EVALUATION OF THIXOTROPIC PARAMETERS FOR LING HEATHER AUTHENTICATIONOsés, S.M.; Ruiz, M.O.; Pascual Maté, A.; Bocos, A.; Fernández Muiño, M.A.; Sancho, M.Universidad de BurgosSpain

5th International Symposium on Bee Products, 7th‐10th May, 2019

Malta 2019

Ling heather honey (Calluna vulgaris (L.) Hull)

Greatly appreciated

authentication

Melissopalynology

Sensory

Rheological

Introduction

Difficult to extract

Expensive

Introduction

NEWTONIAN

NON‐NEWTONIAN

TIME‐INDEPENDENT

PURELY VISCOUSPSEUDOPLASTIC BEHAVIOUR

PURELY VISCOUSDILANTANTBEHAVIOUR

PLASTIC BEHAVIOUR

TIME‐DEPENDENT

THIXOTROPIC

RHEOPECTIC

Newton’s law

)t,(f

)t,(f

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OBJECTIVE

The aim of this work was to assess the reliability of four rheological parameters to help characterize ling heather honeys in comparison with multiflora honeys rich in ling heather pollens and bell heather samples

(Erica spp.), some of them very close to ling heather monoflorality.

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Materials & Methods

HONEY Chestnut Multifloral Honeydew Heather

Number 2 4 1 15

Abreviation C M HD

22 artisanal honeys. 2015. Spanish regions

H

• Ericaceae > 45%• C. vulgaris < 10%

HL

• Ericaceae > 45%• C. vulgaris > 10%

L

• Ericaceae < 45%• C. vulgaris > 10%• Sensory

characteristics

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Materials & Methods

40ºC 30ºC

Moisture

Haake VT 550 Shear rate cycles (25ºC)up-flow ( =0.09-100 s-1 , 300 s)stationary (100 s-1, 60 s)down-flow (100-0.09 s-1, 300 s)

Constant shear rate ( = 100 s-1, 600 s, 25ºC)

Ostwald-de Waele

dx∆ ∆

2 ...∆ ∆

2

Time-dependent

lnWeltmann model

cte

cte

Exp. 1

Exp. 2

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RESULTS

2

3

4

5

6

7

8

0 20 40 60 80 100 120

µ (P

a s)

γ (s-1)

M2

0.09-100 s-1100-0.09 s-1

.

5

6

7

8

9

10

11

12

13

0 20 40 60 80 100 120

µ (P

a s)

γ (s-1)

0.09-100 s-1100-0.09 s-1

HL2Shear rate cycles

Successfully fitted to Ostwald-de Waele model (r>0.996)

All samples are time-dependent fluids

Exp. 1

Good correlation between experimental and calculated apparent viscosity

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0,0

0,2

0,4

0,6

0,8

1,0

1,2

0 5 10 15 20 25 30 35

L HL H C HD M

b.

n dow

n

% Calluna0,0

0,2

0,4

0,6

0,8

1,0

1,2

0 5 10 15 20 25 30 35

L HL H C HD M L3 HL6 M1

a.

n up

% Calluna

n < 1: shear-thinning behaviour

n > 1: shear-thickening behaviour

Newtonian behaviourn =

Different nup with Calluna pollen % Similar ndown ≈ 1

Newtonian behaviourn =

RESULTS

Ostwald-de Waele model

Shear rate cyclesExp. 1

Malta 2019

Sample nup 0.05

L1 0.93 ± 0.03L2 0.98 ±0.06L3 1.09 ± 0.04HL1 0.88 ±0.08HL2 0.90 ±0.03HL3 0.94 ± 0.12HL4 0.89 ± 0.04HL5 0.97 ± 0.02HL6 1.07 ± 0.03HL7 0.97 ± 0.07HL8 1.00 ± 0.06HL9 0.99 ± 0.08HL10 1.01 ± 0.02H1 1.01 ± 0.01H2 1.01 ± 0.04C1 1.03 ± 0.07C2 1.13 ±0.06HD 1.02 ± 0.03M1 0.93 ± 0.05M2 1.07 ± 0.10M3 1.11 ± 0.13M4 1.09 ± 0.02

PSEUDOPLASTIC

NEWTONIAN OR DILATANT

Linear relationship between nup and Calluna pollen %• Calluna > 10% pseudoplastic fluids• Calluna < 10% Newtonian or dilatant behaviour

RESULTS5

6

7

8

9

10

11

12

13

0 20 40 60 80 100 120

µ (

Pa

s)

γ (s-1)

0.09-100 s-1100-0.09 s-1

HL2a.

Shear rate cyclesExp. 1

2

3

4

5

6

7

8

0 20 40 60 80 100 120

µ (P

a s)

γ (s-1)

M2

0.09-100 s-1100-0.09 s-1

Malta 2019

RESULTS

Sample a [Pa/s]

L1 2250L2 5549L3 2026HL1 6994HL2 3447HL3 3870HL4 7763HL5 3272HL6 4340HL7 8035HL8 729HL9 4548HL10 148H1 27H2 992C1 289C2 958HD 780M1 560M2 2058M3 429M4 4106

Area of hysteresis loop

All honeys presented a hysteresis loop with quitedifferent values of “a”

The values of “a” were higher for LING HEATHERhoneys than for non-ling heather.

Shear rate cyclesExp. 1

dx∆ ∆

2 ...∆ ∆

2

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RESULTS

Sample a [Pa/s]

L1 2250L2 5549L3 2026HL1 6994HL2 3447HL3 3870HL4 7763HL5 3272HL6 4340HL7 8035HL8 729HL9 4548HL10 148H1 27H2 992C1 289C2 958HD 780M1 560M2 2058M3 429M4 4106

Area of hysteresis loop

Shear rate cyclesExp. 1

dx∆ ∆

2 ...∆ ∆

2

L and HL samples were the honeys that showed a thixotropic behavior, but samples HL6, HL10, and L3 did not follow that trend.

THIXOTROPIC

Ling heather honeys

RHEOPECTIC

Except for M1, all our non-ling heather honeys (H, HD, M, andC) exhibited a rheopectic behavior.

Non-ling heather M1% Calluna pollen higher

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RESULTS

Sample B (Eq.3) [Pa]

r

L1 11.40 0.987L2 8.48 0.978L3 50.06 0.974HL1 33.12 0.987HL2 3.44 0.932HL3 7.78 0.964HL4 32.89 0.975HL5 10.16 0.978HL6 28.68 0.970HL7 65.32 0.995HL8 19.15 0.965HL9 9.79 0.984HL10 33.49 0.984H1 ‐1.36 0.940H2 ‐0.27 0.935C1 ‐6.56 0.975C2 ‐18.44 0.974HD ‐1.24 0.955M1 ‐2.82 0.937M2 ‐6.12 0.963M3 ‐9.67 0.984M4 ‐24 27 0 965

THIXOTROPIC

RHEOPECTIC

Weltmann model

Constant shear rate assays

ln

Exp. 2

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Ku

nu

B

A

PC1 (66.13%)

PC3 (

9.44%

)

-3 -1 1 3 5-1,7

-1,2

-0,7

-0,2

0,3

0,8

1,3

L1

L2

L3

HL1

HL2

HL3

HL4

HL5

HL6

HL7HL8

HL9

HL10

H1

H2

C1

C2

HD

M1

M2M3

M4

a

Weltmann index B was the best rheological parameters for ling Heather honey authentication

CONCLUSIONSMalta 2019

THANK YOUMalta 2019