Food structure and bioavailability - INFOGEST, 2013

INFOGEST PhD Training School
“Food Digestion and Human Health”
Gdansk, Poland
23th of April 2013
Amélie Deglaire
amelie.deglaire@agrocampus-ouest.fr
Food structure
vs. nutrient bioavailability

2
Introduction
 Nutrient bioavailability
 availability for the metabolic functions of the organism
 ≤ nutrient content of a food
 The best indicator of the nutritional quality of a nutrient
 Influencing factors
 Chemical state of the nutrient
 Interactions with other food components
 Presence of antinutritional factors
 Release from the food matrix
 Recent data : influence of the matrix state of natural foods or the
microstructure of processed foods ( or )
 Increase of publications in food digestion
associating food scientists, nutritionists and
gut physiologists
0
200
400
600
800
1000
1200
1991 1995 2000 2005 2009
Numberofscientificpublications
Year
How the food matrix structure influence food digestion?

3
Outline
1. Definition
1. Food structure
2. Bioavailability vs. bioaccessibility
2. Food structure and macronutrient bioavailability
1. Carbohydrates
2. Proteins
3. Lipids
3. Food structure and micronutrient bioavailability
1. Micronutrients from plant food
2. Carotenoids and beta-carotenes
3. Iron
4. Conclusion
Outline

4
1. Definition
1. Food structure
1. Carbohydrates
2. Proteins
3. Lipids
3. Iron
4. Conclusion
Outline

5
Food structure?
Food structure or ‘‘food matrix’’ = organisation of food constituents at multiple spatial
scales
Provided by nature or imparted during processing and preparation (food manufacturing)
 Impact on food quality in particular on sensory and nutritional aspects
 Insight in food structure and how it changes during processing operations is essential for
producing high quality food
Source: Aguilera, 2005, 2007; COST Action FA1001: insidefood
Multiple scale structural elements
Mackie and Macierzanka, 2010
Interactions proteins - lipids
and their interactions

6
Example of food structures produced by milk
processing
Source : Aguilera, 2005

7
Nutritional quality of a food
 Food  Nutrient content
Synthetic indicator : balance between the « good » and « bad » nutrients
Example: nutritional profil SAIN LIM (Darmon & Darmon, 2008)
Average % of the coverage or excess of the recommendations for
the nutrients of interest
SAIN : Score d’Adéquation Individuel aux recommandations Nutritionnelles /
Adequate Score for Nutritional Recommendations
 Proteins, Fibres, Vitamine C, Calcium, Iron
LIM: score des nutriments à LIMiter / Nutrients to limit
 Sodium, Saturated Fatty Acids, Added Sugars
 Recognized by the French authorities

8
Impact of a process on the nutritionnal
quality profil
Source: Achir et al., Journal of Food Engineering, 2010
5
Apple drying

9Source: Guerra et al., 2012, Trends in Biotechnology
Food digestion : regional specificity of the digestive tract
*
* No lingual lipase coded in humans.
Bacterial origin?
The physical properties of a food matrix can affect the efficiency of the
physical, enzymatic and chemical digestion processes

10
Nutritional quality of a nutrient
 Nutrient  bioavailability
Fraction of a nutrient that has been digested and absorbed
and is available for (has been used by) the metabolic functions of
the organism
IleumMouth Stomach Duodenum Jejunum
Blood
Structured
food
Raw
ingredients
Colon
Faeces
Absorption
Urine
Digestion Excretion
Metabolism

11
Adult Mini-pig Piglet
Human adult Neonate
Use and development of in vivo models
Bioavailability :
 measure in the blood plasma
 metabolic utilization : waste from digestion (faeces) + metabolism
(urine, blood)

12
Blood sampling
Bioavailability measure
Bioavailability = Area Under the Curve (quantity of nutrient absorbed) x 100
quantity of nutrient ingested

13
Bioavailability estimates
Blood
Structured
food
Raw
ingredients
Colon
Faeces
Absorption
Urine
Digestion Excretion
Metabolism
Digestibility: (Ningested – Nfaeces )/Ningested
Net Postprandial Protein Utilisation (NPPU):
(Ningested – Nfaeces – Nurine – Nurea blood)/ Ningested
Biological value: NPPU/Digestibility

14
Nutritional quality of a nutrient / in vitro
 Nutrient  bioaccessibility
fraction of a compound that is released from its matrix in the
gastro-intestinal tract during digestion and thus becomes
available for intestinal absorption (Fernandez-Garcia et al. , Nut Res, 2009)
Blood
Structured
food
Raw
ingredients
Colon
Faeces
Absorption
Urine
Digestion Excretion

15
le VMBB : enzymes
Digestion models for the adult and the neonate
Duodenal
Phase
Static Conditions
Gastric
Phase
Epithelial
Phase
Constant pH
No flow
Constant [Enzymes]
Dynamic Conditions
Partnership with UMR GMPA Grignon
Regulated pH
Dynamic flow
Regulated[Enzymes]
Development of in vitro digestion models
 Bioaccessibility

