2010 Food Structure
FS&FF 1: Food-Body Interactions
Chair(s): I. Appelqvist, CSIRO, Food and Nutritional Sciences, Australia; and M. Paques, Royal FrieslandCampina, The Netherlands
Keynote Lecture: Overview of Field. L. Huang, Monell Chemical Senses Center, USA
Humans and other vertebrates are believed to be capable of detecting at least five primary taste qualities: sweet, bitter, savory, sour and salty. The sensation of taste begins in the oral cavity. Taste buds, each of which consists of 50-100 cells, are the peripheral endorgans of taste. The activation of taste receptors on taste bud cells by sapid molecules triggers intracellular signal transduction cascades, which eventually lead to the release of transmitters such as ATP and serotonin onto the afferent gustatory nerves. While each taste quality seems to be sensed by a particular subset of taste bud cells, many of these signal transduction components are common among these sweet, bitter and savory taste signaling pathways. Interestingly, a number of these signaling molecules, including the G protein-coupled taste receptors, heterotrimeric G proteins, effector enzymes and downstream ion channels have also been found in the epithelial cells of the gastrointestinal tract. Stimulation of these transduction pathways regulates the release of glucagons-like peptide-1 (GLP-1) and other hormones in the GI tract. Therefore, taste receptors and their signaling pathways are not only essential in the initial food assessment in the oral cavity but also participate in monitoring ingesta along the alimentary tract, and taste bud cells and gut chmosensory cells function coordinately in regulating food intake and nutrient absorption.
Gut-expressed Sweet Taste Receptor and Regulation of Intestinal Glucose Transport. S. Shirazi-Beechey, University of Liverpool, Liverpool, UK
Many of the receptors and downstream signalling elements involved in taste transduction are also expressed in enteroendocrine cells where they underlie the chemosensory functions of the gut. We showed, for the first time, that taste receptor 1, T1R, family members, T1R1, T1R2 and T1R3 are expressed in the intestinal epithelium and proposed that the sweet taste receptor, T1R2+T1R3, functions as the luminal sugar sensor. Recent work in our laboratory has determined that T1R2+ T1R3, and the partner G-protein, gustducin, are co-expressed in glucagon like peptide 1 (GLP-1), glucose-dependent insulinotropic peptide (GIP) and serotonin containing endocrine cells. We have been interested in the role played by the intestinal sweet taste receptor in regulation of the intestinal glucose transporter, Na+/glucose cotransporter 1, SGLT1. SGLT1 is the major route for the transport of dietary sugars from the lumen of the intestine into enterocytes. Regulation of this protein is essential for the provision of glucose to the body and, thus, is important for maintenance of glucose homeostasis. We demonstrated that dietary sugars and artificial sweeteners increase SGLT1 mRNA and protein expression and glucose-absorptive capacity in wild type mice, but not in T1R3, or gustducin, knockout mice, indicating that T1R3 and gustducin are required for enhanced expression of SGLT1 in response to lumenal sugars and sweeteners. The findings that gustducin and T1Rs reside in enteroendocrine cells, whereas SGLT1 is expressed in neighbouring absorptive enterocytes implies a signalling event taking place between the chemosensory enteroendocrine cells and absorptive enterocytes. I shall discuss progress made in understanding the mechanisms underlying this cell to cell communication.
Chemosensory Functions of the Brain. Ivan E. de Araujo, The John B. Pierce Laboratory & Yale University School of Medicine, USA
Specialized populations of cells located in regions adjacent to the brain ventricles are thought to act as chemosensors capable of assesing the chemical composition of the bloodstream. Chemicals sensed by these specialized neuronal cells include nutrients such as glucose, lipids and amino acids, as well as minerals and an array of molecular ions. Of particular interest are the mechanisms involved in the sensing of extracellular glucose levels by neurons located in the hypothalamic area. Specifically, it remains unclear if the detection of extracellular glucose levels by “glucosensing” neurons depends on the intracellular metabolism of glucose or, alternatively, on currently unidentified neuronal glucose membrane receptors. In this talk we will review our current knowledge on the physiological and molecular mechanisms underlying neuronal chemosensation. We will in particular review evidence both in favor and against the notion that neuronal glucosensing relies on the existence of membrane glucose receptors, and will present recent data suggesting that “sweet” T1R2/T1R3 receptors might operate as one such brain glucose receptor. We will consider the possible physiological roles that may be associated with brain “sweet taste receptors” and a parallel between brain and gut chemosensory functions will be outlined.
Gut Nutrient Sensing, Gut Hormone Release and Appetite Regulation. G. Frost, Imperial College London, UK
The aim of the lecture will be to give an overview of the relationship between foods, nutrient sensing in the gastro intestinal tract and appetite regulation. The lecture will focus on the role played by gut hormones and/or triggering CNS response. The intention is to debate the role of nutrient receptors in maintaining energy homeostasis. We will bring in the work carried from infusion of gut hormones as evidence for gut hormones as short term satiety signals, and our own team investigating central signalling. We will highlight our recent work investigating the sweet taste receptor T1R2-T1R3 and the fatty acids receptors GPR40, 41 and 43. One of the aims will be to highlight the importance of integrated physiology to understand these systems. I would also like to highlight the impact of physiological change in food structure as a potential method of regulating appetite.
