Modern biopolymer science bridging the divide between fundamental treatise and industrial application

Tai Lieu Chat Luong Academic Press is an imprint of Elsevier 32 Jamestown Road, London NW1 7BY, UK 30 Corporate Drive, Suite 400, Burlington, MA 01803, USA 525 B Street, Suite 1900, San Diego, CA 92101-4495, USA First edition 2009 Copyright Ó 2009 Elsevier Inc All rights reserved No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means electronic, mechanical, photocopying, recording or otherwise without the prior written permission of the publisher Permissions may be sought directly from Elsevier’s Science & Technology Rights Department in Oxford, UK: phone (+44) (0) 1865 843830; fax (+44) (0) 1865 853333; email: permissions@elsevier.com Alternatively visit the Science and Technology Books website at www.elsevierdirect.com/rights for further information Notice No responsibility is assumed by the publisher for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions or ideas contained in the material herein Because of rapid advances in the medical sciences, in particular, independent verification of diagnoses and drug dosages should be made British Library Cataloguing in Publication Data A catalogue record for this book is available form the British Library Library of Congress Cataloging-in-Publication Data A catalog record for this book is available from the Library of Congress ISBN: 978-0-12-374195-0 For information on all Academic Press publications visit our website at www.elsevierdirect.com Printed and bound in United States of America 09 10 11 12 13 10 Contributors Erik van der Linden Agrotechnology and Food Sciences Group, Wageningen University, Wageningen, The Netherlands Anthony R Bird Commonwealth Scientific and Industrial Research Organisation, Food Futures National Research Flagship, and CSIRO Human Nutrition, Adelaide, Australia Charles Stephen Brennan Hollings Faculty, Manchester Metropolitan University, Manchester, UK Amparo Lopez-Rubio Australian Nuclear Science and Technology Organisation, Bragg Institute, Menai, Australia Margaret Anne Brennan Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand David Julian McClements Department of Food Science, University of Massachussets Amherst, Amherst, USA Sarah L Buckley Edwin R Morris Department of Food & Nutritional Sciences, University College Cork, Ireland Highton, Australia Allan H Clark Pharmaceutical Science Division, King‘s College London, London, UK Vic J Morris Phil W Cox School of Engineering-Chemical Engineering, University of Birmingham, Edgbaston, UK Institute of Food Research, Colney, UK Ian T Norton School of Engineering-Chemical Engineering, University of Birmingham, Edgbaston, UK Steve W Cui Guelph Research Food Centre, Agriculture and Agri-Food Canada, Guelph, Canada David E Dunstan Chemical & Biomolecular Engineering, University of Melbourne, Victoria, Australia Amos Nussinovitch Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, Rehovot, Israel E Allen Foegeding Department of Food Science, North Carolina State University, Raleigh, USA Kunal Pal Department of Chemistry and Biology, Ryerson University, Toronto, Canada Michael J Gidley Centre for Nutrition & Food Sciences, University of Queensland, Brisbane, Australia Allan T Paulson Department of Chemistry and Biology, Ryerson University, Toronto, Canada Liam M Grover School of Chemical Engineering, University of Birmingham, Edgbaston, UK Keisha Roberts Guelph Research Food Centre, Agriculture and Agri-Food Canada, Guelph, Canada Victoria A Hughes Chemical & Biomolecular Engineering, University of Melbourne, Victoria, Australia Yrjoă H Roos Department of Food & Nutritional Sciences, University College Cork, Ireland Stefan Kasapis School of Applied Sciences, RMIT University, Melbourne, Australia Simon B Ross-Murphy Pharmaceutical Science Division, King’s College London, London, UK Sandra I Laneuville Dairy Research Centre STELA and Institute of Nutraceutical and Functional Foods INAF, Laval University, Quebec, Canada De´rick Rousseau School of Nutrition, Ryerson University, Toronto, Canada Ashok K Shrestha Centre for Nutrition & Food Sciences, University of Queensland, St Lucia, Australia Peter J Lillford CNAP-Department of Biology, The University of York, York, UK vii viii CONTRIBUTORS Alan M Smith School of Chemical Engineering, University of Birmingham, Edgbaston, UK Fotios Spyropoulos School of Engineering-Chemical Engineering, University of Birmingham, Edgbaston, UK Sylvie L Turgeon Dairy Research Centre STELA and Institute of Nutraceutical and Functional Foods INAF, Laval University, Quebec, Canada Johan B Ubbink Nestle Research Centre Switzerland, Savigny, Switzerland Preface It has been a while since a book was put together to address the issues of the physics and chemistry of biopolymers in industrial formulations, including concise treatments of the relation between biopolymer functionality and their conformation, structure, and interactions In these intervening years, some materials and concepts came to prominence while other ones have changed in their appeal or application As ever, the industrialist is faced with the challenge of innovation in an increasingly competitive market in terms of ingredient cost, product added-value, expectations of a healthy life-style, improved sensory impact, controlled delivery of bioactive compounds and, last but not least, product stability Proteins, polysaccharides and their co-solutes remain the basic tools of achieving the required properties in product formulations, and much has been said about the apparent properties of these ingredients in relation to their practical use There is also an ever increasing literature on the physicochemical behaviour of well-characterised biopolymer systems based on the molecular physics of glassy materials, the fundamentals of gelation, and component interactions in the bulk and at interfaces It appears, however, that a gap has emerged between the recent advances in fundamental knowledge and the direct application to product situations with a growing need for scientific input The above statement does not detract from the pioneering work of the forefathers in the field who developed the origins of biopolymer science For example, there is no question that the pioneering work on conformational transitions and gelation, the idea of phase separation into water in emulsions, the development of physicochemical understanding that lead to the concept of fluid gels and the application of the glass transition temperature to dehydrated and partially frozen biomaterials has resulted not only in academic progress but in several healthy and novel products in the market place Thus the first phase of the scientific quest for developing comprehensive knowledge at both the theoretical and applied levels of functional properties in basic preparations and systems has largely been accomplished It is clear, though, that the future lies in the utilization of this understanding in both established and novel foodstuffs, and non-food materials (e.g pharmaceuticals) with their multifaceted challenges A clear pathway for processing, preservation and innovation is developing