16
Estomac Duodénum Jéjunum Iléonestomac duodénum jéjunum iléon
Will the liquid dairy sample
coagulate when entering in
the stomach???
Prediction of the
rheological behaviour of an
IF in gastric conditions
Viscosity of the gel
Macroscopic scale
Proteins Lipids Microscopic scale
Stomach Duodenum Jejunum Ileum
0
5
10
15
20
25
30
35
0 25 50 75 100 125 150 175 200
time (min)
G'(Pa)
3.00
3.50
4.00
4.50
5.00
5.50
6.00
6.50
pH
Sample 1
Sample 2
pH
Multi-scale characterization of digested food

17
Mass Spectrometry
Surprol
More than 4700
peptides identified in
the human jejunum
ELISA
0%
10%
20%
30%
40%
50%
Est 30' Est 1h30 Est 3h30
-lactoglobulin
-lactalbumin
Caseins
Multi-scale characterization of digested food
Antibody arrays Molecular scale

18
Development of in vitro digestion & absorption models
Source : Prada & Aguilera, 2007
CaCo-2 cells: human epithelial colorectal adenocarcinoma cells  differentiated
enterocyte  absorption
HT29-MTX cells : goblet cell clone  mucus secretion (Walter et al., 2000)

19Source : Fernandez-Garcia et al. , Nut Res, 2009
Bioavailability & bioaccessibility

20
Outline
1. Definition
1. Food structure
1. Carbohydrates
2. Proteins
3. Lipids
3. Iron
4. Conclusion

21
Carbohydrate : starch
Amylose : linear structure
( gel)
Amylopectine : branched structure
( viscosity)
Amylose content varies with the botanic species (mean : 20% / waxy wheat : 0%)
Starch digestion  hydrolysis of glycosidic bond
•Linkage -1,4 : salivary and pancreatic amylase
•Linkage -1,6 (amylopectine) : membrane isomaltase (after amylase)
Starch microstructure: granular (2-130 µm ) / cristalline

22
Starch granule organisation
Source Jenkins et al., 1996

23
Starch granule
Native and modified starch
granules

24
Starch cooking
 Raw starch : insoluble in cold water, low digestibility
 Cooking with water and heat
– gelatinisation : destruction of the cristalline structure, starch granule
swelling increased digestibility
– retrogradation of starch (semi-cristalline structure) with cooling
 decreased digestibility
Source: B. Boursier, techniques de l’ingénieur, 2005
 Different behaviour
according to the botanical
sources (ex: potato vs. cereal)

25
Structure evolution of starch during
gelatinisation
Source: Bogracheva et al. 2006 ; Crowther, 2012
Light microscope
under polarised
light
20 µm
Light microscope
under polarised
light

26
Starch cooking
 Cooking with dry heat (dextrinisation)
Extrusion/milling :
starch destructuration: digestibility increased
 Resistant starch (retrogradation, raw, non accessible,
high amylose content)
digestibility decreased(« fonctionnal fibers »)

27
Glycemic index : glucose release kinetics
CarbohydratesFood
Gastric
emptying
Digestion
Viscosity
Energy
Lipids
X
X
Absorption
Nature & structure
-Composition
- amylose/amylopectine
- associated nutrients
-Mecanical and thermal treatments
- water cooking (gélatinisation)
- extrusion (fusion)
-Dry cooking (dextrinisation)
-Milling

28
Glycemic index (GI)
1. 50 g of carbohydrates to test
2. Blood sampling (at regular intervals for 2-3 h)
3. Blood glucose content
4. Comparison with the reference (glucose)
5. Average on 8-10 volunteers
Source: Brand-Miller et al., AJCN, 2005
GI (%)=100 x AUC food
AUC reference

29
High
Average
Low
GI
Alone Mixed diet
Food GI

30
High
Average
Low
GI
Alone Mixed diet
Food GI

31
GI & health
Glucose as reference
Low GI (spagetthis: 50) < 55
Average GI(pain blanc: 69) 55-70
High GI (corn flakes: 80) > 70
Low GI
prolonged glucose disposal
 before exercise (toughness)
 potentially with a satiating effect
 hypoglycaemia delayed
High GI
short glucose disposal
 after exercise: stock recovery
 Diet with high GI : potential impact on weight gain, food intake,
triglyceride synthesis increased , oxydative stress

32
 GI (Amylopectine) > GI(Amylose)
branched chain of amylopectin: more area accessible to enzymes
 amylose: more rigid gel less accessible to enzymes/ more retrogradation
Starch nature & GI
(Behall et al., Am J Clin Nutr 1988)
n=26

33
 Starch gelatinisation increases its
digestibility
Source Holm et al, Am J Clin Nutr 1988Degree of hydrolysis of starch at
différent degree of gelatinisation (DG)
Correlation among degree of
gelatinisation, digestion rate, plasma
glucose and insuline in rat
DG0
DG14
DG37
DG71
DG85
Starch structure and digestibililty
In vitro digestion
Metabolic response in rats

34
Starch cooking, degree of gelatinisation (DG) and blood
glucose (GI)
Parada & Aguiliera, 2009,2012
 Gelatinisation of starch increases its glycemic index
Starch structure and GI
n=1

