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Probe Structure-function Relationships in Foods Using Nuclear Magnetic Resonance Paul Chen, Ph.D., Senior Research Associate Department of Bioproducts and Biosystems Engineering Program Director Center for Biorefining UNIVERSITY OF MINNESOTA

2 Outline Introduction Probe structure-function relationships in foods using NMR techniques Future research and teaching in cereal science and technology

3 Agric-product Processing
Structure-function Functional and health-promoting ingredients Shelf life of foods Heat and mass transfer Non-thermal processes Biorefining process development Modeling Areas of Interest Agric-product Processing Pomology Food Science BS MS PhD 1983 1986 1990 1994 1997 2002 Botany Physiology Biochemistry Microbiology Genetics Breeding Pathology Postharvest handling Food chemistry Food nutrition Food processing Food storage Courses Faculty Post-doc Res. Assoc. Sr. Res. Assoc. LM TEM Cryo-SEM X-ray microanalysis Viscometry TPA Color analysis Mass transfer Math modeling Techniques Research Teaching Papers Reports Grants Services Responsibilities

4 Snapshots of Some Projects
Structure-function relationships of highly refined cellulose (HRC) – dietary fiber Functional and health-promoting ingredients in red corn (anti-oxidant), buckwheat (fagopyritol), and lily (soluble polysaccharides) Hardening of dehydrated fruits in breakfast cereals Stickiness of tortilla wraps Water migration between pizza crust and toppings Rheological and water properties of flour dough Foods/ingredients Functional Cereals/Flour-based Foods

5 Snapshots of Some Projects (cont’d)
Staling of baked goods and cooked wild rice Caking of powered foods Firming of high protein bars, caramel candies Ozone-aided corn steeping process Ozone treatment for barley malting Fusarium scab and mycotoxin in wheat Non-destructive analysis of sweet corn maturity Water distribution in corn kernel and soybeans during soaking and drying Effect of storage on dry bean soaking Food polymer Science Grain Processing

6 - Dr. Allen Levine, Prof. and Head, FScN 2004 Annual Report
Structure-Function “Our strength resides in two signature areas: The structure and function, including sensory and microbial properties, of healthy, safe, and high quality foods; and The impact of nutrients and bioactive food components on chronic diseases and obesity across diverse populations.” - Dr. Allen Levine, Prof. and Head, FScN 2004 Annual Report

7 Structural Elements Chemical structure (molecular level)
Small chemicals: water, salts, minerals, simple sugars (e.g., plasticizers in state transition) Macromolecules: proteins, complex carbohydrates (e.g., starch retrogradation vs staling) Physical structure Microscopic level: cellular structure, food matrix Macroscopic level: dimensions, multi-components (e.g., particulate foods in soup, sandwich)

8 Functional Elements Physical Physiochemical
Enzymatic and non-enzymatic reactions Digestibility and bioactivities Microbial deterioration Disease prevention Texture Viscosity Cohesiveness, stickiness Hydration Dehydration Heating/cooling Solubility Diffusion Deformation Porosity Molecular mobility Geletinization Crystallization Melting Phase/state transition Properties of water Emulsification and foaming Biological & Health Physical Rheological Physiochemical Processing

9 NMR Relaxometry & MRI Major relaxation parameters: A function of:
Signal intensity – proportional to proton density Relaxation times: spin-lattice relaxation time (T1) and spin-spin-relaxation time (T2) – related to molecular mobility A function of: Concentration of proton-containing compounds (e.g., water & lipids) Chemical and physical structures Temperature In magnetic resonance imaging (MRI), spatial information is encoded into the signal intensity, T1 and T2

10 NMR and MRI Non-destructive Non-invasive Temperature control
MARAN DRX, 21.4 MHz, Resonance Instruments, Oxon, UK

11 Large Bore MRI Whole food items Small processing devices Small animals

12 Analysis of Structure-function in Foods Using NMR Techniques
Dough rheology Firming of baked and boiled starch-based foods Firming of food bars Caking of dry powders Physiochemical properties of extrudates, breakfast cereals, wraps Physiology of sweet corn Freezing of dough Heat and mass transfer during soaking, drying, cooling, and heating

13 Examples Chemical structure changes Starch retrogradation
Bread staling Water-solid interactions State transition Caking of powdered ingredients Multi-component system Process modeling Heating of particulates-in-liquid system

14 Chemical structure changes Starch retrogradation Bread staling

15 Starch Retrogradation and Bread Staling
Native crystalline starch Gelatinization Amorphous starch Retrogradation Crystalline starch Change in Firmness of Crumb During Storage

16 NMR Relaxation Properties of Bread Crumb
To Analyze change in the properties of water in bread-with-crust with normal packaging Mobility Intensity Low mobility water Medium mobility water High mobility water

17 Structure transformation and properties of water
Change during Staling Mobility Amount Crust & Surroundings Gluten transformation releasing water Plasticization Water incorporated into crystalline amylopectin Fraction 3 Hi mobility Fraction 2 Me mobility Fraction 1 Lo mobility

18 Water-solid interactions State transition
Caking of powdered ingredients

19 State Transition Glass-rubber transition and glass transition temperature Texture, physiochemical changes, chemical and biological reactions Measurement: DSC, DMA, DMTA, …… Water - plasticizer and probe NMR based techniques

20 NMR State Diagram Temperature increasing Relationship between spin-spin relaxation time (T2) and temperature in PLA Spin-spin relaxation time (T2) as a function of temperature (T) in maltodextrins (DE15). The legends indicate the grams of water in 1kg maltodextrins.