which is particularly important if progress is to be made in the preparation of indulgent yet healthy foods which are stable, for example, in distribution and storage This requires a multi-scale engineering approach in which material properties and microstructure, hence the product performance are designed by careful selection of ingredients and processes Examples of this can be found in the pioneering work on fat replacement and the reliance on the phenomenon of glass transition to rationalise the structural stability and mouthfeel of a complex embodiment Within this context of matching science to application, one feels compelled to note that a dividing line has emerged, which is quite rigorous, with researchers in the structurefunction relationships of biopolymers opting to address issues largely in either high or low-solid systems This divide is becoming more and more ix x PREFACE pronounced, as scientists working in the highsolid regime are increasingly inspired by the apparently ‘‘universal’’ molecular physics of glassy materials, which may or may not consider much of the chemical detail at the vicinity of the glass transition temperature By comparison, their colleagues working on low-solid systems are shifting their focus from the relatively universal structure-function relationships of biopolymers in solution to the much more specific ones involving multi-scale assembly, complexation and molecular interactions Sharing the expertise of the two camps under the unified framework of the materials science approach is a prerequisite to ensuring fully ‘‘functional solutions’’ to contemporary needs, spanning the full range of relevant time-, lengthand concentration scales This effort may prove to be the beginning of a modernized biopolymer science that, one the one hand, utilizes and further develops fundamental insights from molecular physics and the advanced synthetic polymer research as a source of inspiration for contemporary bio-related applications On the other hand, such modernized science should be able to forward novel concepts dealing with the specific and often intricate problems of biopolymer science, such as the strong tendency for macromolecular hydrogen bonding, thus serving as an inspiration for related polymer advances and industrial applications Sincere thanks are due to all our friends and colleagues whose outstanding contributions within their specialized areas made this a very worthwhile undertaking Stefan Kasapis Ian T Norton Johan B Ubbink C H A P T E R Biopolymer Network Assembly: Measurement and Theory Allan H Clark and Simon B Ross-Murphy King’s College London, Franklin-Wilkins Building, 150 Stamford Street, London, UK A number of biopolymer systems can selfassemble to form networks and gels and the assembly can occur by a variety of mechanisms In this chapter we consider the nature of biopolymer gels and networks, the kinetics of assembly, and their characterization by rheological methods The necessary theory to explain, for example, the complexities of gelation kinetics is then described in some detail Before reaching this, we discuss the nature of network assembly, and the character of gels and their gelation are important for synthetic polymer systems, but are less relevant for biopolymers Here, where the solvent is water or electrolyte, we can also introduce the term ‘hydrogel’ 1.1.1.2 What is a Gel? We have already defined a gel above as a swollen polymer network, but unfortunately, one of the major issues in chapters such as the present one is that the term ‘gel’ means very different things to different audiences In this respect, the widely cited 1926 definition by Dorothy Jordan Lloyd, that ‘the colloidal condition, the gel, is one which is easier to recognize than to define’ (Jordan Lloyd, 1926) is quite unhelpful, since it implies that a gel is whatever the observer thinks it is Consequently we commonly see such products described as shower gels and pain release or topical gels Neither of these classes of systems follows a rheological definition such as that of the late John Ferry, in his classic monograph (Ferry, 1980) He suggests that a gel is a swollen polymeric system showing no steady-state flow; in other words if subjected to simple steady shear deformation it will fracture or rupture Clearly neither shower nor topical gels follows this rule; 1.1 BIOPOLYMER NETWORKS AND GELS 1.1.1 Gels Versus Thickeners 1.1.1.1 What is a Polymer Network? Polymer networks are molecular-based systems, whose network structure depends upon covalent or non-covalent interactions between macromolecules The interactions can be simple covalent cross-links, or more complex junction zone or particulate-type interactions Figure 1.1 illustrates different types of polymer network Solvent swollen polymer networks are commonly known as gels – un-swollen networks Kasapis, Norton, and Ubbink: Modern Biopolymer Science ISBN: 978-0-12-374195-0 Ó 2009 Elsevier Inc All rights Reserved BIOPOLYMER NETWORK ASSEMBLY: MEASUREMENT AND THEORY FIGURE 1.1 These diagrams illustrate three different types of polymer network; note that the three figures are not necessarily to scale indeed if they did, they would not be useful as products In fact, commercial shower gels, for example, are simply highly viscous fluids formed by the entanglement of (often rod-like) micelles For more rigorous definitions, at this stage it is necessary to introduce some common terminology Most modern rheological experiments on gelation (see below) employ oscillatory shear In the simplest form of this, a small sinusoidal strain wave of frequency u (typically 103–10 s1) is applied to the top surface of a gelling system (most likely constrained between parallel metal discs) and the resultant stress transmitted through the sample is measured In general the stress and strain waves differ in both phase and amplitude, but using phase resolution, it is easy to extract the in-phase and 90o out-of-phase components Then G0 is the storage modulus given as the ratio of in-phase stress divided by strain, and G00 is the loss modulus, the ratio of 90o out-of-phase stress to strain There are other relationships between these and common experimentally determined parameters, as we describe later, but for now we are interested only in the storage – sometimes called elastic component – of the modulus, G0 For a perfect, so-called Hookean elastic material, such as a steel rod, G0 is effectively independent of the oscillatory frequency The constancy of G0 with respect to frequency is then a useful definition of a solid One rheological definition of a gel is therefore a system that shows ‘a plateau in the real part of the complex modulus’ – G0 – ‘extending over an appreciable window of frequencies they are viscoelastic solids’ (Burchard and Ross-Murphy, 1990) A slightly later definition accepts this, but extends it and the Ferry definition by identifying a gel as a soft, solid or solidlike material, which consists of two or more components, one of which is a liquid, present in substantial quantity (Almdal et al., 1993) They therefore follow Ferry in accepting substantially swollen polymer networks as gels