Investigations into Structure Formation of Dairy Products [Elektronische Ressource] / Monika Stephanie Brückner-Gühmann. Betreuer: Bernhard Senge

De
Investigations into Structure Formation of Dairy Products vorgelegt von Diplom-Ingenieur Monika Stephanie Brückner-Gühmann aus Overath Von der Fakultät III – Prozesswissenschaften der Technischen Universität Berlin zur Erlangung des akademischen Grades Doktor der Ingenieurwissenschaften Dr.-Ing. genehmigte Dissertation Promotionsausschuss: Vorsitzender: Prof. Dr. sc. techn. F. Thiemig Berichter: Prof. Dr. sc. techn. B. Senge Berichter: Prof. Dr. habil. St. Drusch Tag der wissenschaftlichen Aussprache: 13.10.2011 Berlin 2011 D 83 Zusammenfassung Eine gleichbleibend hohe Produktqualität determiniert maßgeblich die Akzeptanz beim Verbraucher und den Erhalt der Marktstellung. Dieses Ziel lässt sich nur realisieren, wenn eine Qualitätskontrolle der involvierten Prozesse und Rohmaterialien erfolgt. Vielfach existieren zur Qualitätsbeurteilung nur aufwendige analytische Methoden, die eine schnelle Kontrolle und ein unmittelbares Eingreifen verhindern. Mit dieser Arbeit sollen die Strukturbildung und -änderung im Verlauf verschiedener Prozesse in der Produktionstechnologie der Milchindustrie untersucht und Prüfprocedere entwickelt werden, die als Schnellmethoden ein kurzfristiges Bewerten der Rohstoffe und ein Eingreifen in den Produktionsprozess ermöglichen. Die labinduzierte Gerinnung wurde sowohl mit Rohmilch gesunder Kühe und Ziegen als auch mit Milch euterkranker Kühe durchgeführt.
Publié le : samedi 1 janvier 2011
Lecture(s) : 29
Source : D-NB.INFO/1017839808/34
Nombre de pages : 207
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Investigations into Structure Formation of
Dairy Products





vorgelegt von
Diplom-Ingenieur
Monika Stephanie Brückner-Gühmann
aus Overath





Von der Fakultät III – Prozesswissenschaften
der Technischen Universität Berlin
zur Erlangung des akademischen Grades
Doktor der Ingenieurwissenschaften
Dr.-Ing.


genehmigte Dissertation





Promotionsausschuss:

Vorsitzender: Prof. Dr. sc. techn. F. Thiemig
Berichter: Prof. Dr. sc. techn. B. Senge
Berichter: Prof. Dr. habil. St. Drusch