Nutrient and Taste Receptors in the GI-Tract: Consequences for Food Preferences and Intake. R. Mattes, Purdue University, USA
It is widely acknowledged that the sensory properties of foods are critical determinants of food choice. The affective responses they elicit have inherent and learned components. The former provides the hedonic framework for judging food acceptability, but is modified through experience. This starts in utero and continues throughout life. The primary mechanism entails associative learning where the sensory properties of a food are paired with consequences of its ingestion and can be used subsequently to guide ingestive decisions. Recent findings have expanded understanding of the mechanisms and functions of sensory systems in this context. The concept of a limited number of taste primaries is being challenged by evidence of gustatory responses to compounds like fat that do not fall within traditional categories. Further, there is accumulating evidence that the transduction mechanisms for taste compounds in the oral cavity are functional throughout the gastrointestinal tract. Thus, the chemical signals in foods influence not only decisions to internalize a substance, but also its digestion, absorption and peripheral metabolism. Feedback from the combination of these processes then become the substrate upon which future decisions are made regarding what, when, how much and in what form that food should be consumed in the future.
Food Preferences Conditioned by Nutrient Actions in the Gut. A. Sclafani, Department of Psychology, Brooklyn College-CUNY, Brooklyn, NY, USA
Food preferences are determined not only by the orosensory (taste, odor, texture) properties of food but also by the post-oral actions of nutrients. Flavor preferences are conditioned in rodents by intragastric (IG) or intraduodenal nutrient infusions. These conditioned preferences are very persistent, can reverse the animal’s natural taste aversions (e.g., to bitter) and are produced by a variety of nutrients (carbohydrate, fat, protein). The presence of taste signaling proteins in the GI tract suggests that conditioned preferences might be mediated by gut “taste” cells, but this has not been confirmed. Knockout mice missing the T1R3 sweet taste receptor do not prefer sweet solutions, but learn to prefer flavors paired with IG sucrose solutions. Also, the effectiveness of IG glucose but not fructose infusions to condition flavor preference suggests that carbohydrate conditioning is mediated by a glucose sensor rather than a sweet receptor. Similarly, although CD36 may act as a gustatory lipid receptor, CD36 knockout mice learn to prefer flavors paired with IG fat infusions. A greater understanding of the gut nutrient sensing pathways that mediate food preference learning may lead to new approaches to diet-related disorders.Supported by DK31135
A Gut Feeling for Satiety—Are Gut Receptors a Potential Target for Energy Intake Control?. Martin Foltz, Unilever R&D, Vlaardingen, The Netherlands
Developing functional foods calls for fundamental understanding of the physiology of the benefit area and includes identification of key regulators targetable with foods. The GI tract is a potential target region for influencing body weight as recent findings show that energy intake is inter alia determined by gastrointestinal stimuli.A variety of nutrients triggers gut hormone secretion and activate the vagus. The underlying initiation events seems to include activation of receptors and transporters sensitive towards fatty acids, peptides, amino acids, sweet and bitter compounds. The true physiological role of specific gastrointestinal nutrient receptors and their overall contribution for regulation of energy intake is poorly understood. We have recently characterized selected bitter receptors from the TAS2R family, the peptide receptor GPR93 and the umami receptor T1R1/R3. In the presentation in vitro, ex vivo, and animal in vivo data will be presented. The results point to a potential route of action by which selected natural compounds might influence appetite control. Our data provide additional evidence that bitter and peptide sensing mechanisms are coupled to hormone release from enteroendocrine cells. Their relevance as molecular target for influencing energy intake in man needs testing using specific food grade receptor antagonists.
FS&FF 2: Design of Successful Performing Interfaces
Chair(s): K. Dewettinck, Ghent University, Belgium; and Y. Wang, Kraft Foods Inc., USA
Factors Governing Partial Coalescence in Oil-in-Water Emulsions: a Review. K. Dewettinck1, E. Fredrick1, P. Walstra2, 1Ghent University, Belgium, 2FrieslandCampina, The Netherlands
The consequences of the instability mechanism partial coalescence in oil-in-water food emulsions show a discrepancy. On the one hand, it needs to be avoided in order to achieve an extended shelf life in food products like sauces, creams and several milk products. On the other hand, during the manufacturing of products like ice cream, butter and whipped toppings partial coalescence is required to achieve the desired product properties. It contributes to the structure formation, the physicochemical properties (stability, firmness, overrun) and the sensory perception, like fattiness and creaminess of the final food products. Both the process parameters, like the flow condition, the temperature history and the actual temperature, and the formulation of the oil-in-water emulsions, defining the distribution of the components between the continuous aqueous phase, the dispersed oil phase and the interfacial layer, determine to a large extent the rate of partial coalescence. This review critically summarises the findings of partial coalescence in oil-in-water emulsions in order to provide insight in how to enhance and retard it. Next to the pioneering work, a large set of experimental results of more recent work is used to illustrate the key factors.
