www.crcpress.com FM_Tecnomic_Brody_183011 5/9/01 10:13 PM Page v Table of Contents Preface Acknowledgements Abbreviations, Acronyms, and Symbols 1.INTRODUCTION Oxidative Deteriorative Reactions Odor Control Minimally Processed Foods Active Packaging Opportunities Outline Bibliography 2.OXYGEN SCAVENGERS Introduction Definitions Rationale for In-Package Oxygen Scavenging Measures to Exclude Oxygen Oxygen Entry After Closure Historical Background of Oxygen Absorbers and Scavengers Commerical Applications United States Military Applications Japanese Situation Bibliography ©2001 CRC Press LLC FM_Tecnomic_Brody_183011 5/9/01 10:13 PM Page vi 3.OXYGEN SCAVENGER SYSTEMS Antioxidants Sulfites Boron Glycols and Sugar Alcohols Unsaturated Fatty Acids and Hydrocarbons Palladium Catalysts Enzymes Yeast The Package Material as a Reducing Agent Ferrous Iron-Based Scavengers Economics Developmental Bibliography 4.OXYGEN SCAVENGING IN 2000 AND BEYOND Labels Incorporation of Oxygen Scavengers Into Plastic Structures Sandwiching Oxygen Scavengers Resin-Based Systems United States Military Applications Premature Reaction to Oxygen Recent Patents and Patent Applications Additional Activities Conclusion Bibliography 5.MOISTURE CONTROL Relative Humidity Control Within Packages Moisture Removers Conclusion Bibliography 6.GAS-PERMEABILITY CONTROL Avoidance of Anoxic Conditions Temperature-Sensitive Structures Bibliography 7.ETHYLENE CONTROL Potassium Permanganate Reaction Other Ethylene Scavengers ©2001 CRC Press LLC FM_Tecnomic_Brody_183011 5/9/01 10:13 PM Page vii Dunapack Sachet Ethylene Scavengers Activated Carbon Ethylene Removers Activated Earth Ethylene Removers Novel Ethylene-Removing Packaging Conclusion Bibliography 8.ODOR REMOVERS Activated Carbon Odor Adsorbers Absorbent Pad Odor Removers Vitamin E and BHT as Odor Reducers In Plastic Packaging Molecular Sieves as Plastic Odor Reducers Aldehyde Scavengers Amine Odor Removal Conclusion Bibliography 9.AROMA EMISSIONS FROM PLASTICS Polyvel Fragrance Concentrate Suppliers Aroma Concentrates Extrusion Boundaries Other Suppliers/Technologies Bibliography 10.ANTIMICROBIAL PACKAGING Anhydrides as Antimicrobial Agents Bacteriocins Antimicrobial Enzymes Radiation-Emitting Film Antimicrobial Activity of Silver Ions Examples of Zeolite Products Additional Antimicrobials Benomyl Mathematical Modeling of Antimicrobial Food Packaging Conclusions Bibliography ©2001 CRC Press LLC FM_Tecnomic_Brody_183011 5/9/01 10:13 PM Page viii 11.OTHER SYSTEMS Carbon Dioxide Absorbers Carbon Dioxide Emitters/Generators The Future Further Reading Appendix ©2001 CRC Press LLC FM_Tecnomic_Brody_183011 5/9/01 10:13 PM Page ix Preface HIS text was derived from a draft technical report for the U.S. Army Sol- Tdier and Biological Chemical Command (SBCCOM), Natick Soldier Center (formerly the U.S. Army Natick Research, Development and Engineer- ing Center), prepared by Rubbright●Brody, Inc., entitled “Active Packaging Applications to Enhance the Preservation and Quality of Contained Foods.” The purpose of this original report was to identify and characterize domestic and international active packaging technologies with potential for direct U.S. military application. The report reviews commercial and developmental tech- nologies concerning oxygen-scavenging, odor and moisture removal, aroma emission, and antimicrobial systems to better retain the quality of contained food. With the gracious cooperation of those who generated the original docu- ment and the permission of all of the sponsoring parties, this book updates, ex- pands, and enhances the original text to the broader focus of the commercial world. This book focuses on active packaging in all of its manifestations. As we in- dicate in this text, literally thousands of citations from the peer-reviewed, trade, commercial, and patent literature were found, classified, and reviewed. Those who wrote the references and those who did not but who worked on the laboratory benches, in the pilot plants, and on the production floors were inter- viewed in depth and became our contributing authors and critics. We have highlighted oxygen-scavenging packaging because it has the longest history and the largest use. More significantly, oxygen control is a jus- tifiably growing technology that will ultimately graduate from adjunct to full status as a means to enhance food and beverage preservation. The role of oxygen-scavengers in this evolving food-preservation enhance- ment has not yet been defined but is almost certain to become significantly ©2001 CRC Press LLC FM_Tecnomic_Brody_183011 5/9/01 10:13 PM Page x more important in the future. The same is true for the other active packaging technologies discussed in this book: odor control, moisture control, carbon dioxide control, and