Tag der wissenschaftlichen Aussprache: 13.10.2011


Berlin 2011

D 83

Zusammenfassung
Eine gleichbleibend hohe Produktqualität determiniert maßgeblich die Akzeptanz beim
Verbraucher und den Erhalt der Marktstellung. Dieses Ziel lässt sich nur realisieren,
wenn eine Qualitätskontrolle der involvierten Prozesse und Rohmaterialien erfolgt.
Vielfach existieren zur Qualitätsbeurteilung nur aufwendige analytische Methoden, die
eine schnelle Kontrolle und ein unmittelbares Eingreifen verhindern. Mit dieser Arbeit
sollen die Strukturbildung und -änderung im Verlauf verschiedener Prozesse in der
Produktionstechnologie der Milchindustrie untersucht und Prüfprocedere entwickelt
werden, die als Schnellmethoden ein kurzfristiges Bewerten der Rohstoffe und ein
Eingreifen in den Produktionsprozess ermöglichen.
Die labinduzierte Gerinnung wurde sowohl mit Rohmilch gesunder Kühe und Ziegen
als auch mit Milch euterkranker Kühe durchgeführt. Ziel der Untersuchungen war eine
Analyse der biochemischen Veränderungen des Caseins und der
Strukturierungsmechanismen. Der Untersuchungsschwerpunkt umfasst die zeitliche
Abfolge und Kopplung zwischen biochemischen Reaktionen am Casein und den
Strukturveränderungen von der Milch zum Labgel durch inline-online-Erfassung der
Prozessviskosität. Die Kinetik der enzymatischen Reaktion am Beispiel der Freisetzung
von Caseinmakropeptid und die resultierenden Strukturbildungsmechanismen wurden
untersucht und modelliert. Es zeigt sich ein deutlich abweichendes Verhalten der Milch
von euterkranken Kühen. Durch Kopplung der Strukturparameter mit den Ergebnissen
der hydrophoben Interaktionschromatographie werden Veränderungen am Caseinprofil
der Milch von euterkranken Kühen nachgewiesen. Daher sollte diese im Rahmen der
Promotion entwickelte Analytik in eine Eingangskontrolle der Milch aufgenommen
werden. Bezüglich der Optimierung der Käseproduktion bietet die rheologische
Methode eine Möglichkeit den optimalen Schneidezeitpunkt nicht mehr visuell zu
beurteilen, sondern objektiv anhand der Endviskosität zu bestimmen.
Die Untersuchungen zur Labgerinnung von Ziegenmilch dienen der Überprüfung der
Übertragbarkeit der rheologischen und spektrophotometrischen Methode. Es werden
klare Unterschiede zum Gerinnungsverhalten von Kuhmilch vor allem bei der
Gelausbildung gefunden.
Üblicherweise wird bei dem Prozess der Säuregerinnung (Joghurtproduktion) die
Trockensubstanz der Prozessmilch erhöht, was unter anderem durch Zugabe von
Molkenproteinkonzentratpulvern geschehen kann. Aus der Industrie ist das Auftreten
einer erheblichen Anzahl von Fehlfermentationen bekannt, die in einer mangelhaften
Funktionalität der Pulver begründet sind. Thermisch denaturierte Molkenproteinpulver
bilden Partikelgele aus, was sich wiederum als Störgröße auf den Technologieablauf
und die Produktqualität (Synärese) auswirkt. Es besteht daher ein großes
wirtschaftliches Interesse an einer Schnellmethode zur Bewertung der Pulverqualität.
In der vorliegenden Arbeit wird die Laserdiffraktometrie als Verfahren zur Bewertung
des Lösungsverhaltens gewählt und die Anwendbarkeit durch eine umfassende
Methodenentwicklung und verschiedene Untersuchungen bestätigt.
Als wichtige dritte Produktionstechnologie in der Milchindustrie wird die
Sprühtrocknung am Beispiel der Herstellung von Quarkpulver betrachtet. Hierbei muss
besonders beachtet werden, dass es sich um ein plastisches, nicht-NEWTON`sches
System handelt. Die Produktionstechnologie wird im Folgenden untersucht, wobei
kritisch angemerkt werden muss, dass anstatt der üblichen Zerstäubung für
hochkonsistente Produkte über eine Scheibe eine Düse gewählt wurde, die
ursprünglich zur Trocknung von Magermilchkonzentrat ausgelegt war. Zudem wurde
der Einfluss von Scherenergie und Wärme auf die Destrukturierung vor Trocknung
untersucht.
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Abstract
The production of dairy products of a consistently high quality significantly determines
consumer acceptance and will occupy a similarly important market position in the
future. This objective can be realized if a quality control of the involved processes and
raw materials is undertaken. In many cases, only elaborate analytical methods exist
which represent a barrier to a rapid control and direct intervention. In this work the
structure formation and structural changes in the course of various processes in dairy
production technology should be examined and methods should be developed, which
