DESIGN AND TESTING OF AN APPARATUS TO MEASURE CARBON DIOXIDE SOLUBILITY IN LIQUID FOODS By THELMA FRANCISCA CALIX LARA 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 2008 1 © 2008 Thelma Francisca Calix Lara 2 To those that have guided and inspired me 3 ACKNOWLEDGMENTS I wish to express my special gratitude to my major advisor, Dr. Murat O. Balaban, for his valuable support, guidance and for being an example of motivation and hard work to us. I also like to thank my advising committee, Dr. Charles A. Sims and Dr. Allen F. Wysocki, for their guidance, assistance and time for my research. I am very grateful for my lab partners and friends, Luis, Jose, Max, Milena, Alberto, Zareena, Mutlu, Diana, Wendy, Yavuz, Maria and Giovanna for their assistance and for making the work in the lab such an enjoyable experience. I thank infinitely to my parents, Winston and Sagrario, my sister and my brother, Lourdes and Winston, for their unconditional love and support during my entire life. They have been my primary inspiration to pursue my goal. Finally, my dearest thanks to Jorge, for all the support and happiness he brought to my life. 4 TABLE OF CONTENTS page ACKNOWLEDGMENTS ...............................................................................................................4 LIST OF TABLES...........................................................................................................................7 LIST OF FIGURES .........................................................................................................................9 ABSTRACT...................................................................................................................................11 CHAPTER 1 INTRODUCTION ..................................................................................................................14 2 LITERATURE REVIEW .......................................................................................................17 2.1 Carbonated Soft Drinks ....................................................................................................17 2.2 Carbon Dioxide.................................................................................................................19 2.2.1 General Information ...............................................................................................19 2.2.2 Applications............................................................................................................22 2.3 Carbonation.......................................................................................................................23 2.3.1 Definition................................................................................................................23 2.3.2 Methods and Apparatus for Carbonation ...............................................................29 2.4 Supercritical Carbon Dioxide ...........................................................................................31 2.4.1 Definition................................................................................................................31 2.4.2 Dense Phase Carbon Dioxide .................................................................................33 2.4.3 Supercritical Fluid Extraction (SFE)......................................................................34 2.6 Constituents that Affect Carbon Dioxide Solubility in Beverages...................................35 2.6.1 Carbonated Soft Drinks ..........................................................................................35 2.6.1.1 Carbohydrate sweetener ...............................................................................36 2.6.1.2 Acidulants.....................................................................................................38 2.6.2 Milk ........................................................................................................................39 3 MATERIALS AND METHODS ...........................................................................................40 3.1 Design of the High Pressure Carbon Dioxide Solubility Apparatus ................................40 3.2 Preparation of the Samples ...............................................................................................46 3.2.1 Distilled Water........................................................................................................46 3.2.2 Fructose ..................................................................................................................46 3.2.3 Malic Acid..............................................................................................................46 3.3 Experimental Procedure....................................................................................................47 3.3.1 Preliminary Procedure............................................................................................47 3.3.2 Pumping the Liquid Sample into the System .........................................................48 3.3.3 Carbonating the Sample .........................................................................................48 3.3.4 Measuring Solubility ..............................................................................................49 3.3.5 Cleaning the Apparatus ..........................................................................................50 5 3.4 Experimental Design ........................................................................................................50 3.5 Data Analysis....................................................................................................................51 4 RESULTS AND DISCUSSION.............................................................................................53 4.1 Solubility of Carbon Dioxide in Distilled Water..............................................................53 4.2 Solubility of Carbon Dioxide in Fructose Solutions.........................................................55 4.3 Solubility of Carbon Dioxide in Malic Acid Solutions ....................................................58 5 SUMMARY, CONCLUSIONS AND SUGGESTIONS FOR FUTURE STUDY................61 5.1 Summary...........................................................................................................................61 5.2 Conclusions.......................................................................................................................62 5.3 Suggestions for Future Study............................................................................................62 APPENDIX A DESIGN OF THE HIGH PRESSURE CARBON DIOXIDE SOLUBILITY APPARATUS.........................................................................................................................63 B THE HIGH PRESSURE CARBON DIOXIDE SOLUBILITY APPARATUS PROCEDURES ......................................................................................................................73 LIST OF REFERENCES...............................................................................................................76 BIOGRAPHICAL SKETCH .........................................................................................................81 6 LIST OF TABLES Table page 2-1 Physical properties associated with the phase diagram of CO2 .........................................20 2-2 Quality standard of carbon dioxide....................................................................................21 2-3 Soft drink components and their typical use level.............................................................36 2-4 Properties of bulk sweeteners ............................................................................................37 2-5 Acidulants used in beverage formulation ..........................................................................38 3-1 Different levels of each variable in the two phases of the experiment ..............................51 4-1 Experimental results of solubility of CO2 in pure water....................................................53 4-2 Summary of the analysis of variance (ANOVA) of the solubility of CO2 in pure water...................................................................................................................................54 4-3 Summary of the least square mean (LS Mean) analysis of the solubility of CO2 in pure water...........................................................................................................................54 4-4 P-values from the least significant difference (LSD) test between experimental mean data and literature data of solubility of CO2 in pure water ................................................54 4-5 Experimental results of CO2 solubility in solutions with different concentration of fructose...............................................................................................................................55 4-6 Analysis of variance (ANOVA) of solubility of CO2 in fructose solutions of different concentrations ....................................................................................................................57 4-7 Least Square (LS) Mean analysis of solubility of CO2 in fructose solutions of different concentrations .....................................................................................................57 4-8 P-values from the least Significant Difference