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2008 Food Structure

FS&FF 1: Colloid and Interfacial Properties of Food

Chair(s): K. Dewettinck, Ghent University, Belgium; and Y. Wang, Kraft Foods Inc., USA

Nutritional and Technological Aspects of Milk Fat Globule Membrane Material. K. Dewettinck1, R. Rombaut1, N. Thienpont2, T.T. Le1, K. Messens2, J. Van Camp1, 1Ghent University, Belgium, 2University College Ghent, Belgium

The milk fat globule membrane (MFGM) has gained a lot of attention recently, due to thegrowing interest in its nutritional and technological properties. The whole membrane as wellas the separate lipid and protein components have great potential for new unique product applications. This review focuses on the nutritional and technological aspects of the MFGM material, but also gives an overview of the gathered information about the composition, structure and isolation methods of the MFGM from different dairy sources.

Engineering Oil-Binding Capacity and Crystallinity of Organogels. M.A. Rogers1, A.J. Wright2, A.G. Marangoni1, 1Department of Food Science, University of Guelph, Guelph, Ontario, Canada, 2Human Health and Nutritional Science, University of Guelph, Guelph, Ontario, Canada

The oil binding capacity of 12HSA-canola oil organogels was modified by changing the post-crystallization storage temperature. Gels, stored at 5°C, had highly immobilized oil, as evidenced by the presence of a large T2 relaxation peak at 50 to 70ms by pulsed nuclear magnetic resonance. When the gels were stored at 30°C, a significantly shifted and shorter T2 relaxation peak was observed. At 30°C, the 12HSA network′s crystallinity was enhanced, having fewer inclusions of liquid oil, as determined by pNMR. The increased crystallinity and decreased oil binding capacity was attributed to the nanostructure of the 12HSA network measured using pNMR. The crystallinity decreased as the degree of inclusions increased or the length or thickness of the 12HSA supramolecular network decreased. At 30°C, the strands were more annealed due to fewer crystallographic mismatches and therefore the strands were larger, leading to less inclusions of oil in the supramolecular network. However, this also leads to the greater pore formation which is correlated with a greater oil exudation from the network. The variable strand length of the gels stored at 30°C is apparent by cryo-SEM imaging, indicating a dilute cayley tree fractal structure. Therefore, the oil binding capacity of the gels can be modified by influencing the nanostructure of the supramolecular network.

Crystallization and Melting Behaviour of Saturated and Unsaturated Monoglycerides. J. Vereecken1, I. Foubert1, W. Meeussen2, A. Lesaffer2, K. Dewettinck1, 1Ghent University, Ghent, Belgium, 2Vandemoortele N.V., Izegem, Belgium

Monoglycerides are generally known as emulsifiers in food products. They are also widely used as bread improvers in dough systems. Other applications are their use in cosmetics, as antimicrobial agents, in drug delivery systems, in gel networks with water (formation of mesomorphic phases), in membrane systems etc. In spite of their different applications in food products, monoglycerides show some similarities with triglycerides. They both are products of the interesterification reaction between glycerol and fatty acids and they both are characterized by a specific crystallization and melting profile which is influenced by the polymorphism of the crystal structures. Although these properties are important for the applications of the monoglycerides, literature sources about crystallization, melting and polymorphism of monoglycerides are very scarce and quite old. Therefore the aim of this research was an investigation of the crystallization and melting behaviour of both saturated and unsaturated monoglycerides. This study was performed using DSC and synchrotron XRD. Also a comparison between monoglyceride standards and commercially available monoglycerides has been made.The results demonstrate among other things the importance of the chain length of the monoglycerides and the big difference between saturated and unsaturated monoglycerides.

Synchrotron X-ray Microbeam Analysis of Lipid Crystallization in O/W Emulsion. Satoru Ueno1, Yuya Shinohara2, Yoshiyuki Amemiya2, Kiyotaka Sato1, 1Hiroshima University, Higash-Hiroshima, Japan, 2Tokyo University, Kashiwa, Japan

We have made x-ray microbeam analysis of the crystallization behavior of n-hexadecane (C16) in oil-in-water emulsion droplets that were formed by using surfactants with different types of hydrophobic moieties. It was confirmed that the molecular-shape matching between the hydrophobic moiety and C16 caused the following crystallization behavior: when the molecular shape of the hydrophobic moiety was similar to C16, high-intensity x-ray diffraction of the rotator phase of C16 were detectable at the initial stage of crystallization and the long-chain axes of C16 crystals aligned normal to the membrane interface. The present results provided the first evidence of interfacial heterogeneous nucleation caused by molecular interactions at the emulsion membrane, which would be related to the interfacial freezing that is observed for water-oil interface with surfactants in bulk system.

Microencapsulation of a Low-trans Fat as Affected by Formulation and Physical State of a Matrix. Marina Cerdeira1, Roberto J. Candal2, Maria Lidia Herrera1, 1Buenos Aires University, Department of Industries, Buenos Aires, Buenos Aires, Argentina, 2INQUIMAE, CONICET, Buenos Aires, Buenos Aires, Argentina

A low-trans fat blend with crystalline material formulated with 40 wt. % sunflower seed oil (SFO) in high melting fraction (HMF) of milk fat was encapsulated by freeze-drying emulsions. The matrix was a 20 wt. % trehalose aqueous solution. The selected emulsifiers were a mixed of 50 wt. % of the palmitic sucrose esters (SE) P-170 and P-1670, sodium caseinate (NaCas) or a 50 wt. % blend of SE and NaCas. Initial efficiency of encapsulation and the ability to retain the core material with time was studied by storing the powders at different water activities. Efficiency of encapsulation was strongly dependent on emulsifier type. Initial retention value was 89.7 ± 0.1 for NaCas formulation. SE and SE/NaCas formulations, however, were less efficient. Retention values were 64.9 ± 0.8 and 55.5 ± 1.0, respectively. NaCas formulation was also more efficient retaining core material during storage. The formulation with a protein and a small surfactant had the lowest performance. Retention with time was determined by the counteracting effects of interactions among stabilizers, matrix and core material, crystallinity of matrix and droplet size distribution.

