Emulsion structure in relation to sensory and and digestive functionality
Food is essential to provide the nutritional support for the body and is almost always of plant or animal origin. However, consumer acceptance and bioavailability of the food materials is greatly increased by processing the raw food materials into a broad range of food structures.
Being the portal of the gastrointestinal tract, the mouth is functional for testing the safety and expected nutritional value, pleasure and possible toxicity of the food and to prepare the food in the form of a slippery, smooth bolus that does no longer contain large solid structures that are difficult to digest or become stuck in the gastrointestinal tract, or sharp objects that could penetrate the mucous epithelial surfaces of the gastro intestinal tract. During oral processing, the food is broken up into pieces and mixed with saliva, during which tastants and aromas are released and detected. The swallowing reflex occurs when a sufficiently smooth cohesive bolus is formed that can be easily swallowed and passed to the esophagus without the risk of food material entering the windpipe. Once swallowed, the bolus enters the gastrointestinal tract, which is a very efficient machinery to extract the required nutrients in a safely absorbable form. The gastrointestinal tract is organized in such a way that the food is stored in the stomach, from which it is gradually released at a controlled rate into the intestine, where a large assembly of chemicals (emulsifiers, enzymes) is activated and the residence time is regulated to ensure an efficient digestion and absorption of the food. Gastrointestinal receptors continuously monitor the remaining nutrient availability, which translates into signals that control food intake.
Some of these oral and gastro-intestinal processes are consciously perceived and described as oral texture, flavor, taste, fullness and hunger. Altogether, perception, intake and bioavailability of the food materials are highly dependent not only on the structure and composition of the food before intake, but especially also on the behavior during oral and gastro-intestinal processing.
Nevertheless, in spite of the high level of control by the intricate machinery of our body, the highly digestible and sensorial attractiveness of modern food, in combination with a sedate lifestyle, can lead to health problems. Of particularly concern is the metabolic syndrome, which encompasses a number of appearances such as obesity, diabetes, hypertension and cardiovascular disease. Since caloric over-consumption of especially sugars and fats in the diet seems to be the main food-driver of metabolic syndrome, there is an urgent need to reduce the caloric intake from these components.
Two recent TIFN projects have been focusing on the food emulsion side of this issue, one related to the role of emulsified fat on sensory perception, and one focusing on emulsion digestion. This presentation will o
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1. Emulsion structure
in relation to
Jennifer Aniston (W Magazine photo shoot )
sensory and and
digestive
George van Aken
functionality george.vanaken@nizo.com
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2. FOCUS
COMBAT METABOLIC SYNDROME
OPTIMAL FAT FORMULATION IN WEIGHT
MANAGEMENT PRODUCTS?
HOW CAN WE DESIGN EMULSIONS TO AVOID
OVEREATING?
3. Positive energy balance
METABOLIC SYNDROME:
Obesity, CardioVascular Disease
inflammation, diabetes type II,
high blood pressure, atherosclerosis
Enlarged adipocytes: Ectopic fat storage
• Impared adiposite liver, heart, pancreas.
Fat storage exceeds differentiation and function skeletal muscle,abdominen
the normal storage • Modulated endocrine
function
capacity of adiposites
High blood triglycerides
Impaired glucose homeostasis
Heilbron et al, Int. J. Obesity, (2004)
4. Approaches against metabolic
syndrome
• Reduce ectopic fat
• Reduce caloric intake
• Increase satiety
• Sport
• Burn more fat, built more muscles
• Improved clearance of inflammatory pro-
atherogenic blood lipoprotein remnants
• Increase in Omega-3 and short and medium chain fatty acid,
Increase fibers. Reduce sugar. Increase fibers.
• Reduce saturated (palmitic) fatty acids (Challenged)
• Lower blood pressure, less vessel injury
leading to better cardiovascular health
• Low salt, less stress
• Low glycemic index
• Low sugar, slow starch, slower gastric emptying, slower absorption
5. Approaches against metabolic
syndrome
• Reduce ectopic fat
• Reduce caloric intake
• Increase satiety
• Sport
• Burn more fat, built more muscles
• Improved clearance of inflammatory pro-
atherogenic blood lipoprotein remnants
• Increase in Omega-3 and short and medium chain fatty acid,
Increase fibers. Reduce sugar. Increase fibers.
