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Effect of storage at high temperature on chemical (composition) and techno-functional characteristics of E471 food emulsifiers applied to aerosol whipping cream
Journal Pre-proof Effect of storage at high temperature on chemical (composition) and techno-functional characteristics of E471 food emulsifiers applied to aerosol whipping cream Max Blankart, Claudia Oellig, Sonja Averweg, Wolfgang Schwack, Jörg Hinrichs PII:
S0260-8774(19)30525-4
DOI:
https://doi.org/10.1016/j.jfoodeng.2019.109882
Reference:
JFOE 109882
To appear in:
Journal of Food Engineering
Received Date: 26 October 2019 Revised Date:
16 December 2019
Accepted Date: 17 December 2019
Please cite this article as: Blankart, M., Oellig, C., Averweg, S., Schwack, W., Hinrichs, Jö., Effect of storage at high temperature on chemical (composition) and techno-functional characteristics of E471 food emulsifiers applied to aerosol whipping cream, Journal of Food Engineering (2020), doi: https:// doi.org/10.1016/j.jfoodeng.2019.109882. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Published by Elsevier Ltd.
1 1
Effect of storage at high temperature on chemical (composition) and techno-functional
2
characteristics of E471 food emulsifiers applied to aerosol whipping cream
3 4
Max Blankart*1, Claudia Oellig2, Sonja Averweg1, Wolfgang Schwack2 and Jörg Hinrichs1
5 6
1
7
Biotechnology, University of Hohenheim, Garbenstrasse 21, 70593 Stuttgart, Germany
8
2
9
Germany
Department of Soft Matter Science and Dairy Technology, Institute of Food Science and
Institute of Food Chemistry, University of Hohenheim, Garbenstrasse 28, 70593 Stuttgart,
10 11 12
*Corresponding author. Tel.: +49 711 459 24208; fax: +49-711-459-23617
13
E-mail address: [email protected] (M. Blankart).
2 14
Abstract
15
Various foods are processed with addition of mono- and diacylglycerol (MAG and DAG)
16
emulsifiers to adjust techno-functional properties. Exposure to and application of high
17
temperatures during production, processing and transport of these emulsifiers can induce
18
compositional changes and thereby affect techno-functional properties. Emulsifiers were stored
19
above their respective melting point and their chemical composition was determined by high-
20
performance thin-layer chromatography–fluorescence detection. Storage for 8 weeks decreased
21
the MAG content of a saturated MAG by about 36% by transesterification into 1,3-DAG, while a
22
rearrangement of 1,2- into 1,3-DAG was observed for a saturated MAG/DAG emulsifier.
23
Emulsifiers were applied to aerosol whipping cream, and viscosity, particle size, overrun, foam
24
firmness and drainage were determined. The increasing 1,3-DAG content of the saturated MAG
25
emulsifier was found to increase the drainage of aerosol whipping cream from 15% to 50%.
26 27 28 29
Keywords Technical emulsifier, temperature-time load, chemical composition, techno-functional properties, high-performance thin-layer chromatography–fluorescence detection (HPTLC-FLD)
3 30
1.
Introduction
31
Mono- and diacylglycerols (MAGs and DAGs, E471 emulsifiers) are the most frequently
32
used emulsifiers in the food sector, applied in the processing of bread, pastry, margarines, ice
33
cream, aerosol whipping cream and other dairy products (Norn 2015). They enable the
34
adjustment of techno-functional properties such as viscosity, creaming, emulsion stability and
35
foam stability (Norn 2015; Munk et al. 2013; Méndez-Velasco und Goff 2012). Based on the
36
production process, E471 emulsifiers of different composition are obtained. In general, MAGs
37
and DAGs are produced by transesterification of triacylglycerols (TAG) with glycerol or direct
38
esterification of glycerol with fatty acids. Both reactions require an inorganic alkaline catalyst
39
and temperatures of 220 to 260 °C and result in a p roduct with a MAG content between 10 and
40
60%, the other parts comprise DAG, TAG, free fatty acids (FFA) and glycerol. By means of
41
molecular distillation under vacuum at temperatures of 140 – 170 °C MAGs can be enriched (>
42
95%). Direct esterification enables the production of E471 with a specific fatty acid composition,
43
while transesterification results in MAGs/DAGs with a mixed fatty acid composition. MAG/DAG
44
content and esterification position are adjusted by process conditions (Norn 2015; Fregolente et
45
al. 2006; Rarokar et al. 2017).
46
Techno-functional properties of E471 emulsifiers depend on their chemical composition.
47
In case of milk products, saturated MAGs (sMAGs) where shown to be incorporated in the fat
48
globule membrane, and displace proteins form the membrane if used at higher concentrations.
49
When the temperature is lowered, the adsorbed sMAGs crystallize and form a solid layer
50
around the fat globule, thereby stabilizing it against coalescence and aggregation (Fredrick et al.
51
2013; Munk et al. 2014b; Méndez-Velasco und Goff 2012). Unsaturated MAGs (usMAGs) also
52
displace proteins from the fat globule membrane (Munk et al. 2014a). In contrast to sMAGs,
53
however, usMAGs destabilize fat globules (Davies et al. 2001). The destabilizing process, called
54
dewetting, is described as crystalline and liquid fat that partly breaks through the fat globule
55
when usMAGs adsorb to the fat globule membrane. The protruding fat crystals may then act as
56
crystal thorns that pierce the membrane of colliding fat globules, while the liquid fat glues fat
57
globules together, leading to partial coalescence of fat globules (Spicer und Hartel 2005; Munk
4 58
et al. 2013; Munk et al. 2014a; Méndez-Velasco und Goff 2012). This destabilizing effect is
59
utilized in the processing of reconstituted whipping cream and ice cream as the foam structure
60
of these systems relies on the formation of a partially coalesced fat globule network (Fredrick et
61
al. 2013; Goff 1997). In a previous paper, we found that addition of usMAG to aerosol whipping
62
cream prevents foaming, leading to the hypothesis that foam stabilization is not caused by
63
partially coalesced fat globules. SMAG led to high emulsion and foam stability, while addition of
64
a mono-/diacylglyceride (MAG/DAG) emulsifier provided lower emulsion stability and decreased
65
the foam stability (Blankart et al. 2020) . The position of the esterification (1- or 2- in a MAG;
66
1,2- or 1,3- in a DAG) may as well modify the techno-functional properties, but has not yet been
67
investigated to our knowledge.
68
The chemical composition of E471 emulsifiers is determined directly after production as
69
quality control. For transportation and further processing, food emulsifiers are often handled in
70
molten form. We hypothesize, that temperatures above the respective melting point during
71
transportation and processing may gradually change the chemical composition and thereby the
72
techno-functional properties of E471 emulsifiers. To prove this hypothesis, three E471
73
emulsifiers were stored above their respective melting point for 8 we and chemical composition
74
was determined at certain storage times. Emulsifier samples of selected storage times were
75
applied to model aerosol whipping cream and the techno-functional properties were determined.
76
The simple HPTLC–FLD approach (Oellig et al. 2018) enabled to control the
77
composition of technical emulsifiers fast and easily. Applying the visual fingerprint, differences
78
caused by temperature–time load are directly visible. According to Oellig et al. (2018) a single
79
calibration standard was used for quantitation and the individual lipid classes were collectively
80
quantified.
81
5 82
List of abbreviations
83
MAG:
monoacylglyceride
84
DAG:
diacylglyceride
85
TAG:
triacylglycerides
86
Lo-usMAG:
long-chain unsaturated monoacylglyceride
87
Me-sMAG:
medium-chain unsaturated monoacylglyceride
88
Me-sMAG/DAG:
medium-chain saturated mono-/diacylglyceride
89
FA:
fatty acids
90
FFA:
free fatty acids
91
HPTLC:
high performance thin layer chromatography
92
FLD:
fluorescence detector
93
GC:
gas chromatography
94
MS:
monostearin
95
DS:
distearin
96
TS:
tristearin
97
SA:
stearic acid
98
FSA:
free stearic acid
99
RSD:
relative standard deviation
6 100
2.
Material and methods
101
2.1
Chemicals and materials 1-stearoyl-rac-glycerol
102
(> 99%),
1,2-distearoyl-rac-glycerol
(> 99%),
103
1,3-distearoylglycerol (> 99%), stearic acid (analytical standard grade, > 99.5%), glyceryl
104
tristearate (> 99%), methanol (LC–MS, Chromasolv), diethyl ether (≥ 99.5%, GC, puriss.),
105
n-pentane
106
(TBME; ≥ 99.8%, HPLC, Chromasolv) were obtained from Sigma-Aldrich (Steinheim, Germany).
107
n-Hexane (95%, for pesticide residue analysis, Chemsolute) was purchased from Th. Geyer
108
(Renningen, Germany). Formic acid (>98%, analytical reagent grade) was obtained from Fisher
109
Scientific (Schwerte, Germany). Primuline (dye content 50%) was from Sigma-Aldrich. Ultrapure
110
water (>18 MΩ cm) was supplied by a Synergy System (Millipore, Schwalbach, Germany).
111
HPTLC silica gel LiChrospher F254s plates from Merck (Darmstadt, Germany) were used without
112
pre-washing. The following emulsifiers of the type E471 were provided from two manufacturers:
113
long-chain
114
sMAG/DAG); medium-chain saturated MAG (me-sMAG).
(≥ 99%
for
unsaturated
residue
MAG
analysis,
(lo-usMAG);
Chromasolv)
medium-chain
and
t-butyl
saturated
methyl
MAG/DAG
ether
(me-
115 116
2.2
Storage of emulsifiers at elevated temperatures
117
For each emulsifier 200 g were filled into a Schott flask and stored at elevated
118
temperatures (above respective melting points, Blankart et al. (2020)) for 8 we. The me-sMAG
119
was kept at 80 °C (T5042, Heraeus, Hanau, Germany) whereas the lo-usMAG and the me-
120
sMAG/DAG were stored at 70 °C (Typ 17053099003100 # 980944 WTC Binder GmbH,
121
Tuttlingen, Germany). For determination of the chemical composition, samples were taken after
122
0 h, 2 h, 24 h, 48 h, and 72 h and eventually at weekly intervals for 8 we in all. Samples for
123
techno-functional characterization were taken after 0 h, 1 we, 4 we, 8 we and additionally after
124
24 h for the me-sMAG/DAG.
