. Food Control. In press.
  • C. Gomes, P. F. Da Silva, M. E.Castell-Perez, and R. G. Moreira. 2006. Quality and Microbial Population of Cornish Game Hen Carcasses as Affected by Electron Beam Irradiation. Journal of Food Science, 71(7), E327-336.
  • Kim, J., Moreira, R,G., Rivadeneira, R. and Castell-Perez, M.E. 2006. Monte Carlo-based Food Irradiation Simulator. Journal of Food Process Engineering, 29(1), 72-88.
  • J. Han, M. E. Castell-Perez and R. G. Moreira. 2006. The Influence of Electron Beam Irradiation on the Effectiveness of Trans-cinnamaldehyde Coated LDPE/polyamide Films. Journal of Food Science, 71(5), E245-E251.
  • O. Rodriguez, M. E. Castell-Perez, N. Ekpanyaskun, R. G. Moreira and A. Castillo. 2006. Surrogates for Validation of Electron Beam Irradiation of Foods. International Journal of Food Microbiology, 110(2), 117-122.
  • O. Rodriguez, M.E. Castell-Perez and R.G. Moreira. 2006. Effect of sugar content and storage temperature on the survival and recovery of irradiated Escherichia coli K-12 MG1655. Lebensmittel-Wissenschaft und-Technologie/Food Science and Technology. Available online May 2006.
  • Moreno, M., Castell-Perez, M.E., Gomes, C., Da Silva, P., and Moreira, R.G. 2006. The Effects of Electron Beam Irradiation on Physical, Textural and Microstructural Properties of Tommy Atkins Mangoes (Mangifera indica L.). Journal of Food Science 71(2), E80-E86.


Progress 01/01/05 to 12/31/05

Outputs
We investigated the synergistic effect of antimicrobial film packaging materials combined with e- beam irradiation in the quality and shelf-life of packaged romaine lettuce. The objective was to evaluate the effect of irradiation on the physical and barrier properties of low density polyethylene films coated with a series of GRAS antimicrobials compounds. The minimum inhibitory concentration (MIC) of the antimicrobial agents against Listeria innocua ATCC 33090 was determined using the broth dilution method. A polyamide solution served as the binder medium for incorporating the antimicrobial agents into the film surface. Irradiation tests were carried out using a 2MeV Van de Graaff electron accelerator, and a 10-MeV electron beam linear accelerators (LINAC) located in the National Center for Electron Beam Food Research at A&M University. Each film sample was irradiated with doses ranging from 0.25 to 10 kGy. The mechanical properties of the film strips under large deformations (tension mode) were measured in accordance with ASTM D882-00 (ASTM, 2000) using a TA XT2 Texture Analyzer. Force and elongation values were recorded and the values of tensile strength, percentage elongation-at-break, Young modulus and toughness calculated from the resulting stress strain curve. Stress relaxation tests were also performed. Oxygen and water vapor permeability of the films were measured using oxygen and water diffusion systems, according to the ASTM F1770 Standard Method (ASTM, 1997). The tests were performed under 65% relative humidity and 25C temperature conditions. We also initiated research on development of completely satisfactory in-phantom dosimeter, for food irradiation applications. Development of a phantom that gives quick determination of the amount, field, and penetration of radiation in the food product will break new ground in establishing precise irradiation planning treatments of many types of targets, including food, utensils, and sections of the human body, while minimizing the damage to the target. Previous work on liquid and solid-state phantoms have extensively studied the chemical interactions of radiochromic dyes under gamma or X-rays radiation.The developed phantom allows for rapid validation of calculated dose distribution using Monte Carlo methods.

Impacts
Existing dosimeters are still inaccurate, cannot be used for the whole range of dose, and are too expensive while requiring as long as 2-4 days, a time frame food processors could ill afford to wait, given the highly perishable nature of most foods. In a near future, coupled with mathematical modeling, our research program could be integrated into routine processing. This, in turn, will make real-time dose estimates possible during an irradiation process. This approach is expected to allow for (a) in-process corrections to irradiation parameters (e.g., e-beam current changes, voltage, conveyor speed); and (b) efficient throughput planning and turn-time management. Consequently, the requested instrumentation will enable to further the development of a technology (irradiation) aimed at ensuring the safety and the value of our food supply. The outcome from this research will be an improved technology with great potential for agricultural, medical, military, and other applications that require precise dose delivery. Although not originally intended for bioterrorism purposes, the potential application of antimicrobial carrier films to detect pathogens in a terrorist attack is evident.

