2013 Food Structure
FS&FF 1: Phase Transitions - Engineering and Stability
Chair(s): M. Paques, Royal FrieslandCampina Research, The Netherlands; S. Ghosh, University of Saskatchewan, Canada
Tocopherol and lecithin for edible oleogels
C. Nikiforidis(1), E. Scholten(2)
(1)Top Institute Food & Nutrition and Wageningen University, Netherlands (2)Top Institute Food & Nutrition and Wageningen University, Netherlands
The texture of many food products like margarines, pastry dough, sausages etc., is achieved by including a crystallizing triacylglycerol fraction in the lipid phase of the product. This crystalline network contains considerable amounts of saturated fatty acids, which intake has been demonstrated to raise blood cholesterol and the risk of the occurrence of cardio-vascular diseases. Therefore, the decrease of saturated fatty acids in the crystalline network would be desirable. This is not a straightforward exercise, and therefore novel alternatives for oil structuring have to be generated. According to our findings the gelation of edible oils can be achieved by adding a mixture of tocopherol and lecithin at concentrations from 5 to 20% w/w. The two components individually cannot structure oil, but their mixture, depending on the concentration, can lead to viscous pourable solutions or to non-pourable gel-like structures. The synergistic effect of these two fillers was studied by varying their ratio and their concentration. The properties of the oleogels were evaluated using microscopy techniques, texture analysis, differential scanning calorimetry (DSC), and nuclear magnetic resonance (NMR). The obtained gels were shear-sensitive and the network formation was disrupted when the temperature was higher than 35 oC, but upon cooling they regain their firmness. Moreover, the addition of small amounts of water led to a change in the microstructure of the needle-like crystals and enhanced their rheological properties.
Heat-induced gel From Lysozyme and Ovomucoid Mixture
N. Yuno-Ohta(1), Y. Kimura(2)
(1)Nihon University, Japan (2)Junior College at Mishima, Nihon University, Japan
It is known that Ovomucoid (OM) in egg white is a heat stable protein. We investigated the interaction of lysozyme (LZM) and OM using ultrasound spectroscopy (US) under heating which is followed by cooling treatment, and scanning electron microscopy (SEM) etc.. The phase transition temperature of diluted LZM solution shifted to the higher temperature by the addition of OM. Although 10% OM alone did not formed a gel, a mixture of LZM and OM in suitable proportions formed a gel almost comparable to LZM gel. However the ultrasonic attenuation increments during heat treatment for mixed proteins were small and microstructures made from the denatured protein aggregates were very fine networks different from LZM gel. These results implied that the mixed protein formed gels with higher proportion of hydrogen bonding than LZM gel which is mainly composed of hydrophobic interaction. It suggests that the addition of OM to LZM induced changes in intermolecular forces for the gel formation and regulates the gel properties.
Unsaturated Emulsifier-mediated Modification of the Mechanical Strength and oil Binding Capacity of a Model Edible fat Crystallized Under Shear
N. Acevedo(1), J. Block(2), A. Marangoni(3)
(1)Iowa State University, United States of America (2)Santa Catarina Federal University, Brazil (3)University of Guelph, Canada
The effects of processing using a scraped surface heat exchanger (SSHE) before and after adding unsaturated monoglyceride (UM) on blends of Fully Hydrogenated Soybean Oil (FHSO) and Soybean Oil (SO) was studied. Mixtures of 40:60 and 45:55 FHSO:SO were melted at 80°C for 30 min and crystallized statically or in the SSHE (shear rate of 25s-1) at a cooling rate of 9°C/min. Upon shearing and UM addition, polymorphic transformations towards more (beta) or less (beta prime) stable forms was governed by the combination between system concentration, composition and crystallization conditions, as determined by differential scanning calorimetry and powder X-ray diffraction. Nuclear magnetic resonance was used to measure the solid fat content (SFC) development which showed to increase with processing conditions due to the high nucleation rate induced. Processing conditions greatly affected the nano- and micro-crystalline structures which were characterized by Polarized Light Microscopy (PLM), Cryogenic Transmission Electron Microscopy (Cryo- TEM) and Scherrer Analysis of the powder X-ray diffraction data. Crystallization under shear promoted the longitudinal growth of the nano-platelets; nevertheless meso structural elements showed a decrease in their dimension under the same crystallization conditions. The relative oil loss determined gravimetrically was inversely related to the elastic modulus and yield stress of the sheared fat blends which values were closer to the desirable usability ranges for bakery applications. Our results suggest that fully hydrogenated fats can be functionalized by crystallization in a SSHE and/or by judicious addition of an unsaturated emulsifier.
Nature and Dynamics of the Phase Transition of Monoglyceride-water System: Re-investigate
F. Wang(1), A. Marangoni(2)
(1)University of Gueloh, Canada (2)University of Guelph, Canada
The monoglyceride (MG) ?-gel to coagel phase transition has been discussed in the literature, and it has been suggested that such phase transition causes the release of water from the system. This current study revisits a monoglyceride-water system with MG concentrations lower than 20% (w/w) in order to gain a better understanding of the nature and dynamics of the phase transition in this system. Powder X-ray diffraction , coagel indexes from differential scanning calorimetry, optical microscopy, and rheology measurements were used to probe this phase transition. The phase behaviour and microcrystalline structure of the MG-water system shows a temperature and concentration dependence over time. This study also suggests that the water release of the MG-water system is caused by both the ?-gel to coagel phase transition, and a change in micro-structure. Whether the phase transition and the change in molecular packing are independent from each other needs to be further investigated. This study is aimed at increasing the stability and shelf life of monoglyceride based products such as low fat shortenings alternatives and green cosmetics.
Factors Governing Stability and Texture of Milk fat Based Products Produced at Industrial Scale
S. Rønholt(1), K. Hoeyer(2), J. Kirkensgaard(3), K. Mortensen(4), J. Knudsen(5)
(1)University of Copenhagen, Denmark (2)SPX Flow Technology Copenhagen A/S, Denmark (3)University of Copenhagen, Denmark (4)University of Copenhagen, Denmark (5)University of Copenhagen, Denmark
Development of new milk fat based products may be advanced from a fundamental understanding of the physical and chemical properties of single fat crystals as well as their interactions in a network. In the present study, milk fat based products are produced by using a scraped surface heat exchanger. Sustainable and more efficient refrigerants, such as CO2, are now introduced in industrial equipment, which allows an increase of 40 % in capacity compared to conventional use of NH3. This change in cooling rate and shear during processing is evaluated in relation to textural behavior, the underlying fat crystallization process and the effect on water droplets size. First, the fatty acid composition of the solid fat is determined using an enzymatic essay. Second, the physical properties of the fat crystal network are studied in detail at several length scales by combining rheology, p-NMR and 3D confocal laser scanning microscopy. Third, single crystals and crystallization are characterized by combining X-ray diffraction with differential scanning calorimetry. Our data shows, that for samples having similar fatty acid composition, a high cooling rate increased the hardness and altered the microstructure of the products, without affecting crystal polymorphism. Furthermore, the degree of working significantly affected product behaviour.