35
23 cereal products:
BC : breakfast cereals (5)
BP&C : bakery products and crackers (6)
Bi : Biscuits (12)
 The higher the gelatinisation
degree, the higher is the GI
 Impact of other nutrients
Source : Englyst et al. Br J Nutr 2003
Glycemic index
Degree of gelatinisation
Starch structure and GI
Biscuits baked under very-low-moisture conditions
Degree of gelatinisation reduced
Degreeofgelatinisation
n=13

36
Product
Bread (reference)
Oat flakes
Oat flakes
Oat flakes
Oat flakes
Oat flakes
Kernel
Pretreatment
Oven+Steam
Oven
Steam
Oven
Raw
Thickness
0.5 mm
0.5 mm
1 mm
1 mm
1 mm
Gelatinisation
%
24
16
16
16
0
GI
100a
114 ± 12a
99 ± 10ab
76 ± 8c
72 ± 9c
78 ± 9bc
Degree of gelatinisation, flake thickness
and glycemic index
Granfeldt et al, J Nutr 2000
n=10
 Minimal processing of oat flakes : minor effect on GI features
compared with the more extensive commercial processing

37
Dense Common Bread
Sourdough breadTradition Bread
Tradition Bread + fibres
Dense Tradition Bread
60±8a –0.24
55±9b – D: 0.24
55±8b – 0.30
53±8b – 0.32
62±13a – 0.21
Common Bread + fibres
Common Bread
GI: 75±11a – D: 0.16
Process and composition impact
53±8b – 0.29
GI and
texture
(density: D)
Source: Rizkalla, 2009
Glycemic
index
Insulinemic
index
Bread
density

38
• Starch nature: amylose +++
• RS1: native starch physically inacessible in entire crops (no grinding)
•RS2: native starch granules that resist to digestion (no extensive
gelatinisation : moisture < 40 % ou T<Tgelatinisation)
• RS3 : retrograded starch
High heat treatment (> 120°C) favors the amylose cristallisation during cooling
and limits its capacity to re-gelification
• RS4: starch chemically modified
Resistant starch

40
Source : Murakami et al., Eur J Clin Nutr 2007
 Positive association between high GI diet, low fiber intake
& BMI
Impact of a diet with high glycemic index
on health
n=3931 japanese women

41
 Cardiovascular disease risk increased by high GI diet
Mente et al., Arch Intern Med 2009
on health

42
PlasmaF2-isoprostane(ng/mL)
P for trend : p=0.03
Plasmamalondialdehyde(µmol/L)
P for trend : p=0.02
 Increase of the oxidative stress in plasma
Quartiles of GI diet (Average GI: Q1,50.3; Q2, 53.6; Q3, 55.8; Q4, 59.9, n=291)
Adjusted data for age, gender, BMI, tobacco, alcool, kcal, proteins, fibres, folates and cholesterol
Source: Hu et al., Am J Clin Nutr 2006
Impact of a diet with a high glycemic
index on health

43
Diet with high GI increases the risk of non-insulinodependant
diabetes (type II)
Source: Schulze et al., Am J Clin Nutr 2004
Relative risk and confidence interval at 95% of diabete II according to the GI diet
quintile in 91 249 women
on health

44
(1) Raw material choice (+++)
Balance amylose/amylopectine
Associated nutrients (proteins and fibres)
(2) Mecanical and thermal treatment
Grinding
Extrusion
Water (gelatinisation) / Dry(dextrinisation)
Conclusion: Technology and glycemic
index

45
Outline
1. Definition
1. Food structure
1. Carbohydrates
2. Proteins
3. Lipids
3. Iron
4. Conclusion

46
Kinetics of digestion influence kinetics of AA absorption
Plasma
Am J Clin Nutr, 2006
n=23
-400
-200
0
200
400
600
800
1000
1200
0 1 2 3 4 5 6 7 8 9
Temps (h)AAtotaux(µmol/L)
Prot. Sériques Caséines
0
10
20
30
40
50
60
70
80
90
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6
Temps de digestion (h)
Nombre de
peptides
0
0,1
0,2
0,3
0,4
0,5
0,6
0 0,5 1 1,5 2 2,5 3 3,5 4 4,5 5 5,5 6
Time (h)
Ntot (mmol/mL)
Caseins
Whey Prot.
Surprol
Small intestine
n=14
Caseins
Whey Prot.

47
 Different theoretical models have been proposed
Walstra & Jennes
1984
The «submicellar model »
Holt 1994
The «hard-sphere model »
Milk protein microstructure : casein micelle
Marchin et
al.
2007
Dalgleish et
al.
2004
200 nm
The real organisation of individual caseins within the micelle remains unknown

48
Casein micelle reactivity
From F. Gaucheron, INRA
AcidificationAcidification
HeatHeattreatmentstreatments
>90>90°°CC
Denaturated whey proteins
Calciumphosphate
k-casein, peptides, NH3
Calciumphosphate
Casein(before precipitation)
Addition of diAddition of di
or trivalentor trivalent
cationscations
Cations
Anions
Lactose
Protons
Addition of NaClAddition of NaCl
AdditionAddition
ofof
chelatantschelatants
H2O
Caséines
Calciumphosphate
Calcium
CoolingCooling
Calcium
phosphate
-casein
Caseins
AlkalinisationAlkalinisation
(micellar(micellar
Caseins
H2O
H2O
H2O
H2O
Calcium
&
phosphate
Caseins
AcidificationAcidification
HeatHeattreatmentstreatments
>90>90°°CC
Calciumphosphate
k-
Calciumphosphate
(
Addition of diAddition of di
or trivalentor trivalent
cationscations
Cations
Anions
Lactose
Protons
Addition of NaClAddition of NaCl
AdditionAddition
ofof
chelatantschelatants
H2O
Caséines
Calciumphosphate
Calcium
CoolingCooling
Calcium
phosphate
-casein
Caseins
AlkalinisationAlkalinisation
(micellar(micellar destructuration
Caseins
H2O
H2O
H2O
H2O
Calcium
&
phosphate
Caseins

