Publications

Garcia-Macias, P., Gordon, M.H., Frazier, R.A., Smith K., Gambelli, L., Effect of TAG composition on performance of low saturate shortenings in puff pastry, European Journal of Lipid Science and Technology, 2012, 114(7), 741-747.

Four blends formulated with low saturated fatty acid content, with the saturated component rich in stearic acid, were prepared from shea stearin, interesterified shea stearin, fully hardened soybean oil and high oleic sunflower oil in order to study their performance as shortenings in puff pastry products. The blends had a low saturated fatty acid content (30.1 ± 1.1%) compared to butter (65.9%). Saturates in the four blends examined came mainly from SSS, SOS, SSO and SOO. Puff pastry prepared from the blend that contained SOS as the main source of saturates had better properties than the other blends. It was similar to butter in compressibility of the baked product. The β-polymorphic form was present in all blends, although blends containing the highest levels of SSS also showed some β′ crystals.

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De Graef, V., Vereecken, J., Smith, K.W., Bhaggan, K., Dewettinck, K., Effect of TAG composition on the solid fat content profile, microstructure, and hardness of model fat blends with identical saturated fatty acid content, European Journal of Lipid Science and Technology, 2012, 114(5), 592-601

TAGs play an important role in determining the functional properties of fat-based food products such as margarines, chocolate, and spreads. Nowadays, special attention is given to the role of the TAG structure and how it affects functional properties such as mouth feel, texture, and plasticity. Key to this research is the need to develop more healthy fats with a reduced level of trans and saturated fatty acids (SFAs), while maintaining the desired properties. In this study, fat blends with identical levels of SFA (50%) but differing in the ratio asymmetric/symmetric blends were evaluated by pulsed NMR and texturometry as a function of storage time and storage temperature. A higher trisaturated TAG content gave rise to a higher solid fat content (SFC) at higher temperature and a lower SFC at lower temperature for both palmitic and stearic based blends. On the other hand, the effect of symmetry on the SFC-profile of the blends was only clear for the stearic based blends. At lower temperatures, the SFC of symmetric TAG based blend (blend SM) was markedly lower than that of asymmetric TAG based blend (blend iS). However, from 30°C onwards, the SFC of blend SM was clearly higher than that of blend iS. The microscopic analyses revealed a denser crystal network for a higher degree of trisaturated TAG and for symmetric stearic based blends. Moreover, some blends showed a clear evolution of the microstructure during storage with smaller crystals transforming into larger ones. Finally, texture analyses demonstrated the importance of the crystallization and storage temperature on the hardness of the blends.

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Talbot G., Smith K.W., Bhaggan K., Influence of minor components on fat crystallization,  Lipid Technology, 2012, 24(4), 83-85

Crystallization in fats is of fundamental importance in the production and consumption of fats per se and of food and home and personal care (HPC) products in which fats form a major part. While crystallization of fats as such has been extensively reviewed over the past decade there has been less emphasis on the role of minor components. A review by Smith et al. [1] redressed this; this article is based on that review.

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Garcia-Macias, P., Gordon, M.H., Frazier, R.A., Smith K., Gambelli, L., Performance of palm-based fat blends with a low saturated fat content in puff pastry, European Journal of Lipid Science and Technology, 2011, 113(12), 1474-1480

Four fat blends based on palm fractions in combination with high oleic sunflower oil (HOSF) with a relatively low saturated fatty acid content (29.2 ± 0.85%, i.e. less than 50% of that of butter) were prepared. The saturated fat was located in different TAG structures in each blend. Principal saturated TAG were derived from palm stearin (POs, containing tripalmitoyl glycerol—PPP), palm mid-fraction (PMF, containing 1,3-dipalmitoyl-2-oleoyl glycerol—POP) and interesterified PMF (inPMF, containing PPP, POP and rac-1,2-dipalmitoyl-3-oleoyl glycerol—PPO). Thus, in blend 1, composed of POs and HOSF, the saturates resided principally in PPP. In blend 2, composed of POs, PMF and HOSF, the principal saturate-containing TAG were PPP and POP. Blend 3, composed of inPMF and HOSF, was similar to blend 2 except that the disaturated TAG comprised a 2:1 mixture of PPO:POP. Finally, blend 4, a mixture of PMF and HOSF, had saturates present mainly as POP. The physical properties and the functionality of blends, as shortenings for puff pastry laminated in a warm bakery environment (20–24°C), were compared with each other, and with butter. Puff pastry prepared with blend 1 (POs:HOSF 29:71) and blend 4 (PMF:HOSF 41:59), was very hard; blend 2 (POs:PMF:HOSF 13:19:68) was most similar to butter in the compressibility of the baked product and it performed well in an independent baking trial; blend 3 (inPMF:HOSF 40:60) gave a product that required a higher force for compression than butter.

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Smith K.W., Bhaggan K., Talbot G., Van Malssen K.F., Crystallization of fats – Influence of minor components and additives, Journal of the American Oil Chemists’ Society, 2011, 88(8), 1085-1101

Over the years, there has been a steady stream of publications on the influence that minor components and additives have on the physical properties of fat continuous systems. These have been reviewed here. Both indigenous and added components are taken into account. The various materials have been discussed, ranging from partial glycerides and phospholipids to esterified sugars and polyols. Within the publications in this area, the (sub-)micron effects that these minor components have on nucleation, crystal growth, morphology, heat capacity and polymorphic stability have been described and discussed and, sometimes, explained. Similarly, the effects on a macroscopic level, such as visual aspects, melting profiles, post-hardening and rheology have been the subject of research. Although limited compositional information, especially of additives, hinders appropriate discussions of the relevant mechanisms, some generic guidelines as to what type and strength of effect can be expected have been derived. As a general rule, a more significant influence is observed when the acyl group of the minor component (where present) is similar to those present in the fat itself. Additives may have different effects depending on the fat they are added to, their concentration and the temperature, especially with increasing undercooling (which typically reduces the effect of additives).