Influence of Pickering Crystals on the Freeze-Thaw Stability of Water-in-Oil Emulsions. Supratim Ghosh, Dérick Rousseau, Ryerson University, Toronto, Ontario, Canada

Three different emulsifiers - glycerol monostearate (GMS) glycerol monooleate (GMO) and Span 80 were investigated for their capacity to stabilize water-in-oil emulsions during freeze-thaw temperature cycling of the dispersed and continuous phases. GMS emulsions contained crystal shells at the oil/water interface whereas the GMO and Span emulsions did not. Emulsions were stored at 25°C and subjected to freeze-thaw and heat-cool cycling. For emulsions prepared with monoglycerides, storage stability increased significantly in the presence of GMS compared to GMO, showing that monoglyceride stabilization of emulsions originates from their ability to crystallize at the oil/water interface. GMS-stabilized emulsions broke down upon melting of the interfacial crystal layer during heat-cool cycle whereas Span 80 emulsions (which remained liquid during the temperature cycling) were stable. Both GMS and Span 80-stabilized emulsions were stable to multiple freeze-thaw cycles. However, when Span-80-stabilized emulsions were prepared with a continuous phase that crystallizes prior to the dispersed aqueous phase, they were unstable to multiple freeze-thaw cycles. This study shows that Pickering crystals present around water droplets stabilize water-in-oil emulsions against freeze-thaw cycling.

Physical and Chemical Stability of Encapsulated Solid Lipid Nanoparticles. T.S. Awad1, T. Helgason1,2, K. Kristbergsson2, E.A. Decker1, J. Weiss1, D.J. McClements1, 1Department of Food Science, University of Massachusetts, Amherst, MA, USA, 2Department of Food Science, University of Iceland, Reykjavik, celand

Solid lipid nanoparticle (SLN) suspensions are promising tools that can be used to encapsulate, protect and deliver lipophilic functional components such as omega-3 fatty acids. Susceptibility of SLN suspensions to particle aggregation and gelation during their preparation and storage however potentially limits their industrial utilization. SLN gelation is associated with a shape change from spherical to disk-like due to an α-to-β-polymorphic transition of the emulsified lipid, which promotes hydrophobic attraction between exposed surfactant-free patches. Retarding this polymorphic transformation can therefore be used to stabilize SLN physically as well as to increase the chemical stability of encapsulated actives by preventing their exposure to reactive oxidants. Attempts were made to modify physical and chemical stability of SLN suspensions by retarding particle aggregation as well as oxidation by (a) changing the surfactant type to promote crystallization in the stable β form; (b) using ionic surfactants to increase the electrostatic repulsion between droplets; (c) varying the ratio of saturated to unsaturated fats in the lipid phase using omega-3 rich oil. Results showed that physical and chemical stability are affected by the type of surfactant as well as lipid composition.

FS&FF 2: Programming Food Behavior by Processing

Chair(s): B.T. Tauscher, Federal Research Centre for Nutrition and Food, Germany; and A. Perdon, Kellogg Company, USA

Efficacy, Structure and Physicochemical Properties of Lipid Antimicrobials. Jochen Weiss, University of Massachusetts, Amherst, MA, USA

In this presentation, we will try to answer the fundamental question of why lipid antimicrobials often don't work well in complex foods. We will illustrate that physicochemical incompatibility of antimicrobials with the matrix structure is one of the key factors that may severely limit efficacy. To this purpose, we will look at the complex interactions between (a) the antimicrobial (b) the bacterial pathogens and (c) the food matrix that are responsible for the discrepancies that are often observed when conducting inhibitory activity assays in microbiological model systems versus those conducted in real food systems. We will use these insights to better understand the remarkable resistance of biofilms to traditional remediation methods which is based on the structure and composition of the matrix surrounding the bacterial cells. This matrix provides an effective adsorption layer protecting key microbial cells attached to the substrate surface making it difficult for sanitizers and disinfectants to attack the bacterial targets. Strategies will be presented that are able to effectively overcome these deficiencies i.e. encapsulation of antimicrobials in nano- and microscalar carriers where colloidal interactions can be engineered to optimize efficacy of encapsulated compounds.