21 Implications NMR-determined transition temperatures are generally lower than DSC-determined Tg Mobility is detected below DSC-determined Tg This may be an explanation for reported chemical and biological activities below DSC-determined Tg It is possible that NMR is more temperature sensitive.

22 NMR state diagrams for powdered ingredients
Evaluating Caking Tendency of Dry Powered Ingredients NMR state diagrams for powdered ingredients

23 TTran A B C D Temperature (°C) T2 KPT KBT Schematic demonstration of four different temperature-T2 curve patterns for the dry soup powders. Caking was found to be a function of curve pattern characterized by transition temperature (TTran), slope before transition (KBT), and slope post transition (KPT). This technique is being used by a company for caking prediction and development of caking resistant formula.

24 MRI & Process Modeling Analysis of: Model verification
Moisture, fat, and mobility distribution in foods Water movement during storage, soaking, drying Temperature mapping/heat transfer Model verification Mathematical modeling – numerical simulation Verification by experiment data from MRI

25 2D MR Images Kiwifruit: Conversion of starch and pectin to soluble compounds during maturity of the fruit has an effect on the structure and mobility of water in the tissue. Raw Mature Egg: Cooking caused egg protein to denature, which reduced the mobility of water. Raw Cooked Hard Soft Bruised Strawberry: Softening (high maturity) and physical damages increased the mobility of water in the tissue.

26 2D MR Images of Dough Calculation of volume and distribution of air bubbles Low resolution High resolution

27 3D MR Images of Bagel with Raisins
Low S/N High S/N Bagel with raisins 13 raisins counted

28 3D MR Images of Extrudates
Ununiform distribution of water and mobility – responsible for irregular shapes of baked products?

29 Slice 1 Slice 2 Raw 0h 1.5h 3h 6h 9h 12h Low High MR images showing that moisture distribution in puffed rice kernels during temperingbecame more uniform with increasing tempering time.

30 Multi-component system Process modeling
Ohmic heating of particulates-in-liquid system

31 Modeling of Ohmic Heating and MRI Verification
Ohmic heating is efficient because it does not rely on heat transfer Suitable for cooking/sterilization of solid particles in liquid (e.g., mixture of meats, carrots, potatoes and soup) Difficult to demonstrate actual sterilization value in multi-component systems such as particulates-in-liquid Modeling provides insight into the heating behaviors of ohmic process Instrumental verification is important

32 Ohimic Heater inside MRI Probe
MRI slice Sample Electrode RF Probe Main magnet Transformer Cylindrical potato particulate AC power Liquid 0.2% NaCl + 0.7% CMC Cross-section of sample At MRI slice

33 Modeling Theory: Coupled Nonlinear Partial Differential Equations (PDE)
Electric field: Thermal field: Heat generation: Boundary conditions: Between liquid & particulate: System boundary condition:

34 Model Scheme Generated by FemLab based on Finite Element Method (FEM)
0.02 -0.02 m -0.02 0.02 Cross-section at vessel center Mesh statistics: Number of nodes: 5643 Number of edges: 6139 Number of elements: 26599

35 Model Prediction vs. MRI Map (Case #1, 120 V)
10 Min 40 Min 50 Min

36 Model Prediction vs. MRI Map (Case #2, 240 V)
2.5 Min 7.5 Min 12.5 Min

37 Model Prediction vs. MRI Map: Hot and Cold Spot (Case #1, 120 V)
80 90 Model:potato MRI:potato Model:liquid MRI:liquid 500 1000 1500 2000 2500 3000 3500 10 20 30 40 50 60 70 500 1000 1500 2000 2500 3000 3500 10 20 30 40 50 60 70 80 90 Model:potato MRI:potato Model:liquid MRI:liquid Heating time (s) Temperature ( C) MRI:liquid C) Model:liquid Temperature ( MRI:potato Model:potato Heating time (s)

38 Model Prediction vs. MRI Map: Hot and Cold Spot (Case #2, 240 V)
MRI: liquid Model: liquid MRI: potato Model: potato

39 Summary We can understand the stability, properties, and processes of foods through the analysis of structure-function relationships. Future research should also look into structure-function relationships in biological activities and bioavailability of nutrients. There exist many opportunities for collaborative research with faculty in FScN and the food industry in this signature area.