49
Milk protein microstructure : Whey proteins
-lactalbumin
Lactoferrin
-lactoglobulin
Serumalbumin
• Globular proteins
• Known 3D-structures
• Sensitive to heat-
denaturation
• Highly resistant to
proteolysis (digestion)

50
10
nm
Casein micelle
MW = 0.5-1 x 106 kDa
av. diam = 180 nm
-lactoglobulin
MW = 18.6 kDa
2 SS bridges + 1 SH
-lactalbumin
MW = 14.2 kDa
4 SS bridges
Schematic representation of whey proteins and casein
micelle in a raw milk
k Casein
MW = 19.0 kDa
SS bridges
Milk proteins

51
Milk macrostructure and N bioavailability
Dietary N absorption is slower for yogurt
than for milk
 Kinetics of N bioavailibility related to
physical state of dairy products
(liquid/gel)
milk
yogurt
Gastric emptying
of PEG
Intestinal fluxes
of dietary N
In pig
Gaudichon et al,
J Nutr, 94
yogurtmilk
In human. Gaudichon et al, B J Nutr, 95
time
Dietary N in plasma
Famelart et al., 2011
% N bioavailable

52
Meat macrostructure
Meat cubes
Minced meat
Catheterised mini-pigs
Kinetics of IAA bioavailibility
related to physical state of meat
(cube/minced)
Source: Boback et al., Comparative Biochemistry and Physiology, 2007
Energy needed to digest, absorb, and
assimilate meat meals in pythons

53
Meat macrostructure
Fast proteins (whey proteins)
Slow proteins (caseins)
Meat (high chewing efficiency)
Meat (low chewing efficiency)
 Fast proteins favour postprandial
anabolism in elderly
Anabolicutilisation
%ofNingested
Healthy
teeth
Prothesis
NPPU
Plasmaleucine
Young adults Elderly
Fast
protein
Slow
protein

54
Mild heat treatment (< 100°C): protein conformation impacted
no impact or increase of overall digestibility
Heat treatment & protein bioavailbility
Source: Evenpoel et al., J Nutr, 1998

55
Heat treatment of meat (<100°) and bioavailability
of amino acids
Source: Bax et al., Plos One, 2013
 Cooking temperature (<100°C) can modulate the speed of meat
protein digestion, without affecting the overall efficiency of the small
intestinal digestion
Experiment conducted in mini-pigs (n=6) True ileal digestibility of N
60°C: 94.7 ± 0.5 %
75°C: 96.3 ± 0.4 %
95°C: 95.1 ± 0.7%

56
High heat treatment (> 100°C): modification of the primary
structure of the proteins
– Formation of covalent bonds intra ou intermolecular (Lys, Arg) : 
decrease of protein digestibility and amino acid bioavailability
– Isomerisation of AA (LD): bioavailability decreased (Thr, Ile, Lys)
– Maillard /Strecker reaction (reducing sugars): lysine bioavailability
reduced
– AA destruction (Arg, Thr, Ser, Cys, Ile)
– Toxic derivates (fire grill)
 Example: formation of benzopyrene by pyrolysis of AA  mutagen properties
Heat treatment & protein bioavailbility

57
Scanning Electron
Microscope
micrographs
Transverse sections
of beef muscle raw
and cooked
Source: Palka & Daun, Meat Science, 1999
Raw 50°C
60°C 70°C
80°C 90°C
100°C 121°C

58
Meat cooking (100°C) and protein digestibility
Source: Santé-Lhoutellier et al., J. Agric. Food Chem, 2008
protein hydrophobicity (Bromophenol Blue staining) as observed by microscopy (white scale bar: 100 μm)
Addition of gastric and pancreactic digestion:
-quick cooking (100 °C/5min or 270 °C/1 min)
 no effect on protein digestibility
-Long cooking (100°C, 45 min)
 decrease of digestibility (of 75%)
Effect of 100 °C cooking on
protein aggregation (Nile Red staining)
gastric phase pancreatic phase
In vitro static model of digestion

59
Gastric digestion & oxidative modification of
myofibrillar proteins
Source: Santé-Lhoutellier et al., J. Agric. Food Chem, 2008; Bax et al, JAFC, 2012
Proposed mechanism of pepsin action on meat proteins as raw or
heated at different cooking temperatures

60Source: Petitot et al., Food Chem, 2009
Heat (&water) on in vitro digestibility of cereal protein
of pasta
Low Temperature: 55°C, High Temperature: 70°, Very HT: 90°C moisture level : 20%
VHT-LM: 90°C - low moisture level : 12%
Hydrolysis degree at 10 MIN