Influence of High Hydrostatic Pressure on Anthocyanin Extraction and Stability in Grape By-Products. M.C. Corrales-Moreno, P.B. Butz, B.T. Tauscher, Federal Research Centre for Nutrition and Food, Karlsruhe, Baden-Wuerttember, Germany

In addition to pasteurization and sterilization, High hydrostatic pressure (HHP) can be used for extraction purposes. Moreover, HHP can influence chemical reactions representing an interesting tool for synthesis and degradation of particular compounds. This study showed the application of HHP on anthocyanin enriched food products. Firstly, optimal conditions for pasteurization of anthocyanin enriched products were reported. The stability of main anthocyanins in wines and grape pomace extracts was not affected at 600MPa, 70°C during 10min. Secondly, HHP/temperature conditions for anthocyanin extraction from grape pomace were further investigated. Air-filled pores of fruit tissues are responsible for solvent uptake during HHP extraction. After pressure release the dissolved air exit causing membrane damage. HHP extraction yields were approx. two-fold higher than conventional extractions. Therefore, HHP as an extraction method was also compared to other novel technologies such as pulsed electric fields and ultrasonics. Finally, the degradation of (cyanidine-3-O-glucoside) Cy3gl and formation of pyruvic acid adducts of Cy3gl were also reported. Pyruvic acid adducts formed are precursors of polymerized anthocyanins with different color and chemical properties which may be of relevance at a commercial level.

Microdomain Distributions in Food Matrices: Glass Transition Temperature, Molecular Mobility, and Kinetic Evidences in Model Dough System. Y. Kou, General Mills, Inc., Minneapolis, MN, USA

The concept of a distribution of microdomains within an amorphous food matrix provides a basis for explaining the observed dispersion in its physical properties. These spatially separated doamins correspond to differing molecular arrangements and such arrangements influence local viscosity and molecular mobility. Consequently, the volume averaging of these localized properties in turn determine the global values of such properties as glass transition temperature (Tg), molecular mobility as reflected in proton spin-spin relaxation time (T2), and reaction rate constants (k).In order to understand the nature of these microdomains, their distributions were either discerned or inferred from measurements made on dough matrices of different water contents and at different temperatures. The changes in Tg, T2, and k (for a reduction reaction) as water content and temperature are changed were measured, using primarily electron spin resonance (ESR) and time-domain nuclear magnetic resonance (NMR) techniques. The main implication in the microdomains concept is that such localized differences in structure and properties need to be quantitatively considered to ensure that the physically, chemically, or microbiologically least-stable part of the matrix does not compromise qulity or safety.

Polymorphic Transition in Solid Lipid Nanoparticles (SLN) and Its Influence on Suspension Stability. T. Helgason1,2, T.S. Awad1, D.J. McClements1, K. K. Kristbergsson2, J. Weiss1, 1University of Massachusetts, Amherst, MA, USA, 2University of Iceland, Reykjavik, Iceland

Production of bioactive carrying functional foods has increased in the recent years. Poor stability and low bioavailability of some bioactive ingredients has slowed formulation of new functional products. A promising strategy to overcome these problems involves development of a carrier system using solid lipid nanoparticles (SLN). Thus far SLN have mainly been used in the pharmaceutical industry to deliver unstable and poorly bioavailable drugs. SLN consist of crystallized nanoemulsions with the dispersed phase being composed of a solid carrier lipid. Since a food matrix is more complex than a capsule carrying drug molecules, a substantial amount of research work is required to allow adaptation of this technology to the food industry. In this presentation we will discuss key food issues associated with rearrangement of the triacyglyceride matrix of nanoparticle based on three different polymorphic configurations, i.e. α, β' and β-form. Polymorphic transition may lead to an altered ability of particles to incorporate and carry bioactives and are associated with change in the shape of particles from spherical to needle shaped. Consequently aggregation and release of the bioactive material is often a substantial problem when formulating food grade SLN. We will discuss approaches to control polymorphic transition to overcome these issues.

Static Structures of Liquid-Phase Trilaurin: Computer Simulation and Raman Spectroscopy. R. MacEachern1, A.J. MacDonald1, C. Sandt2, D. Rousseau3, C.B. Hanna4, D.A. Pink1, 1Physics Dept., St. Francis Xavier University, Antigonish, NS, Canada, 2Chemistry Dept., St.Francis Xavier University, Antigonish, NS, Canada, 3School of Nutrition, Ryerson University, Toronto, ON, Canada, 4Dept. of Physics, Boise State University, Boise, ID, USA

Recently it was proposed (Corkery et al. 2007, Langmuir, 23(13) 7241-7246) that, for possibly some restricted temperature range, the liquid phase of trilaurin contains structures in which the molecules form discoids. It was argued that the experimental data available is in accord with such an interpretation. These structures are not necessarily long-lived and might involve various numbers, N, of molecules with the only constraint being N>1. Previously, we created a minimal model of the phase transition of trilaurin which we have now found to be in accord with our recent data obtained from Raman spectroscopy. We have now extended this minimal model to one using dissipative particle dynamics and have studied it using molecular dynamics computer simulation. The intent was to calculate various structure functions, S(q), together with pair correlation functions, in order to establish the structure of the model liquid phase. Among these structure functions is that pertinent to Xray scattering. We shall present results showing the predicted structure and Xray scattering of liquid-phase trilaurin.