facilitate a rapid grading of the raw materials and intervention in the production
process.
Rennet-induced coagulation was investigated for raw bulk cow and goat milk as well as
for milk from infected udder quarters of cows. Experiments were carried out to gain
more scientifically-based information on biochemical changes of the casein and the
mechanism of structuring during rennet-induced coagulation. The main focus of the
research was the time-dependent coupling between the biochemical reaction of the
casein and the structural change from the fluid milk to the rennet gel by inline-online
detection of the process viscosity. The kinetics of the enzymatic reaction─the release
of caseinmacropeptide─and the resulting structuring mechanisms were examined and
modeled. A significantly different behavior of milk from infected udder quarters was
detected. The structure parameter in combination with the hydrophobic interaction
chromatography results proved an altered casein profile. It is imperative that the
analytical method which was developed as part of this thesis be included in milk
grading. Concerning an optimized cheese production, the rheological method offers the
possibility to determine the optimal cutting time not only from a subjective but also from
an objective position by calculated projection of the end viscosity after a definite time
period.
The investigations dealing with the rennet-induced coagulation of goat milk were done
to verify the transferability of the rheological and spectrophotometric method.
Significant differences were detected between the rennet-induced coagulation of cow
and goat milk especially between the gel formation.
Commonly, during the process of acid-induced coagulation (yoghurt production) dairy
powders are used to increase the dry matter of the process milk which is often done by
addition of whey protein concentrate powder. It was found that in the production flow a
large share of defective fermentations might occur, which are related to defective
functionality of the powders. Thermal denaturation of whey proteins leads to the
development of particle gels which act as a disturbance variable during the production
process and for the product quality (syneresis). As a result, the development of a rapid
method for the assessment of the powder quality is of great economic interest. The
principle of laser diffraction was chosen in the present work for the assessment of the
rehydration behavior and the applicability of this method has been confirmed by an
extensive method development and diverse experiments.
The third important production technology in the dairy industry─spray drying─is viewed
exemplarily for the production of quark powder. Attention should be paid to the fact that
quark is a plastic, non-NEWTONIAN system. In the following, production technology
systems are investigated. It has to be remarked here that atomization was done via
nozzle instead of the commonly used wheel atomization for highly consistent products.
The nozzle geometry typically was designed for the drying of skim milk concentrate.
Additionally, the influence of shear energy and temperature on the structure
deformation before drying was investigated.
iii
Acknowledgements
This thesis is based on experimental work at the Chair of Food Rheology at the
Technische Universität Berlin.
First and foremost, I would like to thank Prof. Dr. sc. techn. B. Senge for giving the
support, discussions, and guidance of the work.
I would like to acknowledge Prof. Dr. habil. St. Drusch for taking his time to be a
referee for my thesis and Prof. Dr. sc. techn. F. Thiemig for being the head of the
graduation commission.
A particular thanks to the team of Food Rheology Dr. R. Blochwitz, Dr. N. Hildebrandt,
and Dipl.-Ing. H. Kastner and to the team of Food Quality and Material Science Dr.
U. Einhorn-Stoll, Dipl.-Ing. K. Kern, and A. Kliegel.
Thanks to my diploma students Tanja, Dani, Anne, Kati, and Stefan for your ideas,
engagement, support, and activities.
Thanks to J. Nissen from ZELMI for SEM and the team of Retsch Technology GmbH,
especially A. Bauer and K. Düffels for the refractive index discussions.
Thanks to Dr. B. Lieske for the help during method development and discussions at the
beginning of my first working days.
Special thanks to Dr. P. Bednorz for offering me motivation and constructive criticism
throughout writing.
I am grateful to D. Baerg for reviewing the English version of the thesis.