However, according to them, a gel must also show a flat mechanical spectrum in an oscillatory shear experiment In other words it should show a value of G0 which exhibits a pronounced plateau extending to times of the order of seconds, and a G00 which is considerably smaller than the storage modulus in this region 1.1.1.3 ‘Viscosifiers’ One of the problems in this area follows directly from the overuse of the term gel – as we outlined above, many viscous fluids are also described as gels or hydrogels These include biopolymer solutions, whose properties are determined all but exclusively by entanglements of long chains, in this area typically represented by solutions of the galactomannan guar These are analogous to solutions of common synthetic polymers in organic solvents, where entanglements involve reptation of chains (Doi and Edwards, 1986) Rheologically there are also a number of so-called structured liquids – which can suspend particles and appear BIOPOLYMER NETWORKS AND GELS solid-like – typically formed from liquid crystalline polymers or micellar solutions – and usefully exemplified in the present context by ordered solutions of the microbial polysaccharide xanthan (Richardson and RossMurphy, 1987b) To confuse matters, these have been referred to, in the past, including by one of the present authors as ‘weak gels’ (RossMurphy and Shatwell, 1993) We now reject this term totally, both because of its anthropomorphic connotation, and for its lack of precision – since they can show steady-state flow – in terms of the Ferry definition above 1.1.1.4 Viscoelastic Solids vs Viscoelastic Liquids What then is the main difference between solids and liquids? It is the existence of an equilibrium modulus, i.e a finite value of G0 even as the time of measurement becomes very long (or the oscillatory frequency tends to zero), usually referred to simply as the equilibrium shear modulus G This means that a gel has (at least one) infinite relaxation time Of course such a definition is partly philosophical, since given infinite time, all systems show flow, and in any case, most biopolymer gels will tend to degrade, not least by microbial action However, this remains an important distinction, and in subsequent pages we regard biopolymer networks and gels as viscoelastic solids, and non-gelled systems, included pre-gelled solutions, ‘sols’, as viscoelastic liquids 1.1.2 Brief History of Gels 1.1.2.1 Flory Types 1–4 Historically the term gel follows from the Latin gelatus ‘frozen, immobile’, and gelatin, produced by partial hydrolysis of collagen from, e.g pigs, cattle or fish was probably recognized by early man Gelatin has certainly been used in photography for almost 150 years, although this is, of course, a shrinking market In 1974, Flory (Flory, 1974) proposed a classification of gels based on the following: Well-ordered lamellar structure, including gel mesophases Covalent polymeric networks; completely disordered Polymer networks formed through physical aggregation, predominantly disordered, but with regions of local order Particular, disordered structures In the present chapter, although we will not discuss specific systems in much depth, type gels are represented by ‘cold set’ gelatins, and type gels are represented by denatured protein systems Type systems are archetypal polymer gels These are made up, at least formally, by cross-linking simpler linear polymers into networks, and their mechanical properties, such as elasticity, reflect this macroscopic structure 1.1.2.2 Structural Implications The structural implications of the above should be clear – gels will be formed whenever a super-molecular structure is formed, and Figure 1.1 illustrates the underlying organization of type 2, and gels Of course this is highly idealized; for example if the solvent is ‘poor’, gel collapse is seen Examples of each of these classes include the rubber-like arterial protein elastin – type 2; many of the gels formed from marine-sourced polysaccharides such as the carrageenans and alginates, as well as gelatin, type 3; and the globular protein gels formed by heating and/or changing pH, without substantial unfolding, type Of course, Figure 1.1 is highly idealized and the nature of network strands can vary substantially For example, for the polysaccharide gels, such as the carrageenans, the classic Rees model of partial double helix formation (Morris et al., 1980) has been challenged by both small-angle X-ray scattering (SAXS) and atomic force microscopy (AFM) BIOPOLYMER NETWORK ASSEMBLY: MEASUREMENT AND THEORY measurements, and it now seems likely that aggregation of junction zones and intertwining of pre-formed fibrils are additional contributory factors This is certainly an on-going controversy, but one outside the remit of this chapter, except for its implications for the kinetic processes occurring during gelation There are similar variations for protein gels too When heated close to the isoelectric point, a coarse and random coagulate network is commonly formed but heating many globular proteins above their unfolding temperatures under acid conditions – say at pH – results in fibrillar structures (Stading et al., 1992) that, at least at the nano-length scale, resemble the amyloid structures seen in a number of critical diseases such as Alzheimer’s (Gosal, 2002; Gosal et al., 2002; Dobson, 2003) This is now a very active area of research, but the subject of a separate chapter in this volume (Hughes and Dunstan, 2009) used to raise a small metal sphere within a tube containing gelling material, and then the time taken to fall a fixed distance is registered (Richardson and Ross-Murphy, 1981) Clearly as gelation proceeds from the sol state, the rate of fall decreases, and eventually the sphere does not move any more For low modulus systems there are potential problems since the sphere may locally rupture the gel and cut a channel through it – so-called ‘tunneling’ – and in this limit the method is more akin to a large deformation or failure method The converse method of monitoring the fall of a sphere above a melting gel (or a series of such samples at different concentrations) is very commonly used to determine ‘melting temperatures’ (Eldridge and Ferry, 1954; Takahashi, 1972), but again care must be taken to ensure that true melting is involved rather than localized pre-melt tunneling 1.2.1.2 Oscillatory Microsphere 1.2 RHEOLOGICAL CHARACTERIZATION OF BIOPOLYMER GELS A number of more traditional techniques have been used for gel measurements They often have a major advantage in their low cost, compared to commercial apparatus On the debit side, the actual strain deformation is sometimes unknown or, at best, requires calibration Nowadays these approaches are less commonly employed, as almost all labs possess at least one oscillating rheometer, but they still have some advantages – not least from the financial viewpoint The microsphere rheometer is just the oscillatory analogue of a falling ball system A small magnetic sphere is placed into the sample and using external AC and DC coils, the sphere can be positioned and made to oscillate with the frequency of the AC supply The maximum