Mechanism of Lipolysis and Micellization of β-carotene from Oil-in-Water Emulsions Stabilized with Soy Protein Isolate. A. Malaki Nik, M. Corredig, A.J. Wright, University of Guelph, Guelph, Ontario, Canada
The design of novel interfaces to control the behavior of food colloids during digestion, including lipolysis is an exciting area of research. In the current study, the effect of the oil-water interfacial structure on the lipolysis of an oil-in-water emulsion stabilized with SPI and the subsequent release of β-carotene (BC) was investigated. Particle size distribution of emulsion was significantly altered during simulated gastric digestion. However, the introduction of bio-surfactants, mainly bile salts (BS) and phospholipids (PL) during the duodenal stage resulted in re-emulsification of the oil droplets. Combined with particle size distribution, a significant increase in negative charge was obtained during the 2 h duodenal digestion, i.e. from -40 to -70 mV, indicated that proteins and peptides were displaced in the presence of BS. The pancreatic lipase activity was monitored by the release of free fatty acids. In the presence of BS alone, 60% lipid hydrolysis occurred, while addition of PL was found to inhibit lipolysis and the introduction of colipase significantly increased the extent of lipolysis up to 85%. Investigations of BC micellization showed 70 % transfer in presence of BS alone and addition of PL and colipase affect the rate of BC micellization. The results of this study would enable food industry to design high-quality healthy foods.
Stability and Controlled Release Properties of Double Emulsions. L. Sapei, D. Rousseau, Ryerson University, Toronto, ON, Canada
Food-grade water-in-oil-in-water (W/O/W) double emulsions for the controlled release of food ingredients were developed. Emulsions were prepared with deionized water and canola oil, as well as polyglycerol polyricinoleate (PgPr) and polysorbate 80 as emulsifiers for the primary water-in-oil (W/O) emulsions and secondary (W/O/W) emulsions, respectively. Sodium chloride (NaCl) was entrapped within the internal aqueous phase as a simple model compound to evaluate the stability and release properties of the emulsions. The internal aqueous phase was gelled with gelatin to improve emulsion stability and slow the release of NaCl from the internal aqueous phase towards the external aqueous phase. Stability of the W/O/W emulsions was characterized via sedimentation, optical microscopy, particle size analysis, and conductivity to examine NaCl release profile. There was a significant decrease in the total release and release rate of NaCl with gelatin incorporation compared to the control double emulsions. Release of NaCl was also dependent on initial loading. The initial average oil globules size increased from 45 to 65 µm with an increase of NaCl concentration from 2% to 8% in the internal aqueous phase. All W/O/W emulsions had a high initial salt retention in the inner aqueous phase (>90%), which was very promising for the encapsulation of food ingredients and their controlled release.
The Development of a One-step Double Emulsion Formation Protocol. M. Pradhan, D. Rousseau, Ryerson University, Toronto, ON, Canada
The development of double emulsions typically involves a two-step process whereby an internal emulsion is dispersed into another continuous phase via secondary emulsification. We have now developed a single-stage double emulsification protocol for the development of oil-in-water-oil (O/W/O) emulsions that only requires one surfactant. Two different n-alkane oils and three different emulsifiers were studied, with focus placed on a formulation containing mineral oil, glycerol monooleate (GMO) and deionized water. Depending on the ratio of GMO and water, a critical zone emulsification existed where the O/W/O emulsion yield and stability were highest. Phenomenologically, double emulsion formation originates from the charging of the oil/water interface during emulsification which is balanced by the emulsification capacity of the GMO. At a critical ratio, GMO’s capacity to promote water-in-oil (W/O) emulsion formation is counterbalanced by interfacial charging leading to extensive double emulsification. The role of pH was also investigated, and showed that higher double emulsification occurred at basic pH (~10). With an increase in ionic strength (adjusted with NaCl) from 1mM to 10mM, only single W/O emulsion formation occurred as any interfacial charging effect was diminished.
Formation and Stability of Salt-containing Microemulsions. N. Berry, D. Rousseau, Ryerson University, Toronto, ON, Canada
Alcohol-free water-in-oil (w/o) microemulsions were developed using food-grade ingredients. Vegetable oil was used as the oil phase, with glycerol monooleate and polysorbate 80 used as low and high HLB surfactants, respectively. A pseudo-ternary phase diagram was constructed at 25°C to identify the monophasic microemulsion region. Rheology, conductance, refractive index and dynamic light scattering studies were carried out to characterize these systems. Sodium chloride (NaCl) was incorporated in the dispersed phase of these microemulsions as a model compound and its effects on stability were monitored over time. The monophasic region comprised a third of the phase diagram. For selected compositions along two dilution lines (DLs), the droplet size of the microemulsions, without and with added NaCl, ranged from 7 to 16 nm and 10 to 16 nm, respectively. Without NaCl, the viscosity along DL28 (20 wt% polysorbate 80 and 80 wt % oil phase) was 146.4 cP and 192.1 cP along DL 37 (30 wt% polysorbate 80 and 70 wt % oil phase). Addition of 1 wt% NaCl resulted in lower microemulsion viscosities along both DLs. These systems were stable for several months, with slow changes in dispersed domain size, irrespective of presence of NaCl.