Effect of Surface-Active Stabilizers on the Properties of Coconut Milk Emulsions. N. Tangsuphoom, J.N. Coupland, Department of Food Science, The Pennsylvania State University, University Park, Pennsylvania, USA

Recently we have shown how surface-active stabilizers (0-1 wt% sodium caseinate, whey protein isolate, SDS, and Tween 20) added before and after homogenization affect the stability of coconut milk (CM) emulsions. In this work, we propose a mechanism for these observations based upon by measuring the changes in surface composition and ζ-potential. When added to homogenized CM, at ≥0.25 wt%, small-molecule surfactants displaced the coconut proteins (CP) adsorbed at the surface of emulsion droplets, as resulted in a decrease in protein surface concentration and a change in ζ-potential toward the value of coconut oil emulsions stabilized with the correspond surfactant. The added proteins did not affect the interrface of CM emulsion. Addition of Tween 20 or SDS (≥0.5 wt%) to the CM prior to homogenization completely displaced CP at the interface. Homogenization of CM with proteins resulted in a decrease in protein surface concentration due to the smaller d43 and probably the detachment of multi-layer of CP initially adsorbed at the interface. The protein composition changed as the added proteins displaced over 75% of total surface protein. The change in ζ-potential also reflected the change in protein and surface composition as the values moved close to the value of coconut oil emulsions stabilized solely with the corresponding added stabilizer.

FS&FF 3: Underlying Mechanisms for Food Sensory Performance

Chair(s): I. Appelqvist, Food Science Australia, CSIRO, Australia; and M. Paques, Friesland Foods, The Netherlands

Influence of Oral Processing on Fat Perception of Food Emulsions. E.H.A. De Hoog1,2, D.M. Dresselhuis1,3, M.H. Vingerhoeds1,4, G.A. Van Aken1,2, 1TI Food and Nutrition, Wageningen, The Netherlands, 2NIZO Food Research, Ede, The Netherlands, 3Laboratory of Physical Chamistry and Colloid Science, Wageningen University, Wageningen, The Netherlands, 4Centre for Innovative Consumer Studies, Wageningen University and Research Centre, Wageningen, The Netherlands

Health issues challenge the food industry to find solutions in lowering the caloric values of foods, yet maintaining the appreciation of these foods by consumers. Focus has been on ingredient replacement and validating sensory perception. However, little attention has been paid to the influence of oral processing on the perception of foods.Here, we will elaborate on the structural changes in food emulsions upon oral processing, and how these mechanisms influence the perception of fat. We investigated the effect of the sensitivity towards coalescence of emulsion droplets by varying the adsorbed layer at the oil droplets. It appeared that a higher creamy perception was obtained with most sensitive emulsions. Furthermore, the perceived rough feeling was decreased, which was further studied by lubrication experiments and analysis of the fat deposition at the tongue surface. In a second study the sensitivity to partial coalescence was controlled by variation in fat melting curve and by addition of unsaturated monoglyceride. Most fat related sensory attributes appear to be well-correlated to an increase in viscosity and coalescence in the mouth due to partial coalescence.These studies show that an increased understanding of the structural changes during oral processing provides us tools to engineer emulsions with a controlled fat perception.

Food Structural Design for Appetite Control. L. Lundin1, M. Golding1, T.J. Wooster1, L. Day1, I. Appelqvist2, 1Food Science Australia, CSIRO, Werribee, Victoria, Australia, 2Food Science Australia, CSIRO, North Ryde, New South Wales, Australia

Increasing knowledge of ingredient interactions and structure functionality, in combination with new and emerging processes, is supporting the development of healthier, high quality foods. To support the drive towards nutritional enhancement of foods, there is now an emerging interest in how food systems behave during digestive processes. A particular aspect of this is to develop understanding of how the material properties of foods can be controlled under physiological conditions. Through such understanding food microstructures can be designed not only to ensure appealing and good tasting food products, but also with the ability to deliver enhanced in-body functionality, such as the optimised release and uptake of micronutrients, or the ability to regulate satiety, There is now increased evidence that the breakdown and digestion of food structure in the gastro-intestinal track is influencing the physiological response and the rate of absorption of macro- and micro-nutrients. This presentation will report on research on digestibility of model food emulsion systems with designed structural stability under gastric conditions.

FS&FF 4: Structure-Functionality in Confectionery Products

Chair(s): D. Rousseau, Ryerson University, Canada; and P. Smith, Cargill, Belgium

Influence of Fat Phase Composition on Microstructural Stability of Chocolate. Sopark Sonwai1, Dérick Rousseau2, 1Silpakorn University, Dept. of Food Technology, Nakornpathom, Thailand, 2Ryerson University, School of Nutrition, Toronto, Ontario, Canada

The purpose of this study was to examine how fat phase composition in chocolate alters surface morphology and fat crystal properties. Gradual replacement of cocoa butter (CB) with milkfat (MF) (up to 7.5% w/w) in the fat phase (32% w/w) had a direct effect on the initial surface properties. At t = 0 week, the surfaces of all freshly-tempered chocolates were relatively smooth with limited mottling and surface imperfections. The presence of MF reduced the presence of amorphous mounds (‘cones') on the surface. Temperature-cycling from 26 to 29 °C for 4 weeks resulted in substantial morphological changes, with more MF resulting in slower crystal growth and cone development. Presence of MF also slowed the onset of the form V to VI polymorphic transition and reduced initial solid fat content (SFC). Storage over 4 weeks led to a lower SFC in all MF-containing samples, but not the CB-only chocolate, which also saw its surface whiteness increase the most over time. Overall, the chocolate containing the most MF was slowest to show the form V to VI transition, surface crystal and cone growth and an increase in whiteness.