125 126
7 127 128 129
2.3
Analysis of E471 food emulsifiers by high-performance thin-layer chromatography–fluorescence detection (HPTLC–FLD)
2.3.1 Standard solutions and sample preparation
130
Standard-mix stock solution was prepared by dissolving 2.5 mg of mono-, di-, tristearin
131
and free stearic acid (MS, DS, TS and free SA) in 10 mL of TBME (250 mg/L). The stock was
132
stored at 4°C. The standard-mix stock solution was diluted 1:10 with TBME, resulting in a
133
concentration of 25 ng/µL for MS, DS, TS and FSA in the standard-mix working solution for
134
analysis of the stored emulsifiers. Stored emulsifiers (15 mg) were dissolved in 10 mL of TBME
135
in an ultrasonic bath for 2 min (1.5 mg/mL) and diluted to 37.5 and 300 ng/µL with TBME for the
136
me-sMAG, lo-usMAG and the me-sMAG/DAG emulsifier, respectively.
137
2.3.2 HPTLC–FLD
138
HPTLC was executed on primuline pre-impregnated silica gel LiChrospher plates as
139
described in an earlier publication (Oellig et al. 2018). In brief, an Automatic TLC Sampler 4
140
(ATS 4, CAMAG, Switzerland) was used to apply samples and standards as 6-mm bands on 20
141
cm × 10 cm plates with TBME as the rinsing solvent. After the application, the plate was stored
142
for 10 min in a fume hood. HPTLC plates were two-fold developed in a 20 cm × 10 cm twin-
143
trough chamber (CAMAG). First, diethyl ether was used up to a migration distance of 18 mm.
144
After a drying time of 10 min according to (Oellig et al. 2018), the Automatic Developing
145
Chamber (ADC2, CAMAG) was used for the second development with a mixture of n-
146
pentane/n-hexane/diethyl ether (52:20:28, v/v/v) up to a migration distance of 75 mm. After a
147
drying time of 20 min according to (Oellig et al. 2018), plate images were captured with the TLC
148
Visualizer (CAMAG) under UV 366 nm illumination and the plate was scanned in fluorescence
149
mode (manual detector mode) at UV 366/> 400 nm (mercury lamp) by using the TLC Scanner 4
150
(CAMAG). HPTLC instruments were controlled by the software winCATS, version 1.4.6.2002
151
(CAMAG).
152 153 154
8 155
2.3.3 Sample analysis
156
Sample preparation and HPTLC–FLD analysis were done according to sections 2.3.1
157
and 2.3.2 (n = 2 for each storage period tested). For the analysis of the me-sMAG/DAG
158
emulsifier, only the diluted stocks were applied, whereas for the MAG emulsifiers both the
159
stocks and diluted stocks were applied. Sample application volume generally was 20 µL. The
160
standard-mix working solution (section 2.3.1) was applied with application volumes of 2 – 50 µL
161
leading to 50 – 1250 ng MS/DS/TS and free SA per zone for calibration. The lipid classes were
162
detected as the total, and quantitated against 1,2-DS as described in (Oellig et al. 2018). In
163
brief, taking into account the response factors of the 18:0 representatives of the respective
164
class, the amounts of the lipid classes first were calculated as 18:0 fatty acid and then stated as
165
g MAG, DAG, TAG and free FA per 100 g emulsifier.
166 167
2.4
Processing of model aerosol whipping cream
168
Processing of model aerosol whipping cream was done as described in an earlier
169
publication (Blankart et al. 2020). In brief, anhydrous butter (Uelzena eG, Uelzen, Germany)
170
with emulsifier and skim milk, which was reconstituted from skim milk powder (Milchwerke
171
Schwaben eG, Ulm, Germany), were processed into model aerosol whipping cream via two-
172
stage high-pressure homogenization (4/1 MPa at > 72 °C). Based on the results of (Blankart et
173
al. 2020) 0.4 g/100 g emulsifier were applied. Samples were batch pasteurized at 80 °C for
174
10 min and stored for 1 we at 6 °C prior to analysi s. All samples were produced in triplicates
175
(i = 3).
176
2.5
Particle size analysis
177
Determination of particle size distribution was done as described in an earlier publication
178
(Blankart et al. 2020), with the only difference that 100 µL of the samples were injected. A
179
refractive index of 1.46 for the fat globules and 1.33 for distilled water as dispersion medium
180
was used (Marie-Caroline Michalski et al. 2001). Particle size distributions were evaluated by
181
the volume based arithmetic mean d4,3 and the d10,3 and the d90,3, the diameter which 10% or
9 182
90% of the particles fell off short, based on a volume distribution. Each sample was measured
183
with n =3.
184
2.6
Rheological properties
185
Flow curve measurements were performed as described in an earlier publication
186
(Blankart et al. 2020) with a stress-controlled rotational rheometer (Physica MCR 302; Anton-
187
Paar GmbH, Graz, Austria) equipped with a double-gap concentric cylindrical geometry
188
(do = 27 mm, di = 25 mm, h = 40 mm). Apparent viscosity of the samples was calculated when
189
the shear rate reached 500 s-1 to be representative for nozzle induced instant foam generation.
190
Each sample was measured with n = 2. Software RheoPlus/32 V3.62 was used for instrument
191
control and rheological data evaluation.
192
2.7
Foaming
193
Foaming of the samples was performed according to an earlier publication (Blankart et
194
al. 2020). To ensure temperature equilibration, the foaming siphon was set into a water bath at
195
5 °C. In brief, 250 g sample were filled into a 1 L Gourmet Whip Plus system (iSi GmbH, Vienna,
196
Austria), gassed with 15 g nitrous oxide and equilibrated at 5 °C for 15 min. Subsequently, the
197
can was shaken 20 times and the sample sprayed while holding the can headfirst at a 90 °
198
angle into an acrylic glass cube of 6 cm x 6 cm x 6 cm. For each sample, the siphon was filled
199
two times, while only one cube was filled out of each can for the foam measurements.
200
2.8
Overrun measurements
201
Overrun of the samples was calculated by determining the weight of the foam in the
202
acryl glass cube (mf). Density ρL of the liquid cream was determined to 1.01 kg/m3 at 5 °C with a
203
density meter (DMA 5000 M, Anton-Paar GmbH, Graz, Austria) according to Blankart et al.
204
(2020). V cube - Overrun %= ·100
(1)
10 205
2.9
Foam firmness
206
Foam firmness was measured one time in the center of the cube directly after spraying
207
using a crosshair probe (0.1 cm wire diameter) with a universal testing machine (5944; Instron,
208
Norwood, USA; load cell 2 kN; software Bluehill 3). The test speed was set to 1 mm/s with a
209
measurement time of 15 s. The mean of the last 20 measurement points was calculated.
210
2.10
Drainage test
211
After foam firmness measurements samples were taken out of the cube with a spatula
212
and placed on a square steel wire mesh (10 cm x 10 cm, hole size of 0.3 mm) set on a petri
213
dish. Weight of the sample, the empty petri dish (m0) and the petri dish filled with dripped down
214
liquid cream (mDD) was measured after 1 h of storage in a cooling incubator (Binder GmbH,
215
Tuttlingen, Germany) at 20 °C to calculate the norm alized drainage.
Normalized drainage %=
216
2.11
mDD -m0 ·100 sample weight
(2)
Residual cream
217
Subsequently, after the overrun measurement, the remaining sample in the can was
218
discarded until no further gas flow was detected. With the weight of the filled (mFC) and emptied
219
can (mEC) and the applied sample weight (mc), the percentage of residual cream in the can was
220
calculated.
Residual cream %=
mc - (mFC - mEC ) ·100 mc
(3)
221 222
2.12
Statistical analysis
223
Statistical analyses and plotting of the data was conducted with SigmaPlot (v. 12.5,
224
Systat Software Inc., San Jose, USA). Results are given as arithmetic mean with standard
225
deviation, the number of independent replicates i for each sample was three. Analysis of
11 226
variance (ANOVA) and subsequent comparison of the means by Tukey-Kramer test were done
227
with a significance level of α = 0.05.
228 229
3. RESULTS AND DISCUSSION
230 231
3.1
Chemical composition of stored E471 emulsifiers
232
The effect of elevated temperatures above the melting point of the food emulsifiers was
233
investigated for a me-sMAG, a me-sMAG/DAG and a lo-usMAG emulsifier. HPTLC–FLD
234
according to Oellig et al. (2018) was used to determine the lipid class composition of the
235
emulsifiers after defined storage times: 0 – 2 – 24 – 48 – 72 h and weekly intervals until 8 we of
236
storage. The visual evaluation of the chromatograms under UV 366 nm illumination allowed
237
simple comparison of the emulsifier composition by their fingerprints, when differences were
238
directly visible. By using this method, a change in the lipid class composition in the form of a
239
decrease of 1,3-DAG and the simultaneous increase of 1,2-DAG was directly visible for the me-
240
sMAG/DAG (Figure 1). Figure 2 shows diagrams of the calculated amounts of the lipid classes
241
over the entire storage period for the different emulsifier types, visualizing the quantitative
242
changes in the emulsifier composition. Results were well repeatable with a precision expressed
243
as the relative standard deviation (%RSD) of <10%, except for the minor components with
244
amounts <0.2%, for which higher deviations were obtained. The lipid class composition of the
245
lo-usMAG was stable over the entire storage period. As opposed to this, the composition of the
246
me-sMAG and the me-sMAG/DAG revealed great changes: both me-sMAG (Figure 2 B) and
247
me-sMAG/DAG (Figure 2 C) showed a noticeable decrease in the MAG amount and an
248
increase in the DAG amount, when the conversion was more prominent for me-sMAG/DAG.
249
Only minor changes of TAGs and FFAs were found.
250
In detail, the MAG content of lo-usMAG decreased about 10% over the entire storage
251
period (Table 1). In contrast, the content of both 1,2- and 1,3-DAGs increased about 200%,
252
however, their absolute content was still low with 4.4 g/100 g and 9 g/100 g emulsifier,
12 253
respectively. Overall, the sum of MAGs and DAGs remained stable and the amount of minor
254
components did not change. Considering that MAG emulsifiers with high amounts of
255
unsaturated FAs are usually not applied to aerosol whipping cream products, these results were
256
not further evaluated. However, the stability of the emulsifier regarding the lipid class
257
composition may be helpful for the application of this emulsifier in other (dairy) products.
258
For the me-sMAG, a decrease of the MAG content by about 36% to a final content of
259
60 g/100 g (Table 1) was observed. Decrease started after 1 we and carried on until the end of
260
the investigated storage period. A thermodynamic equilibrium was not obtained (Figure 2 B). In
261
contrast to that, the amount of 1,3-DAG considerably increased from 3 g/100 g to 33 g/100 g,
262
when also no steady state was observable after 8 we. The 1,2-DAG content increased slightly,
263
but was still low with 1.8 g/100 g. Obviously, high temperature led to the formation of DAGs.