The Level of Shear During Crystallization of Milk Fat/rapeseed oil is Important for Final Texture
L. Wiking(1), N. Kaufmann(2), U. Andersen(3)
(1)Aarhus University, Denmark (2)Aarhus University, Denmark (3)Arla Foods, Denmark
The effect of shear on crystallization, polymorphic and rheological behavior of milk fat (AMF) blended with rapeseed oil (RO) was studied. Low, medium and high shear rates were applied during early crystallization. Monitoring the further development of the complex modulus |G*| revealed that the firmest and most rapidly formed network was achieved when a medium shear was applied. Up to 20 % RO could be added without lowering the final |G*|. A similar effect was not obtained at low or high shear rates. Polymorphic behavior was studied by NMR. Both high shear and increasing amounts of RO accelerated the polymorphic transition. Shear applied in 20-30 % blends caused only 2L packing to form, while AMF and statically crystallized blends also formed 3L structures. Crystal size decreased upon increasing shear rate while solid fat content and final amount of ?´ crystals were unaffected. In conclusion, applying medium shear produces a strong crystal network while high shear breaks down the microstructure to the extend which cannot be rebuild during subsequent crystallization, resulting in lower |G*|. The study emphasizes the importance of shear as a tool to tailor the microstructure and crystallization kinetics to achieve the desired texture in fat crystal networks.
Granular Crystal Formation Mechanisms in Plastic Fats
Z. Meng(1), Y. Liu(2), X. Wang(3)
(1)School of Food Science and Technology, Jiangnan University, China (2)Jiangnan University, China (3)Jiangnan University, China
Beef tallow (BT) and Palm oil (PO) are extensivly used in the bakery shortening and margarine manufacturing ascribable its advantageous properties, such as (i) high thermal and oxidative stability, (ii) good plasticity at room temperature, etc. However, the use of BT or PO for solid fats in plastic fat products has encountered serious structural defects, the formation of granular crystals, which impair the consistency and plasticity of fat products. Thus, the understanding and control of granular crystal formation in plastic fats are very important points in the fat industry. In the present study, all BT-based and all PO-based model shortenings prepared on a laboratory scale, respectively, denoted BTMS and POMS, were stored under temperature fluctuation cycles of 5?20 °C until granular crystals were observed. The lipid composition, thermal, polymorphic and isothermal crystallization behavior of the granular crystals and their surrounding materials separated from BTMS and POMS, respectively, were evaluated. The changes of nanostructure including the aggregation of high-melting triacylglycerols and polymorphic transformation from ?? form of double chain length structures to complicated crystal structures, in which the ? and ?? form crystals of triple and double chain length structures simultaneously coexist, had occurred in granular crystals compared with surrounding materials, whether in BTMS or in POMS. Accompanyingly, a slower crystallization rate appeared in granular crystal parts of both model shortenings noted above, which would yield larger and fewer numerous crystals indicated by the Avrami model analysis, and further aggregate to form large granular crystals.
Cavity Formation in High Solids fat Crystal Networks
R. Lencki(1), R. Craven(2)
(1)University of Guelph, Canada (2)University of Guelph, Canada
Proper tempering is essential for producing smooth, dense and bloom-stable chocolate, but it is not entirely clear why this is the case. We have shown that under certain crystallization conditions, at high solids concentrations ?-tending triacylglycerols can form gas-filled cavities within the crystal network, significantly decreasing fat density. Pulse NMR and dilatometry were used to show that cavity formation is due to the density decrease resulting from liquid-to-solid phase transitions within the fat crystal network. This leads to areas of reduced pressure that produce air pockets either via cavitation or convective transfer from the solid surface. This negative pressure effect appears to play an important role in the final microscopic structure of complex TAG mixtures such as cocoa butter. Well-tempered cocoa butter has a relatively smooth surface, higher macroscopic density, and a closed-pore void structure. In contrast, over-tempered samples were rougher, less dense, and contained large continuous gas-filled pores. Under-tempered cocoa butter had properties between these two treatments, with a continuous, yet very fine pore structure. Evidently, negative pressure phenomena have a very significant influence on how a chocolate sample de-molds, its final surface gloss, and its ability to inhibit oil migration during storage.
CANCELLED - Effect of Sorbitan-based Surfactants on the Early-stage Crystallization Kinetics of Coconut Oil
S. Sonwai(1), P. Podchong(2), D. Rousseau(3)
(1)Silpakorn University, Thailand (2)Silpakorn University, Thailand (3)Ryerson University, Canada
FS&FF 2: Novel Approaches to the Characterization of Food Structure
Chair(s): D. Rousseau, Ryerson University, Canada; Y. Wang, Kraft Foods Inc., USA
Novel Crystal Structures: Crystallization of Triglycerides Under Shear in a Confined Gap
T. Tran(1), D. Rousseau(2), S. Ghosh(3)
(1)Ryerson University, Canada (2)Ryerson University, Canada (3)University of Saskatchewan, Canada
Confined gap shear-cooling of fat was used to create novel sphere-shaped crystalline masses. Hydrogenated canola oil (HCO) (10 wt%) in canola oil (90 wt%) was cooled from 70ºC to 25ºC at shear rates in the range of 0-2500 s-1 within the parallel plate geometry (500µm gap) of a controlled-shear rheometer. Different-sized HCO crystal aggregates were observed depending on shear rate. Lower shear rates promoted clustering of previously-formed spherulites into spheroidal aggregated masses with rough surfaces ~140µm in length. Higher shear conditions resulted in spheroids with smoothened surfaces and became smaller and more numerous with gradually higher shear (down to ~20µm in length at high shear). After forming, birefringent Maltese cross extinction patterns provided details on HCO crystal domain structure and symmetry. Given the lack of change in HCO polymorphic behaviour, this confirmed that formation of these novel microstructures was initiated not at a molecular level, but rather at the mesoscale within the environment imposed by the confined gap of the rheometer stage. With ageing, these cross patterns disappeared indicating individual crystal growth and/or reorientation. It was theorized that the spheroid structures were formed by the tumbling and agglomeration of HCO crystals within the shear-induced flow in the confined gap between the parallel plates of the rheometer. Crystal size, morphology, and count was dependent on shear rate with higher shear rates resulting in smaller, more numerous, and more spherical crystals.
Microstructral Approach to Understand oil Absorption During Vacuum and Atmospheric Frying
V. Dueik(1), P. Bouchon(2)
(1)University of Toronto, Canada (2)Pontificia Universidad Catolica de Chile, Chile
The microstructure of the crust region has been considered to be a key product-related determinant of the final oil uptake of atmospheric deep-fat fried food. Also, it seem to play a critical role in vacuum frying, a promising technology that might be an option for the development of low fat snacks. The objective of this study was to understand the relationship between microstructural parameters and oil absorption of atmospheric and vacuum fried vegetable tissues. Potato, carrot and apple slices were vacuum and atmospheric fried using equivalent thermal driving forces. Cumulative pore volume and pore size distribution were determined using gas adsorption. Oil location was studied using confocal laser scanning microscopy. Vacuum frying reduced oil content in potato and carrot slices by 50%. In apples, reduction was by 25%. Overall, we found a strong linear relationship between porosity and oil content, however, vacuum and atmospheric fried products showed the same porosity, the size of those pores seems to be determinant, revealing the importance of capillary suction in oil absorption mechanism. In potatoes and carrots, oil was located in the intercellular spaces, while in apples it seems to be everywhere with most of cells being disrupted. Our findings confirm that oil absorption is a surface related phenomenon and that the development of low fat snacks can be achieved if oil uptake mechanisms are adequately understood.