Effects of Seed Addition on Cocoa Butter Crystallization and Bloom Formation in Chocolate. K. Yasuyoshi1, R.W. Hartel2, 1Morinaga & Co., Ltd., Tokyo, Japan, 2University of Wisconsin - Madison, Madison, WI, USA

Bloom on chocolate with different levels of cocoa butter seed addition was investigated. When insufficient cocoa butter seed crystals were added to give proper temper, the chocolate developed bloom as dark brown spheres withinin lighter color areas, similar to that seen in bloom on untempered chocolate. These dark colored spheres overlapped and the lighter color areas disappeared with increasing seed amount added. The relationship between seed amount and lighter color area (bloom), as quantified by image analysis, showed the minimum seed amount needed to accomplish good tempering. The cocoa butter crystallization behavior with various amounts of seed was observed under microscope. Too few seeds caused sparse  crystallization and massive ' crystallization, which explains the appearance of poorly tempered chocolate bloom. Sufficient seeding caused rapid  crystallization throughout the sample. In addition, DSC analysis was carried out to study crystallization and melting behavior of both cocoa butter and chocolate with different seed amounts. As expected, lower levels of added seeds resulted in greater amounts of unstable crystal formation. However, significant differences between cocoa butter and chocolate behavior suggest that other components in chocolate besides cocoa butter influence crystallization, tempering and bloom.

The Solubilization-Recrystallization Model of Oil Migration through Chocolate. A.G. Marangoni , S. Marty, University of Guelph, Guelph, ON, Canada

Oil migration through chocolate is an important issue for the confectionery industry since migration of oil can be related to bloom formation and softening of the chocolate matrix. The movement of oil through chocolate has usually been considered to take place via diffusion, as well as via capillary movement, mostly due to the t dependence of the oil movement. However, closer inspection of the time dependence of migration, particularly at short times shows a clear induction time prior to oil movement and an eventual slowing down of the migration at longer times. This results in a sigmoidal shape of the migration-time relationship. This clearly indicates that there are other factors at play. Here we provide evidence for the large solubilization of cocoa butter into oil when these two phases come into contact with each other. A large amount of cocoa butter is thus solubilized into the oil. Some of this material then recrystallizes from solution. The net amount of cocoa butter-oil solution is then free to move through the confectionery matrix. Here we show by computer simulation and experiments that oil migration can be explained to a large extent by this balance between solubilization and recrystallization.

Effect of Laminar Shear and Crystalline Orientation on Oil Migration in Cocoa Butter. F. Maleky, A.G. Marangoni, University of Guelph, Guelph, Ontario, Canada

The effect of laminar shear and crystalline orientation on the migration kinetics of Nile Red from a peanut oil-palm oil mixture into CB was quantified. Using a flatbed scanner, the migration of Nile red stain through the CB matrix, crystallized under laminar shear and static condition was monitored for 10 weeks. Oil migration was determined by analyzing the variation of the gray scale intensity, related to the amount of dye present in the CB as a function of distance, in time. Laminar shear crystallization yielded samples with different crystalline orientations, including no crystal orientation, and oriented layers of crystals in one and two directions perpendicular from each other. To understand the effects of orientation on oil migration, migration rate was determined for CB samples completely immersed inside the filling, and for the case where only one surface was in contact with the filling. The migration mechanism of liquid TAG into CB was evaluated: the diffusion coefficients of the dye through CB decreased when it was crystallized under laminar shear compared to static conditions. An increase in migration rate was observed when crystals were oriented in one direction relative to the case with crystal orientation in two directions. Overall, the results suggest that crystalline orientation can affect the migration of liquid TAG through CB.

Computational Modelling of Chocolate Production. B.J.D. Le Révérend, S. Bakalis, P.J. Fryer, University of Birmingham, Birmingham, West Midlands, United Kingdom

The purpose of this paper is to present a new method to model phase change for food materials which exhibit polymorphism. Quick cooling systems are used in the confectionery industry and produce perfectly acceptable Easter eggs, however models available in the literature are suited for isothermal or slow cooling crystallization processes. Therefore a new kind of model taking count of the cocoa butter polymorphism and the polymorphous transitions resulting of these quick cooling processes was needed to understand how these processes work. The model presented is a finite elements multiphysics model which simulates both heat transfer and different phases for the fat fraction of the material represented as different chemical species in a one phase system. The material polymorphism was first studied with Differential Scanning Calorimetry and this data was used to determine the model parameters (crystal growth and nucleation rates, latent heat for the different phases, polymorphous transitions kinetics ...).The system was simplified to only 3 phases (melt, stable or unstable). The model was used to simulate different processing scenarii and compared to heat source (Differential Scanning Calorimetry), phase occurrence (X-Ray Diffraction) with a novel method to identify phases directly in raw chocolate without removal of sugar and temperature profiles (Peltier stage).

Migration Fat Bloom in Composed Chocolate Products: a Phenomenological Approach. F. Depypere, N. De Clercq, K. Dewettinck, Ghent University, Ghent, Belgium

