1. UNIVERSITY OF MINNESOTA
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.