The development of a cured, fermented sheepmeat sausage designed to minimise species and pastoral-diet flavours Yanjun Lu A thesis submitted to AUT University in partial fulfilment of the requirements for the degree of Master of Applied Science (MAppSc) 2010 Primary Supervisor: Associate Professor Dr. Owen Young Secondary Supervisor: Professor Dr. John Brooks School of Applied Sciences Table of Contents Table of Contents ............................................................................................................................ i List of Figures ................................................................................................................................ iii List of Tables ................................................................................................................................. iv Acknowledgement ........................................................................................................................... v Statement of Originality ................................................................................................................ vi Abstract ......................................................................................................................................... vii Chapter 1 ......................................................................................................................................... 1 Introduction ..................................................................................................................................... 1 Brief history of food preservation ............................................................................................... 1 Drying ...................................................................................................................................... 1 Smoking ................................................................................................................................... 3 Chilling .................................................................................................................................... 3 Freezing ................................................................................................................................... 4 Canning .................................................................................................................................... 4 Curing and fermentation .......................................................................................................... 5 Meat curing and fermentation...................................................................................................... 5 Curing ...................................................................................................................................... 5 Toxicity of nitrosamines .......................................................................................................... 8 Fermentation ............................................................................................................................ 9 Fermented meat ..................................................................................................................... 12 Preservation of sheepmeat for international markets ................................................................ 14 The experimental plan ............................................................................................................... 16 Chapter 2 ....................................................................................................................................... 17 Material and Methods .................................................................................................................... 17 Chemicals .................................................................................................................................. 17 Meat purchasing ........................................................................................................................ 17 Modified syringe casing preparation ......................................................................................... 18 Sausage meat preparation .......................................................................................................... 20 Physicochemical analyses ......................................................................................................... 21 Colour measurement .............................................................................................................. 21 Texture profile analysis ......................................................................................................... 22 i pH determination ................................................................................................................... 22 Detection of the growth of fermentation culture ................................................................... 22 Sensory evaluation ..................................................................................................................... 23 Sheepmeat and spice flavours................................................................................................ 23 Preparation of sausage samples ............................................................................................. 24 Hygiene screening ................................................................................................................. 25 Details of sensory evaluation ..................................................................................................... 26 Data analysis .............................................................................................................................. 28 Chapter 3 ....................................................................................................................................... 29 Physicochemical Results and Discussion ...................................................................................... 29 The detection of growth of LAB ............................................................................................... 29 Changes in pH ........................................................................................................................... 30 The changes in colour during fermentation ............................................................................... 31 Texture ....................................................................................................................................... 36 Chapter 4 ....................................................................................................................................... 45 Sensory Evaluation Results and Discussion .................................................................................. 45 Introduction ............................................................................................................................... 45 Hygiene screening for samples used in sensory evaluation ...................................................... 46 Hedonic sensory trial ................................................................................................................. 47 Summary of the sensory results ................................................................................................. 48 Chapter 5 ....................................................................................................................................... 52 Conclusion ..................................................................................................................................... 52 Appendix 1 .................................................................................................................................... 55 Appendix 2 .................................................................................................................................... 56 A sample of Sensory evaluation form ....................................................................................... 56 Appendix 3 .................................................................................................................................... 61 Microbiological Reference Criteria for Food of New Zealand (Ministry of Health October 1995) .......................................................................................................................................... 61 Manufactured, cured or fermented meat - ready-to-eat ............................................................. 61 Appendix 4 .................................................................................................................................... 62 The MPN table (Brooks and McIntyre 2005) ............................................................................ 62 References ..................................................................................................................................... 64 ii List of Figures Figure 1. Nitrosamine formation .................................................................................................. 8 Figure 2. A modified syringe barrel ........................................................................................... 19 Figure 3. Mincing equipment ..................................................................................................... 19 Figure 4. A sample of sausage. ..................................................................................................