Application of Power Ultrasound to a Zero-trans Shortening During Temperature Cycling Under Different Cooling Rates
Y. Ye(1), C. Tan(2), D. Kim(3), S. Martini(4)
(1)Utah State University, United States of America (2)Utah State University, United States of America (3)Mondelez International, United States of America (4)Utah State University, United States of America
The objective of this work was to evaluate the effect of high intensity ultrasound (HIU) on the physical properties of a commercial shortening crystallized under isothermal conditions and during temperature fluctuations. Different ultrasound power levels and different durations were evaluated at a constant temperature and the best conditions were used during temperature cycling. The physical properties tested were crystal microstructure, viscoelasticity, and melting profile. Results show that HIU helps generate small crystals, induce nucleation and promote crystal growth in the shortening with the generation of a more elastic material. The elastic behavior of the shortening was improved when HIU was applied to the shortening during temperature fluctuations. The G? values increased from 662.6 ± 176.8 Pa (no HIU applied) to 3,365.5 ± 426.4 Pa (with HIU applied) at cooling rate of 0.5°C/min (slow cooling rate), while at 1°C/min (fast cooling rate) there?s a G? enhancement from 354.4 ± 49.7 Pa to 1,249.0 ± 19.8 Pa. Higher elastic values were obtained when temperature fluctuations occurred at slow rates when samples were crystallized with and without HIU. During the temperature cycling, the effect of the HIU in generating elastic material under slow cooling rate is higher than that under fast cooling rate.
Ultrasonic Wave Propagation in Cocoa Butter During Crystallization
A. Rigolle(1), J. Descheemaeker(2), K. Van Den Abeele(3), I. Foubert(4)
(1)KU Leuven University Kulak, Belgium (2)KU Leuven University Kulak, Belgium (3)KU Leuven University Kulak, Belgium (4)KU Leuven University Kulak, Belgium
In the production of fat containing food products, insight in the crystallization behavior of fats is of utmost importance to obtain the desired product functionality and product quality. Several methodologies exist to follow the crystallization. In particular non-destructive techniques, such as ultrasonic waves, are interesting in a production environment since these allow for in-line measurements. The aim of the research is to study the potential of advanced ultrasonic techniques to monitor fat crystallization. Most research up to now deals with longitudinal transmission measurements of the solid fat content. In this research however reflection experiments are carried out with shear waves. A sample holder was custom build with a Plexiglas delay line and a temperature control unit. The main advantages of this experimental set-up are that no problems with excessive attenuation of the fat arise and that shear ultrasonic reflectance, unlike longitudinal measurements, seems sensitive to changes in microstructure. Measurements were performed within a centre frequency range of 500kHz to 5 MHz. We conjecture that several particular effects observed in the evolution of the reflection coefficient are due to the various crystallization phases of the cocoa butter.
Oil migration through Cocoa Butters of Different Geographical Origins
F. Maleky(1), A. Marangoni(2)
(1)The Ohio State University, United States of America (2)University of Guelph, Canada
Magnetic Resonance imaging was used to examine the effects of cocoa butter (CB) origin, tempering procedure, and structure on the kinetic of oil migration process. Six different cocoa butter samples from different origins were crystallized under tempered and non-tempered conditions. Samples were prepared as a 2-layer model system of cocoa butter and a cream filling product and were stored at 25°C for a time frame of several months. Using a mass transfer model based on Fickian diffusion, oil transportation through the matrices was quantified. Samples showed distinctly different oil migration rates, as evidenced by quantitative differences in the equilibrium uptake and the kinetic rate constants for the sample types.
A Nanotechnology Approach to Develop Alternative Vegetable oil Structuring Agents
G. John(1), S. Jadhav(2)
(1)The City College of New York - CUNY, United States of America (2)The City College of New York - CUNY, United States of America
Promotion of public health by delivering healthy food is a subject of research with national importance. Vegetable oils are frequently structured to enhance their organoleptic and mechanical properties. With the risk of coronary heart disease associated with commonly used structuring agents, saturated and trans fatty acids, the food industry is intently looking for better alternatives. The present research aims at utilizing the self-assembly concept of nanotechnology to develop a healthy and amphiphilic oil-structuring agent. Chosen precursors for oil gelling amphiphiles (medium chain fatty acids and non-reducing sugars) are FDA approved and GRAS materials; hence the amphiphiles are non-toxic and exhibited high cell viability at concentration ~ 50 ?g/mL. Advantageously, developed structuring agents are deemed healthy as the utilized sugars have low calorific values and fatty acids are non-hypercholesterolemic & exhibit high plasma clearance in the body. Sugar-based gelators readily formed nanoscale lamellar structures to form a coherent network at very low concentrations (1-3% wt/v), which entrapped and immobilized wide range of lipophilic oils (canola, olive, soybean and grapeseed oil). The efficiency was computed in terms of mechanical, thermal and structural properties and found to be a function of type and concentration of structuring agents.
A novel light scattering set up to follow destabilization of colloidal particles during gelation in situ using simultaneously diffusing wave spectroscopy and rheology
K. Kaur(1), M. Corredig(2)
(1)University of Guelph, Canada (2)University of Guelph, Canada
We use a novel, Diffusing wave spectroscopy/rheology, rheo-DWS, setup specially designed to study colloidal destabilization dynamics in situ. In this setup, we perform simultaneous backscattering DWS measurements in a rheological concentric cylinder couette geometry which is fitted with a window to allow a laser beam to pass into the sample. The sol gel transitions of a model system containing soybean oil in water emulsions stabilized with whey protein isolate were monitored in situ. Acid gelation was induced in situ in the rheometer using glucono-delta-lactone. Transmission DWS experiments were also performed in another set-up alongside on the same sample, to evaluate differences in the light scattering behaviour. Changes in the photon transport mean free path (l*) measured with these transmission experiments precede particle aggregation in these gelling structures. In cold gelation of whey protein emulsions, DWS measurements (both forward and back scattering) detected aggregation at an earlier stage than bulk rheological measurements.