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Vereecken, J., De Graef, V., Smith, K.W., Wouters, J., Dewettinck, K., Effect of TAG composition on the crystallization behaviour of model fat blends with the same saturated fat content, Food Research International, 2010, 43(8), 2057-2067

In this study, the crystallization and polymorphic properties of eight fat blends with the same saturated fat content (50%) but with a varying TAG composition were investigated using DSC and X-ray diffraction. Blends were either palmitic (P) or stearic (S) based, and were all diluted with high oleic sunflower oil to obtain the same level of saturated fatty acids. Three different effects were investigated, namely the effect of chain length, the effect of trisaturated TAG and the effect of symmetry. The DSC results suggested that PPP, present in the palmitic based blends, seeded the crystallization process better than did SSS in the stearic based blends. Stop-and-return DSC revealed a two-step crystallization for almost all the blends at 15°C, 20°C and 25°C. This behaviour was further elucidated by WAXD-analysis of the blends, showing an initial crystallization into an unstable polymorph followed by polymorphic transformation during crystallization.

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Vereecken J., Foubert I., Smith K.W., Sassano G.J., Dewettinck K., Crystallization of model fat blends containing symmetric and asymmetric monounsaturated triacylglycerols, European Journal of Lipid Science and Technology, 2010, 112(2), 233-245

In this study, the crystallization and melting properties of four different fat blends with the same saturated fat content (30%) but with different ratios of symmetric and asymmetric monounsaturated triacylglycerols were investigated using pNMR, DSC and polarized light microscopy. Blends were either palmitic (P) or stearic (S) based, and were combinations of SatOSat-rich (Sat = saturated, O = oleic) and SatSatO-rich vegetable oils with high-oleic sunflower oil. The DSC results demonstrate that there was almost no difference in crystallization mechanism and crystallization rate between the two P-based blends. Both blends showed a two-step crystallization, which can be explained by polymorphism. Stop-and-return DSC results suggested an initial crystallization into an unstable polymorph followed by polymorphic transition during the crystallization. For the S-based blends there was a clear difference between the SOS-rich and the SSO-rich blend, with a slower crystallization for the SSO-rich blend. Possibly, this can be explained by fractional crystallization. The microstructure did not differ greatly between the blends. Directly after crystallization, the crystals of the SSO-rich blend were slightly larger than the crystals of the SOS-rich blend.

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Talbot G., Slager H., Smith K.W., Reducing Saturates by Seeding? World of Food Ingredients, 2010, February, 64-65

Food manufacturers are being encouraged by governmental agencies like the UK’s Food Standards Agency to reformulate their products with lower levels of saturated fat. Across the developed world it is acknowledged that we consume far too much saturated fat and that we should be cutting intake by about 20% on average to a level of about 10-11% of dietary energy. If we assume that overall fat intake is about 35% of dietary energy this equates to an average saturated fat level of about 30% in the fat phase of foods. Clearly some foods, notably those based on liquid oils such as rapeseed oil and sunflower oil will contain less saturates than this, while others such as milk and meat fats will contain higher levels of saturates.

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Sangwal K., Smith K.W., On the metastable zone width of 1,3-dipalmitoyl-2-oleoylglycerol, tripalmitoylglycerol, and their mixtures in acetone solutions, Crystal Growth and Design, 2010, 10(2), 640–647

The extensive experimental data reported by Smith et al. (Eur. J. Lipid Sci. Technol. 2005, 107, 583−593) on the metastable zone width of 1,3-dipalmitoyl-2-oleoylglycerol, (POP) tripalmitoylglycerol (PPP), and their mixtures in acetone are analyzed using a novel approach based on classical three-dimensional nucleation theory (Sangwal, K. Cryst. Growth Des. 2009, 9, 942−950) and a self-consistent Nyvlt-like approach (Sangwal, K. Cryst. Res. Technol. 2009, 44, 231−247) to obtain quantitative information on the processes of nucleation of these systems. The relevant equations of the above approaches are (i) (T₀/ΔT_max) = F(1 − Z ln R) and (ii) ln(ΔT_max)/T₀) = Φ + β ln R, where T₀ is the saturation temperature and F and Φ are, respectively, the values of (T₀/ΔT_max) and ln(ΔT_max)/T₀) when ln R = 0, whereas Z is a parameter characteristic of the crystallizing system and the constant β is inverse of the apparent nucleation order m in the Nyvlt approach. It was found that (1) the value of parameters β and Z is relatively insensitive to saturation temperature T₀ but depends on the investigated compound and the technique used for the measurement of maximum supercooling ΔT_max and the presence of PPP impurity in POP solutions; (2) the values of β and Z for PPP and POP decrease with an increase in their solubility in acetone; and (3) the data of Φ and ln(F^1/2) as a function of saturation temperature T₀ follow the Arrhenius-type relation with an activation energy E_sat. Analysis of the results revealed that (1) the values of β and Z are directly connected with the solid−liquid interfacial energy γ; (2) the value of E_sat depends on the nature of ions/molecules participating in diffusion; (3) maximum supercooling ΔT_max measured by turbidimetry corresponds to a nucleation event alone, but that obtained from growth exotherm includes some contribution of growth of stable nuclei after nucleation; and (4) PPP impurity in POP solutions promotes crystallization by acting as growth centers for heterogeneous nucleation.

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Talbot G., Slager H., Smith K.W., Crystallisation of palm-based fats Part II Secondary crystallisation, Innovations in Food Technology, 2009, November

The first part of this article considered the effects on primary crystallisation of of moving from a partially trans-containing fat to a trans-free system based on palm factions. This article considers secondary crystallisation and the analytical processes used to quantify this involving oscillatory rheology and texture analysis. This article produces the results.