deformation can be observed with a traveling microscope, or alternatively tracked, for example, using a position-sensitive detector array A number of different designs have been published and used for measurements on systems including agarose and gelatin gels, and mucous glycoproteins (King, 1979; Adam et al., 1984) The major limitation is that the measurement is very localized, so that again for some systems local rupture and tunneling can occur and then the modulus determined may not be representative of the whole system 1.2.1.1 Falling Ball 1.2.1.3 U-tube Rheometer This is one of the simplest and cheapest methods but, given a few precautions, it can still prove useful In its simplest form, a magnet is In this very simple assembly, originally designed by Ward and Saunders in the early 1950s for work on gelatin, the gel is allowed to 1.2.1 Traditional Methods for Gel Characterization TISSUE ENGINEERING support the formation of fibroblasts and chondrocytes Although it is a complex set of environmental stimuli, both chemical and mechanical, that are known to stimulate the formation of these different cell types and not mechanotransduction alone, providing a suitable mechanical environment to encourage the formation of the desired cell type is obviously an important consideration in the design of a suitable scaffold material 18.2.5 Microengineering of Hydrogels In the body tissues are permeated by a network of blood vessels which serve to supply cells encapsulated within the ECM with nutrients and oxygen and also to remove their metabolic waste products The absence of blood vessels within the majority of tissue engineering scaffolds means that the size of a tissue that can be engineered in vitro is hindered by mass transport limitations There are two ways in which these mass transport problems can be solved: (1) ‘microgels’ may be formed, which when laden with cells can be self assembled to form tissues; (2) hydrogel monoliths can be precisely structured to form a network of capillarylike channels, which enable mass transport or the precise delivery of small quantities of nutrients or active molecules to the cell population The production of both kinds of structure has been made possible by the increased availability of microfabrication facilities, which enable the production of precisely defined polymeric or silicon based molds 18.2.5.1 Microgels The fabrication of microgels of controlled morphology formed by a process of soft-lithography from alginate has previously been reported by Qiu et al (2007) They demonstrated that it was possible to generate alginate particles of defined morphology down to the order of 10 mm and suggested that the increased surface area to 613 volume ratio of the gels would negate masstransport problems Such processing methodologies have enabled researchers to take a new ‘bottom-up’ approach to the development of tissue-engineered structures, allowing more control over tissue structure than ever before By directing the assembly of controlled morphology particles containing cells capable of forming different tissues, it is possible to effectively design complex tissue interfaces at the microlevel Recent work by the Khademhosseini group (Du et al., 2008), for example, has demonstrated that it is possible to direct the assembly of similar gel-based structures into structurally complex multi-tissue constructs by exploiting the tendency of liquid–liquid systems to minimize their surface energy The rapid progress in this area is extremely exciting as it will enable the production of ever more complex structures, opening up the possibility of forming extremely complex tissues with precisely defined biological and mechanical properties in vitro 18.2.5.2 Microfluidic Scaffolds Microchanneled hydrogel structures have also recently been reported in the literature Choi et al (2007) formed a precisely microchanneled alginate structure using soft-lithography Using a micromachined silicon surface, it is possible to form channeled structures with very precisely defined structures with feature sizes down to 30 mm by gelling the alginate on the surface of a silicon wafer (Figure 18.7) The presence of the aligned pore structure throughout the hydrogel monolith would have helped to address mass transport issues, but importantly such channels allow the chemical environment of the encapsulated cells to be precisely controlled by means of the delivery of precise quantities of growth factors and other stimuli In common with the manufacture of microgels, this approach to some extent would enable the production of complex tissue interfaces in vitro In addition, it is possible that this technology could allow us to develop 614 18 HYDROCOLLOIDS AND MEDICINAL CHEMISTRY APPLICATIONS a c b d FIGURE 18.7 The fabrication of a microchanneled structure using a micromachined silicon surface as a mold (A, B and C) The alginate structures cast onto the surface showed good feature reproduction (D) high-throughput assays to evaluate cell and tissue response to a range of chemical stimuli Developing such technologies is becoming more important in a range of different industrial sectors as the use of animal testing to determine the biological response to a range of both chemicals and drugs is becoming increasingly taboo 18.3 FUTURE HORIZONS Biopolymer-derived hydrogels are now used widely in the delivery of drugs and are finding increased use in the fabrication of 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nanosphere with chitosan improved pulmonary delivery of calcitonin by mucoadhesion and opening of the intercellular tight junctions Journal of Controlled Release 102, 373–381 Zhang, L., Russell, D., Conway, B R., and Batchelor, H (2008) Strategies and therapeutic opportunities for the delivery of drugs to the esophagus Critical Reviews in Therapeutic Drug Carrier Systems 25, 259–304 Index AD, see Alzheimer’s disease Adsorption–inhibition model, antifreeze proteins, 118 Adsorption kinetics, emulsifiers, 160 AFGP, see Antifreeze proteins AFM, see Atomic force microscopy AFP, see Antifreeze proteins Alginate coatings fruits and vegetables, 309–310 meat and seafood, 305–306 controlled-release delivery systems applications, 520 diffusion-controlled systems, 545–546 encapsulating agents, 546–547 gelling agents in situ, 546 ophthalmic drug delivery systems, 547 oral delivery systems, 546 overview, 544–545 wound-healing materials, 547 Alzheimer’s disease (AD), amyloid fibrils, 561–563 Amyloid fibrils analytical techniques atomic force microscopy, 568, 574–575 circular dichroism, 567, 571, 575 electron microscopy, 568 fluorescence, 566–567, 570–571 Fourier transform infrared spectroscopy, 567 light scattering, 567 nuclear magnetic resonance, 567–568 X-ray diffraction, 567, 574 application prospects, 588–589 biotechnology implications, 564 detection assays, 574–579 diseases, 561–563 dyes, 575–578 formation pathways nucleation conformational model, 565 nucleation-dependent polymerization, 565 off pathway model, 565–566 partially-folded intermediates, 566 formation promotion chemical factors, 581–582 mutations, 582 overview, 579–581 protein interface, 582–584 shear, 582 