Publications

  • Kim, J., Rivadeneira, R., Castell-Perez, M.E. and Moreira, R.G. 2005. Development and Validation of a Methodology for Dose Calculation in Electron beam Irradiation of Complex-Shaped Foods. Journal of Food Engineering. Corrected Proof. Available online May 2005.
  • Kim, J.; Moreira, R.G.; Rivadeneira, R.; and Castell-Perez, M.E. 2005. Monte Carlo based Food Irradiation Simulator. Journal of Food Process Engineering. In press.


Progress 01/01/04 to 12/31/04

Outputs
We demonstrated that peanut protein could be used as a component of new biopolymeric films for packaging and other applications. Properties of peanut protein films can be substantially modified by physical and chemical treatments, thus helping tailor such films to specific applications. Increased mechanical strength reduced water solubility and increased barrier properties are all desirable improvements. The properties of peanut protein films were modified using physical and chemical treatments, and their effects on color, mechanical strength, water solubility, and barrier to water vapor and oxygen of the films were investigated. Physical treatments consisted of heat denaturation of film-forming solution for 30 min at 60C, 70C, 80C, and 90C, ultraviolet irradiation of films for up to 24 h, and three ultrasound processes of film-forming solution. Chemical treatments consisted of addition of aldehydes and anhydrides. Heat curing at 70C, ultraviolet irradiation for 24 h, ultrasound for 10 min in a water-bath, and formaldehyde and glutaraldehyde addition caused a significant increase in the tensile strength of the films. The water vapor permeability (WVP) and oxygen permeability (OP) of the films decreased after heat denaturation and aldehyde treatment. OP also decreased with UV treatment. Heat curing was the most effective treatment, making the films stronger, more resistant to water, and less permeable to water vapor and oxygen. The action of ionizing radiation on polymers results in the following fundamental processes: cross-linking of the molecular chains, degradation of macromolecules, changes in the number, and nature of the double bonds. These processes can take place simultaneously, controlled by the chemical nature of the polymer. We investigated the effect of electron beam irradiation of the mechanical and barrier properties of low-density polyethylene packaging films. Romaine lettuce hearts (Latica sativa var. Longifolia) pre-treated by washing in chlorinated solution, spun-drying, were packaged in 50.8-mm-thick perforated LDPE bags (16 perforations with 5-mm diameter each). Each bag (25-cm width, 30-cm length, 5-cm depth) contained approximately 510 g (three romaine hearts). Packages were placed on a single layer at the middle of the conveyor of a 10-MeV, 19-kW electron beam linear accelerators (LINAC). Irradiation experiments consisted of single beam exposure (bottom) at three different conveyor speeds (0.3, 0.2, and 0.1 m/s) to obtain doses of 1.0, 1.5, and 3.2 kGy, respectively. Irradiation at 1.5 and 3.2 kGy dose levels improved the oxygen barrier capability of the LDPE bags (7.67% and 4.48%, respectively). Water vapor permeability was unaffected at all the irradiation dose levels. The stiffness of LPDE films measured using stress relaxation methods was not affected by irradiation treatment.

Impacts
The evaluation of the effect of new technologies on properties of food, agricultural and biomaterials is critical for the optimization of the technology to ensure the quality and safety of our food supply. In addition, the potential development of new materials will result in increased added-value for many agricultural and biomaterial commodities.

Publications

  • Han, J. C. L. Gomes-Feitosa, E. Castell-Perez, R. G. Moreira and P. da Silva. 2004. Quality of Packaged Romaine Lettuce Hearts Exposed to Low-dose Electron Beam Irradiation. Lebensmittel-Wissenschaft und-Technologie/Food Science and Technology, 37(7): 705-715.
  • Castell-Perez, M.E., Moreno, M., Rodriguez, O. and Moreira, R.G. 2004. Electron Beam Irradiation Treatment of Cantaloupes: Effect on Product Quality. Food Science and Technology International 10(6): 383-390.
  • Liu, C.C., TellezM.A and Castell-Perez, M.E. 2004. Physical and Mechanical Properties of Peanut Protein Films. Lebensmittel-Wissenschaft und-Technologie/Food Science and Technology 37(7): 731-738.
  • Castell-Perez, M.E. 2004. Friction. ENCYCLOPEDIA OF AGRICULTURAL AND FOOD ENGINEERING (EAFE). Food Engineering - Rheology of Foods. Marcel Dekker, Ed. Dennis Heldman.