264
For me-sMAG/DAG, a decrease in the MAG content of about 10% was observed
265
(Table 1). The content of 1,3-DAGs, which was higher than the 1,2-DAG content in the
266
untreated emulsifier, decreased. Simultaneously, the amount of 1,2-DAGs increased. Thus, a
267
rearrangement of 1,3-DAGs to 1,2-DAGs during the beginning of the storage period is assumed.
268
After 2 we a thermodynamic equilibrium was obtained and the 1,2- and 1,3- DAG contents
269
remained constant. With a decrease of 10% for the MAG content, and the increase regarding
270
the DAG content, respectively, the composition changes are hardly comparable to those in me-
271
sMAG.
272 273
3.2
Techno-functional properties
274
Samples of each emulsifier were taken at defined storage times and applied to model
275
aerosol whipping cream (i = 3). Me-sMAG and lo-usMAG samples were taken and applied after
276
storage of 1 we, 4 we and 8 we, whereas me-sMAG/DAG emulsifier samples were additionally
277
taken after 24 h as preliminary tests showed compositional changes to start at that storage time.
278 279
3.2.1
Particle size distribution
13 280
Figure 3 depicts the particle size distribution of aerosol whipping cream samples
281
processed with emulsifier of different storage times at 70 °C or 80 °C. D10,3, mean and d90,3 were
282
calculated. No effect depending on storage time for me-sMAG, me-sMAG/DAG and lo-usMAG
283
was found. Samples processed with 0.4 g/100 g me-sMAG or me-sMAG/DAG showed similar
284
results for d10,3, mean and d90,3. Processing of aerosol whipping cream with an addition of
285
0.4 g/100 g lo-usMAG led to higher values of d10,3, d4,3 and d90,3 than an addition of me-sMAG or
286
me-sMAG/DAG.
287
The decreasing MAG content of me-sMAG over the storage time (section 4.1) did not
288
affect the size of fat globules. This is in accordance with results from our previous work (Blankart
289
et al. 2020) where we found no difference between particle size distributions of aerosol whipping
290
cream
291
transesterification during the storage of me-sMAG on fat globule sizes was not observed.
292
However, at lower concentration of emulsifier the decreasing content of me-sMAG might lead to
293
concentrations insufficient for complete coverage of the newly created fat globule surface
processed
with
0.4 g/100 g
me-sMAG
or
me-sMAG/DAG.
An
effect
of
the
294
The slight decrease of MAG content and rearrangement of 1,3-DAG into 1,2-DAG during
295
the storage of me-sMAG/DAG (Table 1) did not affect the particle size. The bigger particles of
296
aerosol whipping cream processed with lo-usMAG are caused by the dewetting process
297
(Fredrick et al. 2013). By this, crystalline and liquid fat breaks through the fat globule, leading to
298
thorn-like structures sticking out of the globule. When these fat globules collide with other fat
299
globules, the crystal thorns may pierce the fat globule membrane, resulting in partial coalescence
300
of fat globules (Fredrick et al. 2013). The slight decrease of the MAG content, accompanied by
301
slight increases of 1,2- and 1,3-DAG content, did not seem to affect the dewetting process
302
caused by lo-usMAG.
303 304
3.2.2
Rheological properties
305
Apparent viscosity of aerosol whipping cream processed with 0.4 g/100 g me-sMAG,
306
me-sMAG/DAG or lo-usMAG was calculated for ɣ̇ = 500 s-1 to be representative for nozzle
307
induced foam generation. Storage of the emulsifiers at elevated temperatures did not affect the
14 308
apparent viscosity of aerosol whipping cream processed with those emulsifiers. Samples
309
processed with lo-usMAG showed higher apparent viscosity than samples that were processed
310
with me-sMAG or me-sMAG/DAG (Figure 4).
311
Apparently, the reduction of MAG and the simultaneous increase of 1,2- and 1,3-DAG
312
content observed over the storage of me-sMAG did not affect the apparent viscosity of aerosol
313
whipping cream. This is in accordance with our previous work, where we found no difference in
314
apparent viscosity of aerosol whipping cream processed with 0.4 g/100 g me-sMAG or
315
me-sMAG/DAG. The higher apparent viscosity of samples processed with lo-usMAG is caused
316
by the dewetting effect of usMAG, leading to coalescence of fat globules. As for the particle size
317
distribution, no effect on apparent viscosity was observed for the slight rearrangement of MAG
318
into 1,2- and 1,3-DAG.
319 320
3.2.3
Overrun and foam firmness
321
Overrun and foam firmness of aerosol whipped cream samples processed with the
322
stored emulsifiers are shown in Table 2. Samples processed with lo-usMAG were not foamable
323
at any storage time and the cream left the siphon as a liquid. The sample started to collapse as
324
soon as it was sprayed into the cube, therefore it was only possible to estimate the overrun to <
325
100% (Table 2). Foam firmness was not measurable, as the sample was too soft. Increasing
326
storage time of me-sMAG did not induce an effect on the overrun of aerosol whipped cream, but
327
the foam firmness decreased. Overrun and foam firmness of samples processed with
328
me-sMAG/DAG were not affected by increasing storage time.
329
Results for lo-usMAG are in accordance with our previous study (Blankart et al. 2020),
330
where we found that application of lo-usMAG prevented foam formation at all investigated
331
emulsifier concentrations. The slight decrease of MAG content did not show an effect on the
332
foam formation. The decrease in foam firmness with ongoing storage of me-sMAG is
333
supposedly caused by the reduction of MAG content (Table 1), as previous studies showed that
334
lower concentrations of me-sMAG lead to softer foam (Blankart et al. 2020). The rearrangement
15 335
of 1,3-DAG into 1,2-DAG is not reflected in overrun and foam firmness as no changes were
336
detected, apparently both isomers apparently exhibit similar foaming properties.
337 338 339
3.2.4
Drainage and residual cream
340
In accordance with a previous study (Blankart et al. 2020), in which we showed that only
341
increasing lo-usMAG concentration had an effect on residual cream, no effect of storage on
342
residual cream was detected for the emulsifiers examined. Results for drainage are shown in
343
Table 3. As foaming of samples with lo-usMAG was not feasible, no drainage was measured.
344
Increasing storage of me-sMAG led to a significant increase of drainage up to 50.5 ± 4.0% after
345
8 we. No consistent trend for me-sMAG/DAG was detected.
346
The increased drainage of aerosol whipped cream, induced by the storage of me-sMAG,
347
correlates with the decrease of MAG and increase of 1,2- and 1,3-DAG (Table 1). Both
348
compositional changes contribute to the lower stability of the foam. In a previous study we
349
showed, that lower concentrations of MAG and higher DAG concentrations lead to higher
350
drainage (Blankart et al. 2020). Higher concentrations of DAG seem to actively destabilize the
351
foam of aerosol whipped cream, while lower MAG concentrations simply fail to provide sufficient
352
stabilization of the fat globules and the foam. As no differences were observed over the time of
353
storage of me-sMAG/DAG, for which the proportions of 1,3- and 1,2-DAG changed,
354
conformation of DAG does not seem to have an effect on foam stability, at least not at the
355
tested emulsifier concentration of 0.4 g/100 g.
356 357
4. Conclusions
358
Storage above the respective melting point of the E471 emulsifiers changed the lipid
359
composition. The lipid class composition of long-chain unsaturated monoacylglycerides
360
(lo-usMAG) with high amounts of unsaturated fatty acids (FA) was rather stable over weeks,
361
while the composition of medium-chain saturated monoacylglyceride (me-sMAG) and medium-
362
chain saturated mono-/diacylglyceride (me-sMAG/DAG) emulsifiers with mainly saturated FAs
16 363
was significantly affected. Both emulsifiers with mainly saturated FAs showed a decrease in the
364
MAG amount and an increase in the DAG amount, when in the MAG/DAG emulsifier
365
additionally a rearrangement of 1,3- in 1,2-DAGs was obtained.
366
The effect of the observed compositional changes on the techno-functional properties of
367
food emulsifiers was investigated in model aerosol whipping cream. While lo-usMAG was found
368
unsuitable for application in aerosol whipping cream, the slight compositional changes were
369
found not to affect particle size distribution and apparent viscosity at the applied concentrations.
370
Storage of me-sMAG reduced foam stability (lower foam firmness, higher drainage) of aerosol
371
whipped cream, when both the reduced MAG content and the increased DAG content may
372
contribute to this. No changes in techno-functional properties due to rearrangement of 1,3- into
373
1,2-DAG were found for the me-sMAG/DAG at an addition of 0.4 g/100 g. It is assumed, that the
374
effect of compositional changes during storage would be more prominent if lower emulsifier
375
concentrations were applied.
376
Storage of E471 emulsifiers at temperatures above the respective melting point causes
377
changes both of the chemical composition and the techno-functional properties, when applied in
378
aerosol whipping cream. Although the prolonged storage as conducted in this study does not
379
depict the actual handling of emulsifiers in industrial applications, the effects observed could
380
also take place during filling and storage of emulsifiers.
381 382
Acknowledgements
383
The authors express many thanks to Merck (Darmstadt, Germany) for support with plate
384
material and to DuPont Danisco (Neu-Isenburg, Germany) and BASF (Illertissen, Germany) for
385
providing E471 emulsifiers. Further thanks go to Uelzena eG (Uelzen, Germany) for providing
386
anhydrous butter and Milchwerke Schwaben eG (Neu-Ulm, Germany) for contribution of skim
387
milk powder. The authors also express thanks to Tina Melde, University of Hohenheim, for
388
support in the laboratory.
17 389
This research project was supported by the German Ministry of Economic Affairs and
390
Energy (via AiF) and the FEI (Forschungskreis der Ernährungsindustrie e.V., Bonn, Germany).
391
Project AiF 19355 N.