Characterization of Solid Lipid Nanoparticles as a Novel Emulsifier for Food Applications. Renuka Gupta, Dérick Rousseau, Ryerson University, Toronto, ON Canada
Glyceryl stearate citrate (GSC) is a vegetable-based citric acid ester of mono- and di-glycerides of stearic acid that possesses emulsifying abilities. It is solid at room temperature with a melting range of 59-64°C. In this study, solid lipid nanoparticle (SLN) dispersions of 5% (w/w) GSC in water were made using hot valve homogenization and subsequent quench-cooling. The resultant particles were characterized for their particle size, shape and zeta potential as well as their thermal behaviour with differential scanning calorimetry (DSC).Particle size analysis confirmed the stability of the SLNs, with little change in mean particle diameter over 18 months under refrigeration. The initial SLN size was ≈225 nm which increased to ≈250nm during that time. The zeta-potential of the SLNs was also fairly stable, changing from -90 mV to -104 mV. As well, DSC did not reveal any significant changes in the melting behaviour of the aged vs. newly-formed SLNs and transmission electron microscopy (TEM) showed smooth, spherical spheres with occasional SLN-SLN aggregation after 18 months. These results confirmed that stable SLNs were produced. Current studies are focussing on the incorporation of these SLNs in oil-in-water food emulsions.
FS&FF 3: Phase Transitions and Rheology of Food Structures
Chair(s): D. Rousseau, Ryerson University, Canada; and S. Martini, Utah State University, USA
Use of Ultrasound Spectroscopy to Examine on the Effect of Fatty Acid Sodium Salt on the Gel Formation of Milk Proteins at Ambient Temperature. N. Yuno-Ohta1, M. Corredig2, 1Nihon University, Mishima, Shizuoka, Japan, 2University of Guelph, Guelph, Ontario, Canada
We have reported on the mechanism for fatty acid salts (FAS) induced gel formation of β-lactoglobulin (β-LG) A type. In this study, we investigated the effects of FAS and sodium chloride (NaCl) on the gel formation of milk proteins. Although FAS induced gel formation of β-LG B type like A type at 25 º C, FAS inhibited micelle formation of β-casein (β-CN). The addition of FAS to the mixed protein of β-LG and β-CN promote the formation for the mixed gel by suppressing the micelle formation of β-CN. We also investigated the self-assembling behavior of β-CN in the presence of NaCl without FAS. Twelve % β-CN showed a decrease of velocity difference between with and without NaCl and a transient increase of ultrasound attenuation occurred during the incubation at 30 º C. FT-IR measurements showed that intermolecular β-sheet was once increased accompanying with formation of gel-like aggregates from the sol state, and then intramolecular β-sheet took over intermolecular β-sheet as it softened. These results suggest that the aggregates once formed might breakdown easily.
Monitoring Bubble Dynamics in Soybean Oil. Silvana Martini, Ricardo J. Tejeda Pichardo, Scott C. Jensen, Vern Hart, Timothy Doyle, Utah State University, Logan, UT, USA
High intensity ultrasound (HIU) can generate lipid networks with different crystal sizes, crystal size distributions, textures and melting profiles. Research in sonocrystallization in other systems has suggested that this effect is caused by cavitation. However, very little research in lipid systems has been performed to record and quantify cavitation events. This research explores the use of a SIA-7 ultrasonic system and broadband transducers (central frequency=1 MHz; bandwidth=920 kHz), to detect and acoustic events in soybean oil. Different temperatures (22, 24, 26, 28 and 30 °C), sonication power (6, 18, 38, 60, and 84 W) and duration (5, 10 and 60 seconds) were analyzed. Results from this research showed that attenuation increased during sonication reaching values as high as 25 dB/cm. Higher sonication power produced higher attenuation, especially at frequencies around 1 MHz. In addition, when ultrasound was applied for 10 seconds, attenuation was still observed even after sonication was stopped. This might be due to the presence of stable bubbles in the media. Reflection results showed that most of the reflection occurred at low frequencies (around 0.5 MHz) indicating that big bubbles were responsible for this effect. In addition, regular patterns were observed in these plots suggesting that turbulence might also be generated as a consequence of high intensity sonication.
Fat Crystallization at the Oil-Water Interface under Continuous Shear Flow: a Rheomicroscopy Approach. S. Ghosh, D. Rousseau, Ryerson University, Toronto, ON, Canada
Fat crystal nucleation at the oil-water interface is critically influenced by surfactant structure. Fat crystallization in water-in-oil emulsions under flow was monitored using a rheomicroscope by measuring simultaneous changes in viscosity and microstructure. Emulsions were prepared at 70°C by homogenizing 20% (w/w) water, canola oil, emulsifiers and stabilizing fat, which were then cooled with stirring and stored at room temperature. Glycerol monostearate (GMS), glycerol monooleate (GMO) or polyglycerol polyricinoleate (PGPR) were used as emulsifiers and hydrogenated canola oil (HCO) was added as a continuous phase stabilizer. Microscopy revealed that GMS nucleated strictly at the droplet interface whereas in presence of GMO, HCO nucleation began both at the interface and in the continuous phase, providing combined Pickering and network stabilization. However, in PGPR-stabilized emulsions, HCO nucleated only in the continuous phase. It is proposed that the complex structure of PGPR prevented the correct arrangement and subsequent crystallization of HCO at the interface whereas the complementary fatty acid chain lengths of GMO and HCO permitted organization of HCO near the interface leading to nucleation on the droplet surface. In the case of emulsions prepared with GMS and HCO, the fact that GMS crystallized at a higher temperature excluded HCO molecules from the interface.