The last thank you goes to my family, my parents, grandparents, and friends for always
supporting me! Thank you to André and Vincent—for taking my mind off the pressure
of writing—and to the little boy waiting for sunlight which motivated me especially in the
last weeks of writing.

iv
Table of Contents
ZUSAMMENFASSUNG II
ABSTRACT III
ACKNOWLEDGEMENTS IV
TABLE OF CONTENTS V
LIST OF FIGURES IX
LIST OF TABLES XI
NOMENCLATURE XIII
CHAPTER 1: INTRODUCTION 1
CHAPTER 2: OBJECTIVES 4
CHAPTER 3: THEORETICAL BACKGROUND 6
3.1 Composition of bovine milk 6
3.1.1 Caseins 6
3.1.2 Whey Proteins 9
3.2 Composition of caprine milk 9
3.3 Processes of coagulation 10
3.3.1 Rennet-induced coagulation 10
3.3.1.1 Production technology 10
3.3.1.2 Mechanism of reaction 11
3.3.1.3 Influencing factors 11
3.3.1.4 Method of measurement 14
3.3.2 Acid coagulation 16
3.3.2.1 Production technology 16
3.3.2.2 Rheological measurement of the acid coagulation 17
3.3.3 Combined acid and rennet-induced coagulation 19
3.3.3.1 Production of quark 19
3.3.3.2 Fermentation process 19
3.4 Production of dairy powders 20
3.4.1 Milk powder 20
3.4.2 Skim milk powder 20
3.4.3 Whey protein powder 21
3.4.4 Quark powder 23
3.4.5 Spray drying 24
3.5 Functional properties of dairy powders 26
3.5.1 General 26
3.5.2 Rehydration behavior 27
3.5.3 Factors influencing the rehydration behavior 28
CHAPTER 4: MATERIALS AND METHODS 30
4.1 Materials 30
4.1.1 Milk 30
4.1.2 Sweet whey, whey protein concentrate, and skim milk powder 31
4.1.3 Low fat quark 31
4.2 Chemical methods 32
4.2.1 Determination of the pH value 32
4.2.2 Determination of moisture 33
4.2.3 Determination of ash content 33
4.2.4 Determination of the total nitrogen content 33
4.2.5 Determination of the calcium content 33
4.2.6 Determination of the lactose content 33
4.2.7 Determination of the fat content 33
v
4.2.8 Determination of the rennet activity 34
4.2.9 Determination of the visual clotting time 34
4.2.10 Spectrophotometric analysis of CMP and GMP 34
4.2.11 Development of a fast chemical method for the assessment of the protein solubility 35
4.2.12 Removal of lipids by chitosan 36
4.2.13 High-Performance Size Exclusion Chromatography (HPSEC) 37
4.2.14 Hydrophobic Interaction Chromatography (HIC) 38
4.2.15 SDS-Page 40
4.3 Physical methods 42
4.3.1 Rheological measurements during the rennet-induced coagulation 42
4.3.2 Rheological measurements of quark and quark powder 43
4.3.3 Static laser light scattering 46
4.3.3.1 Principle 46
4.3.3.2 Wet measurements 48
4.3.3.3 Dry measurements 49
4.3.3.4 Refractive indices 49
4.3.3.5 Mathematical fundamentals 49
4.3.4 Particle size distribution analysis—quark powder 50
4.3.5 Scanning electron microscopy 50
4.4 Statistical analysis 50
4.4.1 Quality investigations of dairy powders 50
4.4.2 Rennet-induced coagulation 51
CHAPTER 5: RENNET-INDUCED COAGULATION OF COW MILK 52
5.1 Release of CMP and GMP in the course of the rennet-induced coagulation 52
5.1.1 Normal raw bulk cow milk 52
5.1.2 Cow milk from infected udder quarters 53
5.2 Chemical analysis 55
5.2.1 Rennet activity 55
5.2.2 Raw bulk cow milk 55
5.2.3 Cow milk from infected udder quarters 57
5.3 Rheological measurements of raw bulk cow milk 61
5.3.1 Characterization of the overall process [1-5] 61
5.3.2 Allocation into sections 62
5.4 Rheological measurements of cow milk from infected udder quarters 64
5.4.1 Characterization of the overall process 64
5.4.2 Allocation into sections 67
5.5 Connection of the rheological results to the casein profile analyzed by HIC 70
5.5.1 Normal raw cow milk 70
5.5.2 Infected udder quarters, cow A 71
5.5.3 Infected udder quarters, cow B 72
5.6 Selected results from cow G after medication with antibiotics 73
5.7 Summary of the chapter 75
CHAPTER 6: RENNET-INDUCED COAGULATION OF GOAT MILK 76
6.1 Release of CMP and GMP in the course of the rennet-induced coagulation of goat milk 76
6.2 Chemical analysis 77
6.3 Rheological measurements of raw bulk goat milk 78
6.3.1 Characterization of the overall process 78
6.3.2 Allocation into sections 79
6.3.3 Commercial goat cheese production 81
6.4 Summary of the chapter 82