18 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434
References Blankart, Max; Kratzner, Caroline; Link, Katharina; Oellig, Claudia; Schwack, Wolfgang; Hinrichs, Jörg (2020): Technical emulsifiers in aerosol whipping cream – Compositional variations in the emulsifier affecting emulsion and foam properties. In: International Dairy Journal 102, S. 104578. DOI: 10.1016/j.idairyj.2019.104578. Davies, Emma; Dickinson, Eric; Bee, Rodney D. (2001): Orthokinetic destabilization of emulsions by saturated and unsaturated monoglycerides. In: International Dairy Journal 11 (10), S. 827–836. DOI: 10.1016/S0958-6946(01)00097-8. Fredrick, Eveline; Heyman, Bart; Moens, Kim; Fischer, Sabine; Verwijlen, Tom; Moldenaers, Paula et al. (2013): Monoacylglycerols in dairy recombined cream: II. The effect on partial coalescence and whipping properties. In: Food Research International 51 (2), S. 936–945. DOI: 10.1016/j.foodres.2013.02.006. Fregolente, Leonardo Vasconcelos; Batistella, César Benedito; Filho, Rubens Maciel; Wolf Maciel, Maria Regina (2006): Optimization of Distilled Monoglycerides Production. In: Applied Biochemistry and Biotechnology 131 (1-3), S. 680–693. DOI: 10.1385/ABAB:131:1:680. Goff, H. D. (1997): Instability and Partial Coalescence in Whippable Dairy Emulsions. In: Journal of Dairy Science 80 (10), S. 2620–2630. DOI: 10.3168/jds.S0022-0302(97)76219-2. Marie-Caroline Michalski; Valérie Briard; Françoise Michel (2001): Optical parameters of milk fat globules for laser light scattering measurements. In: Lait 81 (6), S. 787–796. DOI: 10.1051/lait:2001105. Méndez-Velasco, Carlos; Goff, H. Douglas (2012): Fat structure in ice cream: A study on the types of fat interactions. In: Food Hydrocolloids 29 (1), S. 152–159. DOI: 10.1016/j.foodhyd.2012.02.002. Munk, M. B.; Larsen, F. H.; Van Den Berg, F. W.J.; Knudsen, J. C.; Andersen, M. L. (2014a): Competitive displacement of sodium caseinate by low-molecular-weight emulsifiers and the effects on emulsion texture and rheology. In: Langmuir 30 (29), S. 8687–8696. DOI: 10.1021/la5011743. Munk, M. B.; Larsen, F. H.; van den Berg, F. W. J.; Knudsen, J. C.; Andersen, M. L. (2014b): Competitive Displacement of Sodium Caseinate by Low-Molecular-Weight Emulsifiers and the Effects on Emulsion Texture and Rheology. In: Langmuir 30 (29), S. 8687–8696. DOI: 10.1021/la5011743. Munk, Merete B.; Marangoni, Alejandro G.; Ludvigsen, Hanne K.; Norn, Viggo; Knudsen, Jes C.; Risbo, Jens et al. (2013): Stability of whippable oil-in-water emulsions. Effect of monoglycerides on crystallization of palm kernel oil. In: Food Research International 54 (2), S. 1738–1745. DOI: 10.1016/j.foodres.2013.09.001. Norn, Viggo (Hg.) (2015): Emulsifiers in food technology. Second edition. Chichester, West Sussex, Hoboken, NJ: Wiley Blackwell. Oellig, Claudia; Brändle, Klara; Schwack, Wolfgang (2018): Characterization of E 471 food emulsifiers by high-performance thin-layer chromatography-fluorescence detection. In: Journal of chromatography. A 1558, S. 69–76. DOI: 10.1016/j.chroma.2018.05.010. Rarokar, Nilesh Ramesh; Menghani, Sunil; Kerzare, Deweshri; Khedekar, Pramod Bhujangrao (2017): Progress in Synthesis of Monoglycerides for Use in Food and Pharmaceuticals. In: Journal of Experimental Food Chemistry 03 (03). DOI: 10.4172/2472-0542.1000128. Spicer, Patrick T.; Hartel, Richard W. (2005): Crystal Comets: Dewetting During Emulsion Droplet Crystallization. In: ChemInform 36 (51), S. 655. DOI: 10.1002/chin.200551267.
Figure 1 HPTLC plate image after separation of a mono-/diacylglyceride (MAG/DAG) emulsifier at storage periods of 0 h, 24 h, 48 h, 72 h, 1, 2, 3, 4, 5, 6, 7 and 8 we at 70 °C (tracks 1 – 13) and a standard-mix containing monostearin (MS), 1,2-distearin (1,2-DS), 1,3-distearin (1,3-DS), stearic acid (SA) and tristearin (TS) (25 – 1250 ng/zone) on primuline pre-impregnated LiChrospher silica gel plates by two-fold development with diethyl ether to a migration distance of 18 mm and n-pentane/n-hexane/diethylether (52:20:28, v/v/v) to a migration distance of 75 mm under UV 366 nm illumination. Sample amounts were 6 µg MAG/DAG emulsifier/zone.
Figure 2 Mean content of lipid classes in g/100 g emulsifier over a period of 8 w. Long-chain unsaturated monoacylglyceride (lo-usMAG) stored at 70 °C; medium-chain saturated monacylglyceride
(me-sMAG)
stored
at
80
°C;
medium- chain
saturated
mono-/diacylglyceride (me-sMAG/DAG) stored at 70 °C . MAG: monoacylglycerides; DAG: diacylglycerides; FFA: free fatty acids; TAG: triacylglycerides. Each storage time was analyzed with n = 2.
Figure 3 D10,3 (●), arithmetic mean d4,3 (∆) and d90,3 (■) of model aerosol whipping cream (30 g/100 g fat, 3 g/100 g protein) processed with 0.4 g/100 g of the three E471 emulsifiers in dependence of storage time (at 70 °C or 80 °C) of e mulsifiers. Aerosol whipping cream samples were stored for 1 w at 6 °C. Lo-usMAG: long -chain unsaturated monoacylglyceride; me-sMAG: medium-chain saturated monoacylglyceride; me-sMAG/DAG: medium-chain saturated mono/diacylglyceride. The number of independent replicates was i = 3, each replicate was measured three times (n = 3). Values are shown as arithmetic mean ± standard deviation.
Figure 1 Apparent viscosity at ɣ̇ = 500 s-1 at 5 °C of model aerosol whipping cream (30 g/100 g fat, 3 g/100 g protein) processed with 0.4 g/100 g of the three E471 emulsifiers in dependence of storage time (at 70 °C or 80 °C) of e mulsifiers. Aerosol whipping cream samples were stored for 1 w at 6 °C. Lo-usMAG: long -chain unsaturated monoacylglyceride; me-sMAG: medium-chain saturated monoacylglyceride; me-sMAG/DAG: medium-chain saturated mono-/diacylglyceride. The number of independent replicates was i = 3, each replicate was measured two times (n = 2). Values are shown as arithmetic mean ± standard deviation.
Table 1: MAG, DAG, FFA and TAG contents in three untreated (0 h) emulsifiers and in emulsifiers after storage of 8 we at 70 °C (lo usMAG: longchain unsaturated MAG; me-sMAG/DAG: medium-chain saturated MAG/DAG) and 80 °C (me sMAG: medium chain s aturated MAG), respectively, determined by HPTLC–FLD. lo-usMAG Mean content [g/100 g] ±
me-sMAG
me-sMAG/DAG
0h
8w
0h
8w
0h
8w
MAG
95.0 ± 0.07
86.2 ± 0.6
93.5 ± 0.4
60.1 ± 1.1
53.8 ± 0.08
47.1 ± 0.38
1,2-DAG
1.5 ± 0.02
4.4 ± 0.18
0.5 ± 0.01
1.8 ± 0.02
3.0 ± 0.05
16.5 ± 0.53
1,3-DAG
3.2 ± 0.1
9.0 ± 0.38
2.7 ± 0.1
32.8 ± 0.9
36.4 ± 0.09
29.5 ± 0.51
FFA
0.1 ± 0.03
0.2 ± 0.02
0.7 ± 0.05
1.0 ± 0.06
1.7± 0.09
2.1 ± 0.03
TAG
0.2 ± 0.05
0.2 ± 0.04
2.5 ± 0.23
2.6 ± 0.23
5.1± 0.13
4.9 ± 0.36
Sum (MAG and DAGs)
99.8 ± 0.05
99.6 ± 0.06
96.8 ± 0.3
94.8 ± 1.9
93.2± 0.04
93.0± 0.40
a
SD (n = 2)
a
Standard deviation.
Table 2: Overrun in % and foam firmness in mN of aerosol whipping cream (30 g/100 g fat, 3 g/100 g protein) processed with 0.4 g/100 g of the three E471 emulsifiers in dependence of storage time (at 70 °C or 80 °C) of emulsifiers. Ae rosol whipping cream samples were stored for 1 w at 6 °C. Lo-usMAG: long-chain unsaturated m onoacylglyceride; me-sMAG: mediumchain
saturated
monoacylglyceride;
me-sMAG/DAG: medium-chain
saturated
mono-/diacylglyceride. The number of independent repetitions of the experiments was i = 3. Values are shown as arithmetic mean ± standard deviation. Different letter represent significant differences in one emulsifier (ANOVA, Tukey-Kramer, α = 0.05). storage
lo-usMAG
me-sMAG/DAG
me-sMAG
time Overrun
Foam firmness
Overrun
Foam firmness
Overrun
Foam firmness
in %
in mN
in %
in mN
in %
in mN
< 100
n.m.
204 ± 17b
72 ± 49a
274 ± 27a
258 ± 26a
n.c.
n.c.
293 ± 22a
250 ± 45a
n.c.
n.c.
1w
< 100
n.m.
243 ± 38ab
156 ± 86a
242 ± 45a
239 ± 71ab
4w
< 100
n.m.
212 ± 17ab
74 ± 58a
206 ± 22a
137 ± 22b
8w
< 100
n.m.
269 ± 55ab
170 ± 125a
246 ± 21a
132 ± 48b
0h 24 h
n.m.: not measurable n.c.: not conducted
Table 3: Normalized drainage of aerosol whipping cream (30 g/100 g fat, 3 g/100 g protein), processed with 0.4 g/100 g of the three E471 emulsifiers in dependence of storage time (at 70 °C or 80 °C) of emulsifiers. Aerosol whipping cr eam samples were stored for 1 w at 6 °C. Lo-usMAG: long-chain unsaturated monacylglyceride; me-sMAG: medium-chain saturated monoacylglyceride; me-sMAG/DAG: medium-chain saturated mono-/diacylglyceride. The number of independent repetitions of the experiments was i = 3. Values are shown as arithmetic mean ± standard deviation. Different letters represent significant differences in one emulsifier (ANOVA, Tukey-Kramer, α = 0.05). Storage time
lo-usMAG
me-sMAG/DAG
me-sMAG
Normalized drainage in % 0h
n.m.
56 ± 11ab
15 ± 4a
24 h
n.c.
17 ± 9b
n.c.
1w
n.m.
31 ± 9ab
14 ± 12a
4w
n.m.
59 ± 2a
47 ± 6b
8w
n.m.
29 ± 20b
50 ± 4b
n.m.: not measurable n.c.: not conducted
1
Highlights:
2
-
MAG content of E471 emulsifiers decreases over storage at elevated temperatures
3
-
DAG content of medium-chain saturated MAG increases over storage
4
-
DAG is assumed to reduce foaming properties of aerosol whipping cream
5
-
Rearrangements of 1,3- into 1,2-DAG in medium-chain saturated MAG/DAG
6
-
No change in techno-functional properties by rearrangement of 1,3 into 1,2-DAG
Declaration of interest:
Manuscript: ‘Effect of storage at high temperature on chemical (composition) and techno-functional characteristics of E471 food emulsifiers applied to aerosol whipping cream” Journal of Food Engineering Authors: Max Blankart, Claudia Oellig, Sonja Averweg, Wolfgang Schwack, Jörg Hinrichs
Declarations of interest: none.