Development of a single droplet freezing apparatus for studying crystallisation in cocoa butter droplets
A. Talhat(1), G. Moggridge(2), I. Wilson(3), J. Rasburn(4)
(1)University of Cambridge, United Kingdom (Great Britain) (2)University of Cambridge, United Kingdom (Great Britain) (3)University of Cambridge, United Kingdom (Great Britain) (4)Nestle Product Technology Centre York, United Kingdom (Great Britain)
Cocoa butter is the vegetable fat harvested from cacao bean. It consists of a mixture of di- and tri-glycerides and is able to exhibit polymorphic behaviour, existing in up to 6 different crystalline states (labelled Forms I to VI by Willie and Lutton ,1966) with different thermal stabilities. A novel single droplet freezing apparatus, which allows the crystallisation process to be monitored in situ by video microscopy and X-ray diffraction, was used to study cocoa butter droplets undergoing simulated spray freezing (as reported by Pore et al., 2009). It was found that transformation into Form V was significantly faster in droplets (~4 hours) compared to static bulk samples (1 week). This rapid crystallisation is postulated to be due to the low Biot number of the cocoa butter sample, whereby the droplet internal temperature distribution is uniform at any given point in time. The apparatus has since been modified to improve its performance, and is now able to offer consistent and accurate observation of evolving crystalline structure in situ with well-controlled steps in temperature. The system is also being used to study the relationship between origin and polymorphism in different cocoa butters. This presentation reports on the improved design of the apparatus (Figure 1) and presents results quantifying the effect of origin on polymorphism observed in droplets. Wille & Lutton(1966). Polymorphism of Cocoa Butter. JAOCS, 43(8), 491?496. Pore et al (2009). In-Situ X-Ray Studies of Cocoa Butter Droplets Undergoing Simulated Spray Freezing. JAOCS, 86(3), 215?225.
Unusual Crystallization Behavior of Confectionery Fat During Cryogenic Spraying As Compared to Conventional Cooling and Tempering
(1)Nestec York, United Kingdom (Great Britain)
The generation of fat powder by spray chilling has been increasingly employed in recent years by food industry like in confectionery production. The physical changes of the fat during spray-chilling, compared to those which occur during conventional cooling process, have not however been well studied for confectionery fats. In this work tempering fats (cocoa butter) and non tempering fats (cocoa butter replacers) are investigated using differential scanning calorimetry (DSC) for characterizing the triglyceride polymorphic compositions. It is observed that droplet size during spraying is highly critical in the formation of higher form crystal polymorphs yielding polymorphically homogenous samples with >90% beta V crystals as compared to conventionally tempered chocolate where approximately equal proportion of beta` and beta V crystal is obtained. In addition the cooling temperature is observed to have minimum influence on the type of crystal formation. Hence it is postulated that the geometry of individual droplet influences the crystallization through aligning the triglycerides and hence reducing the degree of supercooling needed. This correlates well with the fact that tempering is not required in chocolate panning with little cooling necessary. It has also been observed that spraying of fat blends consisting of trisaturate triglycerides, such as in low trans cocoa butter replacers, produces higher melting crystal structure not possible with conventional cooling. However spraying fat blends comprising of triolein rich oil with hard stearin proves more challenging.
FS&FF 3: Colloid and Interfacial Property of Foods
Chair(s): S. Martini, Utah State University, USA; K. Dewettinck, Ghent University, Belgium
Shellac as a natural structurant for edible soft matter system
A. Patel(1), D. Schatteman(2), K. Dewettinck(3)
(1)University of Gent, Belgium, Belgium (2)University of Gent, Belgium, Belgium (3)University of Gent, Belgium, Belgium
Currently, due to the factors including the sustainable manufacturing, requirement of trans- and saturated fat-free food products and ethical trade practices, the research in the area of identifying natural structurants for oleogelation applications has been regarded as a ?hot topic? in the bio-scientific community. Generally, for a compound to act as an oleogelator, it has to have two characteristic parts, a lipophilic part with a?nity for oils and an interacting part to participate in the formation of supramolecular assemblies. Being a complex mixture of fatty esters and alcohols, shellac (a natural resin) has a lipophilic nature and tends to self-assemble into colloidal structures based on the solvent properties. We found that shellac showed good miscibility with oil above its melting range (> 80°C) and formed an excellent oleogel when the dispersion of shellac in oil was cooled to room temperature. The crystallization and the colloidal network formation of shellac was characterized using PLM and CSLM. The thermal and rheological parameters obtained from heat-cool cycles confirmed the thermoreversibility of oleogels. The crystal network in the oleogel was strongly influenced by temperature as indicated from the rheological data obtained at storage (5°C) and body (37°C) temperatures. The potential application of these systems was demonstrated by preparing a w/o emulsion using shellac oleogel as the continuous phase. The emulsion had a spread-like appearance and showed easy spreadability. Moreover, the microscopy evaluation indicated the presence of shellac crystals at the oil-water interfaces suggesting Pickering stabilization of these emulsifier-free emulsions.
Characterization of Milk Components and Control of Milk fat Globule Size for Improved Functionality
A. Logan(1), L. Day(2), S. Moore(3), T. Singh(4), M. Augustin(5)
(1)CSIRO Animal, Food and Health Sciences, Australia (2)CSIRO Animal, Food and Health Sciences, Australia (3)CSIRO, Australia (4)CSIRO, Australia (5)CSIRO, Australia
The dairy industry is a major part of the Australian agricultural landscape. Data indicates farming practices may influence milk composition and functionality. An understanding of the altered milk composition and structure is needed to ensure milk is suitable for targeted purposes within food applications. The fat content of milk is around 3.5-4% , and exists as small droplets dispersed within a serum phase which range in diameter between 0.1-20um (mean = 4.0um). These droplets are stabilised by a thin membrane composing of phospholipids, proteins and other components, referred to as the milkfat globular membrane. The milkfat itself consist predominantly of triacylglyerol, as well as di- and mono- acylglycerols, free fatty acids, sterols, carotenoids and vitamins. It is believed the composition of the lipid core may vary dependant on the size of the globule and may be influenced by factors such as seasonal variation, lactation, diet and breed. In this study, milkfat globules were fractionated to predominately large or small sizes using lab- and pilot-scale based separation techniques, where the structure and functional properties of these fractions in rennet gels were characterised. The differences in globule size and/or composition led to functional differences such as rennet gelation time, melting behaviour and textural properties of the end product. Selecting milk on the basis of globule size or membrane composition/architecture could be a useful tool for segregating raw milk for the manufacturing of different products based on the desirable characteristics specific to each.
Nanoscale Structures and fat Crystal Networks: Crystalline Nanoparticles, Tagwoods and X-ray Scattering
D. Pink(1), B. Quinn(2)
(1)St.Francis Xavier University, Canada (2)St. Francis Xavier University, Canada
To understand and predict the 3-dimensional structures of fat systems, such as fat crystal networks, is important since these determine functionality of edible fat products. To pursue this, we have made mathematical models of crystalline nanoplatelets (CNPs), the smallest "units" of solid fats, [Acevedo&Marangoni, Cryst.Growth Des., 2010, 10, 3327], and studied their aggregation via attractive van der Waals potentials using Monte Carlo simulation. An infinitely-strong interaction yields fractal structures characteristic of diffusion limited cluster-cluster aggregation. We found that, if the interaction is finite (even if much greater than kT) thus permitting structural relaxation, then linear towers of CNPs ("TAGwoods") are formed. We then made models of TAGwoods interacting via attractive van der Waals potentials and carried out simulations of TAGwood aggregation. We found that static structure functions, S(q), were similar to those reported by Rothenbuhler etal. [RSC SoftMatter, 2009, 5, 3639] for colloidal rods. We found that the structures formed depended upon solid fat content. We shall describe our results, discuss the time-development of aggregation structures, relate them to "oil binding capacity" and outline how TAGwood existence might be established utilizing ultra small angle X-ray scattering (USAXS). Elsewhere we help interpret recent USAXS data [Peyronel etal].
