I
Table of contents
SUMMARY...I LIST OF FIGURES...IV LIST OF TABLES...VIII TABLE OF ABBREVIATIONS...IX TABLE OF SYMBOLS...XI TABLE OF GREEK SYMBOLS...XII TABLE OF PEDICES...XIII1 Basic information……….…….………..1
1.1 Introduction: the WHEYLAYER project……….………….1
1.2 Goals of this work and state of the art ……….………….1
1.3 Why use packaging materials for food preservation……….…….2
1.4 Composition and properties of whey coated packaging material……….5
1.4.1 Whey proteins………..……….5
1.4.2 Plasticizers……….……..7
1.4.3 Substrate………..……….7
1.5 The theory of drying………..………9
1.5.1 Convection………..……….9
1.5.1.1 Convecive heat transfer………..………..9
1.5.1.2 Convective mass transfer……….11
1.5.2 Diffusion………..…….…...11
1.5.3 Drying rate……….……..…………..13
1.5.3.1 Constant Rate Period……….…….………….15
1.5.3.2 Falling Rate Period……….……….…..16
1.6 Production of whey coated packaging material……….….……..17
1.6.1 Corona pretreatment……….…….17
1.6.2 Lacquering process……….…….19
1.6.3 Industrial drying………...21
1.7 Required heat for the drying……….22
1.8 Evaluation of the degree of denaturation of the protein………24
1.8.1 Denaturation process……….24
1.8.2 Differential Scanning Calorimetry and protein’s denaturation………...25
1.9 Barrier properties……….……29
1.9.1 Transport through monolayer polymer film……….……..29
1.9.2 Transport through multylayer polymer films……….………31
1.9.3 Oxygen barrier………..……….31
1.9.4 Water vapour barrier………..……….33
1.10 Light analysis………..……..34
1.10.1 Optical microscope……….……..34
II
1.10.3 Infrared spectroscopy………35
1.11 Mechanical analysis………36
1.11.1 Tensile test………..36
1.11.2 Tear test using trapezoidal test specimen with incision………...41
1.11.3 Bond strength test……….……42
1.11.4 Dynamic Mechanical Thermal analysis……….…….42
1.11.5 Adhesion and adhesion test………..45
1.11.5.1 Adhesion……….…..45
1.11.5.2 Pull test………..…47
1.12 Recycling and enzymatic detergents………..…48
1.13 Evaluation of the Young’s modulus of the WHEYLAYER………....48
2 Materials and methods...50
2.1 Solution preparation………..….52
2.2 Lab scale production………..…….53
2.2.1 Hand coating………..……53
2.2.2 Drying of the sheets into the oven………..……55
2.2.3 Thickness measurements………..…….56
2.2.4 Moisture analysis………57
2.2.5 DSC analysis of the lab sheets………..…57
2.3 Pilot plant production………..……59
2.3.1 Pilot scale coating and drying………..…….59
2.3.2 Tensile test of the pilot scale sheets………..…….63
2.3.3 Adhesion measurements between the coating and. the substrate of the pilot scale sheets………..……65
2.4 Evaluation of the properties of the coating……….…68
2.4.1 Removal of the coating………..68
2.4.2 DMTA analysis………..…69
2.5 Production of a laminated on the pilot plant………..…70
2.5.1 Pilot scale production………..…70
2.5.2 Microtome cut and optical analysis of the laminated……….…….72
2.5.3 Tensile test on the laminated……….73
2.5.4 Tear test on the laminated……….…73
2.5.5 Bond strength test on the laminated……….74
2.6 Analysis of the yellowness of the pilot scale products………..……..75
2.7 Evaluation of the barrier properties of the pilot scale products……….………76
2.7.1 Oxygen Transmission Rate………..…..76
2.7.2 Water Vapour Transmission Rate……….…..78
2.8 Analysis of the kinetik o denaturation in solution……….79
2.8.1 Preparation of the cast films……….79
III
3 Result and discussion………..……….81
3.1 Lab products……….…..81
3.1.1 Lab sheet thickness………..…..81
3.1.2 Residual humidity in the lab sheets………..……81
3.1.3 DSC measurements of the lab sheets………..………82
3.2 Pilot plant products………..………83
3.2.1 Coated sheets from the pilot plant………..…….83
3.2.1.1 Residula humidity of the pilot sheets………..……….83
3.2.1.2 Thickness measurements of the pilot plant sheets……….………….83
3.2.1.3 DSC analysis of the pilot plant sheets………..………84
3.2.1.4 Tensile test of the pilot plant sheets……….………86
3.2.1.5 Adhesion test of the pilot plant products and evaluation of the results………...89
3.2.1.6 Weight loose after washing………..92
3.2.1.7 DMTA results and Young’s modulus of the coating………..………..93
3.2.2 Laminated from the pilot plant………100
3.2.2.1 Microtome cut and optical micrscope analysis………..….100
3.2.2.2 Tensile test of the laminated……….…101
3.2.2.3 Tear test of the laminated………..…103
3.2.2.4 Bond strength test of the laminated………..104
3.2.3 Pilot plant products barrier properties……….…..105
3.2.3.1 OTR of the pilot plant product……….….106
3.2.3.2 WVTR of the pilot plant products……….……..107
3.2.3.3 Comparison with the EvOH barrier properties……..………..107
3.3 Study of the kinetik of denaturation in solution………..………..108
3.3.1 Preparation of the cast films………..…………..108
3.3.2 DSC analysis of the cast films………..109
4 Conclusions……….111
References………113