S0260-8774(19)30525-4
DOI:
https://doi.org/10.1016/j.jfoodeng.2019.109882
Reference:
JFOE 109882
To appear in:
Journal of Food Engineering
Received Date: 26 October 2019 Revised Date:
16 December 2019
Accepted Date: 17 December 2019
Please cite this article as: Blankart, M., Oellig, C., Averweg, S., Schwack, W., Hinrichs, Jö., Effect of storage at high temperature on chemical (composition) and techno-functional characteristics of E471 food emulsifiers applied to aerosol whipping cream, Journal of Food Engineering (2020), doi: https:// doi.org/10.1016/j.jfoodeng.2019.109882. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Published by Elsevier Ltd.
1 1
Effect of storage at high temperature on chemical (composition) and techno-functional
2
characteristics of E471 food emulsifiers applied to aerosol whipping cream
3 4
Max Blankart*1, Claudia Oellig2, Sonja Averweg1, Wolfgang Schwack2 and Jörg Hinrichs1
5 6
1
7
Biotechnology, University of Hohenheim, Garbenstrasse 21, 70593 Stuttgart, Germany
8
2
9
Germany
Department of Soft Matter Science and Dairy Technology, Institute of Food Science and
Institute of Food Chemistry, University of Hohenheim, Garbenstrasse 28, 70593 Stuttgart,
10 11 12
*Corresponding author. Tel.: +49 711 459 24208; fax: +49-711-459-23617
13
E-mail address: [email protected] (M. Blankart).
2 14
Abstract
15
Various foods are processed with addition of mono- and diacylglycerol (MAG and DAG)
16
emulsifiers to adjust techno-functional properties. Exposure to and application of high
17
temperatures during production, processing and transport of these emulsifiers can induce
18
compositional changes and thereby affect techno-functional properties. Emulsifiers were stored
19
above their respective melting point and their chemical composition was determined by high-
20
performance thin-layer chromatography–fluorescence detection. Storage for 8 weeks decreased
21
the MAG content of a saturated MAG by about 36% by transesterification into 1,3-DAG, while a
22
rearrangement of 1,2- into 1,3-DAG was observed for a saturated MAG/DAG emulsifier.
23
Emulsifiers were applied to aerosol whipping cream, and viscosity, particle size, overrun, foam
24
firmness and drainage were determined. The increasing 1,3-DAG content of the saturated MAG
25
emulsifier was found to increase the drainage of aerosol whipping cream from 15% to 50%.
26 27 28 29
Keywords Technical emulsifier, temperature-time load, chemical composition, techno-functional properties, high-performance thin-layer chromatography–fluorescence detection (HPTLC-FLD)
3 30
1.
Introduction
31
Mono- and diacylglycerols (MAGs and DAGs, E471 emulsifiers) are the most frequently
32
used emulsifiers in the food sector, applied in the processing of bread, pastry, margarines, ice
33
cream, aerosol whipping cream and other dairy products (Norn 2015). They enable the
34
adjustment of techno-functional properties such as viscosity, creaming, emulsion stability and
35
foam stability (Norn 2015; Munk et al. 2013; Méndez-Velasco und Goff 2012). Based on the
36
production process, E471 emulsifiers of different composition are obtained. In general, MAGs
37
and DAGs are produced by transesterification of triacylglycerols (TAG) with glycerol or direct
38
esterification of glycerol with fatty acids. Both reactions require an inorganic alkaline catalyst
39
and temperatures of 220 to 260 °C and result in a p roduct with a MAG content between 10 and
40
60%, the other parts comprise DAG, TAG, free fatty acids (FFA) and glycerol. By means of
41
molecular distillation under vacuum at temperatures of 140 – 170 °C MAGs can be enriched (>
42
95%). Direct esterification enables the production of E471 with a specific fatty acid composition,
43
while transesterification results in MAGs/DAGs with a mixed fatty acid composition. MAG/DAG
44
content and esterification position are adjusted by process conditions (Norn 2015; Fregolente et
45
al. 2006; Rarokar et al. 2017).
46
Techno-functional properties of E471 emulsifiers depend on their chemical composition.
47
In case of milk products, saturated MAGs (sMAGs) where shown to be incorporated in the fat
48
globule membrane, and displace proteins form the membrane if used at higher concentrations.
49
When the temperature is lowered, the adsorbed sMAGs crystallize and form a solid layer
50
around the fat globule, thereby stabilizing it against coalescence and aggregation (Fredrick et al.
51
2013; Munk et al. 2014b; Méndez-Velasco und Goff 2012). Unsaturated MAGs (usMAGs) also
52
displace proteins from the fat globule membrane (Munk et al. 2014a). In contrast to sMAGs,
53
however, usMAGs destabilize fat globules (Davies et al. 2001). The destabilizing process, called
54
dewetting, is described as crystalline and liquid fat that partly breaks through the fat globule
55
when usMAGs adsorb to the fat globule membrane. The protruding fat crystals may then act as
56
crystal thorns that pierce the membrane of colliding fat globules, while the liquid fat glues fat
57
globules together, leading to partial coalescence of fat globules (Spicer und Hartel 2005; Munk
4 58
et al. 2013; Munk et al. 2014a; Méndez-Velasco und Goff 2012). This destabilizing effect is
59
utilized in the processing of reconstituted whipping cream and ice cream as the foam structure
60
of these systems relies on the formation of a partially coalesced fat globule network (Fredrick et
61
al. 2013; Goff 1997). In a previous paper, we found that addition of usMAG to aerosol whipping
62
cream prevents foaming, leading to the hypothesis that foam stabilization is not caused by
63
partially coalesced fat globules. SMAG led to high emulsion and foam stability, while addition of
64
a mono-/diacylglyceride (MAG/DAG) emulsifier provided lower emulsion stability and decreased
65
the foam stability (Blankart et al. 2020) . The position of the esterification (1- or 2- in a MAG;
66
1,2- or 1,3- in a DAG) may as well modify the techno-functional properties, but has not yet been
67
investigated to our knowledge.
68
The chemical composition of E471 emulsifiers is determined directly after production as
69
quality control. For transportation and further processing, food emulsifiers are often handled in
70
molten form. We hypothesize, that temperatures above the respective melting point during
71
transportation and processing may gradually change the chemical composition and thereby the
72
techno-functional properties of E471 emulsifiers. To prove this hypothesis, three E471
73
emulsifiers were stored above their respective melting point for 8 we and chemical composition
74
was determined at certain storage times. Emulsifier samples of selected storage times were
75
applied to model aerosol whipping cream and the techno-functional properties were determined.
76
The simple HPTLC–FLD approach (Oellig et al. 2018) enabled to control the
77
composition of technical emulsifiers fast and easily. Applying the visual fingerprint, differences
78
caused by temperature–time load are directly visible. According to Oellig et al. (2018) a single
79
calibration standard was used for quantitation and the individual lipid classes were collectively
80
quantified.
81
5 82
List of abbreviations
83
MAG:
monoacylglyceride
84
DAG:
diacylglyceride
85
TAG:
triacylglycerides
86
Lo-usMAG:
long-chain unsaturated monoacylglyceride
87
Me-sMAG:
medium-chain unsaturated monoacylglyceride
88
Me-sMAG/DAG:
medium-chain saturated mono-/diacylglyceride
89
FA:
fatty acids
90
FFA:
free fatty acids
91
HPTLC:
high performance thin layer chromatography
92
FLD:
fluorescence detector
93
GC:
gas chromatography
94
MS:
monostearin
95
DS:
distearin
96
TS:
tristearin
97
SA:
stearic acid
98
FSA:
free stearic acid
99
RSD:
relative standard deviation
6 100
2.
Material and methods
101
2.1
Chemicals and materials 1-stearoyl-rac-glycerol
102
(> 99%),
1,2-distearoyl-rac-glycerol
(> 99%),
103
1,3-distearoylglycerol (> 99%), stearic acid (analytical standard grade, > 99.5%), glyceryl
104
tristearate (> 99%), methanol (LC–MS, Chromasolv), diethyl ether (≥ 99.5%, GC, puriss.),
105
n-pentane
106
(TBME; ≥ 99.8%, HPLC, Chromasolv) were obtained from Sigma-Aldrich (Steinheim, Germany).
107
n-Hexane (95%, for pesticide residue analysis, Chemsolute) was purchased from Th. Geyer
108
(Renningen, Germany). Formic acid (>98%, analytical reagent grade) was obtained from Fisher
109
Scientific (Schwerte, Germany). Primuline (dye content 50%) was from Sigma-Aldrich. Ultrapure
110
water (>18 MΩ cm) was supplied by a Synergy System (Millipore, Schwalbach, Germany).
111
HPTLC silica gel LiChrospher F254s plates from Merck (Darmstadt, Germany) were used without
112
pre-washing. The following emulsifiers of the type E471 were provided from two manufacturers:
113
long-chain
114
sMAG/DAG); medium-chain saturated MAG (me-sMAG).
(≥ 99%
for
unsaturated
residue
MAG
analysis,
(lo-usMAG);
Chromasolv)
medium-chain
and
t-butyl
saturated
methyl
MAG/DAG
ether
(me-
115 116
2.2
Storage of emulsifiers at elevated temperatures
117
For each emulsifier 200 g were filled into a Schott flask and stored at elevated
118
temperatures (above respective melting points, Blankart et al. (2020)) for 8 we. The me-sMAG
119
was kept at 80 °C (T5042, Heraeus, Hanau, Germany) whereas the lo-usMAG and the me-
120
sMAG/DAG were stored at 70 °C (Typ 17053099003100 # 980944 WTC Binder GmbH,
121
Tuttlingen, Germany). For determination of the chemical composition, samples were taken after
122
0 h, 2 h, 24 h, 48 h, and 72 h and eventually at weekly intervals for 8 we in all. Samples for
123
techno-functional characterization were taken after 0 h, 1 we, 4 we, 8 we and additionally after
124
24 h for the me-sMAG/DAG.
125 126
7 127 128 129
2.3
Analysis of E471 food emulsifiers by high-performance thin-layer chromatography–fluorescence detection (HPTLC–FLD)
2.3.1 Standard solutions and sample preparation
130
Standard-mix stock solution was prepared by dissolving 2.5 mg of mono-, di-, tristearin
131
and free stearic acid (MS, DS, TS and free SA) in 10 mL of TBME (250 mg/L). The stock was
132
stored at 4°C. The standard-mix stock solution was diluted 1:10 with TBME, resulting in a
133
concentration of 25 ng/µL for MS, DS, TS and FSA in the standard-mix working solution for
134
analysis of the stored emulsifiers. Stored emulsifiers (15 mg) were dissolved in 10 mL of TBME
135
in an ultrasonic bath for 2 min (1.5 mg/mL) and diluted to 37.5 and 300 ng/µL with TBME for the
136
me-sMAG, lo-usMAG and the me-sMAG/DAG emulsifier, respectively.
