In memory of my late father, Eliezer, and mother, Rebekah Nussinovitch, who gave me life and taught me to persistently pursue knowledge, beauty, and understanding.
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Library of Congress Cataloging‐in‐Publication Data
Names: Nussinovitch, A.
Title: Adhesion in foods : fundamental principles and applications / by Amos Nussinovitch.
Description: Chichester, West Sussex, UK ; Hoboken, NJ, USA : John Wiley & Sons Inc., 2017. | Includes bibliographical references and index.
Identifiers: LCCN 2016035744| ISBN 9781118851616 (cloth) | ISBN 9781118851609 (epub)
Subjects: LCSH: Food–Analysis. | Adhesion.
Classification: LCC TX541 .N858 2017 | DDC 664/.07–dc23
LC record available at https://lccn.loc.gov/2016035744
A catalogue record for this book is available from the British Library.
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Cover image: ProVectors/Gettyimages
Professor Amos Nussinovitch was born in Kibbutz Megiddo, Israel. He studied chemistry at the University of Tel Aviv, and Food Engineering and Biotechnology at the Technion – Israel Institute of Technology. He has worked as an engineer at several companies and has been involved in a number of R&D projects in both the United States and Israel, focusing on the mechanical properties of liquids, semi‐solids, solids, and powders. He is currently at the Biochemistry and Food Science Department of the Robert H. Smith Faculty of Agriculture, Food and Environment of the Hebrew University of Jerusalem, where he leads a large group of researchers working on theoretical and practical aspects of hydrocolloids. Professor Nussinovitch is the sole author of the following books: Hydrocolloid Applications; Gum Technology in the Food and Other Industries; Water‐Soluble Polymer Applications in Foods; Plant Gum Exudates of the World – Sources, Distribution, Properties and Applications; and Polymer Macro‐ and Micro‐Gel Beads – Fundamentals and Applications. He and Dr Madoka Hirashima from the Faculty of Education of the Mie University in Japan recently co‐authored the book: Cooking Innovations, Using Hydrocolloids for Thickening, Gelling, and Emulsification.
Professor Nussinovitch is the author or co‐author of numerous papers on hydrocolloids and on the physical properties of foods, and he has many patents. This book is devoted specifically to adhesion in foods. Professor Nussinovitch has been working in this area for many years and has studied hydrocolloid wet glues, adhesion related to edible coatings, adhesion in the manufacturing of multilayered food products, pressure‐sensitive adhesives, and tests to check adhesion in foods, among many other applications. Two years ago, Professor Nussinovitch received a lifetime award from the Manufacturers Association of Israel for his unique and considerable contributions to both academia and the food industry in Israel.
This book was written over the course of two years. All of its chapters are devoted to the fascinating topic of adhesion in foods. The first two chapters deal with definitions and nomenclature for adhesion, its mechanisms and measurements. Chapters 3 through 9 deal with various aspects of food adhesion: stickiness in foods and its relation to technological processes, perception of stickiness, hydrocolloids as adhesive agents for foods, adhesion phenomena in coated, battered, breaded, and fried foods, electrostatic adhesion in foods, multilayered adhered food products, and adhesion of substances to food packages and cookware. My hope is that this manuscript will assist readers who are in search of comprehensive knowledge about the fascinating field of adhesion in foods, as well as those seeking up‐to‐date information on the very different current and past uses and applications of edible adhesives and glues in many areas. Comments and questions from these readers will be very much appreciated.