In the European chocolate manufacture market comprising 2000 companies, employing over 200000 people and representing an export value of more than 3 billion Euros, companies differentiate from each other by producing exclusive and niche-oriented products like composed (filled) chocolates. These products are technologically more complicated than plain chocolate bars due to the characteristics of the filling. More than other factors, fat bloom on the surface of composed chocolate products leads to significant reduction of shelf-life, hampering export, and product rejection by consumers. For this reason, the Laboratory of Food Technology and Engineering (FTE) together with the Flemish technological Advisory Centre for the Confectionary Industries (VLAZ) has increasingly been consulted since the last few years to solve migration fat bloom problems in composed chocolate products (e.g., filled pralines, chocolate covered biscuits, chocolate bars with hazelnuts).Compared to polymorphic fat bloom on plain chocolate, far less literature data is available on migration fat bloom in composed chocolates, despite its current higher industrial relevance. Also, the research concerning migration fat bloom mainly uses model systems (e.g., cocoa butter instead of chocolate, stabilized chocolate physically placed on a filling) lacking transferability to industrial products. Through a phenomenological approach, dealing with different case studies of fat bloom development on industrially relevant composed chocolate products, it was found that the current knowledge on migration fat bloom mechanisms is insufficient to explain all cases. There is a lack of studies on the physics of mass transfer phenomena in composed chocolate products and their dependencies on filling and chocolate structure and the respective impact of processing conditions.This presentation will review recent work of FTE and VLAZ regarding influences of chocolate and filling composition, ingredient processing and storage conditions on the development of fat bloom on composed chocolates.

Food Structure & Functionality Forum Posters

Chair(s): D. Kittleson, General Mills, USA

Effect of Wax Addition on the Crystallization Behavior of Anhydrous Milk Fat.
Jiwon Lee, Jennifer Thurgood, Lance Andreasen, Silvana Martini, Utah State University, Logan, UT, USA

The effect of sunflower oil waxes addition on the crystallization behavior of milk fat was studied. The induction of the crystallization at different temperatures was evaluated using differential scanning calorimetry and the morphology of the crystals generated was assessed with polarized light microscopy. As expected, the higher the crystallization temperature, the longer the induction time of crystallization. Results show that the addition of 0.25 and 0.5% of waxes significantly affected both the induction time of crystallization and the morphology of the network formed. Waxes addition induced the crystallization of AMF as evidenced by shorter induction times, especially at higher crystallization temperatures. In addition, after 60 min at crystallization temperature, the lipid network formed with the addition of waxes was more uniform and smaller crystals were observed. No difference was found in the morphology of the crystals obtained in samples with 0.25 and 0.5% of waxes.

Controlled Release of Vitamin E from Dilutable Food-Grade Microemulsions.
Afra Pourdad1, Ricky Yada1, Dérick Rousseau2, 1University of Guelph, Guelph, Ontario, Canada, 2Ryerson University, Toronto, Ontario, Canada

With properties such as spontaneous formation, thermodynamic stability, clear appearance, small domain size (5-100nm) and high solubilization capacity, microemulsions (MEs) are attracting considerable attention in both academia and the food industry, especially as vehicles for nutrient and drug delivery. The objective of this research was to formulate dilutable food-grade MEs that could be used for the controlled release of oil-soluble molecules. The six-component MEs developed consisted of water and propylene glycol (as the continuous phase), Tween 80, ethanol (used as co-surfactant), tricaprylin (as the continuous phase) and vitamin E. The water-continuous regime occurred with MEs containing at least 60% water, based on particle size measurement, conductance and rheology measurements. The fluorescence signal of vitamin E was used to model its release, resulting from addition of NaCl, NaOH, HCl or water to the loaded MEs. During release, the initial narrowly-distributed oil domains (D~15 nm) increased in size as a result of being disrupted. Overall, this study demonstrated that MEs could be successfully used to controllably release labile oil-soluble molecules.

A Novel Method for SLN Preparation.
Muhammad Ali Naqvi1, Iain Scovell 1, Dérick Rousseau2, 1Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada, 2School of Nutrition, Ryerson University, Toronto, Ontario, Canada

A novel approach for the development of solid lipid nanoparticles (SLNs) is described, whereupon a hot mixture of a hydrophobic phase and water produces a uniform fine dispersion upon vigorous agitation and de-gassing via repeated freeze-thaw temperature-cycling. Using the emulsification process pioneered by Pashley (2003. J. Phys. Chem. B 107:1714) where degassing is used to form and stabilise dilute emulsions, these SLNs are produced without the use of surface-active agents. This is counter to other means of SLN production (e.g., homogenization, microemulsions, etc.) where surfactants are critical. Stearic acid SLNs generated via this method may be sub-micron in diameter (400-600 nm) with little polydispersity, as measured by dynamic light scattering. Atomic force microscopy reveals that the particles are generally globular in shape. Advantages of this technique are the lack of surfactants necessary to generate the dispersed phase and the low-energy requirements.

The Effect of Different Kinds of Saturated Fat on the Micro and Macro Structural Properties of Filling Fats.
J. Vereecken1, I. Foubert1, K.W. Smith2, K. Dewettinck1, 1Ghent University, Ghent, Belgium, 2Unilever Research Colworth, Sharnbrook, Bedfordshire, UK

Nowadays, the food industry tries to reduce the level of saturated and trans fatty acids, because they are known as unhealthy. Therefore, health organisations have developed standards for the content of unhealthy fatty acids in food products. Nevertheless, saturated fatty acids give structure to fat rich products, like margarines and confectionery products. Moreover, different fats could be used to give structure to these kinds of products. Therefore, the objective of this research was the investigation of fat blends with the same level of saturated fatty acids, namely 30%, but with a different triacylglycerol composition. The blends could be used as filling fats in the confectionery industry. Three effects were investigated: the effect of the amount of trisaturated triacylglycerols, the effect of the chain length and the effect of interesterification.Crystallization properties were studied by non isothermal and isothermal SFC and DSC. The microstructure was evaluated using polarized light microscopy. The results show the important impact of the triacylglycerol composition on both the crystallization and the microstructural properties. For example, a higher content of trisaturated triacylglycerols gives a faster crystallization and the formation of a dense network of small fat crystals.

