Department of Food and Nutritional Sciences Effects of industrial processing methods on skimmed camel milk properties Thesis submitted for the requirement for the degree of Doctor of Philosophy in Food & Nutritional Science By: Adel Omar BS, MSc. Supervisors: Dr. Maria J. Oruna-Concha Dr. Niamh Harbourne March 2018 Declaration I confirm that this is my own work and the use of all material from other sources has been properly and fully acknowledged. Adel Omar March 2018 ………………………. Table of Contents Abstract ................................................................................................................ v Acknowledgement ............................................................................................. vii List of tables ..................................................................................................... viii List of figures ....................................................................................................... x Chapter 1: Introduction ..................................................................................... 1 1.2. Research hypothesis and objectives ........................................................................................ 2 1.3. Novelty of the research ........................................................................................................... 3 1.4. Significance of the research .................................................................................................... 3 1.5. Thesis outline .......................................................................................................................... 4 Chapter 2: Literature review ............................................................................. 6 2.1. Dromedary camel’s taxonomy and their geographical distribution ............................................. 6 2.2. Dromedary camels for milk production ....................................................................................... 9 2.3. Dromedary camel milk composition .......................................................................................... 11 2.3.1. Water ................................................................................................................................... 12 2.3.2. Fat ....................................................................................................................................... 13 2.3.3. Protein ................................................................................................................................. 13 2.3.4. Lactose ................................................................................................................................ 15 2.3.5. Total solids .......................................................................................................................... 16 2.3.6. Ash....................................................................................................................................... 16 2.4. Therapeutic properties of dromedary camel milk ...................................................................... 17 2.4.1. Antimicrobial and antiviral ................................................................................................. 17 2.4.2. Antidiabetic ......................................................................................................................... 18 2.4.3. Treatment of Autism ............................................................................................................ 18 2.4.4. Treatment of Crohn's disease .............................................................................................. 19 2.4.5. Treatment for allergies ........................................................................................................ 19 2.4.6. Lactose-intolerant ............................................................................................................... 20 2.5. The technological challenges of processing dromedary camel milk.......................................... 20 2.5.1. Heat treatment of camel milk .............................................................................................. 20 2.5.2. Fermented camel milk ......................................................................................................... 23 2.5.3. Yoghurt manufacturing of camel milk ................................................................................. 24 2.5.4. Cheese processing of camel milk ........................................................................................ 25 i 2.5.5. Butter manufacturing of camel milk .................................................................................... 27 2.5.6. Sensory and flavour characteristics of camel milk and its dairy products ......................... 27 2.5.7. Characterisation methods of CM proteins .......................................................................... 29 Chapter 3: Quantification of major camel milk proteins by capillary electrophoresis ................................................................................................... 33 Preface to chapter 3 ........................................................................................................................... 33 Abstract ............................................................................................................................................. 34 3.1. Introduction ................................................................................................ 35 3.2. Material and methods ................................................................................ 36 3.2.1. Materials ................................................................................................................................. 36 3.2.1.1. Chemicals & reagents ...................................................................................................... 36 3.2.1.2. Milk samples .................................................................................................................... 37 3.2.2. Methods................................................................................................................................... 37 3.2.2.1. Chemical composition analysis of raw whole camel milk ............................................... 37 3.2.2.2. Preparation of whey and casein proteins .......................................................................... 37 3.2.2.3. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS–PAGE) ................. 38 3.2.2.4. Capillary electrophoresis (CE) analysis of camel caseins and whey proteins ................. 38 3.3. Results and discussions .............................................................................. 39 3.3.1. Composition of camel milk ..................................................................................................... 39 3.3.2. SDS–PAGE of camel milk whey and casein proteins ............................................................ 40 3.3.3. Capillary electrophoresis (CE) analysis of camel caseins and whey proteins ........................ 40 3.3.4. Quantification of major Camel milk proteins by CE .............................................................. 44 3.4. Conclusion .................................................................................................. 45 Chapter 4: Effects of industrial processing methods on camel skimmed milk properties .................................................................................................. 46 Preface to chapter 4 ........................................................................................................................... 46 Abstract ............................................................................................................................................. 47 4.1. Introduction ................................................................................................ 48 4.2. Materials and Methods .............................................................................. 50 4.2.1. Chemicals and reagents ........................................................................................................... 50 4.2.2. Milk samples ........................................................................................................................... 51 4.2.3. High-Temperature, Short-Time Pasteurisation ....................................................................... 51 4.2.4. Ultra-High-Temperature Processing ....................................................................................... 51 ii 4.2.5. High-Pressure Treatment ........................................................................................................ 52 4.2.6. Proximate composition analysis.............................................................................................. 52 4.2.7. Determination of whey proteins denaturation ......................................................................... 52 4.2.8. Determination of average casein micelle Size ........................................................................ 53 4.2.9. Determination of colour parameters ....................................................................................... 53 4.2.10. Determination of rennet coagulation time and rheological properties of milk ..................... 54 4.2.11. Statistical analysis ................................................................................................................