Probe Structurefunction Relationships in Foods Using Nuclear Magnetic Resonance

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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

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Outline

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

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Agric-product Processing
Food Science
Pomology
PhD
MS
BS
1983
1986
1994
1990
1997
2002
Faculty
Post-doc
Res. Assoc.
Sr. Res. Assoc.
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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

Functional Foods/ingredients
Cereals/Flour-based Foods
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Snapshots of Some Projects (contd)

• 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
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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

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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)

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Functional Elements

• 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
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NMR Relaxometry MRI

• Major relaxation parameters
• 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

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• NMR and MRI
• Non-destructive
• Non-invasive
• Temperature control

MARAN DRX, 21.4 MHz, Resonance Instruments,
Oxon, UK
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Large Bore MRI

• Whole food items
• Small processing devices
• Small animals

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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

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Examples
Chemical structure changes
Starch retrogradation
Bread staling
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Starch Retrogradation and Bread Staling
Native crystalline starch
Gelatinization
Amorphous starch
Retrogradation
Crystalline starch
Change in Firmness of Crumb During Storage
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NMR Relaxation Properties of Bread Crumb
To Analyze change in the properties of water in
bread-with-crust with normal packaging
Mobility
Intensity
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Structure transformation and properties of water
Change during Staling
Mobility
Amount
Fraction 3 Hi mobility
Fraction 2 Me mobility
Fraction 1 Lo mobility
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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

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

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Evaluating Caking Tendency of Dry Powered
Ingredients
NMR state diagrams for powdered ingredients
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TTran
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.
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MRI Process Modeling

• Analysis of
• 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

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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
Strawberry Softening (high maturity) and
physical damages increased the mobility of water
in the tissue.
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2D MR Images of Dough
Calculation of volume and distribution of air
bubbles
Low resolution
High resolution
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3D MR Images of Bagel with Raisins
Low S/N
High S/N
13 raisins counted
Bagel with raisins
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3D MR Images of Extrudates
Ununiform distribution of water and mobility
responsible for irregular shapes of baked
products?
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Slice 1
Slice 2
Raw
0h
1.5h
3h
6h
9h
12h
MR images showing that moisture distribution in
puffed rice kernels during temperingbecame more
uniform with increasing tempering time.
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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

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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
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Modeling Theory Coupled Nonlinear Partial
Differential Equations (PDE)
Electric field Thermal field Heat
generation Boundary conditions Between liquid
particulate System boundary condition
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Model Scheme Generated by FemLab based on Finite
Element Method (FEM)
0.02
-0.02
m
-0.02
0
0.02
Cross-section at vessel center
Mesh statistics Number of nodes 5643 Number of
edges 6139 Number of elements 26599
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Model Prediction vs. MRI Map (Case 1, 120 V)
Model
MRI
10 Min
40 Min
50 Min
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Model Prediction vs. MRI Map (Case 2, 240 V)
Model
MRI
2.5 Min
7.5 Min
12.5 Min
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Model Prediction vs. MRI Map Hot and Cold Spot
(Case 1, 120 V)
MRIliquid
C)

Modelliquid
Temperature (
MRIpotato
Modelpotato
Heating time (s)

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

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Acknowledgements

• 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!
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Questions?
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Cereal Chemistry Technology Bridging Health
Consumer Preferences

• through
• Future Research Teaching
• in the Department of Food Science and Nutrition
• UNIVERSITY OF MINNESOTA

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Presidents 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.

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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
  RD needs and providing first class graduates

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Research Areas
Cereals Health
Structure Functions
Process Dev Model
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New USDA Food Pyramid
Half of the Grains Whole Grains
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Challenge Offer healthy foods without
sacrificing sensory quality
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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

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Aleurone
June 6, 2005, Star Tribune
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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
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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

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

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

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Teaching Experience

• Food TechnologySCAU, China, 1986-1990
• Preservation Processing of Fruits Vegetables
  SCAU, China, 1986-1990
• Cereal BeveragesAACC short course "Asian Food
  Technology," Baltimore, 1996
• Managing Water in Food and Biological SystemsBAE
  8703, UMN, 2003 - present
• Biological Processing EngineeringBAE 4713, UMN,
  2006

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Teaching in FScN

• FSCN 5531 - Grains Introduction to Cereal
  Chemistry and Technology
• Teach other courses related to structure-function
  and preparation of functional ingredients and
  foods
• New course development

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Extension and Outreach

• Public education
• Serve the industry
• Process and product development
• Problem solving
• Seminars/workshops

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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

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Multidisciplinary Collaboration/Interaction
National Center
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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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www.umn.edu/chenx088