In Situ 3d Fractality of Tristearin in Triolein
F. Peyronel(1), J. Ilavsky(2), B. Quinn(3), G. Mazzanti(4), N. Acevedo(5), A. Marangoni(6), D. Pink(7)
(1)University of Guelph, Canada (2)Argonne National Laboratory, United States of America (3)St. Francis Xavier University, Canada (4)Dalhousie University, Canada (5)Iowa State University, United States of America (6)University of Guelph, Canada (7)St. Francis Xavier University, Canada
There is a fundamental need to understand and quantify the 3-dimensional structures arising from fat aggregation in edible oils since such structures are likely responsible for the functionality of fat products. One fundamental problem is to quantify and establish how the fat crystal networks trap triacylglycerol (TAG) oils - the oil binding capacity. We believe that the oil binding capacity can be explained by measuring the 3-dimensional fat fractal dimension, D, and understanding the processes via which it arises. One way of achieving this is to use synchrotron X-ray scattering. To this end, we have used the newly upgraded Bonse-Hart camera of the ultra small angle X-ray scattering 15ID beam line at the Advanced Photon Source (APS), in Argonne National Laboratory, Argonne USA. We measured the X-ray scattering intensity, I(q), of tristearin in triolein at different solid fat contents (SFC). The unified-fit model in the APS Irena software was used to find: 1-the radius of gyration, Rg, 2-the regions of q for which log [I(q)] exhibited linearity and 3- the values of D. We found three regions exhibiting fractal structures. At the highest q-region measured, the Porod regime was found to have D = 2. Values of D for the intermediate q-region lay between 1.7 and 2.1, while at the lowest q-region, D ? 3. We shall report and discuss our results as well as those for radii of gyration. These results are in accord with mathematical models developed by us and studied using Monte Carlo simulations, and presented elsewhere.
W/o Emulsions Stabilized by Candelilla wax Organogels
J. Pérez-Martínez(1), R. Mauricio-Pérez(2), J. Toro-Vazquez(3), M. González Chávez(4), J. Ornelas-Paz(5)
(1)Autonomous University of San Luis Potosi, Mexico (2)Autonomous University of San Luis Potosi, United States of America (3)Autonomous University of San Luis Potosi, United States of America (4)Autonomous University of San Luis Potosi, United States of America (5)Centro de Investigación en Alimentación y Desarrollo, United States of America
Water in oil emulsions (W/O-E) stabilized by candelilla wax organogels (CWO) were produced by high pressure homogenization of the hot mixture and subsequent cooling through a heat exchanger. The continuous phase of these systems were selected based on the melting profiles (i.e., melting peak below 40 °C) and the organogelling capacity of a set of mixtures with 0.5% to 4% candelilla wax (CW) and 0.25% or 0.5% monoglycerides (MG) in high oleic safflower oil. Macroscopically homogeneous W/O-E with solid-like behavior were produced with lipid phase containing 2% or 3% CW and 0.25% or 0.5% MG. The W/O-E stabilized with CWO were evaluated by polarized light microscopy (PLM), texture, and sedimentation measurements. The PLM and texture of W/O-E were compared to that of the organogels with the same amount of CW, MG, and time-temperature processing conditions. W/O-E showed water droplets immobilized throughout the organogel matrix without indication of pickering stabilization. The work of shear (WS) of the W/O-E were up to 40% lower than that of the organogels with the same amount of CW, MG, and time-temperature processing conditions, yet both systems presented higher WS that the organogels developed under static isothermal conditions. No macroscopic sedimentation was observed in the W/O-E.
Encapsulation through the use of emulsified microemulsions
D. Rousseau(1), R. Rafanan(2)
(1)Ryerson University, Canada (2)Ryerson University, Canada
Emulsified microemulsions (EMEs), first described in detail in 2005 by Garti?s group, consist of a thermodynamically stable water-in-oil microemulsion phase (W1/O) further dispersed within an aqueous continuous phase (W2). These internally-structured W1/O/W2 dispersions are promising controlled release vehicles for flavouring compounds, drugs and nutraceuticals as the oil phase may encapsulate desired compounds. With a stable internal droplet structure, storage stability is improved over non-thermodynamically stable structured emulsions and may exhibit unique controlled release behaviour. Use of food-grade components allows for wider and safer applications in food and pharmaceutical products. A food-grade W1/O microemulsion consisting of glycerol monooleate, tricaprylin and water was dispersed in an aqueous (W2) phase by membrane emulsification and stabilized by a caseinate-pectin complex to produce a 25% v/w W1/O/W2 EME with a w/w composition of 1.25/23.75/75. The resulting EME showed no signs of phase separation for 2+ weeks at room temperature. The microemulsion and emulsified microemulsion were characterized by differential scanning calorimetry (DSC) and small angle x-ray scattering (SAXS) to determine whether the microemulsion?s internal structure was maintained after emulsification. It was shown that EME droplets displayed ordering around the periphery consistent with some loss of microemulsion structure, but maintained the characteristic disordered microemulsion structure at the droplet core.
Homogenization with solid lipid nanoparticles under cold conditions: A novel approach to bioactive delivery in oil-in-water emulsions
D. Rousseau(1), R. Gupta(2)
(1)Ryerson University, Canada (2)Ryerson University, Canada
Oil-in-water (O/W) emulsions stabilized by solid lipid nanoparticles (SLNs) containing flaxseed oil (FSO) were developed. FSO SLNs were generated using hot homogenization and subsequent quench-cooling of the hot O/W nanoemulsions containing the lipid glyceryl stearyl citrate (GSC) (5 wt%), FSO (2.5 wt%) and lutein (antioxidant, 0.006 wt%) dispersed in water. The SLNs? mean volume-weighted diameter was ~130 nm (90% particles < 200 nm) and their zeta potential was ~-55 mV. No significant change in mean particle size, melting and crystallization peaks were observed on repeated thermal cycling (5 times), further supporting SLN stability. O/W emulsions (FSO oil phase volume fraction 0.2) containing either FSO SLNs or FSO-free SLNs (as a control) were prepared via cold temperature homogenization. Emulsion droplets had a volume-weighted mean oil droplet diameter of ~530 nm and a zeta potential of ~-50 mV. Both emulsions remained stable for months under refrigeration and did not show any visual phase separation over time. Microstructurally, the SLNs acted as Pickering stabilizers as well as forming a crystal network in the continuous phase leading to the formation of stable emulsions in both cases. However, the emulsions containing FSO in the oil phase rather than in the SLNs showed a higher oxidative stability given its lower peroxide values. Overall, cold homogenization is a suitable approach for the delivery of thermally-sensitive bioactives such as flaxseed oil.