Progress 01/01/03 to 12/31/03

Outputs
We have investigated the effect of alternative technologies on food and packaging materials. Preliminary work on electron beam irradiation of selected fruits and vegetables, including and cantaloupes, packaged romaine lettuce hearts, indicate that it is possible to treat fresh produce to reduce the risk of contamination while minimizing product quality defects. For example, we observed that irradiation of whole and fresh-cut packaged cantaloupes (Cucumis melo, L.) with dose up to 1.0 kGy causes no significant changes on the fruit physical and nutritional quality attributes. Irradiating at higher doses had an undesirable effect on product quality. The fresh-cut packaged cantaloupe may be irradiated up to 1.5 kGy without worsening the product quality attributes. In both cases, carotene content increased as irradiation dose increased. In general, samples irradiated with dose levels between 1.0-1.5 kGy had better quality attributes than the non-irradiated samples. Firmness of the lettuce decreased by 49.58 % (leaves) and 29.13 % (ribs), as the dose level increased. Sensory attributes such as overall quality, color, sogginess, and off-flavor were found less acceptable at the higher dose level. Irradiation affected the respiration rates inside the packages, with lower (10.38%) O2 and higher CO2 levels than the control. Irradiation at 1.5 and 3.2 kGy dose levels improved the oxygen barrier capability of the low-density polyethylene (LDPE) bags (7.67 % and 4.48 %, respectively). Water vapor permeability was unaffected for all the irradiation dose levels. The stiffness of LPDE films did not change due to irradiation treatment. This study shows that low dose (1.0 kGy) electron beam irradiation of packaged romaine lettuce hearts is feasible without altering the quality of the produce as well as the LDPE packaging characteristics. Further work will evaluate the combined effect of the technology on the product quality and microbiological safety. We will also work on the development of an accurate and efficient dosimeter technology to optimize the irradiation treatment. The use of alternative packaging materials to serve as indicators of irradiation treatment will also be investigated.

Impacts
The evaluation of the effect of new technologies on properties of food, agricultural and biomaterials is critical for the optimization of the technology to ensure the quality and safety of our food supply. In addition, the potential development of new materials will result in increased added-value for many agricultural and biomaterial commodities.

Publications

  • Brescia, G., Moreira, R.G., L. Braby and Castell-Perez, M.E. 2003. Monte Carlo simulation and dose distribution of low energy electron irradiation of an apple. Journal of Food Engineering 60(1): 31-39.
  • Castell-Perez, M.E. and Moreira, R.G. 2003. Decontamination Strategies. Chapter 25 in The Future of Food Safety. CRC Press, Iowa.
  • Castell-Perez, M.E. 2003. Non-Newtonian Models. ENCYCLOPEDIA OF AGRICULTURAL AND FOOD ENGINEERING (EAFE). Food Engineering - Rheology of Foods. Mnarcel Dekker, Ed. Dennis Heldman.