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Talbot, G., Slager, H., Smith, K.W., Crystallisation of palm-based fats Part I Primary crystallisation, Innovations in Food Technology, 2009, August

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Talbot G., Slager H., Smith K.W., Transforming Fillings, Innovations in Food Technology, 2009, May

Fats used in confectionery and bakery fillings have a number of functions and attributes such as sensory characteristics, hardness, coolness and flavour release. The choice of filling fat can, therefore, be critical to the success in both functional and sensory terms of the product. This article from Geoff Talbot, The Fat Consultant, Kevin Smith, Unilever Research, and Hennie Slager, Loders Croklaan, of The Netherlands, points out that, however, just as important as these properties are, the whole issue of the nutritional characteristics of the filling fat has become critical. Solidity which provides hardness comes from saturated or trans fatty acids, but they increase the ‘bad’ LDL cholesterol. But replacing these fats by a non-hydrogenated equivalent results in much softer and generally unacceptable products. The article also considers fatty acid compositions and melting profiles as well as hardness. In summary it says that changing from a trans- containing, high-saturates filling fat to one that is trans-free and lower in saturates will require certain changes to be made to the processing of the filling.

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Talbot G., Smith K., Velds P., Slager H., Versatile shortenings for a trans-free world, 2009, February

One of the great virtues of hydrogenated fats was that they made excellent pastry, biscuit and cake shortenings. The problem with such fats is their trans fatty acid content and both oils and fats processors and bakery manufacturers have been looking for non-hydrogenated alternatives. This article looks at Loders Croklaan’s palm oil-based shortenings as non-hydrogenated alternatives to traditional trans-containing fats. Indeed Loders Croklaan is introducing new trans-free shortenings under the brand names Biscuitine™ in Europe and SansTrans™ in the US. The company has funded research into how these fats perform in bakery with The University of Reading in the UK and this article summarises this research and how it applies to bakery shortenings.

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Vereecken J., Foubert I., Smith K.W., Dewettinck K., Effect of SatSatSat and SatOSat on crystallization of model fat blends, European Journal of Lipid Science and Technology, 2009, 111(3), 243-258

In this study, the crystallization and melting properties of six different fat blends with the same saturated fat (30%) but with a varying content of trisaturated and disaturated triacylglycerols were investigated using pulsed NMR, DSC and polarized light microscopy. Blends were either palmitic (P) or stearic (S) based, and were combinations of SatSatSat-rich (Sat = saturated) and SatOSat-rich (O = oleic) vegetable oils with high-oleic sunflower oil. The DSC results suggested that PPP forms mixed crystals with POP, leading to a better seeding of the crystallization process than did SSS with SOS. Some blends showed a two-step crystallization, which can be explained by polymorphism. Stop-and-return DSC results suggested an initial crystallization into an unstable polymorph followed by polymorphic transformation during the crystallization for those blends with significant amounts of SatSatSat. Polymorphic transformation was not seen for the blends with low SatSatSat. However, the microstructure of such blends changed dramatically during storage, while the microstructure of the blends with the higher SatSatSat content did not.

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Smith K.W., Crystallisation and physical properties of fats (Special Issue Editorial), European Journal of Lipid Science and Technology, 2009, 111(3), 217-218

As people become ever more health conscious and aware of what they eat, attention is directed towards reducing the fat content of food and switching to a healthier fat type. Consequently, much is published these days concerning the nutritional characteristics of lipids and novel plant sources of edible and functional oil. However, the physical properties of fats are also important, since the feasibility of producing suitable healthy alternative food products can rest on such characteristics.

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Smith, K.W., ‘t Zand, I., Talbot, G., Effect of antibloom fat migration from a nut oil filling on the polymorphic transformation of cocoa butter, Journal of Agricultural and Food Chemistry, 2008, 56(5), 1602-1605

In confectionery products, loss in texture contrast between chocolate and filling and the appearance of fat bloom on the surface of the chocolate can be caused by fat migration. Bloom is often linked to the transformation of the cocoa butter β_V polymorph into β_VI. A previous study showed that small additions (1%) of nut oil can have a significant impact on the rate of transformation and that migration of nut oil from a filling would increase polymorphic transformation of cocoa butter. In the present study, antibloom fat was added to the filling in a model System. The antibloom fat migrated with the nut oil and inhibited the transformation of cocoa butter from the β_V polymorph into β_VI. Despite experiencing migration of greater amounts of nut oil, cocoa butter closest to the filling transformed more slowly than that farther away (i.e., the reverse of the situation in the absence of antibloom fat).

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Talbot G., Slager H., Smith K.W., The holistic approach to temper, Innovations in Food Technology, November 2008

It is interesting to look at the individual processes that chocolate goes through and try to define the common perceptions (and, in some cases, misconceptions) of what each of these is meant to do and on what parameters they depend.

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Talbot, G., Smith, K.W., Slager, H., First bite: Texture analysis can be a good prediction of sensory hardness in confectionery coatings, International Food Ingredients, 2008, Apr, 7-10

What are the first sensory characteristics you look for in a bar of chocolate? Appearance is probably the first thing we are aware of–whether the chocolate has a good gloss, whether or not it has bloomed. Then, perhaps aroma as we open the wrapper on the bar. But when we first bite into the chocolate we become immediately aware of how hard the chocolate is, particularly what we have termed to be its “”hardness at first bite””. This sensory attribute is an important one, irrespective of whether it is chocolate or a compound coating …

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Talbot G., Slager H., Smith K.W., Effect of refining and conching on chocolate properties 1. Particle size distribution and viscosity, Innovations in Food Technology, February 2008

If chocolate was produced by simply mixing the ingredients together before tempering and moulding, a very poor chocolate would result. There are two reasons for this. First, the human palate is able to detect particles which have a diameter of more than about 25 microns. Without any process of particle size reduction taking place the size of the particles in the non-fat solids (sugar, cocoa powder, and milk powder) would be much higher than that and so the chocolate would taste gritty. So a particle size reduction process, known as refining, is necessary. Second, the cocoa solids in their native state have quite an unacceptable taste which is removed by a process known as conching. This article explores further.