temperature, 581 gels, 586–588 kinetics of formation, 579 nano tubes and nano wires, 585–586 natural functions, 563–564 overview of properties, 560–561 pharmaceutical implications, 564 protein aggregation studies fluorescence, 574 imaging, 574 light scattering, 573–574 overview, 572–573 sedimentation velocity, 573 protein misfolding, 559, 564 soluble intermediate studies, 568–572 strength and stability, 584 structural variants b-helix, 579 nanotubes, 579 spherulites and capsids, 579 topography and surface interactions, 585 toxicity, 563 Antifreeze proteins applications, 121–124 discovery, 93 economics, 123 evolution, 94 function, 93–94 619 ice binding studies AFGP, 106–107 AFP I native and synthetic protein binding studies, 104–105 motif for ice binding, 105–106 AFP III, 107–108 ice hemisphere binding site technique, 109 plant proteins, 108–109 ice crystal shape antifreeze protein effects AFP I, 113–114 AFP II, 115–116 AFP III, 114–115 AFP IV, 116 AFP mixtures, 115 nanoliter osmometry principles, 112–113 plant proteins, 116–117 growth principles, 109–111 morphology in solution, 111 mechanism of function adsorption–inhibition model, 118 Button Mattress model, 120 Hall and Lipps model, 120–121 Kelvin effect, 119 properties ice surface-binding site, 101–102 protein-binding sites, 102–103 recrystallization inhibition, 99–101 thermal hysteresis, 98–99 recombinant protein generation, 123–124 species distribution, 94 types and structures Daucus carota protein, 97–98 fish proteins AFGP, 94–95 AFP I, 95–96 AFP II, 96 AFP III, 96 insect and plant proteins, 96–97 620 Antifreeze proteins (Continued ) Lolium perennae protein, 98 spruce budworm larvae protein, 97 Atomic force microscopy (AFM) amyloid fibrils, 568, 574–575 applications gels and networks polysaccharide gels, 374–376 protein gels, 376 protein networks, 377 plant cell walls, 385–386 polysaccharides, 370–371 protein–polysaccharide complexes, 371–373 proteins, 371 protein–surfactant interactions, 377–380 starch, 380–385 force measurements and mapping, 387–391 image formation, 365–366 imaging modes, 366–369 overview, 365 surface roughness measurement, 386–387 Binding affinity, emulsifiers, 160 Biopolymer film, see Film, biopolymer Blending laws, see Gelling biopolymer mixtures Branching theory experiments versus theory, 19–21 models and phase separation, 21–22 overview, 14–18 Bridging flocculation, biopolymer emulsifiers, 161 Button Mattress model, antifreeze proteins, 120 Caffeine, diffusion in high-solids carbohydrate matrix, 248–250 Caking, mechanisms, 271–272 Calcium pectinate, see Gelling biopolymer mixtures Carbohydrate glass aging and structural aspects, 284–285 analytical techniques, 278–279 applications, 277–278, 287 encapsulated citrus oil oxidation studies, 290–291 glass transition and dynamic properties, 285–288 INDEX lipid vesicle stabilization, 291 molecular packing, 281–284 phase transitions, 277–278 prospects for study, 292 water effects, 279–281, 288–289 Carboxymethylcellulose (CMC), coating of fruits and vegetables, 310–311 Carrageenan controlled-release delivery systems, 520 deacetylated konjac glucomannan and k-carrageenan gelling mixture, 192 CD, see Circular dichroism Cellulose controlled-release delivery systems applications, 520 esters for drug delivery, 543–544 overview, 542–543 temperature sensitivity, 543 Cereal, see Fiber, dietary Chelating capacity, dietary fiber, 411–412 Chitin/chitosan controlled-release delivery systems applications, 520 cardiovascular delivery systems, 542 chemically-modified systems for drug delivery, 541–542 gelling agents in situ, 542 matrices for biologically active agents, 540s ocular delivery systems, 542 overview, 540 particle systems, 541 stimuli-responsive systems, 541 Chitosan cell-adhesive hydrogels, 608 coatings fruits and vegetables, 310 meat and seafood, 307 Circular dichroism (CD), amyloid fibrils, 567, 571, 575 CMC, see Carboxymethylcellulose Coacervation, see Protein + polysaccharide mixed systems Coalescence, emulsion instability, 142–144 Collagen cell-adhesive hydrogels, 606–607 controlled-release delivery systems applications, 520 cross-linking, 534–535 gene and hormone delivery, 535 matrices for drug delivery, 536 ophthalmic drug delivery, 535 oral delivery system formulations, 535–536 overview, 534 film formation, 297 Collapse phenomena, glass transition temperature, 271–272 Collision efficiency, emulsion droplets, 142 Collision frequency, emulsion droplets, 142 Colloidal cluster, gels, 40–42 Congo red, amyloid fibril staining, 575–576 Controlled-release delivery systems, see also Ocular drug delivery; Oral drug delivery alginate systems applications, 520 diffusion-controlled systems, 545–546 encapsulating agents, 546–547 gelling agents in situ, 546 ophthalmic drug delivery systems, 547 oral delivery systems, 546 overview, 544–545 wound-healing materials, 547 cellulose systems applications, 520 esters for drug delivery, 543–544 overview, 542–543 temperature sensitivity, 543 chitin/chitosan systems applications, 520 cardiovascular delivery systems, 542 chemically-modified systems for drug delivery, 541–542 gelling agents in situ, 542 matrices for biologically active agents, 540 ocular delivery systems, 542 overview, 540 particle systems, 541 stimuli-responsive systems, 541 collagen systems applications, 520 cross-linking, 534–535 gene and hormone delivery, 535 INDEX matrices for drug delivery, 536 ophthalmic drug delivery, 535 oral delivery system formulations, 535–536 overview, 534 crosslinking of matrix genipin, 530–531 glutaraldehyde, 529–530 overview, 529 polyelectrolytes, 532–533 quinones and phenols, 531–532 diffusion modeling Fick’s first law, 523 Fick’s second law, 523–524 measurement techniques, 522–523 drug loading and release, 521–522 gelatin systems applications, 520 implantable systems for wound healing, 538 matrices for biologically active agents, 539–541 nanoparticle and microparticle systems, 538–539 overview, 536 peptide delivery, 536–538 stimuli-responsive systems, 538 Higuchi’s model, 524–525 hydrogel types, 521–522 overview, 519–520 polymer–drug interactions, 533–534 prospects for study, 547–548 swelling controlled systems equilibrium swelling and Flory-Rehner theory, 527–528 overview, 525–526 pH-sensitive hydrogels, 526–527 stimulus-responsive delivery, 526 temperature-sensitive hydrogels, 526z Cooling rate, processing effects on fluid/sheared gels, 206, 229 C-reactive protein (CRP), dietary fiber response, 407 Creaming, emulsion instability, 141–142 Critical exponents, gelation theory, 22–23 Critical gel concentration, 12–13 CRP, see C-reactive protein Cryopreservation, antifreeze protein applications, 121–122 Daucus carota, antifreeze proteins, 97–98 Delivery systems, see Controlledrelease delivery systems Denaturation, protein, 59–63 Depletion flocculation, biopolymer emulsifiers, 161 Dextran, controlled-release delivery systems, 520 Diabetes, see also Glycemic response dietary fiber benefits, 404–407 resistant starch benefits, 460 Differential scanning calorimetry (DSC) electrostatic interactions of gelatin and pectin, 183 ethylcellulose structure in propylene glycol dicaprylate gel, 252–253 glass transition measurements, 