Modelling Edible Oils: Computer Simulation of Nanophase Separation and Binding Energies in Multi-component Oils
E. Co(1), E. Szabo(2), A. Marangoni(3), D. Pink(4)
(1)Department of Food Science, University of Guelph, Canada (2)Department of Physics, University of Guelph, Canada (3)Department of Food Science, University of Guelph, Canada (4)Faculty of Science, Physics, St. Francis Xavier University, United States of America
It is important to address the question of what are the factors that determine "oil binding capacity" for the answer to this could open the door to understanding what determines functionality. We have shown that (i) triolein (OOO) will not be retained (it will "leak away") between two solid tristearin (SSS) crystals and that (ii) a mix of dieladic-monoooleic triacylglycerol (EEO) and triolein will phase separate on a nanoscale with the former "coating" the surface of a tristearin solid, but a mix of monoelaidic-dioleic (OOE) and triolein exhibits no nanophase separation [MacDougall et al., Faraday Disc. 158, 2012]. These results suggest that oil binding capacity is a consequence of nanoscale phase separation of partially-trapped oil mixtures. Here we report on investigating nanophase separation in other cases: (a) 2-component mixtures of OOO and SSO, SOS, OSS, OOS, OSO or SOO. Here we have investigated to what extent binding to the SSS surface depends upon the relative positions of the fatty acid chains. (b) "graded" phase separation in a 3-component mixture of SSO, EEO and OOO. Our hypothesis is that we shall find that graded nanophase separation takes place at or near the model tristearin slab surface. We used atomic scale molecular dynamics in the NVT ensemble, represented the solid tristearin by flat continuum slabs, and used the GROMACS software package. We shall compute the potential of mean force for graded nano-phase separation as well as for nanophase separation of one component with the other two components remaining as a random mix.
Molecular Level Observation of Growing Steps on fat Crystal
H. Hondoh(1), G. Sazaki(2), K. Sato(3), Y. Furukawa(4), S. Ueno(5)
(1)Hiroshima University, Japan (2)Hokkaido University, Japan (3)Hiroshima University, Japan (4)Hokkaido University, Japan (5)Hiroshima Univeristy, Japan
Step movement on the surface of trilaurin (LLL) single crystals in melt has been observed by advanced optical microscopy. The single crystal of LLL consists of (110), (010), (-1-10), (0-10) and (001), (00-1) faces, which were determined from the unit cell dimension and the law of constant interfacial angle. We could not identify the Miller indices of the crystal faces with the positive and negative values because the space group of LLL beta form is P-1. The LLL crystals showed smooth the lamellar (001) faces, which were the most developed faces, in molecular level under low supercooling in melt. We observed steps movement generated from the spiral centers on (001). The step velocities depended on the crystallographic direction. This reflected the low symmetry of LLL beta form. Step velocity and density increased with increasing supercooling. Two dimensional nucleation on the surface of (001) was not observed even though the heterogeneous nucleation was occurred under the 2 degree Celsius supercooling. These results indicate that the morphology and the network of fat crystals could be controlled by changing supercooling.
Food Structure & Functionality Posters
Cancelled-Preparation, Characterization and Optimization of Liposomes Containing Eicosapentaenoic and Docosahexaenoic Acids; a Methothodology Approach ?
z. hadian(1), M. Sahari(2), H. Moghimi(3), M. Barzegar(4), S. Abbasi(5)
(1)Shahid Beheshti University of Medical Sciences, Iran (2)Tarbiat Modares, United States of America (3)Shahid Beheshti University of Medical Sciences, United States of America (4)School of Agriculture, Tarbiat Modares University, United States of America (5)School of Agriculture, Tarbiat Modares University, United States of America
Production of an Extended Shelf Life Water-soluble Derivative of Conjugated Linoleic Acid (cla)
(1)Universiti Putra Malaysia (UPM), Malaysia
Conjugated linoleic acid (CLA) reported to be an extraordinary essential fatty acid with functional effects on human body. The water insolubility and oxidative instability of commercial CLA are the barriers limited the applications of CLA for fortification of beverages. This research aimed to investigate the production of an oxidative stable hydrophilic derivative of CLA by incorporation of Lysine (Lys), a polar amino acid, into CLA molecule. Formation of Lys-CLA was confirmed by FT-IR at 1650 and 1550 cm-1. Through the visual inspection test, no phase separation or precipitation was observed in solution of Lys-CLA in neutral water at up to 2% (2 weeks of storage at 25 ± 1 ºC). Peroxide value (PV) of CLA was increased by approximately 16-fold (12 h of storage at 60 ºC); however, the PV of Lys-CLA was increased by 1.4-fold. Antioxidant activities of Lys-CLA, CLA and Lys were evaluated using 2,2?-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2?-diphenyl1-picrylhydrazyl (DPPH) assays. All samples displayed radical scavenging activities in a dose-dependent manner in both assays. Lys-CLA with the smallest half maximal inhibitory concentration (IC50) showed the maximum antioxidant activity among the rest (p < 0.05). The antioxidant activity of Lys-CLA complex found to be synergistic in DPPH assay.This study showed that production of Lys-CLA can improve the oxidative stability, antioxidant capacity and water solubility of CLA and thus the suggested approach can expand the application of CLA in various foods and drinks.
Effect of Salt and Liver / fat Ratio on Microstructure, Stability and Texture of Liver Paste
I. Foubert(1), L. Steen(2), I. Fraeye(3), O. Goemaere(4), H. Paelinck(5)
(1)KU Leuven University Kulak, Belgium (2)KAHO Sint-Lieven, Belgium (3)KAHO Sint-Lieven, Belgium (4)KAHO Sint-Lieven, Belgium (5)KAHO Sint-Lieven, Belgium
Little is known about the structural changes during the production process of spreadable liver paste, a warm processed, fine, emulsion-like meat product prepared from liver, fat, salt, water, emulsifier(s) and small amounts of additives and spices. Liver paste batter emulsions were first formed by mixing liver batter and precooked fat at two liver / fat ratios with water and some minor ingredients. Salt was added or not. After pasteurization and cooling, spreadable liver pastes were obtained. An in depth understanding of the characteristics of the intermediates and the end product will help to understand how the product structure is formed. This will aid to control its functionality, improve existing products and help in the development of new strategies to obtain products with a healthier image. First, the viscoelastic properties of the different products were studied. Generally, the moduli of liver paste batter and liver paste increased with the addition of salt while a higher liver / fat ratio only increased those of the liver paste batter. The effect of salt and liver / fat ratio was also studied on emulsion stability and texture to assess the relationship between the structural characteristics and the stability of the intermediates and the texture of the end product.
The Relationship Between Physical Properties and Functionality for Margarine Products
Z. Zhi-ming(1), H. Zhang(2), Y. Bi(3), X. sun(4), X. Xu(5)
(1)Henan University of Technology, China (2)Wilmar Biotechnology Research and Development Center Co, LTD, China (3)Henan University of Technology, China (4)Wilmar Biotechnology Research and Development Center Co, LTD, China (5)Wilmar Biotechnology Research and Development Center Co, LTD, China
The physical properties (solid fat content (SFC), hardness and rheological behaviors) and functionality (spreadablity and foaming degree) of nine margarines were investigated and correlated with each other. The hardness had significant correlation with spreadability and no linear correlation with foaming degree, but it gave influence on the whipping process. Although SFC was always a crucial evaluation index of margarine, low correlation was observed between SFC of storage temperature and other properties. Therefore, it is unreliable to predict other properties of margarine by SFC alone. The hardness had significant correlation with static yield value and highly significant with storage modulus (G'), loss modulus (G"), tangent phase angle (tan?), complex modulus (G*) and complex viscosity. This result indicated that rheological behaviours have important influence on texture. Spreadability and static yield value had high correlation (R2=0.962), as well as foaming degree and tan? after thixotropy (R2=0.868). This result indicated that spreadability and foaming degree of margarine could be predicted accordingly by rheometer replace traditional method.