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Talbot, G., Smith, K., Favre, L., ‘t Zand, I., Tackling migration, Food Ingredients, Feb 2008, 22-24

Migration of oils from soft filling fat phases into outer chocolate coatings has long been a problem for the confectionery industry. Such migration causes a softening of the chocolate and a hardening of the filling, thus losing much of the textural difference found in the original, fresh product. To a large extent, such effects are understandable. It is the liquid phase of the filling which moves out of the filling so what is left must be more solid and, hence, harder. As it is also the liquid phase of the filling which moves into the chocolate, the chocolate must become richer in liquid and, hence, softer. It’s obvious, really! What is not quite so obvious is that such oil migration is often accompanied by the formation of fat bloom on the chocolate surface. Why should migration of oils from a filling into chocolate accelerate the formation of fat bloom?

Talbot G., Smith K.W., ‘t Zand I., Checking polymorphic changes in filled chocolates, eFood – European Food Scientist, 2008, Jan 30th

The consequence of the polymorphic nature of cocoa butter is that, when used in chocolate, the chocolate needs to be tempered in order to crystallise the cocoa butter in one of the stable forms β_V or β_VI. It is not possible for the cocoa butter to crystallise directly into the β_VI form which is its most stable form so a well-tempered chocolate will contain cocoa butter in the β_V form. Over time the β_V form will gradually transform into the β_VI form. This change is often accompanied by the formation of fat bloom. It also occurs in the presence of liquid oils There are three ways in which the liquid oil content of chocolate is increased: by storing it at a higher temperature; by deliberate addition of liquid oils to the chocolate; as a result of migration of liquid oils from a centre filling into the chocolate.

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Talbot G., Smith K., Slager H., ‘t Zand I., Temper – it’s not just about the fats, Innovations in Food Technology, 2007, 39 (November), 22-23

It is often thought that the main factors in defining the whole process of tempering chocolate are the amount and type of fat present. Although these do play a major part in the process the other components in the chocolate sugar, cocoa powder, skimmed milk powder and lecithin also play a role, in some instances an unexpected role. This article on behalf of IOI-Loders Croklaan, of Womerveer, The Netherlands, explains. It concludes that far from being inert filler components in chocolate, the main non-fat components have surprisingly significant effects on both the amounts of solid fat present at temper and the viscosity of the chocolate at this stage.

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De Graef V., Foubert I., Smith K.W, Cain F.W., Dewettinck K., Crystallization behavior and texture of trans-containing and trans-free palm oil based confectionery fats, Journal of Agricultural and Food Chemistry, 2007, 55(25), 10258-10265

The objective of this study was to gain insight into the role of trans fatty acids in determining the crystallization behavior and texture of palm-based confectionery fats. Therefore, the isothermal crystallization behavior of two series, each of three fats, one trans-containing and one trans-free, was examined by pNMR, DSC, and rheology. Furthermore, the hardness of these samples was examined at three different storage times at 10°C. All of the trans free samples showed a two-step crystallization at 10°C which is hypothesized to be an α-mediated β’ crystallization at 10°C which is hypothesized to be an α-mediated β’ crystallization for two of the samples and a fractionated crystallization in the β’ polymorph for the third, while the trans-containing fats crystallized in a single step, probably a direct β’ crystallization. The trans-containing fat series clearly crystallized faster than the trans-free fat series and also yielded higher hardness values at all storage times investigated. The presence of trans fatty acids seems to reduce the effect of compositional variations on the crystallization process. For the trans free fats, chemical composition was much more critical in determining the crystallization rate, the SFC, and the final hardness value.

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Smith K.W., Smith P.R., Furó I., Pettersson E.T., Cain, F.W., Favre L., Talbot G., Slow recrystallization of tripalmitoylglycerol from MCT oil observed by ²H NMR, Journal of Agricultural and Food Chemistry, 2007, 55(21), 8585–8588

The crystallization and recrystallization of fats have a significant impact on the properties and quality of many food products. While crystallization has been the subject of a number of studies using pure triacylglycerols (TAG), recrystallization in similarly pure systems is rarely studied. In this work, perdeuterated tripalmitoylglycerol (²H-PPP) was dissolved in medium chain triacylglycerol oil (MCT) to yield a saturated solution. The solution was heated to cause partial melting of the solid and dissolution of the molten fraction of ²H-PPP in MCT and was then cooled to the original temperature to induce recrystallization from the supersaturated solution. ²H NMR was used to monitor the disappearance of ²H-PPP from the solution and showed that recrystallization occurred in two steps. The first step was rapid, taking place over a few minutes, and accounted for more than two-thirds of the total recrystallization. The second step was much slower, taking place over a remarkably long timescale of hours to days. It is proposed that dissolution occurs from all parts of the crystals, leaving an etched and pitted surface. The first step of crystallization is the infilling of these pits, while the second step is the continued growth on the smoothed crystal faces.

