Food Science Text Series The Food Science Text Series provides faculty with the leading teaching tools. The Editorial Board has outlined the most appropriate and complete content for each food science course in a typical food science program and has identifi ed textbooks of the highest quality, written by the leading food science educators. Series Editor Dennis R. Heldman Editorial Board David A. Golden, Ph.D., Professor of Food Microbiology, Department of Food Science and Technology, University of Tennessee Richard W. Hartel, Professor of Food Engineering, Department of Food Science, University of Wisconsin Hildegarde Heymann, Professor of Food Sensory Science, Department of Food Science and Technology, University of California-Davis Joseph H. Hotchkiss, Professor, Institute of Food Science and Institute for Comparative and Environmental Toxicology, and Chair, Food Science Department, Cornell University Michael G. Johnson, Ph.D., Professor of Food Safety and Microbiology, Department of Food Science, University of Arkansas Joseph Montecalvo, Jr., Professor, Department of Food Science and Nutrition, California Polytechnic and State University-San Luis Obispo S. Suzanne Nielsen, Professor and Chair, Department of Food Science, Purdue University Juan L. Silva, Professor, Department of Food Science, Nutrition and Health Promotion, Mississippi State University For further volumes: http://www.springer.com/series/5999 Harry T. Lawless Laboratory Exercises for Sensory Evaluation Harry T. Lawless Department of Food Science Cornell University Ithaca, NY, USA ISSN 1572-0330 ISBN 978-1-4614-5682-7 ISBN 978-1-4614-5713-8 (eBook) DOI 10.1007/978-1-4614-5713-8 Springer New York Heidelberg Dordrecht London Library of Congress Control Number: 2012948339 © Springer Science+Business Media New York 2013 This work is subject to copyright. 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Permissions for use may be obtained through RightsLink at the Copyright Clearance Center. Violations are liable to prosecution under the respective Copyright Law. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a speci fi c statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein. Printed on acid-free paper Springer is part of Springer Science+Business Media (www.springer.com) Preface Laboratory exercises are a necessary part of scienti fi c education. They teach students how to perform various tests and procedures through learning by doing. It is of course possible to teach sensory evaluation only from lectures and book learning, but our philosophy is that a great understanding is achieved by hands-on experience. Laboratory exercises provide important opportuni- ties to reinforce concepts, principles, and practices discussed in lectures. Furthermore, sensory evaluation is a science of test procedures, statistical analyses, and proper interpretation of results. The procedures, analysis, and conclusions are best learned by actually conducting the tests. Many of the critical details in methods and good practices are hard to absorb and remem- ber without having been in the test situation itself. The objectives of a laboratory course in sensory evaluation are: 1. To teach students how to set up and conduct sensory tests. 2. To give students experience in analyzing data from sensory tests. 3. To develop an understanding of the meaningful, valid interpretation of results. 4. To develop skills in writing reports and industrial memos. 5. To give students experience in participating in sensory tests. 6. To reinforce information taught in the lecture section of the course. 7. To provide experience in evaluating a variety of products using the senses. Sensory evaluation is unlike chemistry and biology. Analytical procedures in those disciplines can be spelled out in exquisite detail and followed in cook- book fashion. However, every food product is different, and the real chal- lenge is in devising a sensory test method that fi ts the product and is both sensitive and unbiased. This need for fl exibility can be quite challenging and unsettling to people who are used to rote procedures. This was written to be procedurally speci fi c and “cookbookish” as is reasonable. I have noted where procedures may be modi fi ed to suit the situation of individual schools and professors. I hope that each professor may use these exercises as a starting point and allow his or her own expertise to contribute modi fi cations and dis- cussion points as they see fi t. The structure of this manual includes eleven longer laboratory exercises, in Chaps. 3 through 13. They are best suited for a 3-h laboratory period but require less time if more preparation is done ahead of time. The fi rst lab con- cerns panelist selection and testing the acuity of a person’s senses of taste and smell. Three exercises are related to discrimination, thresholds, and signal v vi Preface detection theory. Two scaling exercises involve a comparison of methods and time-intensity scaling. Three exercises are related to descriptive analysis, including fl avor profi le, ballot and term generation, and use of reference stan- dards. Finally, two labs are concerned with acceptance and preference testing and product optimization. There is one group project in Chap. 14 on descrip- tive analysis, a topic that lends itself to a group effort. There are four briefer exercises in Chap. 15, on probability, shelf life, consumer questionnaires, and development of a procedure for a dif fi cult-to-handle meat product. The fi nal chapter gives some examples of statistical problem sets that could be used as part of the laboratory course or main sensory course. All of the laboratory exercises in the current work were conducted in one form or another for many years at the Cornell University Food Science Department course in sensory evaluation, with the exception of Chap. 11, use of reference standards. That exercise is based on the actual experience of the author in training descriptive panels or being a panelist myself, and so I feel con fi dent that Chap. 11 can be executed as written or with only minor modi fi cations. At Cornell, the class consisted mostly of senior (fourth year) undergraduates and some graduate students. If your course is given earlier in terms of the students’ experience or year, you may wish to consider simplify- ing some of the activities. This manual owes a double debt of gratitude to Professor Hildegarde Heymann of the University of California at