QUALITY ENHANCEMENT OF COFFEE WITH ACID AND ENZYME TREATMENT By LUIS FEDERICO MARTINEZ A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2007 1 ©2007 Luis Federico Martinez 2 To my Wife, Son, Mother and Grandparents 3 ACKNOWLEDGMENTS I would like to thank my advisor Dr. Murat O. Balaban for all his support and guidance through the last three years of my life and throughout my research. I have learned from him how important it is to show productivity in everything we do, to pursue goals without intimidation, to work as a team and to use critical thinking in every aspect of our life. I would also like to thank Dr. Marty R. Marshall and Dr. Allen Wysocki for all their support and for being part of my committee, Dr. Charles Sims for helping me with sensory evaluation, Dr. Lynette Orellana and the University of Puerto Rico Experimental Station in Adjuntas, Cinnamon Bay Coffee - Ambex Roasters Inc. for their help with roasting and cupping, Joseph Tsai for helping with the SEM and all professors and staff that have contributed to this dissertation. I would like to thank my wife, my mother, grand parents and all my family for all their help and support every day of my life. I would also like to thank all my dear friends and coworkers for their help with the trained panel and the experiments, but especially I would like to thank Lorenzo Puentes, Stefan Crynen, Max Ochsenius, Jose Aparicio, Alberto Azeredo, Thelma Calix, Jorge Cardona and Wendy Marin for all the long hours they spent helping me in all aspects of my research. 4 TABLE OF CONTENTS Page ACKNOWLEDGMENTS ...............................................................................................................4 LIST OF TABLES...........................................................................................................................7 LIST OF FIGURES .........................................................................................................................9 ABSTRACT...................................................................................................................................12 CHAPTER 1 INTRODUCTION ..................................................................................................................14 2 LITERATURE REVIEW .......................................................................................................16 Coffee: Composition, Production and Overview....................................................................16 Coffee Processing ...................................................................................................................20 Introduction .....................................................................................................................20 Plant Selection and Harvesting........................................................................................20 Coffee Processing Methods.............................................................................................20 Dry processing..........................................................................................................21 Wet processing .........................................................................................................22 Pulped natural process..............................................................................................23 Ecological process....................................................................................................23 Coffee Drying..................................................................................................................24 Coffee Roasting...............................................................................................................25 Introduction ..............................................................................................................25 Roasting techniques..................................................................................................26 Changes produced by roasting .................................................................................28 Grinding...........................................................................................................................32 Coffee Aroma ..................................................................................................................32 Cup Quality .....................................................................................................................34 Kopi Luwak ............................................................................................................................35 Instrumental Analysis .............................................................................................................37 Machine Vision ...............................................................................................................37 Electronic Nose ...............................................................................................................38 Scanning Electron Microscope........................................................................................39 Sensory Analysis ....................................................................................................................40 Objective of the Study ............................................................................................................41 3 MATERIALS AND METHODS ...........................................................................................42 Preliminary Experiments ........................................................................................................42 Experiments ............................................................................................................................50 Coffee Harvesting............................................................................................................50 5 Green Coffee Processing .................................................................................................50 Green Coffee Storage ......................................................................................................51 Coffee Treatments ...........................................................................................................51 Coffee Roasting...............................................................................................................52 Coffee Grinding and Brewing .........................................................................................53 Experimental Design ..............................................................................................................53 Color and Texture Analysis by Machine Vision and Lens Eye Software ..............................55 Electronic Nose.......................................................................................................................56 Sensory Analysis ....................................................................................................................58 Coffee Cupping.......................................................................................................................59 Scanning Electron Microscope...............................................................................................59 4 RESULTS AND DISCUSSION.............................................................................................61 Sensory analysis .......................................................................................................61 Scanning electron microscope..................................................................................66 Electronic nose .........................................................................................................76 Machine vision .........................................................................................................79 5 SUMMARY AND CONCLUSIONS.....................................................................................83 6 FUTURE WORK....................................................................................................................86 APPENDIX A CUPPING AND SENSORY EVALUATION .......................................................................88 B SCANNING ELECTRON MICROSCOPE IMAGES AND ANALYSIS ..........................101 C ELECTRONIC NOSE DATA AND GRAPHS ...................................................................118 D MACHINE VISION IMAGES.............................................................................................121 E COFFEE PROCESSING......................................................................................................124 LIST OF REFERENCES.............................................................................................................125 BIOGRAPHICAL SKETCH .......................................................................................................131 6 LIST OF TABLES Table page 2-1 Coffee production in the 10 largest producing countries and world total..........................19 2-2 Coffee roast colors and characteristics ..............................................................................27 2-3 Roasting characteristics of the arabica and robusta coffees..............................................30 2-4 Content of chlorogenic acids in green and roasted coffees and percentage loss during roasting...............................................................................................................................31