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Jirasubkunakorn W., Bell A.E., Gordon M.H., Smith K.W., Effects of variation in the palm stearin: palm olein ratio on the crystallisation of a low-trans shortening, Food Chemistry, 2007, 103, 477-485

Changes in the rheological properties during crystallisation and in the crystal size and morphology of blends containing rapeseed oil with varying percentages of palm stearin (POs) and palm olein (POf) have been studied. The crystals formed from all three blends were studied by confocal laser scanning microscopy, light microscopy and environmental scanning electron microscopy, which revealed the development of clusters of 3–5 individual elementary “spherulites” in the early stages of crystallisation. The saturated triacylglycerol content of the solid crystals separated at the onset of crystallisation was much greater than that in the total fat. Fat blends with a higher content of palm stearin had a more rapid nucleation rate when observed by light microscopy, and this caused an earlier change in the rheological properties of the fat during crystallisation. Using a low torque amplitude (0.005 Pa, which was within the linear viscoelastic region of all samples studied) and a frequency of 1 Hz, the viscoelastic properties of melted fat during cooling were studied. All samples, prior to crystallisation, showed weak viscoelastic liquid behaviour (G″, loss modulus >G′, storage modulus). After crystallisation, a more “solid like” behaviour was observed (G′ similar to or greater than G″). The blend having the highest concentration of POs was found to have the earliest onset of crystallisation (27% w/w POs; 12 mins, 22% w/w POs; 13.5 mins, 17% w/w POs, 15 mins, respectively). However, there were no significant differences in the time to the point when G′ became greater than G′ among the three blends.

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Vereecken J., Foubert I., Smith K.W., Dewettinck K., Relationship between crystallization behavior, microstructure, and macroscopic properties in trans-containing and trans-free filling fats and fillings, Journal of Agricultural and Food Chemistry, 2007, 55(19), 7793-7801

The objective of this study is to investigate the architecture to feature physical functionality of filling fats. This means an investigation of the different structure levels (crystallization, microstructure, macrostructure, etc.) that lead to good technological functionality. The isothermal crystallization behavior of two filling fats (one trans-containing and one trans-free) was examined by differential scanning calorimetry and microscopy. Furthermore, the hardness of the samples was examined after cooling in a water bath at two different temperatures and at three different storage times. The trans-containing filling fat crystallized faster and in smaller crystals as compared to the trans-free filling fat. The crystallization behavior of the trans-free filling fat was more complex, with the formation of different polymorphic forms. The hardness of the fillings was not only governed by the amount of solid fat present in the network but also by the structure of this network. The filling matrix components seem to have a pronounced influence on the microstructure and thus on the macroscopic properties.

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Smith P.R., Furo I., Smith K.W., Cain F., The effect of partial acylglycerols on the exchange between liquid and solid tripalmitoylglycerol, Journal of the American Oil Chemists’ Society, 2007, 84 (4), 325-329

Exchange of molecules between liquid and solid components of a triacylglycerol (TAG) system is an important process in the degradation of many food components as well as for many industrial processes such as fractionation. NMR is a technique that can be used to measure the exchange between solid and liquid phases. In this work we show that monoacylglycerols (MAG) and diacylglycerols (DAG) have a retarding effect on the rate of exchange between solid and liquid TAG. In particular dipalmitoylglycerol significantly retards the rate of exchange. It is postulated that this result suggests that exchange occurs primarily through certain hotspots, probably kinks and defects on the crystal surface. MAG and, in particular, DAG can block these hotspots. It is suggested that because of their molecular structure they can partially co-crystallize with the TAG crystal during the exchange process and then block further exchange.

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Mykhaylyk O.O., Smith K.W., Martin C.M., Ryan A.J., Structural models of metastable phases occurring during the crystallization process of saturated/unsaturated triacylglycerols, Journal of Applied Crystallography, 2007, 40, s297-s302

Isothermal crystallizations of saturated and mixed saturated/unsaturated triacylglycerols (TAGs) have been studied by simultaneous time-resolved small-angle and wide-angle X-ray scattering measurements (SAXS/WAXS). The projection of the electron density profile along the layer normal derived from the lamellar peaks of the α₂-phase can be assembled from two types of molecular dimers initially formed in the liquid state. One dimer corresponds to a typical two-chain packing of TAGs and the other is formed by opposing molecules overlapping by their two-acyl-chain sides. This structure occurs only in triacylglycerols containing both saturated and unsaturated acyl chains. The structural organization of the α₂-phase is analogous to smectic A interdigitated phases. In the particular case of 1,3-distearoyl-2-oleoyl-sn-glycerol, StOSt, the α₂-phase can evolve into a mixture of two phases (α₁ and γ) with double and triple (2L and 3L) chain packing, respectively. A calculation of X-ray scattering patterns for simulated structures of randomly packed three-chain and two-chain layers of StOSt (2L + 3L) reproduced the three diffuse scattering peaks observed in the experimental SAXS patterns.

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Smith K.W., Cain F.W., Talbot G., Liquid-liquid phase separation in acetone solutions of palm olein: Implications for solvent fractionation, European Journal of Lipid Science and Technology 2007, 109(4), 350-358

The quality of palm mid fractions (PMF) obtained by dry fractionation has increased, but the best-quality PMF for application in many confectionery fats are still produced by solvent fractionation. In the present study, liquid-liquid phase separation has been observed in acetone solutions both for pure triacylglycerols and for palm olein. The temperature at which phase separation occurs increases as the oil concentration is increased and linearly as the water content of the system is increased. The triacylglycerol compositions of the two liquid phases that form do not differ. However, the oil-rich phase is depleted with respect to the polar components. The temperature at which liquid-liquid phase separation occurs is reduced by about 0.2 and 0.4°C per percent of free fatty acids and diacylglycerols, respectively. When oil-rich droplets appear, crystallisation occurs within them rather than in the oil-depleted phase, due to the higher oil concentration. Thus, liquid-liquid phase separation prior to crystallisation raises the nucleation temperature but may lead to a greater concentration of entrained olein in the filter cake, leading to a poorer-quality PMF.