137
2.3.2 HPTLC–FLD
138
HPTLC was executed on primuline pre-impregnated silica gel LiChrospher plates as
139
described in an earlier publication (Oellig et al. 2018). In brief, an Automatic TLC Sampler 4
140
(ATS 4, CAMAG, Switzerland) was used to apply samples and standards as 6-mm bands on 20
141
cm × 10 cm plates with TBME as the rinsing solvent. After the application, the plate was stored
142
for 10 min in a fume hood. HPTLC plates were two-fold developed in a 20 cm × 10 cm twin-
143
trough chamber (CAMAG). First, diethyl ether was used up to a migration distance of 18 mm.
144
After a drying time of 10 min according to (Oellig et al. 2018), the Automatic Developing
145
Chamber (ADC2, CAMAG) was used for the second development with a mixture of n-
146
pentane/n-hexane/diethyl ether (52:20:28, v/v/v) up to a migration distance of 75 mm. After a
147
drying time of 20 min according to (Oellig et al. 2018), plate images were captured with the TLC
148
Visualizer (CAMAG) under UV 366 nm illumination and the plate was scanned in fluorescence
149
mode (manual detector mode) at UV 366/> 400 nm (mercury lamp) by using the TLC Scanner 4
150
(CAMAG). HPTLC instruments were controlled by the software winCATS, version 1.4.6.2002
151
(CAMAG).
152 153 154
8 155
2.3.3 Sample analysis
156
Sample preparation and HPTLC–FLD analysis were done according to sections 2.3.1
157
and 2.3.2 (n = 2 for each storage period tested). For the analysis of the me-sMAG/DAG
158
emulsifier, only the diluted stocks were applied, whereas for the MAG emulsifiers both the
159
stocks and diluted stocks were applied. Sample application volume generally was 20 µL. The
160
standard-mix working solution (section 2.3.1) was applied with application volumes of 2 – 50 µL
161
leading to 50 – 1250 ng MS/DS/TS and free SA per zone for calibration. The lipid classes were
162
detected as the total, and quantitated against 1,2-DS as described in (Oellig et al. 2018). In
163
brief, taking into account the response factors of the 18:0 representatives of the respective
164
class, the amounts of the lipid classes first were calculated as 18:0 fatty acid and then stated as
165
g MAG, DAG, TAG and free FA per 100 g emulsifier.
166 167
2.4
Processing of model aerosol whipping cream
168
Processing of model aerosol whipping cream was done as described in an earlier
169
publication (Blankart et al. 2020). In brief, anhydrous butter (Uelzena eG, Uelzen, Germany)
170
with emulsifier and skim milk, which was reconstituted from skim milk powder (Milchwerke
171
Schwaben eG, Ulm, Germany), were processed into model aerosol whipping cream via two-
172
stage high-pressure homogenization (4/1 MPa at > 72 °C). Based on the results of (Blankart et
173
al. 2020) 0.4 g/100 g emulsifier were applied. Samples were batch pasteurized at 80 °C for
174
10 min and stored for 1 we at 6 °C prior to analysi s. All samples were produced in triplicates
175
(i = 3).
176
2.5
Particle size analysis
177
Determination of particle size distribution was done as described in an earlier publication
178
(Blankart et al. 2020), with the only difference that 100 µL of the samples were injected. A
179
refractive index of 1.46 for the fat globules and 1.33 for distilled water as dispersion medium
180
was used (Marie-Caroline Michalski et al. 2001). Particle size distributions were evaluated by
181
the volume based arithmetic mean d4,3 and the d10,3 and the d90,3, the diameter which 10% or
9 182
90% of the particles fell off short, based on a volume distribution. Each sample was measured
183
with n =3.
184
2.6
Rheological properties
185
Flow curve measurements were performed as described in an earlier publication
186
(Blankart et al. 2020) with a stress-controlled rotational rheometer (Physica MCR 302; Anton-
187
Paar GmbH, Graz, Austria) equipped with a double-gap concentric cylindrical geometry
188
(do = 27 mm, di = 25 mm, h = 40 mm). Apparent viscosity of the samples was calculated when
189
the shear rate reached 500 s-1 to be representative for nozzle induced instant foam generation.
190
Each sample was measured with n = 2. Software RheoPlus/32 V3.62 was used for instrument
191
control and rheological data evaluation.
192
2.7
Foaming
193
Foaming of the samples was performed according to an earlier publication (Blankart et
194
al. 2020). To ensure temperature equilibration, the foaming siphon was set into a water bath at
195
5 °C. In brief, 250 g sample were filled into a 1 L Gourmet Whip Plus system (iSi GmbH, Vienna,
196
Austria), gassed with 15 g nitrous oxide and equilibrated at 5 °C for 15 min. Subsequently, the
197
can was shaken 20 times and the sample sprayed while holding the can headfirst at a 90 °
198
angle into an acrylic glass cube of 6 cm x 6 cm x 6 cm. For each sample, the siphon was filled
199
two times, while only one cube was filled out of each can for the foam measurements.
200
2.8
Overrun measurements
201
Overrun of the samples was calculated by determining the weight of the foam in the
202
acryl glass cube (mf). Density ρL of the liquid cream was determined to 1.01 kg/m3 at 5 °C with a
203
density meter (DMA 5000 M, Anton-Paar GmbH, Graz, Austria) according to Blankart et al.
204
(2020). V cube - Overrun %= ·100
(1)
10 205
2.9
Foam firmness
206
Foam firmness was measured one time in the center of the cube directly after spraying
207
using a crosshair probe (0.1 cm wire diameter) with a universal testing machine (5944; Instron,
208
Norwood, USA; load cell 2 kN; software Bluehill 3). The test speed was set to 1 mm/s with a
209
measurement time of 15 s. The mean of the last 20 measurement points was calculated.
210
2.10
Drainage test
211
After foam firmness measurements samples were taken out of the cube with a spatula
212
and placed on a square steel wire mesh (10 cm x 10 cm, hole size of 0.3 mm) set on a petri
213
dish. Weight of the sample, the empty petri dish (m0) and the petri dish filled with dripped down
214
liquid cream (mDD) was measured after 1 h of storage in a cooling incubator (Binder GmbH,
215
Tuttlingen, Germany) at 20 °C to calculate the norm alized drainage.
Normalized drainage %=
216
2.11
mDD -m0 ·100 sample weight
(2)
Residual cream
217
Subsequently, after the overrun measurement, the remaining sample in the can was
218
discarded until no further gas flow was detected. With the weight of the filled (mFC) and emptied
219
can (mEC) and the applied sample weight (mc), the percentage of residual cream in the can was
220
calculated.
Residual cream %=
mc - (mFC - mEC ) ·100 mc
(3)
221 222
2.12
Statistical analysis
223
Statistical analyses and plotting of the data was conducted with SigmaPlot (v. 12.5,
224
Systat Software Inc., San Jose, USA). Results are given as arithmetic mean with standard
225
deviation, the number of independent replicates i for each sample was three. Analysis of
11 226
variance (ANOVA) and subsequent comparison of the means by Tukey-Kramer test were done
227
with a significance level of α = 0.05.
228 229
3. RESULTS AND DISCUSSION
230 231
3.1
Chemical composition of stored E471 emulsifiers
232
The effect of elevated temperatures above the melting point of the food emulsifiers was
233
investigated for a me-sMAG, a me-sMAG/DAG and a lo-usMAG emulsifier. HPTLC–FLD
234
according to Oellig et al. (2018) was used to determine the lipid class composition of the
235
emulsifiers after defined storage times: 0 – 2 – 24 – 48 – 72 h and weekly intervals until 8 we of
236
storage. The visual evaluation of the chromatograms under UV 366 nm illumination allowed
237
simple comparison of the emulsifier composition by their fingerprints, when differences were
238
directly visible. By using this method, a change in the lipid class composition in the form of a
239
decrease of 1,3-DAG and the simultaneous increase of 1,2-DAG was directly visible for the me-
240
sMAG/DAG (Figure 1). Figure 2 shows diagrams of the calculated amounts of the lipid classes
241
over the entire storage period for the different emulsifier types, visualizing the quantitative
242
changes in the emulsifier composition. Results were well repeatable with a precision expressed
243
as the relative standard deviation (%RSD) of <10%, except for the minor components with
244
amounts <0.2%, for which higher deviations were obtained. The lipid class composition of the
245
lo-usMAG was stable over the entire storage period. As opposed to this, the composition of the
246
me-sMAG and the me-sMAG/DAG revealed great changes: both me-sMAG (Figure 2 B) and
247
me-sMAG/DAG (Figure 2 C) showed a noticeable decrease in the MAG amount and an
248
increase in the DAG amount, when the conversion was more prominent for me-sMAG/DAG.
249
Only minor changes of TAGs and FFAs were found.
250
In detail, the MAG content of lo-usMAG decreased about 10% over the entire storage
251
period (Table 1). In contrast, the content of both 1,2- and 1,3-DAGs increased about 200%,
252
however, their absolute content was still low with 4.4 g/100 g and 9 g/100 g emulsifier,
12 253
respectively. Overall, the sum of MAGs and DAGs remained stable and the amount of minor
254
components did not change. Considering that MAG emulsifiers with high amounts of
255
unsaturated FAs are usually not applied to aerosol whipping cream products, these results were
256
not further evaluated. However, the stability of the emulsifier regarding the lipid class
257
composition may be helpful for the application of this emulsifier in other (dairy) products.
258
For the me-sMAG, a decrease of the MAG content by about 36% to a final content of
259
60 g/100 g (Table 1) was observed. Decrease started after 1 we and carried on until the end of
260
the investigated storage period. A thermodynamic equilibrium was not obtained (Figure 2 B). In
261
contrast to that, the amount of 1,3-DAG considerably increased from 3 g/100 g to 33 g/100 g,
262
when also no steady state was observable after 8 we. The 1,2-DAG content increased slightly,
263
but was still low with 1.8 g/100 g. Obviously, high temperature led to the formation of DAGs.
264
For me-sMAG/DAG, a decrease in the MAG content of about 10% was observed
265
(Table 1). The content of 1,3-DAGs, which was higher than the 1,2-DAG content in the
266
untreated emulsifier, decreased. Simultaneously, the amount of 1,2-DAGs increased. Thus, a
267
rearrangement of 1,3-DAGs to 1,2-DAGs during the beginning of the storage period is assumed.