The Influence of Seed Crystals on Fat Crystallization within Oil-in-Water Emulsion Systems Using Ultrasound Velocity Techniques. A.S. Richards1, M.J.W. Povey2, 1CSIRO Food and Nutritional Sciences, Werribee, VIC, Australia, 2School of Food Science and Nutrition, The University of Leeds, Leeds, UK
Seed crystals are a complex matrix of triacylglycerol, phospholipids, glycolipids and water, and are believed responsible for primary nucleation events within the process of heterogeneous fat crystallisation. The crystallisation behaviour of an oil-in-water emulsion system can also depend upon droplet size, degree of droplet to droplet interaction, and the type of emulsifier used. The present study examines the role of seed crystals and solid fat content within a bimodal system as a function of temperature, using ultrasound velocity measurements. Here we produced stable bimodal systems consisting of a 10%w/w palm, palm kernel, sunflower or blended oil phase stabilised by Caflon phc060 surfactant and resulting in reproducible crystallisation behaviour across a temperature sweep of (i) 0 to 80 °C and (ii) -2 to 80 °C.
Destabilization of W/O Emulsion by Continuous Phase Fat Crystals. S. Ghosh1, H. Hajir2, D. Rousséau1, 1Ryerson University, Toronto, ON, Canada, 2Université de la Réunion, Ile de la Réunion, France
The formation of a fat crystal network in water-in-oil (W/O) emulsions normally provides dispersed phase stabilization. In this study, the critical solid fat content that induces dispersed phase destabilization in model emulsions was determined. W/O emulsions containing 20% (w/w) water and an 80% (w/w) oil phase consisting of canola oil, polyglycerol polyricinoleate (PGPR) and up to 50% (w/w) molten hydrogenated canola oil (HCO) were homogenized at 80°C and quenched-cooled to 25°C. Emulsions were temperature-cycled ten times from 25°C to 70°C and back to melt and re-crystallize the HCO. The stability after each cycle was evaluated by sedimentation, water droplet size, microstructure and thermal behaviour. The presence of 10% and 20% HCO in the continuous phase led to major improvements in emulsion stability compared to the HCO-free control. With 30% or more HCO, emulsion destabilization was observed. Micrographs of these emulsions showed droplet crowding and deformation by the crystallizing fat phase. As HCO crystallized, the droplets were forced to still-liquid regions of the continuous fat phase, which led to thinning and rupture of interdroplet oil films. With repeated temperature-cycling, greater droplet coalescence occurred, leading to an increase in emulsion destabilization. These results serve as the foundation for a theory to model the maximum solid fat that can be used without destabilizing an emulsion.
The Importance of Microstructure in Controlling Migration Fat Bloom. C. Delbaere, F. Depypere, N. De Clercq, S. De Pelsmaeker, R. Januszewska, X. Gellynck, K. Dewettinck, Ghent University, Gent, Belgium
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. Compared to polymorphic fat bloom on plain chocolate, far less literature data is available on migration fat bloom in composed chocolates, despite its higher industrial relevance. Through a phenomenological approach, dealing with different case studies of fat bloom development on industrially relevant composed chocolate products, it was concluded that the current knowledge on migration fat bloom mechanisms is insufficient to explain all cases. Moreover, oil migration from the filling to the surrounding chocolate was not always found to result into visual fat bloom. Therefore a better understanding of the relationship between oil migration and the incidence of visual fat bloom is needed. Literature data suggest a crucial role for the microstructure of the composed chocolate product, particularly that a more dense microstructure could retard or reduce both oil migration as well as visual fat bloom.This presentation will discuss the importance of microstructure in controlling migration fat bloom. This will be illustrated with recent work regarding effects of storage conditions on the development of fat bloom on composed chocolates.
Key Components and their Microstructural Functionality in the Chocolate Matrix. K. Dewettinck, D. Vandewalle, F. Depypere, Ghent University, Department of Food Safety and Food Quality, Laboratory of Food Technology and Engineering, Belgium
Chocolate is a dispersion of sugar particles, cocoa solids and milk powder (in the case of milk chocolate) in a continuous fat phase and is manufactured through different steps, namely mixing and refining, conching, tempering and cooling. Both the ingredients as well as the processing conditions influence the microstructure of the chocolate matrix which on its turn affects the macroscopic and sensory properties. Understanding the relationship microstructural - macroscopic properties is crucial in the development of innovative chocolate products.
Measurement of Elastic Waves Generated by Biscuits during Chewing Simulation. Alex Fok1, Haiyan Li1, Xiaozhou Liu2, 1Minnesota Dental Research Center for Biomaterials and Biomechanics, USA, 2Peking University, Beijing, China
This study aims to characterize the textures of biscuits by measuring the elastic waves generated during chewing simulation using the acoustic emission (AE) technique.Three kinds of cereal crackers (General Mills, USA) were mechanically tested in an artificial dental articulator. Each specimen was put between the maxillary and mandibular second molars and a MTS machine was used to close the articulator. An AE sensor was attached to the buccal surface of the maxillary second molar to collect the AE signals. The load and AE events were recorded simultaneously and subsequently correlated to describe the fracture process of the biscuits. The accumulated amplitude of all the AE events from each specimen was used to assess the elastic energy released during fracture. Frequency analysis of the elastic waves was also carried out.A rapid increase of AE events was obtained during cracking of the biscuits. The mean failure loads (standard deviations) for the three groups were 41.46N (8.22N), 7.20N (2.56N) and 6.88 (2.27N). The average numbers of AE events for the three groups were 379(73), 237(122) and 139(68), with accumulated amplitudes of 20,633dB (3,903dB) and 13,306dB (6,638dB) and 7,763dB (3,775dB). The predominant frequency of the elastic waves from all three biscuit groups was around 150kHz, which was much higher than those reported for food sounds.