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Smith K.W., Cain F.W., Talbot G., Effect of nut oil migration on polymorphic transformation in a model system, Food Chemistry 2007, 102 (1), 656–663

Fat migration in confectionery products can lead to significant deterioration in quality. This occurs not only through loss in texture contrast between chocolate and filling but also through the appearance of fat bloom on the surface of the chocolate. This latter aspect is often, although not exclusively, linked to the transformation of the cocoa butter β_V phase into β_VI. In this study, the influence of hazelnut oil on the polymorphic transformation of cocoa butter has been determined, showing that even small additions (1%) of nut oil can have a significant impact on the rate of transformation. Additionally, use of a model system has shown that polymorphic transformation in cocoa butter is linked to the degree of migration of nut oil from a filling. Portions of the cocoa butter close to the filling experience both greater degrees of migration and faster transformation.

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Bell A., Gordon M.H., Jirasubkunakorn W., Smith K.W., Effects of composition on fat rheology and crystallisation, Food Chemistry, 2007, 101(2), 799–805

The crystallisation behaviour of three fat blends, comprising a commercial shortening, a blend of fats with a very low trans fatty acid content (“low-trans”) and a blend including hardened rapeseed oil with a relatively high trans fatty acid content (“high-trans”) was studied. Molten fats were lowered to a temperature of 31 °C and stirred for 0, 15, 30, 45 and 60 min. Samples were removed and their rheological properties studied, using a controlled stress rheometer, employing a frequency sweep procedure. Effects of the progressive crystallisation at 31 °C on the melting profile of fat samples removed from the stirred vessel and solidified at −20 °C were also studied by differential scanning calorimetry (DSC).

The rheological profiles obtained suggested that all of the fats studied had weak viscoelastic “liquid” structures when melted, but these changed to structures perceived by the rheometer as weak viscoelastic “gels” in the early stages of crystallisation (G′ (storage modulus) > G″ (loss modulus) over most of the measured frequency range). These subsequently developed into weak viscoelastic semi-solids, showing frequency dependent behaviour on further crystallisation. These changes in behaviour were interpreted as changes from a small number of larger crystals “cross-linking” in a liquid matrix to a larger number of smaller crystals packed with a “slip plane” of liquid oil between them.

The rate of crystallisation of the three fats was in the order high trans > low-trans > commercial shortening. Changes in the DSC melting profile due to fractionation of triacylglycerols during the crystallisation at 31 °C were evident for all three fats.

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Talbot G., Smith K., ‘t Zand I. Sans trans shortening, European Baker, Sept/Oct 2007, 24-27

Historically, bakery shortenings have been produced from either animal fats such as lard or from partially hydrogenated vegetable oils. While, in terms of functionality, both types of fat make good bakery shortenings both are problematic. Lard would not only be prohibited in food products designated Kosher or Halal but would also be considered questionable in terms of its level of saturates (greater than 40 per cent) in a climate looking to reduce saturated fat. Partially hydrogenated vegetable oils contain trans fatty acids and are being replaced by non-hydrogenated alternatives.

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Talbot G., Smith K., ‘t Zand I., Effect of liquid oil in chocolate on polymorphic changes, Innovations in Food Technology, 2007, 36 (August), 20-21

It is often thought that the main factors in defining the whole process of tempering chocolate are the amount and type of fat present. While these do play a major part in how chocolate tempers, the other components in the chocolate, sugar, cocoa powder, skimmed milk powder and lecithin also play a role, in some instances an unexpected role.

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Talbot G., Smith K., ‘t Zand I., Polymorphic changes in chocolate, Innovations in Food Technology, 2007, 36 (August), 18-19

It has been known for a long time that cocoa butter is a polymorphic fat. This means that it can crystallise in a number of different forms of varying stabilities. For many years, both fat and chocolate specialists have thought that there were six polymorphic forms. These were defined, in different ways, by Wille and Lutton (1966) and by Larsson (1966).

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Talbot G., Smith K., ‘t Zand I., Checking polymorphic changes in filled chocolates, eFood, June 2007, 20-21

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Foubert I., Vereecken J., Smith K.W., Relationship between crystallization behavior, microstructure, and macroscopic properties in trans containing and trans free coating fats and coatings, Journal of Agricultural and Food Chemistry, 2006, 54 (19), 7256-7262

The objective of this study is to gain further understanding into the relationship between crystallization behavior, microstructure, and macroscopic properties in coating fats. The isothermal crystallization behavior of two coating fats (one trans containing and one trans free) was examined, both as pure fats and in coatings, by DSC and microscopy. Furthermore, the hardness of the samples was examined after cooling in a water bath at two different temperatures and at three different storage times. Both fats seemed to show an α-mediated β’ crystallization at lower temperatures and a direct β’ crystallization at higher temperatures. The trans free coating fat clearly crystallized faster and in smaller crystals. The hardness was governed not only by the amount of solid fat present in the network but also by the structure of this network. The coating matrix components seem to have a pronounced influence on the microstructure and thus on the macroscopic properties.

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Talbot G., Smith K.W., Cain F.W., Solvent fractionation of palm oil. INFORM – International News on Fats Oils and Related Materials, 2006, 17(5), 324-326

Manufacturers on both sides of the Atlantic are under increasing pressure to remove trans fatty acids and hydrogenated fats from their products. While there are a number of alternatives potentially available to them there is, nevertheless, usually a need for these alternatives to be able to provide structure and stability to the end product. That generally means having some solid fat present. If this solid fat cannot be produced by hydrogenation because the consumer has been ‘taught’ by the popular media to equate this on a label to the presence of trans fats, then oils naturally rich in solid triglycerides must be used. The most readily available of these oils is palm oil.