Progress 01/01/02 to 12/31/02

Outputs
Studies on characterization of the staling process using rheological procedures were completed. The extent of corn tortilla staling was quantified in terms of degree of amylopectin crystallization using data from stress relaxation and polymer crystallization theory. The staling process in corn tortillas was studied as a function of time (fresh up to 10 days) and storage temperature (6C- 35C). Fresh corn tortilla has a lower value of stiffness than stale tortilla thus indicating how tortilla becomes firmer with time. The stiffness of tortilla decreases with increasing temperature. The Avrami-nucleation model was applied to the kinetic data. This model was selected to describe the extent of crystallization of amylopectin in corn tortilla using stress relaxation techniques in the temperature range of 6-30C with the maximum nucleation rate at temperature of 12.3C. Results correlated well with subjective measurements of tortilla rollability. Current work includes application of this methodology to flour and sorghum tortillas. Several methodologies were tested to produce films from peanut protein isolate (PPI), and film-forming procedures with different treatments were investigated. Distilled water was added to the PPI, which was made from defatted peanut flour, to provide a 5% protein content in the film-forming solution. Ninety percent glycerol was tested as an optimal plasticizer. Film was formed at 90C for 16 h, and then peeled off after cooling. Attempts were made to enhance the film properties by using physical (heat curing, ultraviolet, ultrasound) and chemical (anhydrides and aldehydes) methods. Analyses of the films were performed with different techniques involving physical properties (color, thickness, solubility), tensile strength, barrier properties (oxygen and water vapor), rheological properties (stress relaxation), glass transition temperature, and microscope images (ESEM). Heat curing was the most effective modification for peanut protein films, followed by the ultraviolet irradiation, aldehyde treatments, based on the improvement of increased mechanical strength, reduced water solubility, and reduced barrier properties. Anhydride treatments did not show any significant effect compared with the untreated (control) films in the exception of increased water solubility. Results provide an evaluation of the mechanisms affecting the mechanical and barrier properties of peanut protein films using different modification treatments. The dominant influential parameter on the films properties is the degree of protein cross-linking. Hence, the effect of modification treatment on film properties could be evaluated, and the performance of peanut protein films may be predicted using a quantitative expression of the degree of cross-linking. The mechanisms and effects of physical and chemical treatments are diverse. Peanut protein does have the potential to be used as packaging material, and film functionality can be enhanced by the physical and chemical treatments. Properties of peanut protein films can be substantially modified by treatments, thus, helping tailor such films to specific packaging applications.

Impacts
Results provide valuable data on engineering properties of biological materials, and improved utilization of agricultural crops. The studeis on biobasedfilms should provide guidelines for potential alternative use of peanuts and peanuts waste. This could generate new market for U.S. agricultural commodities and also help reduce the solid waste problem due to disposal of other plastic materials.

Publications

  • Limanond, B., Castell-Perez, M.E. and Moreira, R.G. 2002. Quantifying Texture Changes in Corn Tortillas due to Staling. Journal of Texture Studies, Volume 33, 1: 35-45
  • Limanond, B., Castell-Perez, M.E. and Moreira, R.G. 2002. Modeling Staling of Corn Tortilla. Journal of Food Engineering. 53(3): 237-247.
  • Dissertation: Liu, C.C. 2002. Mechanisms to Enhance Functionality of Peanut-Protein Films Ph.D.. Dissertation. Agricultural Engineering Department, Texas A&M University.


Progress 01/01/01 to 12/31/01

Outputs
The retrogradation process responsible for staling of corn tortillas was modeled using three starch crystallization models: the Avrami-nucleation model, the Macrokinetics model, and the modified Avrami model. The degree of crystallization in the starch fraction was determined using stress relaxation data. Tortilla strips (70x35 mm) were subject to stress relaxation under tension at 3% strain. Force versus distance values were transformed into the textural indicator of stiffness. Fresh corn tortilla had significantly lower stiffness values than the stale tortilla (up to 10 days old). Stiffness decreased with increasing storage temperature from 6oC up to 35C. The kinetics of texture changes due to staling in corn tortillas was best explained by the Avrami-nucleation model in the temperature range of 6-30C. This suggests that amylopectin crystallization in corn tortilla is a nucleation-limited process. The maximum nucleation rate occurred at a temperature of 12.3C. This storage temperature should be avoided to prevent accelerated tortilla staling. The stiffness value from stress relaxation tests may be used as an objective indicator of tortilla texture. Peanut protein is a potential ingredient for development of biopolymeric films for packaging applications. However, mechanical and barrier properties of peanut-protein films are inferior to those of synthetic films. Our objective was to elucidate the mechanisms for improving the functional, mechanical and barrier properties of peanut-protein films subjected to several modification treatments. Distilled water was added to peanut protein isolate (> 95% protein). Films were casted by pouring 10 mL of solution (heated at 95C for 25 min, filtered) into Teflon petri dishes and allowed to dry overnight at room temperature. The pH was adjusted to 9.0 by adding 1N NaOH. Films were formed at 90C for 16 h, then peeled off after cooling and kept in Ziploc bags in a desiccator until further testing. Different methods to enhance film functionality were tested: (1) plasticizer type and amount (glycerin and polyethylene glycol @ 25, 50, 75, 90%); (2) heat curing (60, 70, 80, and 90C for 30 min); (c) UV light for 0, 2, 4, 8, 16, 24 h; (d) ultrasound dosage at 10 and 30 min; and (e) addition of anhydrides and aldehydes. Film thickness, color, solubility, mechanical strength, water vapor and oxygen permeability were measured. The degree of crosslinking was quantified using glass transition theory and viscoelasticity data from stress relaxation tests. Microstructural techniques (ESEM) were used to relate the microstructure changes to the film properties. Glycerin 75% glycerin and cross-linking due to UV and heat curing promoted favorable changes in the functional, physical, and barrier properties as related to the modified molecular size and shape. Film strength and flexibility were significantly improved. Barrier properties improved by 20%. Ultrasound treatment did not affect the film's functionality. The enhanced film performance was related to endothermic polymerization of protein denaturation, more aggregated structures with a denser protein matrix and larger pores.