61Source: Petitot et al., Food Chem, 2009
Elution profile of proteins by steric exclusion chromatography
Soluble proteins
Insoluble proteins
Heat (&water) treatment impact on protein
aggregation

62
Impact of milk heat treatment on casein digestion
CNs: major allergen in neonates
Native CNs very sensitive to hydrolysis
Step 2 :
Heat
treatment
80°C/20 s 105°C/60 s
85°C / 3 min
80°C/20 s 105°C/60 s
85°C / 3 min
Concentrate 1 Concentrate 2
Step 1:
water suspension 25% Dry Matter 35% Dry Matter
Ultra low heat fat-free
milk powder
Step 3 :
Drying
control
In vitro digestion / neonate model
Sample preparation
Source : Dupont et al. Mol Nutr Food Res, 2010

63
Source : Dupont et al. Mol Nutr Food Res, 2010
Milk powder
60 min
pH 3.0
+ pepsin
+ PC
Gastric
phase
Duodenal
phase
30 min
pH 6.5
+ trypsin
+ chymotrypsin
+ bile salts
Sampling at 0, 1, 2, 5, 10, 20, 40
and 60 min
Sampling at 0, 1, 2, 5, 10, 15 and
30 min
Biochemical characterisation
SDS-PAGE, LC-MS-MS, ELISA
Neonate digestion : in vitro model

64
 Heat treatment (>100°C) increases casein restistance to digestion
SDS-PAGE gels
of the digesta
T
A C
E G
66.3
55.4
36.5
31.0
21.5
14.4
6.0
3.5
2.5
0 1 2 5 10 20 40 60 1 5 15 30
0 1 2 5 10 20 40 60 0 1 2 5 10 20 40 60
0 1 2 5 10 20 40 600 1 2 5 10 20 40 60
1 5 15 30 1 5 15 30
1 5 15 30 1 5 15 30
66.3
55.4
36.5
31.0
21.5
14.4
6.0
3.5
2.5
66.3
55.4
36.5
31.0
21.5
14.4
6.0
3.5
2.5
66.3
55.4
36.5
31.0
21.5
14.4
6.0
3.5
2.5
66.3
55.4
36.5
31.0
21.5
14.4
6.0
3.5
2.5
Gastric Duodenal
Gastric Duodenal
Gastric Duodenal
Gastric Duodenal
Gastric Duodenal
0 1 2 5 10 20 40 60 1 5 15 30
Gastric Duodenal
F
Gastric Duodenal
B
1 5 15 300 1 2 5 10 20 40 60
T
A C
E G
66.3
55.4
36.5
31.0
21.5
14.4
6.0
3.5
2.5
0 1 2 5 10 20 40 60 1 5 15 30
0 1 2 5 10 20 40 60 0 1 2 5 10 20 40 60
0 1 2 5 10 20 40 600 1 2 5 10 20 40 60
1 5 15 30 1 5 15 30
1 5 15 30 1 5 15 30
66.3
55.4
36.5
31.0
21.5
14.4
6.0
3.5
2.5
66.3
55.4
36.5
31.0
21.5
14.4
6.0
3.5
2.5
66.3
55.4
36.5
31.0
21.5
14.4
6.0
3.5
2.5
66.3
55.4
36.5
31.0
21.5
14.4
6.0
3.5
2.5
Gastric Duodenal
Gastric Duodenal
Gastric Duodenal
Gastric Duodenal
Gastric Duodenal
0 1 2 5 10 20 40 60 1 5 15 30
Gastric Duodenal
F
Gastric Duodenal
B
1 5 15 300 1 2 5 10 20 40 60
T
A C
E G
66.3
55.4
36.5
31.0
21.5
14.4
6.0
3.5
2.5
0 1 2 5 10 20 40 60 1 5 15 30
0 1 2 5 10 20 40 60 0 1 2 5 10 20 40 60
0 1 2 5 10 20 40 600 1 2 5 10 20 40 60
1 5 15 30 1 5 15 30
1 5 15 30 1 5 15 30
66.3
55.4
36.5
31.0
21.5
14.4
6.0
3.5
2.5
66.3
55.4
36.5
31.0
21.5
14.4
6.0
3.5
2.5
66.3
55.4
36.5
31.0
21.5
14.4
6.0
3.5
2.5
66.3
55.4
36.5
31.0
21.5
14.4
6.0
3.5
2.5
Gastric Duodenal
Gastric Duodenal
Gastric Duodenal
Gastric Duodenal
Gastric Duodenal
0 1 2 5 10 20 40 60 1 5 15 30
Gastric Duodenal
F
Gastric Duodenal
B
1 5 15 300 1 2 5 10 20 40 60
A: 25% DM, 80°C, 20s B: 25% DM, 85°C, 3 min C: 25% DM, 105°C, 60 s
E: 35% DM, 80°C, 20s F: 35% DM, 85°C, 3 min G: 35% DM, 105°C, 60 s
control
Caseins