268
After 2 we a thermodynamic equilibrium was obtained and the 1,2- and 1,3- DAG contents
269
remained constant. With a decrease of 10% for the MAG content, and the increase regarding
270
the DAG content, respectively, the composition changes are hardly comparable to those in me-
271
sMAG.
272 273
3.2
Techno-functional properties
274
Samples of each emulsifier were taken at defined storage times and applied to model
275
aerosol whipping cream (i = 3). Me-sMAG and lo-usMAG samples were taken and applied after
276
storage of 1 we, 4 we and 8 we, whereas me-sMAG/DAG emulsifier samples were additionally
277
taken after 24 h as preliminary tests showed compositional changes to start at that storage time.
278 279
3.2.1
Particle size distribution
13 280
Figure 3 depicts the particle size distribution of aerosol whipping cream samples
281
processed with emulsifier of different storage times at 70 °C or 80 °C. D10,3, mean and d90,3 were
282
calculated. No effect depending on storage time for me-sMAG, me-sMAG/DAG and lo-usMAG
283
was found. Samples processed with 0.4 g/100 g me-sMAG or me-sMAG/DAG showed similar
284
results for d10,3, mean and d90,3. Processing of aerosol whipping cream with an addition of
285
0.4 g/100 g lo-usMAG led to higher values of d10,3, d4,3 and d90,3 than an addition of me-sMAG or
286
me-sMAG/DAG.
287
The decreasing MAG content of me-sMAG over the storage time (section 4.1) did not
288
affect the size of fat globules. This is in accordance with results from our previous work (Blankart
289
et al. 2020) where we found no difference between particle size distributions of aerosol whipping
290
cream
291
transesterification during the storage of me-sMAG on fat globule sizes was not observed.
292
However, at lower concentration of emulsifier the decreasing content of me-sMAG might lead to
293
concentrations insufficient for complete coverage of the newly created fat globule surface
processed
with
0.4 g/100 g
me-sMAG
or
me-sMAG/DAG.
An
effect
of
the
294
The slight decrease of MAG content and rearrangement of 1,3-DAG into 1,2-DAG during
295
the storage of me-sMAG/DAG (Table 1) did not affect the particle size. The bigger particles of
296
aerosol whipping cream processed with lo-usMAG are caused by the dewetting process
297
(Fredrick et al. 2013). By this, crystalline and liquid fat breaks through the fat globule, leading to
298
thorn-like structures sticking out of the globule. When these fat globules collide with other fat
299
globules, the crystal thorns may pierce the fat globule membrane, resulting in partial coalescence
300
of fat globules (Fredrick et al. 2013). The slight decrease of the MAG content, accompanied by
301
slight increases of 1,2- and 1,3-DAG content, did not seem to affect the dewetting process
302
caused by lo-usMAG.
303 304
3.2.2
Rheological properties
305
Apparent viscosity of aerosol whipping cream processed with 0.4 g/100 g me-sMAG,
306
me-sMAG/DAG or lo-usMAG was calculated for ɣ̇ = 500 s-1 to be representative for nozzle
307
induced foam generation. Storage of the emulsifiers at elevated temperatures did not affect the
14 308
apparent viscosity of aerosol whipping cream processed with those emulsifiers. Samples
309
processed with lo-usMAG showed higher apparent viscosity than samples that were processed
310
with me-sMAG or me-sMAG/DAG (Figure 4).
311
Apparently, the reduction of MAG and the simultaneous increase of 1,2- and 1,3-DAG
312
content observed over the storage of me-sMAG did not affect the apparent viscosity of aerosol
313
whipping cream. This is in accordance with our previous work, where we found no difference in
314
apparent viscosity of aerosol whipping cream processed with 0.4 g/100 g me-sMAG or
315
me-sMAG/DAG. The higher apparent viscosity of samples processed with lo-usMAG is caused
316
by the dewetting effect of usMAG, leading to coalescence of fat globules. As for the particle size
317
distribution, no effect on apparent viscosity was observed for the slight rearrangement of MAG
318
into 1,2- and 1,3-DAG.
319 320
3.2.3
Overrun and foam firmness
321
Overrun and foam firmness of aerosol whipped cream samples processed with the
322
stored emulsifiers are shown in Table 2. Samples processed with lo-usMAG were not foamable
323
at any storage time and the cream left the siphon as a liquid. The sample started to collapse as
324
soon as it was sprayed into the cube, therefore it was only possible to estimate the overrun to <
325
100% (Table 2). Foam firmness was not measurable, as the sample was too soft. Increasing
326
storage time of me-sMAG did not induce an effect on the overrun of aerosol whipped cream, but
327
the foam firmness decreased. Overrun and foam firmness of samples processed with
328
me-sMAG/DAG were not affected by increasing storage time.
329
Results for lo-usMAG are in accordance with our previous study (Blankart et al. 2020),
330
where we found that application of lo-usMAG prevented foam formation at all investigated
331
emulsifier concentrations. The slight decrease of MAG content did not show an effect on the
332
foam formation. The decrease in foam firmness with ongoing storage of me-sMAG is
333
supposedly caused by the reduction of MAG content (Table 1), as previous studies showed that
334
lower concentrations of me-sMAG lead to softer foam (Blankart et al. 2020). The rearrangement
15 335
of 1,3-DAG into 1,2-DAG is not reflected in overrun and foam firmness as no changes were
336
detected, apparently both isomers apparently exhibit similar foaming properties.
337 338 339
3.2.4
Drainage and residual cream
340
In accordance with a previous study (Blankart et al. 2020), in which we showed that only
341
increasing lo-usMAG concentration had an effect on residual cream, no effect of storage on
342
residual cream was detected for the emulsifiers examined. Results for drainage are shown in
343
Table 3. As foaming of samples with lo-usMAG was not feasible, no drainage was measured.
344
Increasing storage of me-sMAG led to a significant increase of drainage up to 50.5 ± 4.0% after
345
8 we. No consistent trend for me-sMAG/DAG was detected.
346
The increased drainage of aerosol whipped cream, induced by the storage of me-sMAG,
347
correlates with the decrease of MAG and increase of 1,2- and 1,3-DAG (Table 1). Both
348
compositional changes contribute to the lower stability of the foam. In a previous study we
349
showed, that lower concentrations of MAG and higher DAG concentrations lead to higher
350
drainage (Blankart et al. 2020). Higher concentrations of DAG seem to actively destabilize the
351
foam of aerosol whipped cream, while lower MAG concentrations simply fail to provide sufficient
352
stabilization of the fat globules and the foam. As no differences were observed over the time of
353
storage of me-sMAG/DAG, for which the proportions of 1,3- and 1,2-DAG changed,
354
conformation of DAG does not seem to have an effect on foam stability, at least not at the
355
tested emulsifier concentration of 0.4 g/100 g.
356 357
4. Conclusions
358
Storage above the respective melting point of the E471 emulsifiers changed the lipid
359
composition. The lipid class composition of long-chain unsaturated monoacylglycerides
360
(lo-usMAG) with high amounts of unsaturated fatty acids (FA) was rather stable over weeks,
361
while the composition of medium-chain saturated monoacylglyceride (me-sMAG) and medium-
362
chain saturated mono-/diacylglyceride (me-sMAG/DAG) emulsifiers with mainly saturated FAs
16 363
was significantly affected. Both emulsifiers with mainly saturated FAs showed a decrease in the
364
MAG amount and an increase in the DAG amount, when in the MAG/DAG emulsifier
365
additionally a rearrangement of 1,3- in 1,2-DAGs was obtained.
366
The effect of the observed compositional changes on the techno-functional properties of
367
food emulsifiers was investigated in model aerosol whipping cream. While lo-usMAG was found
368
unsuitable for application in aerosol whipping cream, the slight compositional changes were
369
found not to affect particle size distribution and apparent viscosity at the applied concentrations.
370
Storage of me-sMAG reduced foam stability (lower foam firmness, higher drainage) of aerosol
371
whipped cream, when both the reduced MAG content and the increased DAG content may
372
contribute to this. No changes in techno-functional properties due to rearrangement of 1,3- into
373
1,2-DAG were found for the me-sMAG/DAG at an addition of 0.4 g/100 g. It is assumed, that the
374
effect of compositional changes during storage would be more prominent if lower emulsifier
375
concentrations were applied.
376
Storage of E471 emulsifiers at temperatures above the respective melting point causes
377
changes both of the chemical composition and the techno-functional properties, when applied in
378
aerosol whipping cream. Although the prolonged storage as conducted in this study does not
379
depict the actual handling of emulsifiers in industrial applications, the effects observed could
380
also take place during filling and storage of emulsifiers.
381 382
Acknowledgements
383
The authors express many thanks to Merck (Darmstadt, Germany) for support with plate
384
material and to DuPont Danisco (Neu-Isenburg, Germany) and BASF (Illertissen, Germany) for
385
providing E471 emulsifiers. Further thanks go to Uelzena eG (Uelzen, Germany) for providing
386
anhydrous butter and Milchwerke Schwaben eG (Neu-Ulm, Germany) for contribution of skim
387
milk powder. The authors also express thanks to Tina Melde, University of Hohenheim, for
388
support in the laboratory.
17 389
This research project was supported by the German Ministry of Economic Affairs and
390
Energy (via AiF) and the FEI (Forschungskreis der Ernährungsindustrie e.V., Bonn, Germany).
391
Project AiF 19355 N.