Coherent Anti-Stokes Raman Scattering Microscopy Study of Lipid, Water and Protein Distribution at the Surface of Food Structures. Eric O. Potma, Department of Chemistry, University of California, Irvine, CA 92697, USA
We have used coherent anti-Stokes Raman scattering (CARS) microscopy to map out the distribution of lipid, water and protein at or near the surface of various food specimens. Chemical selective imaging without the use of labels was achieved at rapid image acquisition times, permitting quick inspection of food surface quality with microscopic resolution. By making use of advanced image analysis methods, including principle component analysis (PCA), high resolution chemical maps were obtained. Such maps allow a detailed assessment of microscopic structure, topology and composition of food specimens. It will be shown furthermore that CARS imaging can be performed with a fiber-coupled probe, allowing flexible inspection and analysis of food samples in real time.
FS&FF 4: New Processing Approaches for the Creation of Novel Food Structures
Chair(s): P. Smith, Cargill, Belgium; and G. Yang, Kellogg North America Co., USA
Polycarbonyls: Modelling the Interactions Between Fats in a liquid phase. D.A. Pink1, D. Rousseau2, S. Razul1, C. MacDougall1, J. Marsh1, 1St. Francis Xavier University, Antigonish, NS, Canada, 2Ryerson University, Toronto, ON, Canada
The interactions between triglyceride molecules give rise to interesting solid state crystalline structures. Interesting also are the possibilities of a range of structures in the liquid phase (Corkery et al. Langmuir 23, 7241 (2007), Pink et al. J. Chem. Phys. 2010 in press). Recent work has involved modelling them analytically and via atomic scale molecular dynamics. Here we consider modifications to the glycerol cores via the replacement of the carbonyl groups by polycarbonyls. We shall describe the appearance of structures in a liquid phase and discuss how they might be detected.
How Useful is Lifshitz Theory? Modelling Complex Fats in a Liquid Medium. D. Pink, B. Quinn, S. Razul, C. MacDougall, J. Marsh, St. Francis Xavier University, Antigonish, NS, Canada
An understanding of the interactions between two solid fats surfaces in an liquid medium are not only of importance to the food industry but is an intrinsically-interesting problem. Lifshitz theory together with the work of Parsegian and Ninham opened the way to better calculating Hamaker coefficient(s) in such complex systems. There are systems, however, for which other approaches are useful. Thus, the presence of tethered polymers near the surfaces introduces complexities not normally considered. This paper will show the use of alternative theoretical techniques using analytical and computer simulation methods set within the context of Lifshitz theory, and propose experiments using atomic force microscopy.
Solid Lipid Encapsulation of Water-soluble Compounds for Controlled Release Applications. M. Ray, D. Rousseau, Ryerson University, Toronto, ON, Canada
A multiple emulsion technique was used to develop cocoa butter (CB)-based solid capsules that contained a water-based marker (sodium chloride). Hot water-in-CB emulsions stabilized with PGPR were formulated and their droplet size distribution and sedimentation were ascertained. Salt-containing solid CB particles were developed by quench-cooling the hot water-in-CB emulsion in 4ºC water containing Tween 80 for emulsification. The resultant particles were characterized by inverted microscopy for particle size and differential scanning calorimetry for melting behaviour. The salt release profile from the solidified CB particles was measured via conductivity. The CB particles’ initial size distribution influenced the total percentage of incorporated salt release, with smaller particles demonstrating lower percentage of total salt release over 9 hrs (e.g., particles with average size of ~350 µm showed ~40% total salt release) compared to larger particles (~600 µm particles showed ~51% total salt release). Storage time of the CB particles impacted salt release, with total salt release increasing with storage time. This study demonstrated that CB particles may potentially be used as a matrix for the controlled release applications of water-soluble compounds.
Engineering Crystallographic Mismatches of Self-Assembled Fibrillar Networks: Shedding Synchrotron Light on a Molecular Problem. R Lam1, L Quaroni2,3, T Pederson2, M. A. Rogers1, H Rutherford1, 1University of Saskatchewan, Saskatoon, Saskatchewan, Canada, 2Canadian Light Source, Saskatoon, Saskatchewan, Canada, 3University of Manitoba, Winnipeg, Manitoba, Canada
The lengths of the 12-hydroxystearic acid (12HSA) fibers are influenced by crystallographic mismatches resulting from the imperfect incorporation of 12HSA monomers into the crystal lattice. This is differentiable using synchrotron Fourier transform infrared spectroscopy by monitoring the change in area of the 1700 cm-1 and 3200 cm-1 peaks, corresponding to the dimerization of the carboxylic acid groups and hydroxyl non-covalent interactions, during crystallization. The crystallographic mismatch is attributed to a plateau in the apparent rate constant for the dimerization of the carboxylic acid head groups while the hydroxyl interactions linearly increase as a function of cooling rate. The rate constant for hydroxyl interactions linearly increases as a function of cooling rate while a plateau is observed for the rate of dimerization at cooling rates between 5 and 7 °C min-1. At cooling rates greater than 5 to 7 °C min-1 12HSA monomers do not effectively dimerize before being incorporated into the crystal lattice causing crystal imperfections impeding linear epitaxial crystal growth and produces branched fibers. Slow cooling rates (less than 5 to 7 °C min-1), produce long fibers with a fractal dimension between 0.95 and 1.05. Rapid cooling rates (greater than 5 to 7 °C min-1) produce short branched fibers with a fractal dimension between 1.15 and 1.32.