The Crystallization Behavior of Palm oil With HIU Irradiation
F. Chen(1), H. Zhang(2), X. Wang(3), X. Sun(4)
(1)Jiangnan university, China (2)Wilmar Biotechnology Research and Development Center (Shanghai) Co., L, Denmark (3)Jiangnan University, China (4)Wilmar Biotechnology Research and Development Center (Shanghai) Co., L, China
The objective of this study is to study the effect of high intensity ultrasound (HIU) on the crystallization behavior of Palm Oil (PO). The induction time, crystallization rate, morphology, hardness and melting behavior of PO crystallized with and without the application of HIU were evaluated. Results showed that the effects of HIU on the crystallization were greatly depended on the degree of supercooling. HIU significantly (P<0.05) reduced the induction time and accelerated the crystallization rate at crystallization temperatures (Tc) between 25-36 °C, but no significant difference was observed when Tc=20 °C due to the high supercooling. The morphology of crystals changed greatly from the plate-like shape to the irregular shape with 95W-60 s ultrasound application, the particle sizes of crystal significantly decreased at the same time. These effects became more obvious at higher power level and longer irradiation time. Besides, harder crystals were also observed by texture analyzer. The melting peaks of sample crystallized with HIU were sharper and with a narrower melting range. However, the melting enthalpies were not signi?cantly di?erent among samples crystallized with and without HIU for all temperatures. It indicates that HIU promoted crystallization mainly on the generation of small crystals rather than the total amount of crystal materials.
Effect of Tempering and Cocoa Butter Content on the Texture and Bloom of Lauric Compound Chocolate
H. Shen(1), H. Zhang(2), S. Xie(3), X. Wang(4)
(1)Jiangnan University, China (2)Wilmar (Shanghai) Biotechnology R&D Center Co., Ltd., Denmark (3)Wilmar (Shanghai) Biotechnology R&D Center Co., Ltd., China (4)Jiangnan University, China
Phase behavior of cocoa butter (CB) and fully hydrogenated palm kernel stearin (FHPKS) mixtures was studied with isosolid diagrams. Without tempering, the isosolid phase diagram showed a dilution effect with the increase of CB. With tempering, a eutectic behavior occurred in mixtures contain 30~50% CB. The hardness, crystal morphology and melting behavior of compound chocolate with various CB/FHPKS ratios were evaluated by texture analyzer, polarized light microscopy and differential scanning calorimetry during storage at 20 °C. Tempering gave a significant effect on the hardness of chocolate. The hardness decreased with increasing the ratio of CB from 0% to 50%. As the ratio of CB increased more than 50%, two different trends occurred. The hardness of tempered chocolate increased obviously, but a constant trend was observed for untempered one. The degree of bloom for untempered chocolate showed a positive correlation with the content of CB. With tempering, chocolates contained 30~50% CB were firstly observed bloom formation. DSC and fatty acids composition results indicate that polymorphic transformation was the reason for the bloom of untempered chocolate contain higher cocoa butter (>50%), and the fat migration due to the incompatibility of CB and FHPKS may mainly attribute to bloom formation of chocolate with less CB.
Functionalization of Non-interesterified Mixtures of Fully Hydrogenated Fats Using Shear Processing
N. Acevedo(1), J. Block(2), A. Marangoni(3)
(1)Iowa State University, United States of America (2)Santa Catarina Federal University, United States of America (3)University of Guelph, United States of America
Functionalization of mixtures of fully hydrogenated soybean oil (FHSO) and soybean oil (SO) by crystallization under specific shear and temperatures fields was explored. Blends of FHSO and SO at mass ratios of 40:60 and 45:55 were prepared and crystallized statically, under laminar shear (LS) at 30s-1 and 240s-1, and in a scraped surface heat exchanger (SSHE). Crystalline nano- and meso-structure were affected in a different way upon crystallization in a SSHE and LS cell. Meso-crystals showed a decrease or no change in size, meanwhile nano-platelets were significantly longer after shearing. The storage modulus (G?) and yield stress (?*) of the mixtures were significantly reduced (from 35 to 90%) after both shear processing. Furthermore, G? and ?* of samples crystallized in a SSHE were significantly smaller than those of samples crystallized under LS; an effect related to a higher degree of crystal breakage and mechanical working. A direct relationship was observed between mechanical properties and crystal sizes at the meso-scale, while an inverse and closer relationship was found with the nano-scale crystal dimensions. Crystallization under shear induced a significant decrease in the oil binding capacity of the blends, compared to static conditions. Although we achieved mechanical properties of a functional fat material with both crystallizers; LS processing at a rate of 30s-1 yielded more desirable oil loss values than rates of 240s-1 and SSHE processing. Our findings demonstrate that the problem of functionalization of fully hydrogenated fats can be approached using simple shear processing.
Crystallization Behavior of High-oleic High-stearic Sunflower oil Stearins Under Dynamic and Static Conditions
S. Martini(1), J. Rincon Cardona(2), Y. Ye(3), C. Tan(4), R. Candal(5), M. Herrera(6)
(1)Utah State University, United States of America (2)National University of San Martin, Argentina (3)Utah State University, United States of America (4)Utah State University, United States of America (5)National University of San Martin, Argentina (6)University of Buenos Aires, Argentina
Soft (SS) and hard (HS) stearins obtained from high stearic high oleic sunflower oil were isothermally crystallized under dynamic (with agitation) and static conditions at 16, 17, 18, 19, and 20 °C and 24, 25, 26, 27, and 28 °C, respectively. Both fractions crystallized under the alpha-form at early stages of crystallization for all temperatures (Tc) tested. Polymorphic behavior strongly changed with Tc and shear conditions for both fractions. SS fractions were characterized by ??1 for lower Tc (16 °C) and ?2 or ?1 crystals for higher Tc (20 °C) when crystallized under dynamic conditions, while ??2 crystals were obtained at lower Tc (16 °C) and ??1 at higher Tc (20 °C) when crystallized under static conditions. Similarly, HS samples were characterized by ??1 crystals at lower Tc (24 °C) and ?2 or ?'1 crystals at higher Tc (28 °C) when crystallized under dynamic conditions; while ??2 crystals were obtained at lower Tc (24 °C) and alpha and ??1 crystals when crystallized at higher Tc (27 °C) under static conditions. These results suggest that agitation promotes the formation of more stable polymorphic forms. These different polymorphic behaviors are translated in different textural behavior of the samples.
HARDFATS ADDED TO PALM OIL: CHANGES IN MICROSTRUCTURE AND CONSISTENCY.