vi

CHAPTER 7: QUALITY INVESTIGATIONS OF DAIRY POWDERS 83
7.1 Artifacts—defects in whey protein functionality 83
7.2 Chemical analysis 85
7.2.1 Chemical analysis—Section I 85
7.2.2 Chemical analysis—Section II 86
7.2.3 Chitosan treatment 87
7.2.4 Results of the high-performance size exclusion chromatography (HPSEC) 88
7.2.5 Protein profiles determined by SDS-PAGE 93
7.3 Physical analysis 94
7.3.1 Rheological measurements 94
7.3.2 Static laser light scattering 94
7.3.2.1 Optimization of the measuring method—dry measurements 94
7.3.2.2 Results of the dry measurements—Section I 95
7.3.2.3 Results of the dry measurements—Section II 96
7.3.2.4 Optimization of the measuring method—wet measurements 98
7.3.2.5 Results of the wet measurements 105
7.4 Discussion of the results of the chemical and physical analysis 110
7.4.1 Rehydration behavior of dairy powders 110
7.4.2 Peak classification 115
7.4.3 Assessment of the solubility of the powders 116
7.4.4 Comparison of the results of the dry and wet measurements 117
7.4.5 Particle size and composition 117
7.4.6 Particle size and results of the HPSEC 118
7.5 Summary of the chapter 120
CHAPTER 8: PRODUCTION OF QUARK POWDER 122
8.1 Investigations into the production technology 122
8.1.1 Production of quark powder on a pilot plant and small-scale dryer (pressure nozzle
atomizer) 122
8.1.1.1 Rheological measurements 122
8.1.1.2 Assessment of the powder functionality 124
8.1.2 Production of quark powder on large-scale dryer, Section I 125
8.1.2.1 Rheological measurements 125
8.1.2.2 Particle size analysis 125
8.1.2.3 SEM results 126
8.1.2.4 HIC analysis 126
8.2 Material characteristics 126
8.2.1 Determination of the properties of the low fat quark 126
8.2.2 Influence of thermal and mechanical parameters on the low fat quark 130
8.2.3 Detection of interactions between mechanical energy and temperature 131
8.3 Assessment of the powder functionality (wheel atomizer), Section II 132
8.3.1 Rheological measurements 132
8.3.2 Particle size analysis 133
8.3.3 SEM results 134
8.4 Assessment of the powder functionality of competitor‘s products 135
8.4.1 Rheological measurements 135
8.4.2 Particle size analysis 136
8.4.3 HIC analysis 137
8.5 General remarks 137
8.6 Summary of the chapter 139



vii

CHAPTER 9: RECOMMENDATIONS 140
CHAPTER 10: CONCLUSIONS 141
CHAPTER 11: REFERENCES 144
CHAPTER 12: APPENDIX 155
HPSEC 155
Rheological measurements 156
Rennet-induced coagulation 157
Quality investigations of dairy powders 160
Production of quark 180
EIDESSTATTLICHE ERKLÄRUNG 190
LIST OF PUBLICATIONS 191

viii
List of Figures
Figure 3-1: Schematic model of a casein micelle [36] ................................................................................... 7
Figure 3-2: Model of a casein micelle [38;40] ................................ 8
Figure 3-3: Model of a casein micelle [37] ..................................................................... 8
Figure 3-4: Protocol for the manufacture of Emmental cheese [48] ............................. 10
Figure 3-5: Process flow chart of stirred yoghurt [48] .................................................................................. 16
Figure 3-6: Process viscosity and pH curve of conventional acidification .................... 17
Figure 3-7: Process viscosity and pH curve of non-conventional acidification ............. 18
Figure 3-8: Production of quark [134] .......................................... 19
Figure 3-9: Course of process viscosity and pH value during the combined acid and rennet-induced
coagulation [123] ....................................................................................... 19
Figure 3-10: Technological production scheme of skim milk powder [11] ...................... 21
Figure 3-11: Manufacturing scheme of WPC and WPI [48] ........... 22
Figure 3-12: Representation of a spray dryer [173] ....................... 24
Figure 3-13: Classification of models of disintegration [176] .......................................................................... 26


