Kuwait. ICEF-12 Quebec City, Canada, 14th to 18th June 2015 ... Sieving has been termed as the 'Cinderella' of particle size analysis methods; it does most of ...
EFFECTS OF PARTICLE SIZE AND TEMPERATURE ON OSCILLATORY RHEOLOGY AND CREEP BEHAVIOR OF SELECTED FLOUR DOUGHS
Jasim Ahmed, Ph.D. Food & Nutrition Program Kuwait Institute for Scientific Research Kuwait ICEF-12 Quebec City, Canada, 14th to 18th June 2015
Outline • Particle size and its importance • Conventional powder materials • Food flour particles
• Particle size and rheology • Oscillatory rheology and creep behavior • Deviation from the rule • Conclusions •
Significance of particle size • Solids are reduced to smaller particles to obtain
desirable properties -Contains a wide range of particles -Increase in surface area -Enhances reactivity -Increases mechanical, thermal optical properties
and
• The fullest description of a powder is given by
its particle-size distribution
Particle size measurement and related to food 1.E-10
1.E-09
nm
1.E-08
1.E-07
1.E-06
1.E-05
mm
1.E-04
1.E-03
1.E-02
1.E-01
mm
1.E+00
m
• The wide size range covered for food, from nanometers to millimeters
Coarse
Fine
Interest to food
Simple particle size measurement: Sieving • Sieving has been termed as the 'Cinderella' of particle
size analysis methods; it does most of the hard work and gets little consideration (Heywood, 1970). • For a non-spherical particle, the sphericity is: • 𝜑𝑠 =
6𝑣𝑝 𝐷𝑝 𝑠𝑝
• Where Dp equivalent diameter; sp-surface area and vp-
volume of one particle.
Particle size and rheology contd. • The particle size and its distribution, the shape of the particles
influence the rheology • The relative volume fraction, 𝝓r=𝝓/𝝓m, which was quite
successful in predicting the relative viscosity of suspensions having a wide concentration range, where 𝝓 is the vol. fraction of the filler • Mostly, the mechanical rigidity of powder increased with finer
particles in dispersion (e.g. cement, coal, ash). • Particles have a large influence on
-hydration kinetics, -microstructure development -ultimate properties of materials
Rheological behavior of materials with particle size Common materials
Food materials
• e.g. coal, cement, silica
slurry
G’
G’
Size
ɷ
ɷ
Particle size and Food rheology • Limited data available on food products especially for
flour, which, in contrast to model suspensions, often represent complex multiphase systems • Particle size is crucial for the sensory perception • Food is very complex in nature and it does not follow material science rule in strict sense • Individual food requires in-depth study to correlate mechanical property with particle size
Focus of the presentation • Particle size analysis of selected flour
samples -Rice -b-glucan Concentrate -Lentil -Chestnuts • Oscillatory
rheology and creep behavior of flour doughs as function of particle size and temperature
Particle size and rheology
Particle size decreases; no. of particles increase; Particle-particle interaction increase
High PDI packs particles better with easy flowing than the low PDI
Particle size and rheology: Non-isothermal heating of Rice flour 5000
1000 297-micrometer 105-micrometer
4000
74.4 C
750
74-micrometer Time-temperrature
3000
77.5 C
500 2000
Time (s)
h* (Pa.s)
75.9 C
250
1000
0
0 50
60
70 80 Temperature (oC)
90
100
The h* increased with decreasing particle size.
Particle size and rheology: b-glucan concentrate dough 12000 595 micrometer 74 micrometer 105 micrometer
297 micrometer 149 micrometer
h* (Pa.s)
9000
6000
3000
0 25
50
Temperature (o C)
75
100
Particle size and rheology: Lentil flour
Particle size and rheology: Chestnut flour 16000
80.1 C
h* (Pa.s)
12000
8000 88-micrometer 80.6 C 4000
74-micrometer
0 30
50
70 Temperature (oC)
90
110
Creep behavior of BGC: Effect of particle size 0.8 297 micrometer
149 micrometer
105 micrometer
74 micrometer
0.6
Strain (%)
595 micrometer
0.4
0.2
0 0
250
500
Time (s)
750
1000
Possible reasons for the difference in rheological behavior
WHC; F/W ratio
Food Compo sition Interacti on protein, starch
Particle size
Process paramete rs T, P etc.
Effect of flour to water (F/W) ratio on rheology (e.g. BGC) 0.001
30000
1 to 4
1 to 6
25000 20000
J(t) (Pa -1)
G' (Pa)
1 to 5
15000 10000
1 to 4
1 to 5
1 to 6
5000 0.1
1 Frequency (Hz)
0.0005
10
0 0
F/W ratio selected based on WHC values
50
100 Time (s)
150
200
Effect of flour to water ratio and temperature on mechanical rigidity of b-glucan concentrate dough b
40000
BGC to water=1:4 BGC to water=1:5 BGC to water=1:6
G' (Pa)
30000
20000
10000
0 25
55
70 85 o Temperature ( C)
HC/25
Effect of temperature (isothermal heating) on complex viscosity of rice (Giza) dough with selected particles at a. 60 C and b. 80 C. 7500
50000
60o C 6000
80oC 595-micrometer
595-micrometer
40000
297-micrometer
297-micrometer 105-micrometer
74-micrometer
4500
h* (Pa.s)
h* (Pa.s)
105-micrometer (595+297+74) micrometer
3000
1500
74-micrometer
30000
(595+297+74) micrometer
20000
10000
0
0.1
1 Frequency (Hz)
10
0 0.1
1 Frequency (Hz)
The h* reversed for the finest particle between 60 and 80 ◦C.
