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Accelerating Shelf-life Tests (ASLT)
New formulations always have to be analyzed in terms of physical stability beside
chemical and sensory evaluation leading to time-consuming development processes. The
industry consequently employs ASLTs to accelerate these changes. In difference to beer a
systematic approach to evaluate the effect of artificial storage conditions for rapid tests in
emulsion based beverages is not available yet. Therefore, different tests were compared in
regard to physical changes of beverages with orange oil emulsion.
C) Low Homog. Pressure
12 % Emulsifier (OSA-starch)
6 % Orange oil6 % Weighting agent
HP-homogenization:
1x 250/50 bar
x90= 5710 nm
Comparative study of accelerated shelf-life tests on physical ageing of beverages containing
weighted flavor emulsions
Conclusion
Motivation
Sören Rossmann, Verena Wolff, Ulrich Müller, Jan Schneider
North Rhine Westfalia Institute of Food Technology ILT.NRW, Lemgo, Germany
References
www.ilt-nrw.de
[1] Piorkowski, D. T. and McClements, D. J. (2014): Beverage emulsions: Recent developments in formulation, production, and applications, Food Hydrocolloids, 42.
[2] Tan, C.-T.: Beverage Emulsions, in Friberg, S. E. and Larsson, K. (Eds.)(1997): Food emulsions, 3. ed., rev. and expanded, Dekker, New York.
[3] Reiner, S. J.; Reineccius, G. A. and Peppard, T. L. (2010): A Comparison of the Stability of Beverage Cloud Emulsions Formulated with Different Gum Acacia- and Starch-
Based Emulsifiers, Journal of Food Science, 75,5.
[4] Lim, S. S.; Baik, M. Y.; Decker, E. A.; Henson, L.; Michael Popplewell, L.; McClements, D. J. (2011): Stabilization of orange oil-in-water emulsions: A new role for ester gum
as an Ostwald ripening inhibitor, Food Chemistry, 128,4.
Results
ContactILT.NRW
Beverage Technology
Sören Rossmann
Emulsion based beverages
Beverage emulsions are an important product for the preparation of increasingly popular
beer-based mixed drinks and soft drinks in order to incorporate water insoluble colors or
flavors (flavor emulsion), to generate turbidity (cloud emulsion) or both combined [1].
Compared to other oil-in-water food emulsions, beverage emulsions are a unique class of
type, as they are highly concentrated semi-finished products and after being processed in-
to drinks finally consumed considerably diluted [2].
Experimental Setup
A) Reference Emulsion
12 % Emulsifier (OSA-starch)
6 % Orange oil6 % Weighting agent
HP-homogenization:
2x 300/50 bar
B) Reduced Ester Gum
12 % Emulsifier (OSA-starch)
10 % Orange oil2 % Weighting Agent
HP-homogenization:
2x 300/50 bar
x90= 736 nm x90= 620 nm
D) Reduced Emulsifier
6 % Emulsifier (OSA-starch)
6 % Orange oil6 % Weighting agent
HP-homogenization:
2x 300/50 bar
x90= 785 nm
Emulsions A to D were diluted to Ready-to-drink beverages for stability analyzing:
0,12 % emulsion diluted with beverage base (10 °Bx sucrose, pH 3,2)
Instability indices showing the deterioration of the beverages containing emulsions A to D
(different produ t defe ts over a storage period of 50 days (accelerated) and 180 days
(real-time storage), respectively. To compare the efficiency of the ASLTs, exponential
functions were fitted to the measured values, which allow calculation of the accelerating
factors of the ASLTs against the real-time storage.
Particle size distribution of the beverages with the four emulsions A to D directly after
preparation (left) and after storage under accelerating conditions (right).
50 days storage under accelerating storage conditions:
(Comparative real-time storage: 180 d at 20 °C)
Before storage After storage
Enhan ing physi al insta ilities y integrating artifi ial „produ t defe ts“:
Agitation
20 °C, 120 min-1
Light box
40 °C, 5000 Lx
Thermostat
cabinet, 40 °C
Instability-
mechanism [1,4]
A) Reference emulsion 8.2 9.1 7.9 (Diffusion)
B) Reduced Ester Gum 7.7 5.8 6.5 Ostwald Ripening
C) Low Homog. Pressure 11.0 9.1 9.6 Creaming
D) Reduced Emulsifier 9.2 8.7 7.9 (Diffusion)
The examined ASLTs are capable of accelerating the physical deterioration of emulsion-
based beverages remarkably. Accelerating factors of 5.8 up to 11.0 were achieved
regardless of the predominant instability mechanism. Surprisingly, the periodic agitation
without elevated temperatures reveal the highest acceleration. Unfortunately, agitation
exhibits large deviations in the resulting extent of instability compared to real-time
storage. Considering all intrinsic deficiencies of the emulsion beverages, the warm storage
with additional illuminance shows the deterioration most similar to the real-time storage.
Since the differences in time are not extreme this test condition reveals as most
promising.
It is thus obvious that the results cannot be easily transferred to other emulsion formula-
tions. Nevertheless, for practical purposes the results of the presented work can serve as a
basis for the development and assessment of accelerated shelf-life tests.
Lab-shaker Light box: 5000 Lx, 40 °C Thermostat cabinet: 40 °C
12 h·d-1 at120 min-1 6500 K daylight lamps dark
Physical stability was analyzed with:
- Turbidity measurement (Optek):
direct analyzing of scattered light in the bottle
- Particle size measurement (Malvern):
laser diffraction
- Calculation of instability index:
Insta ilit inde = 1− tur idit τ tinitial turbidiy τ0
Physical stability problems
Despite the use of stabilizing ingredients and in-
tensive mechanical forces like high-pressure
homogenization, physical instability phenomena
are a great issue:
Crea i g Ri gi g Turbidity Loss
Sedimentation Inhomogeneity
The reason is the inherent instability of beverage
emulsions as generally known from macroemul-
sions. In addition, governmental regulations
restrict the application of stabilizers. Visible ringing of an orange soft drink
Reference Emulsion Reduced Ester Gum
Low Homogenization Pressure Reduced Emulsifier
Storage time [d]
Storage time [d]Storage time [d]
Storage time [d]
Inst
ab
ilit
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de
x[-
]In
sta
bil
ity
ind
ex
[-]
Inst
ab
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x[-
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dark agitation
Accelerating factors of the ASLTs
Acknowledgements: This work was funded under the program FHprofUnt (FKZ: 03FH037PX3)
by the Federal Ministry of Education and Research (BMBF) of the German Government.