• Reduce saturated (palmitic) fatty acids (Challenged)
• Lower blood pressure, less vessel injury
leading to better cardiovascular health
• Low salt, less stress
• Low glycemic index
• Low sugar, slow starch, slower gastric emptying, slower absorption
6. Product requirements
• Should reduce caloric intake
• Early satiety
• Long lasting hunger reduction
• Should be healthy
• Low glycemic index
• Reduce blood triglycerides, improve inflammatory
response
• Should be preferred by consumer
• Sensory quality
• Creamy, full taste and aroma
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7. Goals:
• Healthy: low calorie intake at satiety
• Sensorially liked: creamy, smooth, full
2 finalized projects at TIFN:
- Improved satiety by emulsified fat
- Improved creaminess by emulsified fat
Application
Contract research
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8. Main findings of the two
projects
• Sensory perception of emulsions determined
by the behaviour during oral processing
• Satiety by emulsions influenced by the
structure and dynamics in the gastro-intestinal
tract
Needed is a better understanding and control of
the interactions of the emulsions with the
human body product formulation
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9. TIFN Project team:
Diane Dresselhuis
Unilever Erika Silletti
DSM Guido Sala
Cosun Els de Hoog
Avebe Monique Vingerhoeds
FrieslandCampina Jan Benjamins
Franklin Zoet
NIZO food research
Jerry van Maanen
TNO
Eefjan Timmerman
WUR Willem Norde
Martien Cohen Stuart
George van Aken
Sensory pereption
ORAL BEHAVIOUR OF
EMULSIONS
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10. Product developers approach
Sensory paneling
Product development: Product characteristics:
composition, structure sensory properties
• reduced fat
Correlations
correlations • not so creamy, thin, slimy, gritty
• thickeners are often • off tastes, off flavours, unbalanced
flavours
• particles
• aroma’s poor
• sugar replacers Instrumental measurements:
• viscosity, gel strength, fracture behavior
• friction measurement
• droplet and particle size
• aroma and flavour release
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11. Sensory perception of food
Appearance
color, shine,
structure, flow, aroma
Brain
Receptors
First bite
rheology, temperature
Feed back
Masticatory Gut signals
oral processing Satiety, well being
many structural changes,
flavour release swallow After taste
oral and
pharyngeal coating,
11
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12. Tribological regimes of papillae
(Stribeck curve)
Hydrodynamic modelling
Friction force of the soft deformable
Static surface bonds papilla surface*
Static friction
“Smooth” thickness
Transient surface bonds and particle size
corrugations
palate boundary Only viscous
forces
Liquid starts to
interpenetrate
hydrodynamic
papilla Gap-width
mixed
increases with
speed viscosity
“Rough speed
tongue” viscosity
astringency
* Van Aken, G.A., Modelling texture perception by soft epithelial surfaces, Soft Matter, 2010, 6, 826–834
13. Emulsions:
Large structural changes, even for thin liquid emulsions:
THIS is what you taste!
TI food and
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14. Structural changes in the oral cavity
Food emulsions
Saliva-induced Formation of slimy
droplet aggregation structures
Droplet-coating of Inhomogeneous coverage
oral surfaces of tongue papillae
Amylase induced
Droplet coalescence starch breakdown
Fat spreading at air Droplet spreading at
bubble surfaces tongue surface
Fracture of gels into Release of
‘crumbs’ emulsions droplets
Van Aken et al., Food Colloids, Dickinson ed., RSC, 2005, pp.356 – 366; TI food and
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14 Curr. Opin. Colloid Interface Sci. 2007, 12, 251-262. .
15. Saliva-induced flocculation
1:1 mixtures of emulsions with saliva
E. Silletti et al., Food Hydrocolloids 21 (2007) 596–606; J.Colloid Interface Sci. 313 (2007) 485–493
50
emulsion
40 mixture
30
32
20
d
10
0
-100 -50 0 50 100
Emulsion -potential (mV)