267 non-interacting phase-separated gels, 231 resistant starch formation studies, 483 structure studies, 488 whey protein isolate co-gelation with crosslinked starch, 178–179 xanthan–konjac glucomannan interactions, 185–188 Diffusion modeling, controlled-release delivery systems Fick’s first law, 523 Fick’s second law, 523–524 measurement techniques, 522–523 Digestive processing mouth, 213–216 small intestine, 219–220 stomach, 216–219 Droplets, see Food emulsions Drug delivery, see Controlled-release delivery systems; Ocular drug delivery; Oral drug delivery DSC, see Differential scanning calorimetry EC, see Ethylcellulose Edible film, see Film, biopolymer Electron microscopy amyloid fibrils, 568 resistant starch studies, 486–488 Electrostatic interactions emulsion droplets, 138–139 gelatin and pectin, 182–184 621 protein + polysaccharide mixed systems charge density effects, 340 charge distribution effects, 340, 341 concentration effects, 339 conformation effects, 340 ionic strength effects, 340 mixing ratio effects, 339 molecular weight effects, 341 pH effects, 339–340 Emulsion, see Food emulsions; Water-in-water emulsions Ethylcellulose (EC) applications, 251 structure in propylene glycol dicaprylate gel, 251–253 External phase, emulsions, 129 Falling ball, gel characterization, Fat, dietary low-fat foods, 225–226 textural and mouthfeel implications of reduction in foods, 226–227 Fat-binding capacity (FBC), dietary fiber, 411 FBC, see Fat-binding capacity Fiber, formation by proteins, 67–70 Fiber, dietary analysis crude fiber method, 401–402 detergent methods, 401 enzymatic gravimetric method, 401 overview, 400–401 Southgate method, 401 Uppsala method, 402 cereal b-glucans commercial applications, 419–420 gelatin properties, 415–416 grain composition, 413 Konjac flour, 425 molecular weight and conformation, 413–415 organoleptic properties, 417–418 physiological properties, 417–418 psyllium, 420–426 structures, 413 viscoelastic properties, 417 challenges of study, 409 definitions, 399–400 insoluble fiber lemon albedo, 439 overview, 435–436 resistant starch, 441 622 Fiber, dietary (Continued ) rice bran, 439–440 wheat bran, 436 white grape dietary fiber, 439 inulins applications, 430 chemical properties, 427–428 digestion, 431 food sources, 426, 427 functional properties, 427–428 physiological effects immunomodulation, 433–435 lipid metabolism, 432–433 prebiotics, 435 short-chain fatty acid production, 432 side effects of fermentation, 435 production and processing, 427 physiological effects cardiovascular disease, 403–408, 435 diabetes, 404–407 overview, 402–404 prebiotic activity, 409 prospects for study, 439–440 regulatory issues, 409–410 starch digestibility manipulation in processed foods, 516–517 technological properties chelating capacity, 412 fat-binding capacity, 412 gel-forming capacity, 411–412 viscosity, 410–411 water-holding capacity, 411 Fibrils, see Amyloid fibrils Fibrin, cell-adhesive hydrogels, 607–608 Fibroblast growth factor, controlledrelease delivery systems, 537 Fick’s law, diffusion modeling in controlled-release delivery systems, 523–524 Filled gel effects, biopolymer emulsifiers, 161 Film, biopolymer application stages, 299 biopolymer selection, 300–301 coating solutions, 298–299 edible protective films food additive inclusion, 303–305 fried food coatings, 311–312 fruit and vegetable coatings, 308–311 INDEX meat and seafood coatings, 305–308 miscellaneous coatings, 312–314 novel products, 314–316 packaging materials fit for human consumption, 301–302 prospects, 316–318 evaluation, 299–300 formation mechanisms, 295–298 market, 295 non-food gum coatings, 316 Flavor partitioning, food emulsions, 151–152 Flocculation, emulsion instability, 142–143 Flory-Rehner theory, controlled-release delivery systems, 527–528 Flory–Stockmayer model, gelation kinetics, 13–14 Food emulsions appearance as quality factor, 149 biopolymer emulsifiers interfacial activity and emulsion stabilization, 153–154 overview, 152–153 polysaccharide emulsifiers gum arabic, 157 miscellaneous polysaccharides, 158 modified cellulose, 158 modified starch, 157 protein emulsifiers characteristics, 155–156 egg proteins, 156 meat proteins, 156 milk proteins, 156 plant proteins, 156–157 protein–polysaccharide complexes, 158 selection factors, 158–160 texture modification, 160–163 color factors affecting disperse phase volume fraction, 150 droplet size, 150 relative refractive index, 150 mathematical modeling, 149–150 droplet characteristics charge, 132 concentration, 131 droplet–droplet interactions, 133 interfacial properties, 132–133 size distribution, 131–132 flavor overview, 150–151 partitioning, 151–152 release, 152 homogenization in production devices, 137 emulsifier roles, 137 homogenization, 135 physical principles, 136–137 post-homogenization, 135–136 pre-homogenization, 133–135 rheology factors affecting continuous phase rheology, 147 disperse phase volume fraction, 148 droplet size, 148–149 droplet–droplet interactions, 148 measurements, 146 modeling, 146–147 stability droplet–droplet interactions electrostatic interactions, 138–139 hydrophobic interactions, 139–140 overall potential, 140–141 short-range forces, 140 van der Waals interactions, 138 instability mechanisms chemical and biochemical reactions, 145–146 coalescence, 142–143 creaming, 141–142 flocculation, 142–143 Ostwald ripening, 144–145 partial coalescence, 143–144 phase inversion, 145 sedimentation, 141–142 overview, 137–138 terminology, 129–131 Fourier transform infrared spectroscopy (FTIR) amyloid fibrils, 567 carbohydrate glass, 278 resistant starch studies, 492 Fractal models, gels, 23–24 FTIR, see Fourier transform infrared spectroscopy INDEX Gel, see also Gelling biopolymer mixtures; Gel network characterization controlled strain versus controlled stress rheometers, 6–7 falling ball, mechanical spectroscopy, 5–6 oscillatory microsphere, time-dependent systems gelation time measurement, 9–10 Ginf and equilibrium modulus, 11–12 kinetic gelation, 8–9 range of viscoelastic linearity, 11 Winter–Chambon method, 10–11 time-independent systems, 7–8 U-tube rheometer, 4–5 criteria, 30–31 definitions, 1–2 Flory classification, mechanical spectrum, 7–8 processing effects on fluid/sheared gels, 203–210 structure, 3–4 theory branching models and phase separation, 21–22 critical gel concentration, 12–13 exponents and critical exponents, 22–23 Flory–Stockmayer model, 13–14 fractal models, 23–24 gelation time, 13 lattice and off-lattice simulation, 24 random branching, 14–21 Gelatin calcium pectinate co-gels, see Gelling biopolymer mixtures controlled-release delivery systems applications, 520 implantable systems for wound healing, 538 matrices for biologically active agents, 539–540 nanoparticle and microparticle systems, 538–539 overview, 536 peptide delivery, 536–538 stimuli-responsive systems, 538 Gelation time extrapolation, 10 measurement, theory, 13 Gelling biopolymer mixtures associative interactions electrostatic interactions of gelatin and pectin, 182–184 overview, 168 xanthan–konjac glucomannan interactions, 184–188 low-solid versus high-solid binary co-gels experimental observations across range of