Impacts
Critical results have been obtained in tools to evaluate quality characteristics of processed foods such as tortillas and potato chips. Developments in biopolymric films provide the way to further work on active or smart packaging materials for improved food safety.

Publications

  • Braud, L.M., Moreira, R.G. and Castell-Perez, M.E. 2001. Mathematical Modeling of Impingement Drying of Corn Tortillas. Journal of Food Engineering 50(3): 121-128.
  • Limanond, B., Castell-Perez, M.E. and Moreira, R.G. 2001. Modeling the Kinetics of Corn Tortilla Staling using Stress Relaxation Data. Journal of Food Engineering. In press.
  • Caixeta, A., Moreira, R.G. and Castell-Perez, M.E. 2001. Impingement Drying of Potato Chips. Journal of Food Process Engineering. In press.


Progress 01/01/00 to 12/31/00

Outputs
The quality of corn tortilla changes dramatically within the first 12 hours and then shows smaller changes for the remainder of shelf-life. This is known as staling and the economic losses caused by this phenomenon are extremely important to both producer and consumer. The extent of corn tortilla staling was quantified in terms of degree of amylopectin crystallization using stress relaxation, Differential Scanning Calorimetry (DSC), and polymer crystallization theory. The staling process was studied as a function of time (fresh-10 days) and temperature (6-35oC). Fresh corn tortilla showed lower stiffness (softer) and dissipated more energy than stale tortilla. Refrigerated storage (6oC ) caused a significant increase in tortilla stiffness compared to the room temperature treatment. Stiffness correlated well with subjective rollability scores. As the staling progressed, an amylopectin endotherm appeared in the DSC thermogram, indicating a development of amylopectin crystallization. This was absent in the fresh tortilla thermogram. Differences in area under DSC traces represent an enthalpy difference between the subglass transition temperature states. At a constant storage time, the staling enthalpy increased as storage temperature decreased. The melting point of fresh tortilla endotherm was significantly less than its value at longer storage time for all temperatures. This means that amylopectin develops more perfect crystals as staling progresses. The glass transition temperature increased sharply from 24 to 48 hours at 6oC; however, no significant difference was found at other temperatures. The degree of amylopectin crystallization was modeled using an Avrami model as a function of time. The temperature dependence of the crystallization rate constant suggested that amylopectin crystallization is a nucleation-limited process and the Avrami-Nucleation model was developed. Other models were tested to describe the extent of amylopectin crystallization. The storage temperatures of 10.2-14.8oC should be avoided to prevent an accelerated rate of nuclei formation (staling). Production of low-fat snack products is the driving force for the evaluation of drying methods of tortilla chips before frying. Superheated steam impingement drying of foods has the advantage of improved energy efficiency and product quality. Impingement drying of corn tortillas was modeled using governing equations for heat and mass transfer during the drying process. Mass transfer within the product was modeled as diffusion-driven mass flux. Heat transfer was driven according to Fourier's Law of conduction. Boundary conditions for drying in both air and superheated steam were incorporated into the model. Product thickness and drying medium temperature had a significant effect on moisture content and temperature profile over time.