16. Viscosity increases due to saliva-induced droplet
aggregation → increased creaminess
ξ<0 ξ>0
Liquid emulsion
at 100 s-1
Saliva-induced
droplet
aggregation
Vingerhoeds et al. Food Hydrocolloids, 23(3) (2009), 773-785. TI food and
16 Van Aken to the next level Colloid Interface Sci. 12 (2007), 251-262.
Together et al., Curr. Opin. Nutrition
17. Interaction with the tongue
PhD study of Diane Dresselhuis
Visualization of fat
retention on pig tongue
CSLM image
500 500 m
10 wt% SF oil; 1 wt% WPI
red: oil; green: tongue papillae
Dresselhuis et al., Journal of Colloid and Interface Science (2008)
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18. 0 .3 s pit
Fat retention on the tongue rins e
gram fat remaining in mouthin m ou th
emulsions varying in stability to coalescence
00.2
.2 o/w emulsion
0 .3 sFat
pit
gr am fat rem ain ing
remaining
rins e
7% SF (sunflower oil)
gr am fat rem ain ing in m ou th
after first stabilized with protein WPI
spit stable unstable
0 .2
0 0.1
.1 Fat WPI 1 0.3
remaining [%]
0 .1
after water D[3,2] 0.92 1.15
rinsing [ m]
1.6 1.4
0 0.0
.0 (@51 s-1)
0 1% W P I S F
.0 0.3 w t% W P I S F 1% W P I S F L
1% W P I S F 0.3 w t% W P I S F 1% W P I S F L [mPa s]
stable unstable
Fat adhesion and retention larger for more unstable emulsions
→ increased creaminess
Dresselhuis et al., Journal of Colloid and Interface Science (2008)
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19. Friction between PDMS (hydrophobic) and glass
(boundary friction regime) Dresselhuis et al. Food Biophysics (2007)
0.6
Effect of adsorption of fat
onto the surface
0.4
Friction coefficient
Fat content (wt%)
0.2
0.3 wt%WPI unstable emulsion
1.0 wt%WPI stable emulsion
0.0 Dewetting of saliva
0 10 20 30 40 from the oral surfaces
Fat content (wt%)
Fat reduces the friction (→ increases creaminess), but an increase
in fat content has no further effect
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20. What makes emulsions creamy?
GEL FRACTURING dependent on gelling
agent and droplet interaction
ACTIVE saliva
VISCOUS
BOLUS of
gel particles Thick
INACTIVE and saliva
saliva
Gelled
emulsion
porous Rich
HIGHER VISCOSITY by saliva
–induced droplet flocculation rubbing,
EXTENDED
aroma release
Creamy
shear
saliva
Smooth
shear LUBRICATING
saliva FATTY COATING
Liquid Droplet coating
on oral surfaces Coating
emulsion
26 refereed journal publications and 8 book chapters (2005-2011) by the TIFN project team
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21. Restored creaminess in
reduced fat products
• Restore boundary lubrication:
• Emulsion sensitized to coalescence (increase solid fat
content, adjusted emulsifier mix, OSA starch)
• Specific lubricating emulsifiers
• Reduce acidity and astringency (polyphenols)
• Restore viscosity:
• Smaller droplet size
• Similar thinning behavior during oral processing
• Thickeners, compatible with saliva (polysaccharides,
resistant starch)
• Small particles (size below detection limit)
• Restore flavour:
• Flavor rebalancing
• Controlled release
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22. TIFN project team:
Unilever
DSM
Raymond Schipper
CSM
Anne Helbig
VION
Man Minekus
FrieslandCampina
Lex Oosterveld
NIZO food research
Erika Silletti
TNO
Esther Bomhof,
WUR
George van Aken
Digestion
GASTRO-INTESTINAL
BEHAVIOUR OF EMULSIONS
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23. Engineered sensory and dietary
functionality of dispersed fat
Develop fundamental knowledge on the oro-gastro-intestinal behaviour of
food emulsion systems and how this behaviour relates to physiological responses
Physical chemistry Oral/Gut Biochemistry
Structural Behaviour in oral-
Adsorbed layer
component gastro-intestinal
Droplet size
tract
Fat type
Continuous phase
Physiological
responses
Physiology
B-1007: Engineered sensory and dietary functionality of dispersed fat
24. Line up of experimental models with
increasing complexity
In vitro,
in vivo Tongue
cup
mouth
model
Belly
Quintet
In vitro gastric
Artifical and intestinal
mouth models TinyTIM
Artificial
digestion model
Pig Model MRI
pH STAT
of stomach
Animal Model
Human Studies
Human
subjects
In silico
modeling
B-1007: Engineered sensory and satiating functionality of dispersed fat
26. What is the problem with fat
digestion?
Triglycerides are insoluble in water and therefore
cannot be detected and absorbed directly
• Lipases are water soluble and can only be active at
the oil/water interface → efficient lipolysis requires
large O/W interfacial areas (small droplet sizes)
• Adsorbed layer of emulsifiers and lipolytic products
(fatty acids, monoglycerides) may hinder lipase activity
• For saturated C12 and longer, the lipolytic products
(fatty acids, monoglycerides and diglycerides) are
insoluble solids
• Unsaturated long chain monoglycerides (e.g. C18:1)
form cubic liquid crystals
27. Role of bile in the small intestine
• Bile removes emulsifiers from the interface
• Pancreatic lipase hydrolyses triglycerides into
pancreatic lipase
fatty acids and sn-2 monoglycerides by lipases
• For saturated C12 and longer, the formed fatty
acids, monoglycerides and diglycerides are
insoluble solids
carboxyl ester lipase
• Unsaturated long chain monoglycerides (e.g.