antimicrobials. Carbon dioxide is no longer merely a gas that imparts a tongue tingle sensa- tion to beverages, but rather an integral component of much modified-atmosphere packaging in which the physiological biochemistry is altered and manipu- lated to prolong quality retention. Colors, flavors, and pathways may be disrupted. Optimal concentrations in the dynamic environment of living tissue are changed by the very presence of carbon dioxide as quality retention is maximized. Thus, like oxygen control, the independent control of carbon dioxide is cru- cial to the preservation of post-harvest plants and of animal tissue whose mi- crobiological populations may be suppressed. Another challenge is the elusive target of destroying or retarding microbio- logical growth by means of antimicrobial agents. Among the rules of thumb with which we must contend are the following: chemicals that can control micro- organisms are often toxic to humans; many chemicals may be selectively anti- microbial; contact of the chemical with the microorganism is usually required; and too many of these agents impart disagreeable flavors. Most of the numerous reports extolling the virtues of antimicrobial agents in package materials minimize the caveat that direct contact is required. What of the irregular surfaces of most foods? And what about all of the microorgan- isms buried beneath the surfaces? Some proposed agents, such as ethyl alcohol or allylisothiocyanate, can be vaporized to permeate foods and thus extend their effectiveness. But what about their residual flavor and selectivity? And regulatory implications? These and many other issues are raised and explored in this meticulously researched volume. Can package materials and structures be truly active—sensing and reacting in a positive manner while remaining benign to other properties? This book will suggest that technology has progressed far in offering to control oxygen and, to some degree, in controlling moisture, odor, and microorganisms. As of this writing, however, we have not yet arrived at a point where we can depend on a package material or structure. We must continue to think and act holisti- cally—to combine the tried, such as barrier and clean operations, with our new technologies. Then we should consider hurdle technologies—combining oxy- gen control with antimicrobials, for example. Some have learned that aseptic packaging may become hurdle technology for extended shelf life refrigerated preservation. Now, if we stretch our think- ing, we can embrace our as-yet-limited knowledge of active packaging to enhance quality in concert with existing technologies. If this book teaches anything, it is that active packaging is still in its ele- mentary stages. If we can learn something, it is that we should succumb to the wiles of how easy it might be to read a paragraph out of context and instantly ©2001 CRC Press LLC FM_Tecnomic_Brody_183011 5/9/01 10:13 PM Page xi cry out, “This is the answer!” Like its ancestors of gas-barrier, retort-pouch, and modified-atmosphere packaging, active packaging has a distance to travel. Together with its acknowledged antecedent, Michael Rooney’s Active Food Packaging, this book should help propel us along the path of appreciating and understanding the challenges and opportunities that we shall surely gain from active packaging. ©2001 CRC Press LLC FM_Tecnomic_Brody_183011 5/9/01 10:13 PM Page xiii Acknowledgements HE authors wish to gratefully acknowledge the special contributions of TMr. Michael Rooney, who drafted part of the original section on oxygen- scavenging; Dr. Jung Han, who contributed a chapter on antimicrobial pack- aging; and Mrs. Lauren Milch, Physical Scientist, and Dr. William Porter, Chemical Technical Consultant, of the U.S. Army Natick Soldier Center, Natick, Massachusetts. We received remarkable cooperation from the community of researchers who have been intimately involved with active packaging for the past decade or more: Mr. Michael Rooney of Food Science Australia, formerly Australia’s Commonwealth Scientific Industrial and Research Organization (CSIRO); Dr. Joseph Hotchkiss of Cornell University; Mr. Ron Idol, formerly of Multi- sorb Technologies, Inc., and now with Air Liquide America; Dr. John Floros, formerly of Purdue University and now Chair, Department of Food Science and Technology, Pennsylvania State University; Dr. John Krochta of University of California, Davis, and his student, Dr. Jung Han, now Assistant Professor, University of Manitoba, Canada; Dr. James P. Smith of McGill University, Canada; and Dr. Boh C. Tsai, formerly of Amoco Chemicals and now with George O. Schroeder Associates. Each offered considerable in- formation that was employed extensively throughout the preparation of this manuscript.