Structure and Flow Behaviour of Plant Particle Suspensions.
T. McCann1,2, S. Oiseth1,2, M. Xu1,2, L. Day1,2, L. Lundin1,2, A. Richards1,2, 1Food Futures National Research Flagship, North Ryde, NSW, Australia, 2Food Science Australia, Werribee, Victoria, Australia

In the food processing system, mechanical shear processing has been used to separate and disrupt plant cells, thereby producing a suspension containing particles at various size and shapes. In addition, thermal processing causes the solubilisation of pectin substances of the middle lamella and the softening of plant cell wall, which could affect viscosity and flow behaviour of a suspension. The rheology properties of particulate suspension have been known to be dependent on the size, chape and concentration of particles as well as the presence of soluble biopolymers. Accordingly, knowledge of thermal and shear processes on the production of the suspension containing plant cell particles at various size and shape could be used in developing or controlling desired textural properties on foods. In this study a combination of thermal and mechanical treatments were used to create plant cell wall suspensions with different morphology. Raw, blanched (80ºC, 10 min) and cooked (100ºC, 30 min) carrot pieces were further processed using shearing conditions (i.e. blending and high shear homogenising). The structure of carrot plant cell wall particles was evaluated using confocal laser scanning microscopy and particle size measurements. The rheological properties of the suspensions were determined as a function of shear stress.The results showed that heating treatment has caused the solubilisation of pectin substances, leading to the separation on the cell wall. The shear processing disrupted the plant cells and produced the suspension containing either cluster or fragment cells depending on level of shear rate. The combination of thermal and mechanical shear treatments on plant materials can produce the suspension at a particular modulate of the viscosity as a function of particle size and shapes. These finding could assist processing designs to control viscosity and flow properties of plant material based ingredient to achieve desirable food texture.

Structuring Anhydrous Milk Fat by Using High Intensity Ultrasound.
Andreia Suzuki1, Silvana Martini1, Richard Hartel2, 1Utah State University, Logan, UT, USA, 2University of Wisconsin-Madison, Madison, WI, USA

Trans-fatty acids have been evocated to increase the risk of cardiovascular disease. These fats have been widely used in food industry, mainly because of the desirable physical properties added to the final product. There is a strong need to find alternative lipids that will improve the nutritional quality of foods while maintaining the physical properties of trans-fats. Our study applies high intensity ultrasound (HIU) in anhydrous milk fat (AMF) to induce crystal nucleation, promote crystallization and obtain harder lipid structures. Results show that HIU not only induces the crystallization of AMF but also generates smaller crystals. These microscopic events result in an increase in the hardness and viscosity of AMF samples, improving the texture and consistency of the AMF. The effect of HIU on the crystallization behavior of AMF depends on the crystallization temperature, duration of the ultrasound application and the time at which HIU is applied. This data suggests that HIU could be used to structure AMF, which could be further applied in food industry as a trans-fatty acids replacement.

Freeze-Thaw Stability of Oil-In-Water Emulsions As Affected By Water Phase and Oil Phase Compositions.
Ratjika Chanamai, Tawanna Childs, Jason Schmidt, Steve Simonin, Wayne Reeves, Greg Horn, WILD Flavors, Erlanger, KY, USA

The influence of emulsifier types (Gum arabic, Modified starch and Tween 80) on the physical properties of model oil-in-water emulsions (butter oil, coconut oil, peanut oil, safflower oil and sunflower oil) at various oil concentrations (12, 8, 4 and 1%) has been investigated. The emulsions were prepared using a high pressure homogenizer, and stored at -20C, 4C, 20C and 37C for 24 hrs to cause crystallization in oil phase only or in both oil and water phases. The emulsions then were held for additional 24 hrs at 37C before measuring the particle size. The same temperature cycle was repeated two more times for each sample. Emulsion stability was expressed as changes in mean particle size, gravitational separation and creaming index. The results showed that emulsions stabilized with Tween 80 were most unstable to the freeze-thaw cycles while gum arabic or modified starch stabilized emulsions had better stability. Among different oil types, the higher the melting point of the oil, the lower the stability of the emulsions. For a given oil type, the higher the oil concentration, the less stable the emulsions were to the freeze-thaw conditions.

Heat Stability of Oil-In-Water Emulsions With Different Emulsifiers and Oil Phase Compositions.
Ratjika Chanamai, Tawanna Childs, Jason Schmidt, Steve Simonin, Wayne Reeves, Greg Horn, WILD Flavors, Erlanger, KY, USA

The heat stability of model oil-in-water emulsions stabilized with gum arabic (GA), modified starch (MS) or Tween 80 (TW) with different oil phase compositions (mixture of orange terpene and ester gum from 1:0.5, 1:1, 1:1.5 and 1:2) and concentrations (15, 10 and 5 wt%) was investigated in pilot plant scales. The oil-in-water emulsions were prepared using a high pressure homogenizer. The emulsions then were exposed to various heat treatments (130, 140, 150, 160, 170, 180, 190, 200 and 210F for 30sec) using a Microthermics heat processor. The stability of the emulsions was expressed in term of the change in particle size, viscosity and creaming index. We found that the physical properties of emulsions were greatly affected by emulsion compositions and degree of heat treatment. Emulsions showed high heat stability when stabilized with GA, MS and TW respectively, possibly due to thicker layers of interface surrounding the oil droplets providing better protection through steric repulsion at high temperature. The heat stability of emulsions seemed to increase as the oil concentration decreased. At the same oil concentration, the heat stability of emulsions decreased with decreasing concentrations of ester gum in the oil phase.