solids, 242–243 mechanism of transformation to high-solid biomaterials, 243–244 structural properties with high cosolute levels, 245–248 viscoelasticity changes with cosolute level changes, 244–245 phase composition partition of polymers and solvent in biphasic co-gels, 173–174 segregation in solution state, 172–173 phase separation, 168–169 polymer blending laws applicability to biphasic networks, 170–172 gelatin–calcium pectinate co-gel analysis experimental design, 174–176 moduli analysis, 177 phase structure, 176–177 overview, 169–170 possible outcomes of mixing, 167–168 prospects for study, 193–194 segregative interactions in single-phase mixtures deacetylated konjac glucomannan and k-carrageenan, 192 guar gum effects on thermal gelation of whey protein isolate, 191–192 overview, 168 soluble biopolymer effects gelatin gelation, 192–193 gelation from single-phase mixtures, 193–194 self-association of calcium pectinate, 189–191 structural properties for two-phase synthetic polymer systems 623 dynamic solvent partition between phases, 238–240 filler shape and blending law refinement, 240–242 whey protein isolate co-gelation with crosslinked starch blending law analysis, 181–182 differential scanning calorimetry, 178–179 generation, 178 phase structure, 180–181 starch networks, 179–180 Gel network building block morphology, gel structure, and variations, 53–54 modeling arrested states and gelation, 50–51 colloidal cluster, 40–42 linear branch theory, 33–34, 39–40 overview, 30–35, 51, 56–57 percolation, 32–39 phase separation and structural transitions, 42–50 morphology, elements, and structural details, 52 protein aggregation/gelation denaturation, 58–62 general model for denaturation and aggregation, 63–66 hydrolysis enzymatic, 62–63 non-enzymatic, 63 overview, 57–58 refolding, 61 protein fiber formation, 67–70 protein particulate formation, 67–68 texture large strain and fracture properties, 72–73 microstructure, 73–74 oral processing, 71–72 overview, 70–71 sensory evaluation, 74–78 Genipin, crosslinking of controlledrelease delivery systems, 530–531 Glass transition, see also Carbohydrate glass collapse phenomena above glass transition temperature, 271–272 crystallization, 273 624 Glass transition (Continued ) definition, 261–262 detection, 266–267 food system equilibrium and nonequilibrium state relationships, 262–263 frozen foods, 272–273 glass formation, 265–266 mechanical properties and relaxations, 269–271 recrystallization, 273 stability implications, 273–275 state diagrams, 264, 273–275 stiffness, 271 thermodynamics, 262–264 water, 267–269 water activity relationship, 269 b-Glucans, see Fiber, dietary Glutaraldehyde, crosslinking of controlled-release delivery systems, 529–530 Glycemic index flour oat products, 406 processed foods, 512 Glycemic response, see also Diabetes extrusion parameters and processing effects on food quality, 512–513 fiber manipulation of starch digestibility, 516–517 manipulation in extruded snack products, 513 processing and carbohydrate digestibility, 511–512 prospects for study, 517 slowly versus rapidly digestible carbohydrates, 514–516 Guar gum, effects on thermal gelation of whey protein isolate, 191–192 Gum arabic coatings, 313 food emulsions, 157 Hall and Lipps model, antifreeze proteins, 120–121 Higuchi’s model, controlled-release delivery systems, 524–525 HPMC, see Hydroxypropylmethyl cellulose Hyaluronic acid, controlled-release delivery systems, 520 Hydrolysis, protein enzymatic, 62–63 non-enzymatic, 63 INDEX Hydrophobic interactions, emulsion droplets, 139–140 Hydroxypropylmethyl cellulose (HPMC) applications, 313–314 coating of fried foods, 311 Hypercholesterolemia, dietary fiber benefits, 407–408 Ice antifreeze protein binding studies AFGP, 106–107 AFP I motif for ice binding, 105–106 native and synthetic protein binding studies, 104–105 AFP III, 107–108 ice hemisphere binding site technique, 109 plant proteins, 108–109 antifreeze protein ice surface-binding site, 101–102 crystal shape antifreeze protein effects AFP I, 113–114 AFP II, 115–116 AFP III, 114–115 AFP IV, 116 AFP mixtures, 115 nanoliter osmometry principles, 112–113 plant proteins, 116–117 growth principles, 109–111 morphology in solution, 111 Insulin, controlled-release delivery systems, 537–538 Interfacial force, emulsifier homogenization, 136 Internal phase, emulsions, 129 Inulins applications, 430 chemical properties, 427–428 digestion, 431 food sources, 426, 427 functional properties, 428–429 physiological effects immunomodulation, 433–435 lipid metabolism, 432–433 prebiotics, 432 short-chain fatty acid production, 432 side effects of fermentation, 435 production and processing, 427 Kelvin effect, antifreeze proteins, 119 Kinetic gelation, techniques, 8–11 Konjac flour, 427 Konjac glucomannan, see Gelling biopolymer mixtures Lemon albedo, properties, 439 Linear branch theory, gels, 33–34, 39–40 Lolium perennae, antifreeze proteins, 98 Matrix-type hydrogel, controlledrelease delivery systems, 521–522 Maximum surface pressure, emulsifiers, 160 MC, see Methylcellulose MCC, see Microcrystalline cellulose Mechanical spectrum gels, 7–8 liquids, Methylcellulose (MC) applications, 313–314 coating of fried foods, 312 coating of fruits and vegetables, 309 Microcrystalline cellulose (MCC), food utilization, 240–242 Milk film, formation, 297–298 Minimum droplet size, emulsifiers, 159 Minimum emulsifier load, 159 Mixtures, see Gelling biopolymer mixtures; Phase separation Mouth, processing effects on biopolymer interactions, 213–216 Multilayer formation, biopolymer emulsifiers, 161 Nanoliter osmometry antifreeze protein effects on ice crystal shape AFP I, 113–114 AFP II, 115–116 AFP III, 114–115 AFP IV, 116 AFP mixtures, 115 plant proteins, 116–117 principles, 112–113 Nile Red, amyloid fibril staining, 577 NMR, see Nuclear magnetic resonance Nuclear magnetic resonance (NMR) amyloid fibrils, 567–568 resistant starch studies, 489–490 INDEX Oblate, 313 Ocular drug delivery alginate systems, 547 chitin/chitosan systems, 542 collagen systems, 535 mucoadhesion, 601–602 overview, 600–601 Oiling off, emulsions, 143 Optical tweezers applications, 392–393 modes of operation, 391–392 overview, 391 OR, see Ostwald ripening Oral drug delivery alginate systems, 546 alternative systems, 598–600 biopharmaceutical development, 602–604 capsules, 597–598 collagen system formulations, 535–536 liquids, 598 release profiles, 596 tablets, 596–597 Oral processing digestion, 213–216 gels, 71–72 sensory texture evaluation, 76 Oscillatory microsphere, gel characterization, Ostwald ripening (OR), emulsion instability, 144–145 PALS, see Positron annihilation lifetime spectroscopy Paper, coatings, 316 Pectin, controlled-release delivery systems, 520 Percolation theory, gels, 32–39 Phase inversion emulsion instability, 145 water-in-water emulsions, 211–212 Phase separation branching theory models, 21–22 demixing mechanisms, 202 gel network modeling, 42–50 gelling biopolymer mixtures, 168–169 general considerations and thermodynamics, 200–201 kinetic influences in gels, 227–229 non-interacting phase-separated gels, 230–232 phase diagrams, 201–202 processing aspects, 203 protein–polysaccharide