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Smith K.W., Cain F.W., Talbot G., Crystallisation of 1,3-dipalmitoyl-2-oleoylglycerol and tripalmitoylglycerol and their mixtures from acetone, European Journal of Lipid Science and Technology, 2005, 107(9), 583-593

Crystallisation from acetone of 1,3-dipalmitoyl-2-oleoylglycerol (POP), tripalmitoylglycerol (PPP) and their mixtures has been studied at a range of cooling rates, determining the metastable zone width using turbidimetry. A log-log plot of the cooling rate against the maximum undercooling for POP indicated a relative insensitivity of the metastable zone width to the cooling rate. The PPP metastable zone width demonstrated a slight dependence on concentration. POP crystals were spherulitic, having a more open structure at slower cooling rates. PPP crystals were more plate-like, producing powdery, more amorphous crystals at high cooling rates. In pure POP systems, onset of crystallisation was quickly followed by rapid crystal growth. The presence of PPP markedly increased the temperature of the onset of crystallisation (by 17.7°C at 8% PPP), but the temperature at which crystal growth occurred, although raised, did not increase to the same extent. The clear point of the pure systems was independent of the previous cooling rate, but this was not true in the mixed system, where it decreased with increasing cooling rate. This suggests that a greater proportion of the PPP-rich phase separates during slower cooling. The morphology of the crystals from the mixed system differed from that in the pure POP system, with just 2% PPP being sufficient to shift the structure to a more lamellar appearance.

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Smith K.W., Cain F.W., Talbot G., Kinetic Analysis of Non-Isothermal Differential Scanning Calorimetry of 1,3-Dipalmitoyl-2-oleoylglycerol, Journal of Agricultural and Food Chemistry 2005, 53 (8), 3031-3040

The crystallization of fats has been extensively studied because of its importance in the processing of food and food ingredients. Differential scanning calorimetry (DSC) is widely used in such studies. The aim of this study was to examine the determination of kinetic parameters from nonisothermal DSC crystallization of a model fat, 1,3-dipalmitoyl-2-oleoylglycerol. We applied peak and isoconversional methods to determine activation energies and compared these techniques with a nonparametric method, which separates the temperature dependence and degree of crystallization dependence of the crystallization rate. The Johnson-Mehl-Avrami-Erofeyev-Kolmogorov (JMAEK) model provided the best fit to the data, while the temperature dependence of the rate constant was best explained by a Vogel-Fulcher relationship, where the reference temperature was the melting point of the crystallizing species.

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Talbot G., Smith K., Cain F., Crystallization of 1,3-dipalmitoyl-2-oleoylglycerol (POP) studied using non-isothermal DSC, Lipid Technology, 2005, 17(11), 247-250

With the increasing emphasis on replacing hydrogenated and trans fats in food, oils and fats processors and food manufacturers are looking to palm oil and its fractions as alternative fats. Crystallization is of major importance in the processing of food and food ingredients and differential scanning calorimetry (DSC) has been widely used in studying such crystallization. This article discusses the use of non-isothermal DSC in modelling the crystallization of 1,3-dipalmitoyl-2-oleoylglycerol,one of the main triacylglycerol components of palm oil. Various kinetic crystallization models were used to fit the data, thus allowing the calculation of crystallization parameters. A similar approach may be used in the future to model crystallization in real systems.

Talbot G., Smith K.W., Cain F.W., How does your chocolate flow?, Candy Business, 2005, 7(3), 40-41

As a means of quality control, a large part of the chocolate industry uses the viscosity of chocolate that is measured at a temperature well above that at which it will be tempered. In fact, the IOCCC method recommends measuring this at 104°F (40°C). Although this is fine for ensuring batch-to-batch consistency, research from Loders Croklaan shows that it by no means gives the full picture. Measuring the viscosity of untempered chocolate at 104°F gives little indication of the flow properties of that chocolate when it has been tempered and cooled to, say, 88.5°F. Why?

Cain F., Smith K., Talbot G., Controlling Viscosity, Confectionery Production, June 2005, 2-23

The chocolate industry normally uses the viscosity of chocolate measured at 40°C as a means of quality control.  Whilst such measurements do ensure batch-to-batch consistency they bear no real relationship to the viscosity of the chocolate once it is tempered.  There are two main reasons for this.  Firstly, the temperature of the tempered chocolate will be some 10°C or so lower and this alone will contribute to a higher viscosity.  Secondly, a proportion of the fat phase will have crystallised at temper leaving less of the fat in the liquid phase.  This also will contribute to a higher viscosity.  So tempering chocolate will increase its viscosity.  The questions which then arise from this are (a) by how much, and (b) is the viscosity increase dependent on the way in which the chocolate is tempered?

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Talbot G., Smith K., Cain F., Quality Control of Cocoa Butter Equivalents Using Differential Scanning Calorimetry, Lipid Technology 2005, 17(6), 135-138

Talbot G., Smith K.W., Cain F.W., Fat Bloom on Lauric Coatings: Structure and Control, The Manufacturing Confectioner 2005, Vol. 85(1), p 69-72

Pressure on confectionery manufacturers to move away from high trans-containing compound coatings to either lower trans or completely nonhydrogenated fat bases is increasing as more becomes known about the effects of trans fatty acids on health. But what are the alternatives? Essentially there are four alternatives:
– Move to real chocolate This is more expensive and also requires sophisticated tempering and processing equipment.
– Move to a supercoating This is a coating whose fat base is essentially a cocoa butter equivalent. It is less expensive than real chocolate but sophisticated tempering and processing equipment is still needed.
– Move to one of the new low-trans or no-trans compound coatings The low-trans compound coatings still have an hydrogenated fat base and still contain some trans; the no-trans compound coatings overcome this issue but are still in the stage of being evaluated by the industry.
– Move to a lauric compound coating This is the subject of this paper to explore in more detail.