65
Peptide identification in digesta by LC-MS-MS
Peptide Bioactivity A B C E F G T
β-CN(f108-113) Anti-hypertensif
β-CN(f114-119) Opioïd agoniste
β-CN(f193-202) Anti-hypertensif
β-CN(f193-209) Immunomodulatoire
s1-CN(f1-23) Antimicrobien
s1-CN(f23-34) Anti-hypertensif
s1-CN(f91-100) Anti-stress
s1-CN(144-149) Antioxidant
β-lg(f9-14) Anti-hypertensif
 Peptide profile varies with process

66
unheated milk
(raw milk)
rehydration in
water
heated milk
heat treatment
90 C-10 min
Ultra Low Heat
powder
rennet gel
24h-20 C,
rennet
pH 6.6
rennet gel
24h-20 C,
rennet
pH 6.6
10 µm
microstructure
macrostructure
Impact of milk structure on protein digestion and
amino acid bioavailability
Source : Barbé et al., 2013
Sample preparation

67
 caseins: susceptibility to hydrolysis with or without heat treatment
 β-lactoglobulin: heat-induced susceptibility to hydrolysis
Impact of the microstructure (heat treatment) on protein digestion
unheated milk heated milk
caseins
β-lactoglobulin
β-lactoglobulin
caseins
Impact of milk structure on protein digestion and amino acid bioavailability

68
Formation of soluble and micelle-bound aggregates
Casein micelle in heated milk,
in SEM (Harwalkar et al., 1989)
100 nm
Serum of heated milk
observed by SEM (Rodriguez
del Angel & Dalgleish, 2006)
Heat-induced protein aggregation in milk
Micelle bound aggregates From Guyomarc’h & Famelart
micelle-bound
aggregates
dissociation of
k casein
[b]
[a]
serum aggregates
10 nm
micelle-bound
aggregates
dissociation of
k casein
[b]
[a]
serum aggregates
10 nm
heat treatment (90 C, 10 min) =
¾ of whey protein denaturation
and association to casein
micelles
Jean et al., 2006
denatured -lg
denatured -la
k casein
s2 casein
casein
micelles
10 nm
whey

69
Impact of milk structure on amino acid
bioavailability n = 4 minipigs
Major impact of the macrostructure (liquid vs gel) on leucine bioavailibility
Smaller impact of the microstructure (heat treatment)

70Source: Lacroix et al., JAFC, 2006
Heat treatment impact on bioavailability of milk
proteins in rat
Lower metabolic utilisation of N for spray-dried milk
Unheated
Low-heat pasteurisation
High-heat p asteurisation
Utra High Temperature
Spray-dried milk
Caseins
Whey proteins

71
Heat treatment impact on bioavailability of milk
proteins in human
Source: Lacroix et al, J Nutr, 2008
Dietary N incorporation into plasma amino acids
 digestive kinetics modified
due to protein denaturation
n=25
60
64
68
72
76
80
Microfiltered Pasteurised UHT
Netpostprandialprotein
utilisation(%)

72
Reverse chromatography (RP-HPLC) of milk proteins
Unheated
Spray-dried milk
Caseins
Whey proteins
Source: Lacroix et al., JAFC, 2006 72
Type of milk

73
0 10
Time (min)
OD214nm
Source: Lacroix et al., JAFC, 2006
Reverse chromatography of whey proteins
Unheated milk
Spray-dried milk
Caseins
Whey proteins
Protein aggregation
+ Lactosylation of
beta-lactoglobulines :
first products of the
Maillard reaction

74
– Alkaline treatment
 Vegetal protein extraction
 Detoxification
– Ex: destruction of aflatoxines
 Solubilisation and texturation of vegetal proteins
Destruction/modification AA :
 Isomerisation of AA (Thr, Ile, Lys) from L to D
 Neoformation of AA (cys et phosphosérine 
dehydrolalanine) / formation of covalent bond type :
lysinoalanine (heat treatment)
Reduction of protein digestibility
Reduction of lysine bioavailability
Technological treatment and protein bioavailability

75Source: Friedman et al., JAFC, 1999
Metabolic utilisation reduced for some D-amino acids

76
 Proteins - lipids
– Hydrophobic interaction
– Covalent bond with lipid oxidation derivate
 Reduction of lysine bioavailability and protein digestibility
 Proteins-polyphenols (vegetal food)
– Covalent bond between lysine and quinone (polyphenol
oxidation by enzymes or alkaline pH)
 Reduction of lysine bioavailability and protein digestibility
 Proteins - nitrites, sulfites or chlore derivates
– Minimal decrease of bioavailability
– Formation of toxic compounds (nitrosamines, dichlorovinylcystéine,
methionine sulfoximine)
Protein interaction with other nutrients

77
Outline
1. Definition
1. Food structure
1. Carbohydrates
2. Proteins
3. Lipids
3. Iron
4. Conclusion

78
Technological treatment and lipid bioavailability
Partial hydrogenation (less sensitive to oxidation, liquid solid)
– Insaturated fatty acid cis  trans
Example : margarine (1-2 % for new process, 15 up to 60 % for poor quality process) (ANSES, 2005)
 Metabolised instead of other insaturated fatty acids
 Increased risk of cardiovascular diseases for a daily intake of trans-
fatty acids > 2 % of the total daily energy intake
 increase of LDL cholesterol and decrease of HDL cholesterol
– Insaturated satured (partially) fatty acids
 Increased risk of cardiovascular diseases