Novel Structuring Strategies for Unsaturated Fats-- Meeting the Zero-Trans, Zero-Saturated Fat Challenge. M.A Rogers, University of Saskatchewan, Saskatoon, SK, Canada
Numerous foods acquire their elastic properties (i.e., snap, mouth-feel, and hardness) from the colloidal fat crystal network comprised primarily of trans- and saturated fats. These hardstock fats contribute, along with numerous other factors, to the global epidemics related to metabolic syndrome and cardiovascular disease. A dire need for new technologies capable of structuring unsaturated edible oils, reducing the necessity for trans- and saturated fats, are required. At present, organogels are under-utilized in the food industry but numerous potential organogelators exist including: phytosterols and oryzanols, ceramides, monoglycerides and waxes. When examining these compounds as suitable ingredients for the food industry, they should be food grade, cost effective, have no negative health implications and one should be able to modify their physical properties. This review considers alternatives to colloidal fat crystal networks when structuring unsaturated oils as well as methods to modify their physical properties.
Experiences Using Stearidonic Acid-enriched Soybean Oil, a Source of Omega-3 Fatty Acids, in Shortenings Intended for Use in Baked Goods. J. Whittinghill, B. Lambach, S. Lee, D. Engelbrecht, C. Lucak, D. Welsby, Solae, St. Louis, MO, USA
There is growing consumer demand for food products enriched with omega-3 fatty acids in the market place today. Increasing evidence has shown that consumption of dietary omega-3 fatty acids could have major health benefits. Stearidonic acid (SDA)-enriched soybean oil, intended for use as a food ingredient, offers a plant-based sustainable source of omega-3 fatty acid that can be efficiently converted to eicosapentaenoic (EPA) acid in the human body. Manufacture of SDA-enriched shortenings will be important in food applications where liquid oil would otherwise be difficult to incorporate in the food system.Shortening blends were prepared using SDA-enriched soybean oil and a fully hydrogenated palm kernel oil. Control shortening blends were also prepared using conventional soybean oil. Fatty acid analysis, peroxide values, iodine values, solid fat content as well as DSC were all conducted on the SDA-enriched shortening blends. Chocolate chip cookies and dark chocolate bars were prepared from the shortening blends so as to deliver approximately 375 mg SDA per serving. Sensory evaluation was conducted using consumer acceptance and descriptive sensory profiling scales. Sensory data show that SDA-enriched shortening blends can be used to deliver form, structure and acceptable flavor in baked food products.
Modelling Food Systems Using Computer Simulation. D.A. Pink1, D. Rousseau2, S. Razul1, 1St. Francis Xavier University, Antigonish, NS, Canada, 2Ryerson University, Toronto, ON, Canada
All experimental data is interpreted using mathematical models, whether explictly or implicitly. Simply accounting for such data via a mathematical model is inadequate unless it is accompanied by predictions of new phenomena. This can be especially useful for the Food industry in cases where macroscopic phenomena may depend upon micro- or nano-scale interactions which might not be experimentally accessible. In the last decade, advances in computing hardware and software have made it feasible to consider modelling complex polymeric food systems with a reasonable expectation of success. This talk will give an overview of the techniques of, predominantly, atomic scale molecular dynamics set within the context of monte carlo methods and dissipative particle dynamics: a how-to-use-it primer illustrated by examples from current problems involving complex polymeric systems in the Food industry.
Food Structure and Functionality Forum Posters
Chair(s): K. Dewettinck, Ghent University, Belgium
Impact of Konjac glucomannan on Rheological Properties and Granule Morphologies of Corn Starch.
Yumi Hiwatashi, Takao Nagano, Kawasaki University of Medical Welfare, Kurashiki, Okayama, Japan
Starch and non-starch hydrocolloids are often used together in food systems to modify the texture or improve the stability of food products. Konjac glucomannan (KG) has traditionally been used in Japanese cookery for centuries. However, research concerning interactions between KG and starch during processing is spare. In this study, the effect of KG with different molecular size distribution on the viscoelastic properties and the microstructure was investigated using dynamic viscoelastic measurements and confocal laser scanning microscopy (CLSM). The storage modulus G′ of the starch pastes increased by adding KG with a high molecular size distribution but did not by adding KG with a low molecular size distribution. The mechanical tangent tan δ of the starch pastes is inhibited to decrease by adding KG with a high molecular size distribution but not by adding KG with a low molecular size distribution. CLSM showed that KG with a high molecular size distribution tended to inhibit starch components from leaching out of starch granules to the continuous phase of starch pastes during gelatinization. These results suggest that molecular size distribution be important for KG to control rheological properties of starchy food products.