10
Effect of particle size and temperature on G’ of chestnut dough during isothermal heating and after heating/cooling (HC); (CP-coarse particles: 88-mm and FP-fine particles: 74-mm). 100000
G' (Pa)
10000
1000
100 55C CP 70C FP HC 25C CP
55C FP 85C CP HC 25C FP
70C CP 85C FP
10 0.1
1 Frequency (Hz)
10
Effect of temperature on creep compliance of BGC doughs 0.0012
J(t) (Pa-1)
0.0009
25C
40C
70C
85C
55C
0.0006
0.0003
0 0
50
100
Time (s)
150
200
Creep and recovery model: • The experimental data from creep tests can be described with
the precision by a discrete retardation spectrum, which is a set of 2n positive constants Jk and tk, by means of the following equation (Kaschta & Schwarzl, 1994) :
• Where each retardation time tk is associated with a spectral
compliance magnitude Jk, J0 is the instantaneous compliance, and h0 is the steady-state viscosity.
Creep parameters of particle fractions as function of temperature Creep
595 mm
297 mm
149 mm
105 mm
74 mm
Temp (
J0 (Pa-1) ×10-4
η0
25 40 55 70 85 25 40 55 70 85 25 40 55 70 85 25 40 55* 70 85 25 40 55* 70 85
0.11 0.77 1.61 2.45 3.39 0.02 0.26 0.46 1.46 3.37 0.02 0.53 2.22 3.22 2.98 0.06 0.01 0.11 0.02 0.85 0.06 0.26 0.31 2.57 5.95
2.31 3.43 3.53 1.63 0.52 1.50 3.17 1.64 0.90 0.21 3.99 1.88 1.62 0.52 0.18 4.18 4.24 5.48 0.71 0.18 1.83 3.69 5.85 0.88 0.26
×106
J1 (Pa-1) ×10-5
τ (s)
R2
3.00 5.00 5.02 7.21 8.96 2.06 2.21 4.50 7.75 5.88 2.47 2.39 5.25 1.38 1.43 2.97 2.77 2.95 4.11 1.23 8.70 5.79
2.44 13.47 12.01 13.41 14.75 0.10 0.75 4.54 8.40 22.1 0.06 2.84 0.1 0.05 6.03 0.51 0.08 0.51 0.21 1.32 0.03 0.25
0.95 0.95 0.98 0.99 0.99 0.81 0.95 0.98 0.99 0.99 0.76 0.97 0.98 0.10 0.99 0.58 0.74 0.34 0.86 0.97 0.57 0.91
13.3 22.8
16.15 6.81
0.97 0.98
Factors affecting flour rheology with particle size Rice
WHC (g/g water)
8
6
30C 70C
4
Particle size (mm)
% Protein
% Fat
% Starch
595
7.42
1.13
85.37
297
7.17
1.19
76.58
149
6.56
1.77
76.25
105
6.08
2.35
75.42
74
5.65
3.02
74.64
2
0 0
100
200 300 400 Particle size (mm)
500
600
Chemical composition of BGC and lentil flour samples
BGC
Lentil WHC
Particle % size (mm) Protein 595 13
% BG 18
30 C 3.7
70 C 8.2
WHC Particle size % (mm) Protein % TS 297 27.6 47.2
30 C 1.5
70 C 4.5
297
14.6
19
2.8
6.6
149
16
18
2.6
5.4
149
25.2
41.5
1.5
4.3
105
18
16
2.5
3.7
105
21.3
43.6
1.5
3.7
74
21
13
2.2
3.3
74
21
51.4
1.3
4.3
Osc rheology of BGC and BGC dispersion BGC dispersion
Water soluble part of BGC
30000
900
a
b
25000
700 G' (Pa)
G' (Pa)
20000 15000 10000 5000
25C G'
55C G'
70C G'
85C G'
500
300
25C G'
40C G'
55C G'
70C G'
100 0.1
0 0.1
1 w (Hz)
10
1 w (Hz)
10
Microstructures of flour samples Rice
Lentil
BGC
CN
Conclusions • Understanding of dough rheology is very complex • A thorough understanding of particle composition would
help to explain the rheological behavior of dough having unimodal particle distribution • Functional property, microstructure and PSD significantly influence the flour dough • Understanding dough rheology requires knowledge of chemistry and engineering of food particles and interactions among constituents.
References: Ahmed, J., and Al-Attar H. 2015. Effect of drying method on rheological, thermal, and structural properties of chestnut flour doughs. Food Hydrocolloids, 51, 76-87. Ahmed, J., Al-Jassar, S., and Thomas, L. 2015. A comparison in rheological, thermal, and structural properties between Indian Basmati and Egyptian Giza rice flour dispersions as influenced by particle size. Food Hydrocolloids, 48, 72-83. Ahmed, J. 2015. Effect of barley b-glucan concentrate on oscillatory and creep behavior of composite wheat flour dough. Journal of Food Engineering, 152, 8594. Ahmed, J., Thomas, L, Atar, HA. 2015. Oscillatory rheology and creep behavior of barley β-D-glucan concentrate dough: Effect of particle size, temperature and water content. Journal of Food Science, 80, 1, E73-E83. Ahmed, J. 2015. Effect of β-glucan concentrate on the water uptake, rheological and textural properties of wheat flour dough. International Journal of Food Properties, 18, 1801–1816. Ahmed, J. 2014. Effect of particle size and temperature on rheology and creep behavior of barley β-D-glucan concentrate dough. Carbohydrate Polymer, 11, 89– 100.
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