79
Saturated fatty acids and cardiovascular disease risk
protective
At risk
Source: deOliveira et
al., AJCN, 2012

80
– High heat treatment (frying)
– Destruction of indispensable fatty acids
– Toxic compounds
 Lung cancer in women inhaling vapor from fish frying in China & Taiwan
(Yang et al., 2000)
 Lipid peroxdation : malondialdehyde (MDA) released with prolonged
frying mutagen effect of MDA but not of the oil (Saguy & Dana, J Food
Engineer, 2003)
 Maillard reaction in meat: heterocyclic amines
(reduced release for T<200°C, spices (antioxydant), microowaves)
 risk factor for colon cancer
– Trans fatty acids (repeated frying/ exchange food-oil)
– Hydrolysis of ester bond  free fatty acids more oxidable
– Oxidation  hydroperoxide  plasma oxidative stress
Technological treatment and lipid bioavailability

81
Impact of fat droplet size on lipid bioavailability
Source: Armand et al., AJCN, 1999
Human experiment (n=8)
Emulsion : 50g olive/fish oil (+ carbohydrates + protein)
Fat droplet size : Fine emulsion : 10 µm vs. Coarse emulsion : 0.7 µm
Stomach lipid digestibility
7-16% vs 20-37%
Duodenal lipid digestibility
37-46% vs 57-73%

82
Impact of the emulsifying agent on lipid digestion (in vitro)
Tween 20 Lysolect. Caseinate Whey Prot
Before digestion
+ saliva 5 min
+ gastric juice 2 h
+ dudodenal juice
2 h
Source: Hur et al., Food Chem, 2009

83
Impact of the emulsifying agent on lipid bioavailability
Source: Golding et al., Soft Matter, 2011
Postprandial triglycerids in the plasma
(n=8 healthy subjets)
stearoyl-lactilate sodium

84
Impact of fat structure on bioavailability
Source: Vors et al., AJCN, 20123
n=9 n=9
Spread (non-emulsified)
Emulsion (oil-in-water/milk)
Fat structure impacts fatty
acid and chylomicron plasma
kinetics but not overall
digestibility

85Source: Vors et al., AJCN, 20123
Impact of fat structure on metabolic oritentation
Fat structure impacts fatty
acid oxidation kinetics
Fat structure impacts digestive
kinetics and subsequently metabolic
orientation
 More oxidation for rapidly
digested fat (emulsifion) than
for non-emulsified fat
 Slow vs fast fat

86
Blood triglycerides and cardiovacular
disease risk
Source: Michalski, Eur. J. Lipid Sci, 2009

87
Human milk pasteurisation : impact on protein & lipid
digestion
Pasteurisation
 Aggregation of proteins
around the native fat globule
Mild heat treatment in human milk 
Proteolysis increased for caseins and lactoferrin
No impact on whey proteins (SA and alpha-lac)
3.5
2.5
6
14
21
31
36
55
66
97
116
200
Time (min)
0 30 60 120 150
KDa
IgA
IgG
X0
Lf
SA
Bt
Cas β
Cas κ
α-lac
Gastric digestion

88
Human milk pasteurisation : impact on protein & lipid
digestion
Free Fatty Acids
Diglycerid s(sn-1,2)
/
Cholesterol
Monoglycerid
PL/Prot
Triglycerids
Diglycerid s (sn-1,3)
Time
(min)
0 30 60 120 30 60 120 180
Gastric digestion Intestinal digestion
0 min
30 min
60 min
120 min
150 min
0
25
50
75
0 30 60 120
Greyintensity
(AU)
 Lipolysis reduced in the gastric digestion in
pasteurised milk vs. raw milk
 Due to BSSL inactivation and structure effect ?

89
1. Definition
1. Food structure
1. Carbohydrates
2. Proteins
3. Lipids
3. Iron
4. Conclusion
Outline

90
Micronutrients from plant foods and location
within the tissue
Source: Parada & Aguilera, 2007

91
Plant processing and micronutrient bioavailability

92
1. Definition
1. Food structure
1. Carbohydrates
2. Proteins
3. Lipids
3. Iron
4. Conclusion
Outline

93
Carotenoids
 Carotenoids : natural pigments yellow-orange red-purple,
highly hydrophobic compounds located in specialized plant
plastids (chromoplasts) of fruits, vegetables, mushrooms, algae
 About 10 % of carotenoids (bêta-, alpha-, gamma-carotène,
cryptoxanthine): vitamin A precursor
– Beta-carotène: orange fruits (carott, apricot, mango), red palm oil,
dark green vegetables (hidden by chlorophylle)
– Vitamin A: necessary for vision, epithelium tissu preservation,
bone growth, immune system
93
Liver
(storage form)
Retine
(Vision)
Bone, mucosa

94
 Absorption: requires incorporation of lipophilic
carotenoids into mixed micelles (dietary lipids, bile
salts, and other lipophilic or amphiphilic compounds)
 Liberation : fraction of the test compound released from the food matrix
into the aqueous supernatant
Bioaccessibility : fraction of the test compound released from the food
matrix into the aqueous supernatant and transferred into mixed micelles
 Bioaccessibility / Bioavailability vary according to the
botanical origin : Green vegetables < oranges vegetables <fruits < oil
 Process (thermal and/or mecanical) : increase the
bioavailability of carotens by destruction of the
vegetal matrix (Van Buggenhout et al., Trends in Food Science & Technology 2010)
Carotenoids