40 Acknowledgements Thank You! Dr. Roger Ruan Dr. Ted Labuza
Dr. Gary Fulcher Dr. Paul Addis Dr. Eric Bastien Dr. Joe Warthesen Dr. Zata Vickers Dr. Susan Raatz Dr. Bernhard van Lengerich Dr. Victor Huang Dr. Peter Pesheck Dr. Phil Perkins Dr. Kehua Chang Dr. Lun Yi Mr. Zhenzhong Long Mr. Li Xu Dr. Cheng Zou Dr. Brock Lundberg Dr. Xiaofei Ye Dr. Myonsoo Chung Dr. Hanwu Lei Mr. Jun Han Mr. Lide Chen Ms. Qin Liu Dr. Su Ning Dr. Jinning Qi Ms. Hong Li Mr. Ray Miller Mr. Fred Rigelhof Ms. Regina de Barros Ms. Michele French Mr. Shaobo Deng Mr. Fei Yu Ms. Yun Li Thank You!

41 Questions?

42 Cereal Chemistry & Technology: Bridging Health & Consumer Preferences
through Future Research & Teaching in the Department of Food Science and Nutrition UNIVERSITY OF MINNESOTA

43 President’s Initiative on Healthy Foods, Healthy Lives
The four priority areas: To utilize and advance knowledge about the integration of agriculture, food science, nutrition, and medicine to promote healthy lives; To emphasize prevention of diet-related chronic diseases and obesity through diet, exercise, and human behavior; To enhance food safety at all stages, from farm to table; & To inform public policy. The University of Minnesota is uniquely positioned as a national leader for an initiative focusing on food and health promotion, being one of only two U.S. universities to integrate six key components on one campus: agriculture, human nutrition, medicine, public health, exercise science, and veterinary medicine.

44 My Vision Develop nationally and internationally recognized cereal research and education programs at the University of Minnesota Develop specialized expertise in whole grains and phytochemicals from cereals Serve the local cereal industry by meeting their R&D needs and providing first class graduates I understand that our food science student enrollment is low at moment. On the other hand, there is a great need for graduates trained in food science. But by working with all faculty members and the industry, through public education, A food scientist is not a highly trained chef!

45 Research Areas Cereals & Health Structure & Functions Process
Dev & Model Research Areas

46 Half of the Grains Whole Grains
New USDA Food Pyramid Half of the Grains Whole Grains

47 Offer healthy foods without sacrificing sensory quality
Challenge: Offer healthy foods without sacrificing sensory quality

48 Whole Grain Issues & Opportunities
Unaware of the health benefits Poorly publicized definition Poor sensory quality: “Nothing is better than good old white bread” Limited varieties and expensive Short shelf stability Process modification required


50 Aleurone June 6, 2005, Star Tribune

51 “Whole Grain Additives”
Identification of ingredients and their health benefits Extraction, purification, characterization Incorporation into grain products Testing/trials Rationale Add whole grain benefits to white flour products

52 Potential Projects Extraction and characterization of functional ingredients (“whole grain additives”) from cereals Generation and evaluation of resistant starch using extrusion cooking Evaluation of incorporation of whole grains and “whole grain additives” into cereal-based products in terms of sensory quality and health benefits preservation Safety issues in cereal foods (mycotoxin, acrylamide) In vivo study and modeling of fluid-mechanics and physiochemical properties of cereal foods in the digestive system in small animals using MRI Process modeling and improvement

53 Funding Fed Industry Non-profit State & UMN FScN 2005 Annual Report

54 Publications Food and cereal science and chemistry, food Engineering
Nutrition, biological and health science Interinstitutional co-authorships

55 Teaching Experience Food Technology SCAU, China, 1986-1990
Preservation & Processing of Fruits & Vegetables SCAU, China, Cereal Beverages AACC short course "Asian Food Technology," Baltimore, 1996 Managing Water in Food and Biological Systems BAE 8703, UMN, present Biological Processing Engineering BAE 4713, UMN, 2006

56 Teaching in FScN FSCN  Grains: Introduction to Cereal Chemistry and Technology Teach other courses related to structure-function and preparation of functional ingredients and foods New course development

57 Extension and Outreach
Public education Serve the industry Process and product development Problem solving Seminars/workshops

58 Collaborate as a “Whole”
Future of Whole Grains Nutrition – discover new benefits, verify current claims, provide better definition Consumer research – understand consumers’ expectation, hurdles to acceptance Process and product development – develop/modify processing technology, better quality and more varieties Agronomy and breeding – screen existing grains, develop new grains with better quality through genomics

59 Multidisciplinary Collaboration/Interaction
National Center

60 Summary The breadth and depth of my research experience and expertise allow me to establish strong research programs in the field of cereal chemistry and technology My research will promote the consumption of cereal products that offer health benefits with high sensory quality I have the desire, capability and necessary interface to collaborate with researchers in different fields I am committed to enhance the teaching, extension and outreach programs in this department I have a good track record of research, grants, and publication I work hard and will do my best to make a significant contribution to this great department.



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