PREDICTION OF TEXTURE CHARACTERISTICS IN APPLE DRYING USING COMPUTER VISION By Dandan Wang Submitted in partial fulfilment of the requirements for the degree of Master of Science At Dalhousie University Halifax, Nova Scotia July 2016 © Copyright by Dandan Wang, 2016 Table of Contents List of Tables ....................................................................................................................... v List of Figures ..................................................................................................................... vi Abstract ............................................................................................................................... ix List of Abbreviations Used .................................................................................................. x Acknowledgements .......................................................................................................... xiii Chapter 1. Introduction ........................................................................................................ 1 Chapter 2. Literature Review ............................................................................................... 3 2.1 Effects of Drying Technologies on Microstructure and Texture ............................... 3 2.1.1 Convective Drying .............................................................................................. 4 2.1.2 Freeze Drying ...................................................................................................... 6 2.1.3 Microwave Drying .............................................................................................. 8 2.1.4 Osmotic Dehydration ........................................................................................ 10 2.1.5 Hybrid Technologies ......................................................................................... 12 2.2 Relationship of Food Microstructure to Texture ..................................................... 16 2.3 Food Texture ............................................................................................................ 17 2.4 Food Plant Microstructure ....................................................................................... 24 2.4.1 Initial Structure of Plant Tissue ........................................................................ 24 2.4.2 Food Microstructural Properties ....................................................................... 27 2.5 Relevance for the Industry ....................................................................................... 35 Chapter 3. Hypothesis and Objectives ............................................................................... 36 3.1 Problem Statement ................................................................................................... 36 3.2 Hypotheses ............................................................................................................... 36 3.3 Objectives and Scope ............................................................................................... 37 Chapter 4. Estimation of Total, Open- and Close-Pore Porosity of Apple Slices During Drying ................................................................................................................................ 38 Abstract .......................................................................................................................... 38 4.1 Introduction .............................................................................................................. 39 4.2 Materials and Methods ............................................................................................. 41 4.2.1 Materials and Sample Preparation .................................................................... 41 4.2.2 Instrumentation ................................................................................................. 42 4.2.3 Experimental Procedure .................................................................................... 43 ii 4.2.4 Porosity Estimation ........................................................................................... 43 4.2.5 Statistical Analysis ............................................................................................ 44 4.3 Results ...................................................................................................................... 44 4.4 Discussion ................................................................................................................ 48 4.5 Conclusions .............................................................................................................. 51 Connecting Statement .................................................................................................... 52 Chapter 5. Computer Vision for Bulk Volume Estimation of Apple Slices During Drying ............................................................................................................................................ 53 Abstract .......................................................................................................................... 53 5.1 Introduction .............................................................................................................. 54 5.2 Materials and Methods ............................................................................................. 55 5.2.1 Materials and Sample Preparation .................................................................... 55 5.2.2 Instrumentation ................................................................................................. 55 5.2.3 Experimental Procedure .................................................................................... 56 5.2.4 Bulk Volume Measurements ............................................................................. 56 5.2.5. Statistical Analysis ........................................................................................... 59 5.3 Results and Discussion ............................................................................................ 60 5.3.1 Image Analysis .................................................................................................. 60 5.3.2 Correlation Between Imaging and Physical Caliper Measurements of Diameter .................................................................................................................................... 66 5.3.3 Verification ....................................................................................................... 67 5.3.4 Correlation Between Diameter and Volume ..................................................... 68 5.4 Conclusions .............................................................................................................. 70 Connecting Statement .................................................................................................... 71 Chapter 6. Texture Changes of Apple Slices Under Convective Drying .......................... 72 Abstract .......................................................................................................................... 72 6.1 Introduction .............................................................................................................. 72 6.2 Materials and Methods ............................................................................................. 78 6.2.1 Materials and Sample Preparation .................................................................... 78 6.2.2 Instrumentation ................................................................................................. 78 6.2.3 Experimental Procedure .................................................................................... 80 6.3 Results and Discussion ............................................................................................ 80 6.3.1 Effects of Drying Temperature and Moisture Content on Porosity .................. 80 iii 6.3.2 Effects of Moisture Content on Texture ........................................................... 81 6.3.3 Effects of Drying Temperature, Porosity and Glass Transition on Texture ..... 87 6.4 Conclusions .............................................................................................................. 94 Chapter 7 General Conclusions and Recommendations .................................................... 97 7.1 Achievements and General Discussion of the Results ............................................. 97 7.2 Recommendations for Future Research ................................................................... 98 References ........................................................................................................................ 100 Appendices ....................................................................................................................... 120 Copyright Permission (A) ............................................................................................ 120 Copyright Permission (B) ............................................................................................ 122 Copyright Permission (C) ............................................................................................ 123 Copyright Permission (D) ............................................................................................ 126 Copyright Permission (E) ............................................................................................ 130 Copyright Permission