18 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434
References Blankart, Max; Kratzner, Caroline; Link, Katharina; Oellig, Claudia; Schwack, Wolfgang; Hinrichs, Jörg (2020): Technical emulsifiers in aerosol whipping cream – Compositional variations in the emulsifier affecting emulsion and foam properties. In: International Dairy Journal 102, S. 104578. DOI: 10.1016/j.idairyj.2019.104578. Davies, Emma; Dickinson, Eric; Bee, Rodney D. (2001): Orthokinetic destabilization of emulsions by saturated and unsaturated monoglycerides. In: International Dairy Journal 11 (10), S. 827–836. DOI: 10.1016/S0958-6946(01)00097-8. Fredrick, Eveline; Heyman, Bart; Moens, Kim; Fischer, Sabine; Verwijlen, Tom; Moldenaers, Paula et al. (2013): Monoacylglycerols in dairy recombined cream: II. The effect on partial coalescence and whipping properties. In: Food Research International 51 (2), S. 936–945. DOI: 10.1016/j.foodres.2013.02.006. Fregolente, Leonardo Vasconcelos; Batistella, César Benedito; Filho, Rubens Maciel; Wolf Maciel, Maria Regina (2006): Optimization of Distilled Monoglycerides Production. In: Applied Biochemistry and Biotechnology 131 (1-3), S. 680–693. DOI: 10.1385/ABAB:131:1:680. Goff, H. D. (1997): Instability and Partial Coalescence in Whippable Dairy Emulsions. In: Journal of Dairy Science 80 (10), S. 2620–2630. DOI: 10.3168/jds.S0022-0302(97)76219-2. Marie-Caroline Michalski; Valérie Briard; Françoise Michel (2001): Optical parameters of milk fat globules for laser light scattering measurements. In: Lait 81 (6), S. 787–796. DOI: 10.1051/lait:2001105. Méndez-Velasco, Carlos; Goff, H. Douglas (2012): Fat structure in ice cream: A study on the types of fat interactions. In: Food Hydrocolloids 29 (1), S. 152–159. DOI: 10.1016/j.foodhyd.2012.02.002. Munk, M. B.; Larsen, F. H.; Van Den Berg, F. W.J.; Knudsen, J. C.; Andersen, M. L. (2014a): Competitive displacement of sodium caseinate by low-molecular-weight emulsifiers and the effects on emulsion texture and rheology. In: Langmuir 30 (29), S. 8687–8696. DOI: 10.1021/la5011743. Munk, M. B.; Larsen, F. H.; van den Berg, F. W. J.; Knudsen, J. C.; Andersen, M. L. (2014b): Competitive Displacement of Sodium Caseinate by Low-Molecular-Weight Emulsifiers and the Effects on Emulsion Texture and Rheology. In: Langmuir 30 (29), S. 8687–8696. DOI: 10.1021/la5011743. Munk, Merete B.; Marangoni, Alejandro G.; Ludvigsen, Hanne K.; Norn, Viggo; Knudsen, Jes C.; Risbo, Jens et al. (2013): Stability of whippable oil-in-water emulsions. Effect of monoglycerides on crystallization of palm kernel oil. In: Food Research International 54 (2), S. 1738–1745. DOI: 10.1016/j.foodres.2013.09.001. Norn, Viggo (Hg.) (2015): Emulsifiers in food technology. Second edition. Chichester, West Sussex, Hoboken, NJ: Wiley Blackwell. Oellig, Claudia; Brändle, Klara; Schwack, Wolfgang (2018): Characterization of E 471 food emulsifiers by high-performance thin-layer chromatography-fluorescence detection. In: Journal of chromatography. A 1558, S. 69–76. DOI: 10.1016/j.chroma.2018.05.010. Rarokar, Nilesh Ramesh; Menghani, Sunil; Kerzare, Deweshri; Khedekar, Pramod Bhujangrao (2017): Progress in Synthesis of Monoglycerides for Use in Food and Pharmaceuticals. In: Journal of Experimental Food Chemistry 03 (03). DOI: 10.4172/2472-0542.1000128. Spicer, Patrick T.; Hartel, Richard W. (2005): Crystal Comets: Dewetting During Emulsion Droplet Crystallization. In: ChemInform 36 (51), S. 655. DOI: 10.1002/chin.200551267.
Figure 1 HPTLC plate image after separation of a mono-/diacylglyceride (MAG/DAG) emulsifier at storage periods of 0 h, 24 h, 48 h, 72 h, 1, 2, 3, 4, 5, 6, 7 and 8 we at 70 °C (tracks 1 – 13) and a standard-mix containing monostearin (MS), 1,2-distearin (1,2-DS), 1,3-distearin (1,3-DS), stearic acid (SA) and tristearin (TS) (25 – 1250 ng/zone) on primuline pre-impregnated LiChrospher silica gel plates by two-fold development with diethyl ether to a migration distance of 18 mm and n-pentane/n-hexane/diethylether (52:20:28, v/v/v) to a migration distance of 75 mm under UV 366 nm illumination. Sample amounts were 6 µg MAG/DAG emulsifier/zone.
Figure 2 Mean content of lipid classes in g/100 g emulsifier over a period of 8 w. Long-chain unsaturated monoacylglyceride (lo-usMAG) stored at 70 °C; medium-chain saturated monacylglyceride
(me-sMAG)
stored
at
80
°C;
medium- chain
saturated
mono-/diacylglyceride (me-sMAG/DAG) stored at 70 °C . MAG: monoacylglycerides; DAG: diacylglycerides; FFA: free fatty acids; TAG: triacylglycerides. Each storage time was analyzed with n = 2.
Figure 3 D10,3 (●), arithmetic mean d4,3 (∆) and d90,3 (■) of model aerosol whipping cream (30 g/100 g fat, 3 g/100 g protein) processed with 0.4 g/100 g of the three E471 emulsifiers in dependence of storage time (at 70 °C or 80 °C) of e mulsifiers. Aerosol whipping cream samples were stored for 1 w at 6 °C. Lo-usMAG: long -chain unsaturated monoacylglyceride; me-sMAG: medium-chain saturated monoacylglyceride; me-sMAG/DAG: medium-chain saturated mono/diacylglyceride. The number of independent replicates was i = 3, each replicate was measured three times (n = 3). Values are shown as arithmetic mean ± standard deviation.
Figure 1 Apparent viscosity at ɣ̇ = 500 s-1 at 5 °C of model aerosol whipping cream (30 g/100 g fat, 3 g/100 g protein) processed with 0.4 g/100 g of the three E471 emulsifiers in dependence of storage time (at 70 °C or 80 °C) of e mulsifiers. Aerosol whipping cream samples were stored for 1 w at 6 °C. Lo-usMAG: long -chain unsaturated monoacylglyceride; me-sMAG: medium-chain saturated monoacylglyceride; me-sMAG/DAG: medium-chain saturated mono-/diacylglyceride. The number of independent replicates was i = 3, each replicate was measured two times (n = 2). Values are shown as arithmetic mean ± standard deviation.
Table 1: MAG, DAG, FFA and TAG contents in three untreated (0 h) emulsifiers and in emulsifiers after storage of 8 we at 70 °C (lo usMAG: longchain unsaturated MAG; me-sMAG/DAG: medium-chain saturated MAG/DAG) and 80 °C (me sMAG: medium chain s aturated MAG), respectively, determined by HPTLC–FLD. lo-usMAG Mean content [g/100 g] ±
me-sMAG
me-sMAG/DAG
0h
8w
0h
8w
0h
8w
MAG
95.0 ± 0.07
86.2 ± 0.6
93.5 ± 0.4
60.1 ± 1.1
53.8 ± 0.08
47.1 ± 0.38
1,2-DAG
1.5 ± 0.02
4.4 ± 0.18
0.5 ± 0.01
1.8 ± 0.02
3.0 ± 0.05
16.5 ± 0.53
1,3-DAG
3.2 ± 0.1
9.0 ± 0.38
2.7 ± 0.1
32.8 ± 0.9
36.4 ± 0.09
29.5 ± 0.51
FFA
0.1 ± 0.03
0.2 ± 0.02
0.7 ± 0.05
1.0 ± 0.06
1.7± 0.09
2.1 ± 0.03
TAG
0.2 ± 0.05
0.2 ± 0.04
2.5 ± 0.23
2.6 ± 0.23
5.1± 0.13
4.9 ± 0.36
Sum (MAG and DAGs)
99.8 ± 0.05
99.6 ± 0.06
96.8 ± 0.3
94.8 ± 1.9
93.2± 0.04
93.0± 0.40
a
SD (n = 2)
a
Standard deviation.
Table 2: Overrun in % and foam firmness in mN of aerosol whipping cream (30 g/100 g fat, 3 g/100 g protein) processed with 0.4 g/100 g of the three E471 emulsifiers in dependence of storage time (at 70 °C or 80 °C) of emulsifiers. Ae rosol whipping cream samples were stored for 1 w at 6 °C. Lo-usMAG: long-chain unsaturated m onoacylglyceride; me-sMAG: mediumchain
saturated
monoacylglyceride;
me-sMAG/DAG: medium-chain
saturated
mono-/diacylglyceride. The number of independent repetitions of the experiments was i = 3. Values are shown as arithmetic mean ± standard deviation. Different letter represent significant differences in one emulsifier (ANOVA, Tukey-Kramer, α = 0.05). storage
lo-usMAG
me-sMAG/DAG
me-sMAG
time Overrun
Foam firmness
Overrun
Foam firmness
Overrun
Foam firmness
in %
in mN
in %
in mN
in %
in mN
< 100
n.m.
204 ± 17b
72 ± 49a
274 ± 27a
258 ± 26a
n.c.
n.c.
293 ± 22a
250 ± 45a
n.c.
n.c.
1w
< 100
n.m.
243 ± 38ab
156 ± 86a
242 ± 45a
239 ± 71ab
4w
< 100
n.m.
212 ± 17ab
74 ± 58a
206 ± 22a
137 ± 22b
8w
< 100
n.m.
269 ± 55ab
170 ± 125a
246 ± 21a
132 ± 48b
0h 24 h
n.m.: not measurable n.c.: not conducted
Table 3: Normalized drainage of aerosol whipping cream (30 g/100 g fat, 3 g/100 g protein), processed with 0.4 g/100 g of the three E471 emulsifiers in dependence of storage time (at 70 °C or 80 °C) of emulsifiers. Aerosol whipping cr eam samples were stored for 1 w at 6 °C. Lo-usMAG: long-chain unsaturated monacylglyceride; me-sMAG: medium-chain saturated monoacylglyceride; me-sMAG/DAG: medium-chain saturated mono-/diacylglyceride. The number of independent repetitions of the experiments was i = 3. Values are shown as arithmetic mean ± standard deviation. Different letters represent significant differences in one emulsifier (ANOVA, Tukey-Kramer, α = 0.05). Storage time
lo-usMAG
me-sMAG/DAG
me-sMAG
Normalized drainage in % 0h
n.m.
56 ± 11ab
15 ± 4a
24 h
n.c.
17 ± 9b
n.c.
1w
n.m.
31 ± 9ab
14 ± 12a
4w
n.m.
59 ± 2a
47 ± 6b
8w
n.m.
29 ± 20b
50 ± 4b
n.m.: not measurable n.c.: not conducted
1
Highlights:
2
-
MAG content of E471 emulsifiers decreases over storage at elevated temperatures
3
-
DAG content of medium-chain saturated MAG increases over storage
4
-
DAG is assumed to reduce foaming properties of aerosol whipping cream
5
-
Rearrangements of 1,3- into 1,2-DAG in medium-chain saturated MAG/DAG
6
-
No change in techno-functional properties by rearrangement of 1,3 into 1,2-DAG
Declaration of interest:
Manuscript: ‘Effect of storage at high temperature on chemical (composition) and techno-functional characteristics of E471 food emulsifiers applied to aerosol whipping cream” Journal of Food Engineering Authors: Max Blankart, Claudia Oellig, Sonja Averweg, Wolfgang Schwack, Jörg Hinrichs
Declarations of interest: none.