I wish to thank the publishers for giving me the opportunity to write this book. Special thanks to Nigel Balmforth for his efficient contribution to the formation and processing of this manuscript. I wish to thank my editor, Camille Vainstein, for working shoulder‐to‐shoulder with me when time was getting short, and Yaara Nussinovitch, for her exceptional assistance in finalizing this manuscript. Adriana Szekely's help in locating and rectifying the many old or inaccurate references was above and beyond the call of duty. The permissions that we obtained from various publishers are warmly acknowledged. Special thanks to Bjørn Christian Tørrissen, from bjornfree.com, for the photograph of the underside of a gecko's foot, and Forest Starr & Kim Starr for use of one of their excellent botanical pictures. The many pictures adopted from Wikipedia are acknowledged in their turn, but I feel that it is equally appropriate here to recognize the many who have contributed to the gigantic educational achievement that is Wikipedia itself. I am grateful to Gal Sason and to the illustrator Lotem Sason for drawing the wonderful cover art for this book. The help of my colleague and friend Dr Omri Ben‐Zion of Nagum Company, Israel, who supported me with knowledge and advice, is very much appreciated.
I particularly want to thank my family, Varda, Yaara, Eran, and Yoav, for their love, patience, and support. Last, but not least, I wish to thank the Hebrew University of Jerusalem for being my home and refuge for the last 25 years of very extensive research and teaching.
An adhesive is most simply described as a substance that causes one body to stick or adhere to another. The oldest adhesives were almost certainly fish or bone glues and these have been in use for many thousands of years. Due to the importance of glues and adhesion, the libraries are full of excellent books on the topic, covering: adhesion; adhesion molecules; adhesion of pathogens and bacteria; adhesion technology; fundamentals of adhesion; adhesion related to medicine and in health and disease; surface treatment and adhesion; adhesion of cells, viruses, and nanoparticles; adhesion and adhesives; adhesion promotion techniques; adhesion measurement methods; adhesion of dust and powder; adhesion and bonding in composites; and adhesion measurements of films and coatings, to name but a few.
Adhesion is a very important feature in food throughout its manufacturing, packaging, and storage. Nevertheless, to the best of our knowledge, there is not even one published manuscript that is fully devoted to food adhesion. During many years of research and development at the Hebrew University of Jerusalem and in the industry, I have been involved in studying hydrocolloid wet glues, adhesion related to edible coatings, adhesion in the manufacturing of multilayered food products, pressure‐sensitive adhesives, and tests to check adhesion in foods. Furthermore, I have written several chapters on adhesion related to hydrocolloids, foods, and specialized adhered textures in both my previous books and those of others. The following proposed manuscript outline consists of chapters that are all devoted to the fascinating topic of adhesion in foods.
To the layman, adhesion is a simple matter of how well two different materials stick together, and adhesion measurements provide some indication of the force required to separate them. This chapter will steer the reader to a more scientific definition of adhesion that can be useful for a variety of purposes. Also included are comments on nomenclature and usage and a short review of the history of adhesion.
Mechanisms involved in materials' adhesive processes are related to many fields, including mechanics, thermodynamics, and chemistry. Many theories have been developed to explain adhesion. These include mechanical interlocking, wetting and thermodynamic adsorption, electrostatic adhesion, diffusion, chemical adhesion, and weak boundary layers, and they are all briefly reviewed in this chapter. An overview of useful adhesion‐evaluation methods is also provided, among them weighing, UV absorbance measurements, and adhesive loss measurements. In addition, adhesion strength measurements are reviewed, as well as destructive and non‐destructive methods related to mechanical testing of adhesive joints by tensile test, shear test, and peel test. These tests can be regarded as static tests. Other adhesive tests are also described, including dynamic loading, creep, impact, and fatigue.
Stickiness is a common characteristic of foods. This chapter gives examples of stickiness in different food types. These include, but are not limited to, stickiness of dough and rice, sticky sweets, stickiness in sugar‐rich foods—soft cookies, toffees, and dried fruit—and in some dishes, such as sticky toffee pudding, stickiness of pasta through cooking, stickiness of semi‐solid foods and food powders, stickiness of non‐fat processed cheeses, jams, food powders, and jaggery granules. This chapter also provides a general introduction to other chapters in which various types of food stickiness/adhesion are discussed in more depth. The relationships between technological processes and stickiness are also described, for example, in spray‐drying and freeze–thawing processes with food products, and in the milk industry.