95
Chromoplast structure & bioaccessibility of
carotenoids
Light micrographs of carrot root and mango, papaya, and tomato fruit
mesocarp. Arrows mark chromoplasts.
Source: Schweiggert et al, Food Chem, 2012
Crystalloid
Globular-tubular
BA: 10.1%a BA: 5.3%b
BA: 3.1%cBA: 0.5%d
Beta-carotene: 652 µg/100g
Beta-carotene: 13 080 µg/100g

96
Chromoplast structure & bioaccessibility of
carotenoids
Source: Schweiggert et al, Food Chem, 2012
Liberation and bioaccessibility
Bioaccessibility & oil addition
Impact of
pectin and
other fibers

97
 Carotts: cooking increases bioavailability of beta-carotenes
– Plasma beta-carotene : 2-3 times higher for cooked and process
carotts (canning and heating at 121 C°)
97
Carott processing and bioavailability of carotenoids
Source: Rock et al., 1998; Livny et al., 2003

98
 Carotts: cooking increases bioavailability of beta-carotenes
– Plasma beta-carotene for commercial puree carrot > home-made
puree carrot and raw grated carrot (Edwards et al., 2002)
– Research still necessary to optimise process maximizing
carotenoid bioavailability
98
Vitamin A conversion
Commercial puree: 44 ± 11%a
Home-made puree: 59 ± 12%b
Grated carrot: 63 ± 10%ab
Carott processing and bioavailability of carotenoids

99
Effect of addition of oil on micellarisation of carotenoids from crude
and cooked carrots in respect to the carotenoid content in the corresponding
digest.
Hornero-Mendez et al., 2007
Addition of oil into carotts and bioavailability
of carotenoids

100
Plan
1. Definition
1. Food structure
1. Carbohydrates
2. Proteins
3. Lipids
3. Iron
4. Conclusion

101
Iron & spinach
101
Digestion of
cellular
structures
Breakdown of
cellular
structures
Source : Crispin et al., 2002

102
Plan
1. Definition
1. Food structure
1. Carbohydrates
2. Proteins
3. Lipids
3. Iron
4. Conclusion
Plan

A L I M E N T A T I O N
A G R I C U L T U R E
E N V I R O N N E M E N T
Improving health properties of food by
sharing our knowledge on the digestive
process
COST Action FA1005
INFOGEST
Chair: Dr. Didier DUPONT, Senior Scientist, INRA, France

104
Characterization of raw
materials and processed
food matrices for optimized
nutrient bioaccessibility
WG1
Evaluation of the health
effects
WG3
In vitro, in vivo and in
silico models of
mammalian
gastrointestinal digestion
WG2
- Food allergenicity and immunomodulatory properties
- Kinetics of digestion / regulation of appetite and satiety
- Protein metabolization on human microbiota
- Impact of ACE inhibitors on cardiovascular diseases
Beneficial food component characterization
Stability of bioactives during processing
Multi-scale characterization of food
Harmonization of in vitro digestion models
Comparison in vitro / in vivo
Characterization of the digestion products
Resistance to peptidases and absorption
Active form of food components in the organism
Dairy
Fruits & Vegetables
Egg

105
Riddet Inst
New Zealand
Canada
Laval Univ
Univ Guelph
Nofima
Ege Univ
Rothamsted Res
Centr Food Res Inst
Univ Belgrade
INRA
Wageningen UR
Inst Food Res
MTT
Univ Ghent
Univ Greifswald
Teagasc
Tech Univ Denmark
CSIC
AgroParisTech
Milan State Univ
Univ Bologna
Norwegian Univ Life Sci
Polish Academy of Sci
Leatherhead Food Res
150 scientists - 50 institutions – 26 countries
VTT
Univ Eastern Finland
Max Rubner-Institut
Ben Gurion Univ
KTU Food Inst
Cent Rech Lippmann
Univ Alto Douro
Univ Novi Sad
Agroscope Posieux
Univ LeedsUniv Reading
Univ Aarhus
Technion
ITQB
Pom Med Univ

106
The application of innovative
fundamental food-structure-property
relationships to the design of foods for
health, wellness and pleasure
COST Action FA1001
Food Structure Design
http://www.insidefood.eu

107
Food structure vs. bioavailability

A L I M E N T A T I O N
A G R I C U L T U R E
E N V I R O N N E M E N T
Conclusion
• Nutritionnal quality of a food not only impacted by
nutrient content but also by its structure
• Key factor for processed foods
• Food structure impacts on digestive events (gastric
phase: key step) and subsequently on metabolic
orientation
• Food structure : key parameter to control or modify
nutrient bioavailability nutrition for specific
popultation (elederly, sportmen, baby..)
• Relationship among food structure/digestion/health
 burning topic in science
 further knowledge required

Food structure and bioavailability - INFOGEST, 2013

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Food structure and bioavailability - INFOGEST, 2013