G. Oliveira(1), T. Kieckbusch(2), A. Ribeiro(3)
(1)UNICAMP - University of Campinas, Brazil (2)UNICAMP - University of Campinas, Brazil (3)UNICAMP - University of Campinas, Brazil
The complex crystallization behavior of palm oil is associated with a number of practical problems in the food industry. In order to stabilize the microstructure and to improve the mechanical properties of the crystal network, crystallization modulators known as hardfats, products from fully hydrogenation (FH) of liquid oils, were added to palm oil. Twelve blends with hardfats of palm (FHPO), cotton (FHCO), soybean (FHSO) and crambe (FHCR) oils were prepared at concentrations of 1, 3 e 5% (w/w). Compared to palm oil, a significantly increase in consistency, evaluated as yield value (gf/cm2), was achieved. At 25, 30 and 35oC, the yield values found for all blends with 5% of hardfats indicated that they maintained suitable levels of spreadability. The microstructure (morphology and crystal size) of the samples was observed under polarized light microscopy at 25oC and the results were coherent with the results of consistency. A significant reduction of the residual amount of liquid oil in the blends and increase in the number of crystals were observed. Palm oil showed spherulites-type crystals, with an average diameter of 61.6µm, while the blends FHSO, FHPO, FHCO and FHCR at levels of 5%, had an average diameter of 24.1, 23.6, 21.1 and 12.0µm, respectively. The mixture with 1% FHCR stood out with the number of crystals increasing from 202 to 4363. The addition of hardfats modified crystalline density, texture and functional properties of fat, favoring the use of palm oil in several fatty products.
Evaluation of fatty acids compositions in daily distributed cream and yogurt in Tehran/Iran.
(1)standard organization, Iran
Traditionally consumers are interested in fatty products due to their taste and organoleptic features. The high price and low production of these products, allows replacing them with other oils like vegetable oils. Determination of the plant esterols believes to be a valid method of identification of milk purity, which should be negligible in fat milk. The objective of the study was identification of the vegetable oils including Campestrol, Stigma-esterol and ?-sitoesterol in order to determine the purity of milk fat. Thirty samples of yogurt and twenty six samples of cream were randomly selected from the daily distributed products. Bligh and Dyer method of extraction of fat was used to extract the oils and unsaponified materials. According to the Iran-National-Standard methods No. 6790-8819-8818, estrols were separated using Thin Layer Chromatography. Then the separated estrols were solved in chloroform and evaluated by Gas Chromatography. Also control samples were produced with certain amount of vegetable oils including 2.5, 5, 7.5 and 10 percents. Esterols higher than 5 percents in samples were considered as vegetable oils. No esterol was found in cream samples. However in three samples of yogurts, the total plant esterol was higher than 5 percents. It is concluded that the reduced short chain fatty acids and increased unsaturated fatty acids are indicatives of vegetable oils in fatty products of milks and recommended to be considered as routine evaluations of these products.
Feeding hens flaxseed oil and dried whitebait affects fatty acid composition and sensory characteristics of eggs
K. Hwang(1), H. Yi(2), B. Shin(3)
(1)Seoul National University, Korea, Republic of (2)Seoul National University, Korea, Republic of (3)Haitnimnara Co., Korea, Republic of
Effects of flaxseed oil and dried whitebait in the diets of laying hens on the production traits, quality characteristics, fatty acid composition and sensory characteristics of the eggs were determined. Hy-line brown laying hens fed basal diet containing 1.5% soybean oil (C), 1.5% flaxseed oil (T1), 1.5% soybean oil and 1.5% dried whitebait (T2) or 1.5% flaxseed oil and 1.5% dried whitebait (T3). Egg weight might be affected by flaxseed oil and dried whitebait in the diet, while the flaxseed oil in the diet had no adverse effect on egg production. Addition of flaxseed oil in the diet resulted in increase in ?-linolenic acid (ALA) in the eggs. Eicosapentaenoic and docosahexaenoic acids were the highest in the lipids of the eggs from the hens fed the combination of flaxseed oil and dried whitebait diet. Addition of dried whitebait to the diet resulted in undesirable organoleptic characteristics in off-flavor, buttery taste and overall acceptability of the eggs. The results indicate that the supplementation of basal diet for laying dens with flaxseed oil would be preferable to that with dried whitebait in terms of maximal efficiencies of retention in ?-3 fatty acids in eggs with less undesirable organoleptic characteristics.
Viscoelastic and Melting Behavior of Waxes in Vegetable Oils
C. Tan(1), Y. Heng(2), S. Martini(3)
(1)Utah State University, United States of America (2)Utah State University, United States of America (3)Utah State University, United States of America
The objective of this research is to evaluate the viscoelastic and melting behavior of different types of wax/oil systems. Olive (OO), corn (CO), soybean (SBO), sunflower (SFO), safflower (SAFO) and canola (CAO) oils were mixed with sunflower (SFW), paraffin (PW), and beeswax (BW) at different concentrations (0.1%-10%). Crystallization behavior of wax/oil systems (0.1-1%) was evaluated using a light scattering equipment. In general, phase separation was observed in solutions with low wax content (0.1-0.5%) as a consequence of crystal sedimentation. Therefore wax/oil solutions of 1% - 10% were selected to study the melting and viscoelastic behavior of these materials. Results showed that wax concentration and type were the main factors that affected melting and viscoelastic behavior of the materials. In general, melting enthalpy increased linearly with wax concentration with values of approximately 0.5 J/g for 1% solutions to 5-30 J/g for 10% solutions. Oil type significantly affected enthalpy values for 10% solutions with values between 4.41 ± 0.21 J/g for BW/SBO and 13.3 ± 1.1 J/g for BW/OO. As expected G? values increased with wax concentration. For low wax concentrations (1 and 2.5%) G? had values between 0-600 Pa and decreased in the following order: SFW>PW>BW. For 5 and 10% solutions, G? values were significantly higher (> 103 Pa) and a tendency in G? among wax types and oils was not observed.
A study of lipid distribution and microstructure of thermally processed NZ King Salmon (Oncorhynchus tshawytscha) using MRI, ESEM and Confocal Microscopy
S. Quek(1), D. Larsen(2), L. Eyres(3)
(1)The University of Auckland, New Zealand (2)The University of Auckland, New Zealand (3)ECG Ltd, New Zealand
NZ King Salmon (Oncorhynchus tshawytscha) is an excellent source of Omega-3 fatty acids; however, little is known about the effect of thermal processing has on its properties. We had previously reported the changes to its fatty acid profile and sensory properties during processing. In this part of the work, we aimed to understand the changes that occur to the lipid distribution and microstructure of salmon during thermal processing. Farmed NZ King Salmon was prepared in different ways: poached, steamed, pan fried (no oil), oven baked, deep fried (sunflower oil) and microwaved, according to AOAC 976.16 (method for cooking seafood). Raw sample was used as control. Imaging techniques including Magnetic Resonance Imaging (MRI), Confocal Microscopy and Environmental Electron Microscopy (ESEM) were applied to study the microstructure. MRI images showed that the majority of lipids in salmon were found in the myosepta and dark muscle. Confocal microscopy showed that lipid was released from the tissue as a result of thermal treatment and the extent varied with the type of thermal processing. This method was found to be a suitable method for examining delicate cooked salmon tissue. ESEM showed intact muscle fibers and bound lipid droplets on the surface of the raw Salmon. This structure was not visible on the surface of the thermally processed samples. The results of this study showed correlation between muscle fiber breakdown, the occurrence of free lipid droplet and a lesser amount of total extractable lipids in certain processing methods including poaching, microwaving and frying.