Davis. Professor Heymann is familiar to many of her colleagues and students due to her tenure at the University of Missouri Columbia, where we fi rst began the construction of a comprehensive sensory evaluation textbook, and then for her return to the Davis campus to assume a sensory leadership role in the program in viticul- ture and enology. Almost two decades before, Professor Heymann was instru- mental in the compilation of a set of laboratory exercises in sensory evaluation, under the auspices of the Sensory Evaluation Division of the Institute of Food Technologists. Many of us contributed to that manual, and parallels can be seen in the lab exercises on scaling and acceptance/preference testing. It was intended as a guide to new instructors in sensory evaluation, as there was a dearth of professors in this fi eld at the time (some would say there still is) and those of us “old hands” thought it would be great idea to share some of our labs that seemed to work well. That document was in fl uential in the construc- tion of this work. An even older document from Professor Pangborn’s labs at Davis somehow found its way into my hands, I believe from the archives of Suzanne Pecore. Its level of detail was an eye-opener. Another important resource from my own experience was my undergraduate sensory psychol- ogy course, with labs from the scientists at the John B. Pierce Foundation, notably (in alphabetical order) Ellie Adair, Linda Bartoshuk, Bill Cain, Larry Marks, and Joe Stevens. I had many courses and labs in chemistry, but psy- chology labs with human data were very different. Professor Heymann chose not to coauthor this current work, due to other commitments, but it was our intention early on to have a companion piece to Sensory Evaluation of Foods, Principles and Practices, and that it would be a kind of Lawless and Heymann, p art deux . During various phases of this proj- ect, she offered invaluable guidance and commentary, as well as providing Preface vii the author copies of her laboratory exercises for the sensory evaluation courses at Davis in viticulture and enology. In many ways, she should right- fully be a junior author. Susan Safren and colleagues at Springer Publishing were patient editorial guides to the project. I appreciate her forbearance during a series of strategic changes during the construction and organization of this work. In particular, we suffered over whether there should be separate instructor and student sec- tions for the labs, in totally separate parts of the book, or even whether there should be separate manuals. In the end, the current author decided (unilater- ally) to merge the instructor and student sections for each lab and present each exercise as a kind of book chapter that could be purchased or down- loaded separately. The negative aspect of that merger is that students may not be totally blinded to the nature of the samples, if they simply read ahead. A debt of gratitude is due to my students and teaching assistants. Many of the TAs asked critical questions over the years that fettered out a lot of poten- tial problems with the procedures. Others, thankfully few, manage to make serious but innocent mistakes. These two were informative. In order to avoid those potential mistakes, there are sections noted as “Notes and keys to suc- cessful execution” in each instructor section. One the whole, my TAs at Cornell were excellent in their effort, hard work, and attention to detail and taught me a lot. Pedagogy is a two-way street. Professor Edgar Chambers IV was the source of the laboratory on the Flavor Pro fi le Method, and I fi rst encountered it during a workshop we gave at Kansas State University in the mid-1990s for new instructors in sensory evaluation. It was so much fun and so colorful that I incorporated it in a slightly modi fi ed form into my own course at Cornell the very next semester. Many thanks, Edgar. John Horne was my lab manager when most of these exercises were taking shape, and he applied his editorial hand to early ver- sions. Kathy Chapman also served for many years in that support role. Comments and feedback may be directed to the author at [email protected]. Ithaca, NY, USA Harry T. Lawless Contents Part I Introductory Material and General Instructions 1 Introduction and General Instructions for Students ............... 3 1.1 General Instructions for Students ......................................... 3 1.1.1 Guidelines for Participation ..................................... 3 1.2 Options for Individual or Partner Work ............................... 3 1.2.1 General Option 1: Individual Work .......................... 3 1.2.2 General Option 2: Partner Work ............................... 4 1.3 Suggested Lab Report Formats ............................................ 4 1.3.1 Specific Formats ....................................................... 4 1.3.2 Other Formats Used in Industry and Product Research and Development ......................... 5 1.4 Guidelines for Reporting Statistical Results: Use of Statistical Tables ....................................................... 6 1.5 Graphing Data ...................................................................... 7 1.5.1 General Rules and Guidelines .................................. 8 1.5.2 Common Types of Charts ......................................... 8 1.6 Common Problems in Laboratory Reports .......................... 9 1.6.1 Content ..................................................................... 9 1.6.2 Written Text .............................................................. 9 1.6.3 Organization and Format .......................................... 9 1.7 Appendix: Sample Report (Industrial Style) ........................ 10 2 Introduction for Instructors and Teaching Assistants ............. 13 2.1 General Considerations and Issues....................................... 13 2.2 Specific Options ................................................................... 13 2.3 Resources and Requirements ............................................... 14 2.3.1 Facilities ................................................................... 14 2.3.2 General Supplies and Equipment ............................. 15 2.4 Suggested Kitchen/Lab Rules .............................................. 15 2.5 Challenges and Opportunities .............................................. 15 2.6 Conclusion............................................................................ 16 ix