In word‐association tests with consumers, sticky was the fourth most frequent word used by a panel of 30 university students, and was strongly positively correlated with thick and viscous, and negatively correlated with thin and runny. Stickiness consequently appears to be a readily identifiable textural attribute in foods, but one that is not a major determinant of consumer appeal. It may have an important secondary effect as a negative hedonic factor under certain circumstances, if levels become excessive. This chapter will deal with the perception of stickiness, what affects sensory stickiness, and the correlation of consumer rating of stickiness with objective measurements.
The adhesive properties of many hydrocolloids (gums) have been known for centuries. The word gum means a sticky substance, and has been defined as such. A large number of hydrocolloids have been mentioned in the literature as adhesive agents, and they are briefly mentioned throughout this chapter. Except for individual gums that can be used as is or in adhesives, mixtures of gums and their adhesive potential will also be described for their role in the food and other industries. Special emphasis will be placed on protein hydrocolloids and gum exudates as adhesive agents in foods.
Battered and breaded foods represent a fast‐growing category in most high‐convenience consumer societies. As a result, the per capita consumption of battered and breaded foods is on the rise, as is the annual volume of formulated batters and breadings produced. Moreover, battered and breaded foods are becoming quite common in developing countries. This chapter deals with the effects of ingredients used in batters on the adhesion characteristics of deep‐fat‐fried products, adhesion in fried battered nuggets, performance of different hydrocolloids as pre‐dusts, effect of proteins in improving adhesion in deep‐fat‐fried products, new batters and breadings, the influence of freeze–thaw cycles and the presence of phosphate on the adhesion of commercially produced batter fry coatings to frozen products, and the effect of freezing on breading adhesion.
Electrostatic adhesion is a significant force in the paint and other industries. Nevertheless, food coating involves powders and targets with properties that are far from ideal for electrostatic coating. In addition, the adhesion must be long‐lasting to be useful. This chapter explores the significance of electrostatic adhesion in food coating. The discussion includes descriptions of a range of food powders that have been coated on different kinds of foods electrostatically and non‐electrostatically, and the measured adhesion. In addition, the correlation between effectiveness of the process and resistivity or oil content of the target, resistivity of the powder, and particle size will be explained. Finally, the influence of low relative humidity on electrostatic adhesion will be described in detail.
A simple way of achieving different textures and tastes in the same bite is to construct a food product made of different layers. The chapter starts by describing a few such multilayered products. It also describes how these layers are adhered together, and how some of the mechanical properties of the layered array can be estimated from the properties of the individual layers. The chapter will also focus on different adhesion techniques for multilayered gels and on the adhesion‐strength characteristics of double‐layered gels. A small part of the chapter will discuss these techniques as unique for future products in the food industry and for the development of novel foods and cooking.
The sticking of foods to their packaging is generally regarded as undesirable, resulting in possible damage to the packing material, product loss, and disfigurement of the product surface. It can be surmised that the extent to which this generates an adverse consumer reaction will depend on the extent of the sticking, on the type and cost of the product, and on the availability of alternative product packaging combinations. Adhesion of oils and fatty food products to packages is an important storage problem, because it increases product–package interactions that alter quality. Reducing such adhesion would reduce the costs of recycling and cleaning processes. The aim of this chapter is to demonstrate that some thermodynamic adhesion models are correlated to edible oils’ bulk adhesion as measured experimentally. Models of adhesion will be described for their ability to calculate a solid’s surface tension and the thermodynamic work of adhesion.
This book is designed to serve as a guide for those who want to introduce the fascinating world of food adhesives to the public. It is expected to serve as a useful addition to the traditional libraries of universities and research institutes where food science, food chemistry, life sciences, and other practical and theoretical industrial issues are taught and studied. In this sense, the book is unique, and I am confident that it will be a great success. My hope is that this book will assist all levels of readers. It is dedicated not only to the academic community but also to the broader population of industrialists and experimenters who will find it to be not only a source of knowledge, but also a launching pad for novel ideas and inventions. In particular, this book is expected to be of interest to personnel involved in food formulation, food scientists, food technologists, industrial chemists and engineers, and those who are working in product development.