Morphological Transitions in 12-HSA Crystals Induced by Oscillatory Shear.
E.D. Co, A.G. Marangoni, University of Guelph, Guelph, Ontario, Canada
Vegetable oil organogels structured by a Self-Assembled Fibrillar Network (SAFiN) of 12-hydroxystearic acid (12-HSA) crystalline fibrils have a great number of possible applications in foods, cosmetics and pharmaceuticals. Currently, the macroscopic properties of these gels can be modified using thermal fields. The use of shear to modify the material performance is investigated in this poster. Oscillatory shear was applied to a thin and confined film of the pro-gel solution as the gelator crystallized under non-isothermal (1 °C/min) and isothermal (approximately 30 °C/min) regimes. Non-isothermally crystallized gels displayed preferential growth along a single axis, resulting in strand-like morphologies. Isothermally crystallized samples displayed spherulitic growth, ostensibly due to mass-transfer limitations imposed by the viscosity of the solvent. The application of oscillatory shear under these crystallization regimes drastically modified the microstructural morphology. In the non-isothermal regime, the fibers were aggregated to form thicker fibers. Under the isothermal regime, the typical spherulitic microstructure was absent. Instead, fiber-like morphologies were observed. The effect of shear in modifying the micro-conditions of the material as it crystallizes is of great interest and utility as a processing technique.
**CANCELLED** Monitoring Bubble Dynamics in Soybean Oil.
Rheological Properties of Liver Paste.
L. Steen1,2, S. Impens1, O. Goemaere1, H. Paelinck1, I. Foubert2, 1KaHo St. Lieven, Gent, Belgium, 2K.U.Leuven Campus Kortrijk, Kortrijk, Belgium
Little is known about the structural changes during the production process of liver paste, a typical Belgian finely comminuted meat product composed of liver, fat, salt, water, emulsifier(s) and small amounts of additives and spices. The liver batter (obtained by chopping and salting the liver) and the hot fat fraction (a mixture of minced precooked adipose tissue with broth and emulsifier) are mixed together with spices and additives in order to obtain a homogeneous liver paste batter emulsion, which is subsequently cooked and cooled to obtain the liver paste spread. The purpose of this study was to use rheological techniques to gain insight in the fundamental structure (viscous and viscoelastic behavior) of the batters and end products. Therefore, four liver paste products were prepared with two different ratios of liver and adipose tissue and with and without salt addition.
Formation of Transparent Solid Lipid Nanoparticles by Microfluidization and Influence of Lipid Physical State on Appearance.
T. Helgason1,2, B. Kristinsson 1,2, T. Awad3, K. Kristbergsson2, D. McClements3, J. Weiss1, 1University of Hohenheim, Stuttgart, Germany, 2University of Iceland, Reykjavik, Iceland, 3University of Massachusetts, Amherst, MA, USA
The use of transparent delivery systems has many advantages in the food industry. The objective of this study is to form transparent solid lipid nanoparticles and to investigate the effect of lipid physical state on the solution appearance.A lipid phase (10% w/w octadecane) and a surfactant solution with 1-5% SDS were heated to 45°C and homogenized using a microfluidizer with 5000-28000 psi pressure. Solidification of the lipid matrix was achieved by cooling the emulsion down to 5°C, while emulsions with liquid lipid where kept at room temperature.By varying processing pressure and SDS concentration, z-average sizes of 136.4±1.4, 78.1±1.1 and 36.2±0.4 nm, where achieved using 1% SDS and 5000 psi, 3% SDS and 10000 psi and 5% SDS and 28000 psi, respectively. The solution with the smallest particle size was found to be transparent. Upon solidification of the emulsions the turbidity of solutions increased 138.7±4.5, 28.8±0.85 and 5.4±1.2 percent with 136.4±1.4, 78.1±1.1 and 36.2±0.4 nm z-average size respectively. Solidification of the particles did not influence z-average size significantly, nor was any aggregation detected in the system. These results suggest that formation of truly nanosized particles is possible and that the physical state of the lipid influences the appearance of the solution.
Flavor Characteristics of Docosahexaenoic Acid Fortified Emulsions Formulated under Different Processing Conditions: A Sensory Evaluation Perspective.
Megan Tippetts, Silvana Martini, Utah State University, Logan, UT, USA
The stability and flavor intensity of docosahexaenoic acid (DHA) fortified emulsions as affected by processing temperature (-5 and -10 °C) and oil content (20 and 40% oil-in-water emulsions) was evaluated. Emulsions′ stability was measured using backscattering measurements and flavor attributes such as oxidized, rancid, fishy and buttery were quantified using a descriptive panel. Emulsions crystallized at -5 °C were more stable than the ones crystallized at -10 °C. For all conditions, DHA-fortified emulsions had a significantly higher fishy flavor. In addition, flavor intensities were higher for emulsions crystallized at -10 °C than for emulsions crystallized at -5 °C. These differences were significant (p<0.05) for buttery and rancid. Significant differences in the intensity of the oxidized attribute for emulsions crystallized at -5 °C were eliminated when samples were crystallized at -10 °C. The higher flavor intensity at lower temperature is probably due to the lower stability at -10 °C and the higher availability of the flavors to interact with taste and olfactory receptors.