Impacts
Useful data on material properties has been obtained which should help manufacturers to improve product quality during processing and storage.

Publications

  • Braud, L.M., Castell-Perez, M.E. and Matlock, M. 2000. Risk-Based Design of Aseptic Processing of Heterogeneous Food Products. Society for Risk Analysis Journal, 20(4): 405-412.
  • Singh, S.K., Castell-Perez, M.E. and Moreira, R.G. 2000. Viscosity and Textural Attributes of Reduced-Fat Peanut Pastes. Journal of Food Science , 65(5): 849-853.
  • Braud, L.M., Moreira, R.G. and Castell-Perez, M.E. 2001. Impingement Drying of Corn Tortillas: A Mathematical Model. Journal of Food Engineering. In press.


Progress 01/01/99 to 12/31/99

Outputs
The objective characterization of changes in Meals-Ready-to-Eat (MRE) properties (physical, chemical, mechanical, microbiological and sensory) as a function of packaging type was completed. Two optimum film materials were identified for more efficient packaging of food items for military use under extreme storage conditions (up to 3 years). Two types of Menu Rations were identified for packaging with selected films and further testing. Manufacture of selected films for MRE packaging and thermal processing is in progress. A methodology to manufacture peanut-based films using extrusion and casting methods has been developed. The films were characterized as viscoelastic solids under the linear region of viscoelasticity using stress relaxation techniques. Cast films were more transparent but weaker. Film color tended to be more stable with time. Extruded films were resistant to tension but more yellowish in color. Addition of soy protein isolate increased films resistance to rupture. A special die was designed and constructed for proper films extrusion. Barrier properties (water vapor) of experimental films must be improved by developing a methodology to produce thinner films. The effect of additives such as lipids is being investigated. One graduate student has completed her research objectives and successfully graduated. Another graduate student is currently evaluating different methods (enzymatic, chemical and thermal) to change the structure of the films and therefore improve their strength and barrier properties. Use of gluten, peanut protein isolate and fibers will also be evaluated. Staling is one the most important quality loss characteristics of corn and wheat tortillas in shelflife studies. It can be regarded as the loss of viscoelastic properties due to changes in the starch structure. Ways of mathematically predicting staling characteristics of food products will improve the quality and shelf life of these products. The overall objective is to quantify the staling process in foods such as table tortillas for better understanding of the mechanisms responsible for such change. Current studies on establishing the kinetics of starch retrogradation and modeling of its association into an ordered structure suggest a similarity with modeling of phase change transition of polymers from rubbery to glassy. Initial kinetic data have been collected using different measurement techniques to quantify crystallinity, water mobility and physical states and phase transitions in the food product as a function of time and temperature. Production of low-fat snack products is the driving force for the evaluation of drying methods of tortilla chips before frying. Superheated steam impingement drying of foods has the advantage of improved energy efficiency and product quality. A mathematical model of the drying process and its effects on product quality using fundamental heat and mass transfer equations is in progress. The model will be validated with the already existent experimental data. This model should be easily adapted to drying of other food products.

Impacts
Research on characterization of agricultural and biological materials provide valuable data on engineering properties of biological materials, and improved utilization of agricultural crops. This may generate new markets for U.S. agricultural commodities, help the value-added industry and also reduce the solid waste problem due to disposal of other plastic materials

Publications

  • Lo, T.E., Moreira, R.G. and Castell-Perez, M.E. 1999. Rheological properties of corn meal dough. Food Science and Technology International 5(1): 61-68.
  • Guo, Z., Castell-Perez, M.E. and Moreira, R.G. 1999. Texture of masa and low-moisture corn tortilla using stress relaxation methods. Journal of Texture Studies 30(2): 197-215.
  • Limanond, B., Castell-Perez, M.E and Moreira, R.G. 1999. Effect of Time and Storage Conditions on the Rheological Properties of Masa for Corn Tortillas. Food Science & Technology, Lebensmittel-Wissenschaft und-Technologie 32: 344-348.
  • Tellez, A.M. 1999. Characterization and Development of Alternative Plastic Films for Food Packaging Applications. MS Thesis, Department of Agricultural Engineering, Texas A&M University.