Functionality and Properties of Interesterified High Oleic Shortening Structured with Stearic Acid.
Latifeh Ahmadi, Alejandro G. Marangoni, University of Guelph, Guelph, ON, Canada

Production of shortening is commonly carried out by partial hydrogenation which leads to the production of trans fatty acids (TFA). TFA have been reported to be risk factors involved in cardiovascular diseases. Demand for healthy shortening with desirable functionality is the main reason to exploit interesterification of liquid oil with fully hydrogenated fats free of TFA. In the present study, all purpose shortening was prepared by chemical interesterification (CI) of high oleic sunflower oil and fully hydrogenated canola oil in 70:30 proportions (w/w). The product was crystallized in a Gerstenberg and Agger (Copenhagen, Denmark) votator and tested by baking Chewy Brownie Cookies. The CI process produced a fat with excellent plasticity, solid fat content profile, melting point and hardness, and was appropriate for use as an all purpose shortening. Interestingly, the polymorphism of the CI material was predominantly in the β form, and did not seem to be influenced by the mechanical and cooling treatment. However, small crystals in the range of 10-30 μm were observed. The physical properties of the CI shortening were similar to those of a widely used commercial shortening.

Electroacoustic Monitoring of Competitive Adsorption between Two Different Polysaccharides at the Oil-Water Interface.
Y.-H. Cho, D.J. McClements, University of Massachusetts, Amherst, MA, US

The electroacoustic (EA) technique is a powerful tool for monitoring polyelectrolyte adsorption in concentrated colloidal dispersions. Two different anionic polysacchrides, iota-carrageenan (i-ca) and HM pectin were employed in this study and the adsorption of them onto droplets coated with β-lactoglobulina (β-Lg) was monitored by the EA technique. The electrical charge of the droplets at pH 3.5 changed from positive (≈ +40 mV) to negative (≈ -25 mV or -4 mV) as the i-ca or HM pectin concentrations increased, suggesting the adsorption of anionic polysaccharides onto cationic droplets. Thus carrageenan was able to produce more highly charged droplets because of its higher charge density. The interfacial characteristics of the droplets could be controlled by adsorbing mixed polysaccharides.EA monitoring of concentrated emulsions in situ without dilution could provide rapid information about the interaction of different components at interfaces, this knowledge could be used to design polysaccharide coated droplets with improved properties.

Structural Order of Triacylglicerides During Crystallization Evaluated by Anysotropy.
E. Dibildox-Alvarado1, A. Marangoni2, J.F. Toro-Vazquez1, 1Universidad Autónoma de San Luis Potosí, Facultad de Ciencias Químicas, San Luis Potosí, México, 2University of Guelph, Department of Food Science, Guelph, Canada

The rotational diffusion of a fluorophore (diphenyl hexatriene, DPH) in mixtures of 25% tripalmitin (TP) in triolein (OOO), safflower oil high in triolein (SFO) or soybean oil (SO) was evaluated as a function of time under isothermal conditions (TCr between 36°C and 41°C) measuring anisotropy (r) by fluorescence polarization spectroscopy. A decrease in rotation diffusion of DPH results in an increment in r, a process associated with higher structural order of TAGS molecules in the liquid phase. For a given system the induction time for crystallization (Ti, determined by DSC) increased as a direct function of TCr. However, at a given TCr the Ti increased, probably because POO, PLO, and LLP present in SFO (10.2%) and SO (27.6%) delayed TP nucleation. In the OOO system at all TCr investigated, r remained constant over time decreasing during TP crystallization. The SFO system showed an increase in r right after Ti followed by a decrease until achieving a constant value. Similar results were observed by SO, but the increase in r was before Ti. TP crystallized in the β state in all systems investigated. These results showed that before crystallization, TP had to be segregated first achieving a higher structural order in the liquid phase. The kinetics of this process depends on the molecular interactions between TAGS in the liquid phase and the crystallizing TAGS (i.e., TP).

Modelling the Temperature Dependency of Crystallization Parameters in View of Describing the Non-Isothermal Fat Crystallization Process.
Maarten Sichien1, Imogen Foubert1, Ingmar Nopens1, Peter A. Vanrolleghem2, Koen Dewettinck1, 1Ghent University, Ghent, East-Flanders, Belgium, 2Université Laval, Québec, Canada

The aim of this research is to extend the two-step Foubert model for application under non-isothermal conditions since a lot of fat crystallization processes take place non-isothermally. To accomplish this, the temperature dependence of the isothermal model parameters was studied and included in the model using submodels. Before using the two-step isothermal model in this research, a sensitivity analysis was performed. From this analysis, it could be concluded that the parameters nβ′ and Kβ′ have at the same time an effect on the model output. Therefore it was decided to fix parameter nβ′ to a value of 6. Furthermore it was also decided to fix t_ind to zero as no induction time could be detected. The isothermal crystallization of cocoa butter was then be measured at each crystallization temperature followed by fitting the model to all these crystallization curves. Next, the obtained parameters were plotted as function of temperature and for each parameter a best model to describe the temperature dependency was searched for and calibrated. These submodels were then combined with the basic model. A first validation of the model was performed using data of cocoa butter sequentially crystallized at two different temperatures.