C18:1) form cubic liquid crystals
Bile Bile solubizes the
insoluble lipolytic
micelle products into micelles
28. Fat digestion: main enzymatic processes
Stomach
Gastric lipase Portal
(<10%)
vein to
liver
Small Small intestinal
intestine wall
Serum
albumin
transporter
Pancreatic lipase
(almost complete)
chylomicron
Bile micelles lymph
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29. Effect of the lymphatic route
• Long chain MUFA, SAFA and
vitamins bypass the liver
• Primarily used by the body for
energy (muscles) and stored in
adipose tissue
30. Nerve membrane
Routing of fatty acids - overview
Functional
liver
lipids FA
glucose
Portal vein
C11:0 and shorter
Main ω-3 DHA
blood
ω-6 PUFA serum VLDL stream
albumin
ω-3 PUFA
glucose LDL
chylomicrons
Oleic acid
C12:0 and longer Lymph vessel
Energy Conjugated
double bonds:
CLA
supply Muscles Adiposites
31. Regulated stomach emptying
of nutritious liquids:
Roughly constant nutrient release to the small intestine
duodenum jejunum ileum
Pylorus absorptive cells
Stomach Stomach
intake activity emptying
area concentration absorbable nutrients
bile pancreas
- - + + I-cells detect nutrients
(mainly duodenum, jejunum)
Regulated gastric emptying at 1-2 kcal/min
• Corresponds to 1440 - 2880 kcal/day, similar to the advised daily caloric intake
32. Regulated small intestinal
residence time (ileal brake)
• Compensates for a high caloric entry into the intestine or slow
enzymatic hydrolysis
• Normal condition: nutrients reach ileum but not colon
duodenum jejunum Ileum
Absorptive cells
intake Stomach Pylorus Transit speed
bile pancreas -
L-cells detect nutrients
(ileum and COLON)
33. Computer
modeling
Fed by: physiological literature
in vitro studies
(in vitro gastric, Simfyd, tiny TIM)
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34. In-silico model
absorption
Intake
(water,
protein,fat, Fundus
carbohydrate
as a function
Corpus
pylorus
of time)
Antrum Duodenum
FFA FFA
Jejunum 1
FFA Jejunum 2
Gastric Enough calories
Nutrient
density in
Jejunum 3 FFA
Ileum 1
volume in my stomach ...
chyme FFA
time to stop eating!
FFA
Ileum 2
I-cells L-cells FFA
CCK PYY, GLP1, Ileum 3
Fullness oxymodulin
oxymodulin FFA Ileum 4
oxymodulin
FFA Ileum 5
Hunger Total
Insufficient calories FFA Ileum 6 Colon
absorbable
• Potentiate glucose-stimulated insulin
in my gut...nutrients secretion
• Reduce glucagon
I should eat!
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35. Examples
1. Emulsions that cream in the stomach
2. Emulsions that sediment in the stomach
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36. Increase fullness during eating by improving
the emulsion stability in the stomach
Bulk fat and many emulsions and are unstable in the stomach
(low pH, enzymes) and separate a fat–rich creamed layer .
Consequence: an energy poor lower phase empties fast, quickly
reducing the volume of the stomach
8 12
Fullness Hunger
7
10
6
5
8
Simulation of an emulsion of 40 g
reference
a.u.
a.u.
4
fully creamed fat layer
6 reference
fat and 200 g water; effect of fat
3 fully creamed fat layer
2
4
floating as a creamed layer
2
1
0 0
0 200 400 600 800 0 200 400 600 800
time (min) time (min)
Effect gastric instability of an emulsion
*Marciani et al., British Journal of Nutrition
(2009), 101, 919–928
37. Approach: induce sedimentation in stomach
Collaboration with Alan Mackie (IFR) for in vivo testing
Van Aken et al., Food Hydrocolloids (2011)
5 % triolein, 1 % WPI,
1 % caseinate
• Expected to improve satiety during and shortly after the meal,
reducing meal size.
9 12
Full fat milk
8 Fullness Hunger
10
7
reference
6 8
5 sedimented fat layer
6 Simulation of an emulsion of
a.u.
4
a.u.
3 4
reference
40 g fat and 200 g water;
sedimented fat layer
2
1
2 effect of fat sedimentation,
0 0 leading to an initial emptying of
0 200 400 600 800
-1 0 200 400 600 800
time (min)
-2
time (min)
a 25 % fat emulsion
38. Relevance: suggestions from
experiments and simulation
Thin liquid high-calori drinks:
• Tend to be over-consumed because of quick emptying
before regulated emptying is activated. (less fullness during
the meal)
• The initially fast-emptying nutrients are quickly absorbed, do
not contribute to longer term hunger reduction.
(Semi-)solid high-calori food:
• Is emptied slowly, regulated by caloric content and slowed
down further by gastric “erosion” of food lumps
• Physiological estimation of calories in reserve in the
stomach and small intestine is more accurate.
39. Challenge
• Combine the concepts and techniques
developed for sensory perception, digestion
and satiety of food emulsions to construct
highly liked food emulsions that are more
satiating
• Solutions highly dependent on product type
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