Figure 4-1: Chromatograms of the commercial caseins .............. 39
®Figure 4-2: Molecular weight standard Roti -Mark ...................................................................................... 41
Figure 4-3: Schematic diagram of the rennet-induced coagulation of raw milk [123] ................................... 42
Figure 4-4: Measuring profile of the controlled shear rate measurements ................... 44
Figure 4-5: Schematic configuration of a laser diffractometer [244] ............................. 47


Figure 5-1: Release of CMP and GMP and process viscosity over time of two samples of normal milk ...... 52
Figure 5-2: Release of CMP and GMP and the process viscosity over time of two samples of milk from
nfected udder quarters .............................................................................................................. 53
Figure 5-3: Process viscosity of raw bulk milk during rennet-induced coagulation ....... 61
Figure 5-4: Section 1 of raw bulk milk.......... 62
Figure 5-5: Section 2 of raw bulk milk 62
Figure 5-6: Section 3 of raw bulk milk.......................................................................................................... 63
Figure 5-7: Process viscosity of milk from infected udder quarters .............................................................. 65
Figure 5-8: Section 1 of milk from infected udder quarters .......... 67
Figure 5-9: Section 2 of milk from infected udder quarters 68
Figure 5-10: Section 3 of milk from infected udder quarters .......................................................................... 69
Figure 5-11: HIC chromatogram of casein obtained from raw unprocessed cow milk ... 70
Figure 5-12: Chromatogram (left) and process viscosity during rennet-induced coagulation over time (right) of
sample 1 (A1) ............................................................................................................................ 71
Figure 5-13: Chromatogram (left) and process viscosity during rennet-induced coagulation over time (right) of
sample 2 (A2) 72
Figure 5-14: Chromatogram (left) and process viscosity during rennet-induced coagulation over time (right) of
sample 4 ................................................................................................................................... 72
Figure 5-15: Chromatogram (left) and process viscosity during rennet-induced coagulation over time (right) of
sample 6 ... 73
Figure 5-16: Contents of CMP, GMP, n.-g. CMP and relation GMP/CMP in the course of the udder
inflammation and medication of cow G ...................................................................................... 74
Figure 5-17: Selected process viscosities during udder inflammation and medication of cow G ................... 74


Figure 6-1: Release of CMP and GMP and process viscosity over time of sample 1 (A), sample 2 (B), and
sample 4 (C) (goat milk) ............................................................................................................ 76
Figure 6-2: Process viscosity of raw bulk goat milk during rennet-induced coagulation ............................... 78
Figure 6-3: Section 1 of three goat milk samples ......................... 79
Figure 6-4: Section 2 of three goat milk samples ................................................................ 79
Figure 6-5: Section 3 of three goat milk samples 80
Figure 6-6: Coagulation of goat milk during commercial goat cheese production ........................................ 81


Figure 7-1: Process viscosity during fermentation with altered whey protein functionality [10;11] ............... 84
Figure 7-2: Process viscosity during fermentation with altered whey protein functionality [12] .................... 84
-1Figure 7-3: Chromatogram of a WPC 30 (c = 0.0693 g·10 ml ) .................................................................. 88
Figure 7-4: Chromatogram of WPC 80 1 ..................................... 91
Figure 7-5: Chromatogram of WPC 35 1 ..... 91
Figure 7-6: Chromatogram of WPC 80 3 ..... 92
Figure 7-7: PSD and parameter calculated from the PSD of raw milk with fat (N = 3) ................................. 98
ix
Figure 7-8: PSD and parameter calculated from the PSD of commercial milk ............................................. 99
Figure 7-9: PSD of thin whey, whey concentrate, and final mixed whey ...................... 99
Figure 7-10: PSD of native and pH 4.6 treated WPC 35 1 ........................................... 100
Figure 7-11: PSD of the native, rehydrated sample, sediment and supernatant after pH 4.6 treatment; A:
WPC 60 3, B: WPC 70 1, C: SMP ........................................................................................... 101
Figure 7-12: Cumulative PSD obtained by SEM micrographs and laser diffraction; WPC 35 12 ................. 102
Figure 7-13: SEM micrograph of WPC 35 12 (A) and PSDs during rehydration (B) .................................... 103
Figure 7-14: SEM micrographs.................................................... 104
Figure 7-15: PSD of the SMP after the start and complete rehydration ....................................................... 109
Figure 7-16: PSD of WPC 30 in the course of rehydration and the dry powder ........... 111
Figure 7-17: PSD of WPC 60 3 in the course of rehydration and the dry powder ........................................ 111
Figure 7-18: PSD of WPC 80 4 in the course of rehydration and the dry powder ........ 112
Figure 7-19: PSD of WPC 60 6 in the course of rehydration and the dry powder ........ 112
Figure 7-20: PSD of WPC 70 1 in the course of rehydration and the dry powder ........ 113
Figure 7-21: PSD of WPC 80 3 in the course of rehydration and the dry powder ........................................ 114