associative phase separation kinetics, 330–334 structures formed, 329–330 reaction kinetics for phenomena identification in biopolymer mixtures, 235–237 rheology of phase separation patterns in binary gels, 232–235 pH-sensitive hydrogels, controlledrelease delivery systems, 526–527 Polyacrylic acid, film formation, 316 Polymer blending laws, see Gelling biopolymer mixtures Polymer network, see also Gel network definition, types, Polysaccharide emulsifiers gum arabic, 157 miscellaneous polysaccharides, 158 modified cellulose, 158 modified starch, 157 Positron annihilation lifetime spectroscopy (PALS), carbohydrate glass, 279, 281 Protein emulsifiers characteristics, 155–156 egg proteins, 156 meat proteins, 156 milk proteins, 156 plant proteins, 156–157 Protein + polysaccharide mixed systems associative phase separation kinetics, 330–334 structures formed, 329–330 atomic force microscopy, 371–373 coacervates definition, 330 formation, 337–339 historical perspective, 328 internal structure, 335 rheology, 344 complexes formation, 337–339 internal structure, 335 rheology insoluble complexes, 345–346 soluble complexes, 344–345 625 texturing agents, 347 types, 330 conformational changes, 337 electrostatic interactions charge density effects, 340 charge distribution effects, 340, 341 concentration effects, 339 conformation effects, 340 ionic strength effects, 340 mixing ratio effects, 339 molecular weight effects, 341 pH effects, 339–340 gelation under associative conditions, 346–347 hydrogen bonding, 341–342 hydrophobic interactions, 341–342 interfacial properties bilayer emulsions encapsulation, 353 food applications, 352–353 emulsion properties, 350 foaming, 348–350 mixed emulsions encapsulation, 351–352 food applications, 350–351 limitations for food applications and encapsulation, 353–355 overview, 327–328 processing effects on complexes and coacervates acidification rate, 342–343 homogenization and shear, 342 prospects for study, 355 titration versus mixing, 331 Psyllium applications and health effects, 420 polysaccharides calcium-binding capacity, 423–424 hydration and extraction, 421 organoleptic properties, 424–426 physiological effects, 424–426 structural features, 421–422 viscoelastic and gelling properties, 422–423 Random branching, see Branching theory Recrystallization inhibition, antifreeze proteins, 99–101 Refolding, protein, 63 Reservoir-type hydrogel, controlledrelease delivery systems, 521 626 Resistant starch (RS) definition, 449 enzymatic digestion resistance factors affecting, 491–493 mechanisms, 493, 495–496 overview, 490–491 tables of studies processed starch, 497–499 starch granules, 494 formation principles, 498 health benefits bowels, 459–461 cardiovascular disease, 460 diabetes, 458 obesity, 457–458 overview, 456–457 measurement intake, 461 overview, 450–451 in vitro, 454–456 in vivo, 451–454 overview of properties, 439 processing effects on formation in foods acid or enzyme hydrolysis, 478–479 analysis chain length distribution, 481–484 differential scanning calorimetry, 481 X-ray diffraction, 480–481 baking, 475–476 boiling and high-pressure cooking, 472–475 extrusion cooking, 462, 470–472 fermentation, 479 food types, 463–469 heat treatment, 462 microwave radiation, 479 non-starch material effects citric acid, 477 lipids, 476 soluble sugars, 477 prospects for study, 500 structure analytical techniques, 486–490 chain length and branching characteristics, 484–486 types, 449–560 Rheology biopolymer co-gels, 194 controlled strain versus controlled stress rheometers, 6–7 INDEX food emulsions factors affecting continuous phase rheology, 147 disperse phase volume fraction, 148 droplet size, 148–149 droplet–droplet interactions, 148 measurements, 146 modeling, 146–147 mayonnaise, 209 phase separation patterns in binary gels, 232–235 protein + polysaccharide mixed systems coacervates, 344 complexes insoluble complexes, 345–346 soluble complexes, 344–345 U-tube rheometer, 4–5 water-in-water emulsions, 211 Rice bran, properties, 437–438 RS, see Resistant starch SALS, see Small-angle light scattering SAXS, see Small-angle X-ray scattering SCFA, see Short-chain fatty acid Sedimentation, emulsion instability, 141–142 Sensory evaluation, gel texture, 74–78 Shearing cycle, processing effects on fluid/sheared gels, 204, 208 Short-chain fatty acid (SCFA), dietary fiber as prebiotic, 408–410, 432 Small intestine, processing effects on biopolymer interactions, 219–220 Small-angle light scattering (SALS), phase separation in gels, 229 Small-angle X-ray scattering (SAXS), resistant starch studies, 490 Snack foods, see Glycemic response Soy, film formation, 296–297 Spruce budworm larvae, antifreeze proteins, 97 Stability index, emulsifiers, 159 Stabilizer, emulsion-based food products, 130 Stickiness, mechanisms, 271–272 Stomach, processing effects on biopolymer interactions, 216–219 Storage, processing effects on fluid/ sheared gels, 207 Surface load, emulsifiers, 160 Temperature, processing effects on fluid/sheared gels, 204, 206 Temperature-sensitive hydrogels, controlled-release delivery systems, 526 Texture modifiers, emulsion-based food products, 130 Thermal hysteresis, antifreeze proteins, 98–99 Thioflavin T, amyloid fibril staining, 575–576, 578 Time–temperature superposition (TTS), principles, 8, 248 Tissue engineering cell-adhesive hydrogels chitosan, 608 collagen, 606–607 fibrin, 607–608 principles, 605–606 mechanical conditioning of cells migration, 612–613 morphology, 612 principles, 610–612 microengineering of hydrogels microfluidic scaffolds, 613–614 microgels, 613 non-adhesive hydrogels, 608–610 overview, 604–605 prospects, 614 TTS, see Time–temperature superposition Tumor necrosis-a receptor, dietary fiber response, 407 U-tube rheometer, gel characterization, 4–5 van der Waals interactions, emulsion droplets, 138 Viscoelastic solid, versus viscoelastic liquid, Viscosifier, definition, 2–3 Vogel-Tammann-Fulcher equation, 270 Water carbohydrate glass structural effects, 279–281 INDEX glass transition, 267–269 plasticization, 267–269 Water activity, glass transition relationship, 269 Water-holding capacity (WHC), dietary fiber, 411 Water-in-water emulsions interfacial tension, 210–211 phase inversion, 211–212 quality factors, 210 rheology, 211 WGDF, see White grape dietary fiber WHC, see Water-holding capacity Wheat bran, properties, 436–438 Wheat gluten, film formation, 296 Whey protein isolate (WPI) co-gelation with crosslinked starch blending law analysis, 181–182 differential scanning calorimetry, 178–179 generation, 178 phase structure, 180–181 starch networks, 179–180 edible films, 314 guar gum effects on thermal gelation, 191–192 White grape dietary fiber (WGDF), properties, 439 Williams, Landel, and Ferry (WLF) equation, 246–248, 250–251, 270, 272 Winter–Chambon method, kinetic gelation, 10–11 627 WLF equation, see Williams, Landel, and Ferry equation WPI, see Whey protein isolate X-ray diffraction amyloid fibrils, 560, 567, 574 resistant starch formation studies, 480–481 structure studies, 486, 488–489 Yield stress, processing effects on fluid/ sheared gels, 208–209 Zein coating of fruits and vegetables, 309 film formation, 296