Figure 8-1: Processing of the quark after warming with supply of air ......................................................... 123
Figure 8-2: Comparison of rehydrated quark (small scale) with original quark .......... 124
Figure 8-3: SEM micrographs of the quark powder; Section I, large scale, pressure nozzle atomizer ....... 126
Figure 8-4: Influence of dilution and dispersing at 10 °C on quark matrix .................. 127
Figure 8-5: Influence of dispersing at 10 and 35 °C on quark matrix, 16 % d.m. ....................................... 128
Figure 8-6: Kinetics of the rehydration of reference quark powder ............................................................ 132
Figure 8-7: SEM micrographs of the reference quark powder ... 134
Figure 8-8: SEM micrographs of the quark powder, large-scale dryer ....................... 134
Figure 8-9: SEM micrographs of the quark powder obtained by the small-scale dryer (7.1) ...................... 135
Figure 8-10: Sedimentation of competitor‘s quark powders after 2 h stand-by ............................................ 136


Figure 12-1: Regression lines of the main whey proteins used in the HPSEC ............. 155
Figure 12-2: Elution curves of standard proteins separated individually ...................................................... 155
Figure 12-3: Process viscosity of commercial milk during rennet-induced coagulation ................................ 156
Figure 12-4: PSD of SWP 13 1, 13 2, and 13 3 after the start and complete rehydration ............................ 175
Figure 12-5: PSD of the WPC 30 and 35 1 to 7 after the start and complete rehydration ............................ 176
Figure 12-6: PSD of the WPC 35 8 to 14 after the start and complete rehydration ...... 177
Figure 12-7: PSD of the WPC 60 after the start and complete rehydration .................................................. 178
Figure 12-8: PSD of the WPC 70 after the start and complete rehydration 178
Figure 12-9: PSD of the WPC 80 after the start and complete rehydration 179
-1Figure 12-10: Shear stress behavior at   = 100 s , temperature range 0…70 °C ................................. 182 max
-1Figure 12-11: Viscosity behavior at   = 100 s , temperature range 0…70 °C ....... 182 max
-1Figure 12-12: Shear stress behavior at   = 500 s , temperature range 0…70 °C 183 max
-1Figure 12-13: Viscosity behavior at   = 500 s , temperature range 0…70 °C ....................................... 183 max
-1Figure 12-14: Shear stress behavior at   = 1000 s , temperature range 0…70 °C 184 max
-1Figure 12-15: Viscosity behavior at   = 1000 s , temperature range 0…70 °C ..... 184 max
Figure 12-16: Flow behavior in dependence on shear velocity at 0 °C .......................................................... 185
Figure 12-17: Flow behavior in dependence on shear velocity at 10 °C ........................ 185
Figure 12-18: Flow behavior in dependence on shear velocity at 15 °C 186
Figure 12-19: Flow behavior in dependence on shear velocity at 20 °C 186
Figure 12-20: Flow behavior in dependence on shear velocity at 30 °C ........................................................ 187
Figure 12-21: Flow behavior in dependence on shear velocity at 40 °C 187
Figure 12-22: Flow behavior in dependence on shear velocity at 50 °C 188
Figure 12-23: Flow behavior in dependence on shear velocity at 60 °C ........................ 188
Figure 12-24: Flow behavior in dependence on shear velocity at 70 °C ................................ 189
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