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Talbot G., Smith K.W., Cain F.W., Fat Bloom on Lauric Coatings: Composition, The Manufacturing Confectioner 2005, Vol. 85(1), 65-68

Over the past year or so there has been considerable pressure on food manufacturers to reduce the levels of trans fatty acids used in their products. Indeed, some countries, Denmark for example, have defined legislative limits for trans in food. Others such as the United States are planning to bring in labeling requirements for trans. Confectionery manufacturers are being affected by these changes along with the rest of the food industry. One area where confectionery manufacturers are being particularly affected is that of compound coatings, where there has been widespread use of fats based on partially hydrogenated and fractioned vegetable oils such as soybean oil, rapeseed oil and palm oil. These, of course, then contain high levels of trans fatty acids, often as high as 50 percent. While the oils and fats manufacturers have responded to this by developing lower-trans-content compound coating fats and indeed even a zero-trans content compound coating fat, the confectionery industry has also looked at alternatives.

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Smith K.W., Cain F.W., Talbot G., Nature and Composition of Fat Bloom from Palm Kernel Stearin and Hydrogenated Palm Kernel Stearin Compound Chocolates, Journal of Agricultural and Food Chemistry 2004, 52(17), 5539-5544

Palm kernel stearin and hydrogenated palm kernel stearin can be used to prepare compound chocolate bars or coatings. The objective of this study was to characterize the chemical composition, polymorphism, and melting behavior of the bloom that develops on bars of compound chocolate prepared using these fats. Bars were stored for 1 year at 15, 20, or 25°C. At 15 and 20°C the bloom was enriched in cocoa butter triacylglycerols, with respect to the main fat phase, whereas at 25°C the enrichment was with palm kernel triacylglycerols. The bloom consisted principally of solid fat and was sharper melting than was the fat in the chocolate. Polymorphic transitions from the initial phase to the phase accompanied the formation of bloom at all temperatures.

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Talbot G., Smith K.W., Prediction of the Hardness of Chocolate and Compound Coatings, Kennedy’s Confection 2004, (July), 22-24

The audible snap of a chocolate bar and the hardness of the chocolate as it’s first bitten into are both important parameters and indicators of quality to the consumer.  The snap and hardness and, to a large extent, the contraction of chocolate are all properties that are closely linked.  They are also properties that are closely related to the fat phase of the chocolate. This would then imply that a knowledge of certain properties of the fat phase should help us to define and predict the hardness of the chocolate.

Smith K., Cocoa butter crystallisation, In Working together for a golden future – proceedings of the 50^th technology conference, London, April 2003, BCCCA, London 2003

Hindle S., Povey M.J.W., and Smith K.W., Characterizing Cocoa Butter Seed Crystals by the Oil-in-Water Emulsion Crystallization Method, Journal of the American Oil Chemists’ Society, 2002, 79(10), 993-100

Unambiguous quantitative evidence for the catalytic action of seed crystals in cocoa butter is presented. We used an ultrasound velocity technique to determine the isothermal growth of solid fat content in cocoa butter oil-in-water emulsions, in which the probability of finding a seed crystal in any one droplet was around 0.37 at 14.2°C. The upper limit for the size of seed crystals in West African cocoa butter was around 0.09 μm, the Gibbs free energy for nucleation was 0.11 mj m⁻², and the concentration of seed crystals was in the range of 10¹⁶ to 10¹⁷ m⁻³. X-ray diffraction measurements showed that emulsified cocoa butter crystallizes in the α polymorph and does not appear to transform to the β′ form within the first 25 min of crystallization. Primary nucleation events in cocoa butter emulsions are accounted for by seed crystals. Collision-mediated nucleation, a secondary nucleation mechanism, in which solid droplets (containing seed crystals) catalyze nucleation in liquid droplets, is shown to account for subsequent crystallization. This secondary nucleation mechanism is enhanced by stirring.

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Hindle S., Povey M.J.W., Smith K.W., Kinetics of Crystallization in n-Hexadecane and Cocoa Butter Oil-in-Water Emulsions Accounting for Droplet Collision-Mediated Nucleation, Journal of Colloid & Interface Science, 2000, 232, 370-380

Droplet collision is shown to be important in the propagation of nucleation through supercooled oil-in-water emulsions by the use of a novel membrane technique. On the other hand, nucleation mediated by Tween 20 micelles is shown to be of relatively much less importance in both n-hexadecane and cocoa butter oil-in-water emulsions. The droplet collision phenomenon probably occurs via a surfactant bridge between the colliding droplets. When this process is taken into account we show that the Turnbull model for crystal nucleation kinetics explains very well nucleation in cocoa butter oil-in-water emulsions by seed crystals. On the basis of this model we characterized the seed crystals in cocoa butter via isothermal crystallization studies at 14.2, 15.0, 15.5, and 15.8°C. We suggest that there are few seed crystals whose size exceeds 0.28 μm at 80°C. In our cocoa butter samples there were between 10¹⁶ and 10¹⁷ seed crystals m⁻³ whose average size we inferred to be less than 0.09 μm. A value of 0.133 mJ m⁻² is obtained for the Gibbs free energy of the nucleating surface in our West African cocoa butter samples. There is evidence that the α-polymorph of POS comprises the nucleating layer in the seed crystal. There is no evidence that surfactant influences the primary nucleation of oil crystals. However, the surfactant has a big effect on the kinetics of the secondary nucleation process, mediated by droplet collision.

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Minato A., Ueno S., Yano J., Smith K., Seto H., Amemiya Y., Sato K., Thermal and Structural Properties on sn-1,3-Dipalmitoyl-2-oleoylglycerol and sn-1,3-Dioleoyl-2-palmitoylglycerol Binary Mixtures Examined with Synchrotron Radiation X-Ray Diffraction, Journal of the American Oil Chemists’ Society, 1997, 74 (10), 1213-1220

Thermodynamic and polymorphic behavior of POP (sn-1,3-dipalmitoyl-2-oleoylglycerol) and OPO (sn-1,3-dioleoyl-2-palmitoylglycerol) binary mixtures was examined using differential scanning calorimetry and conventional and synchrotron radiation X-ray diffraction. A molecular compound, β_C, was formed at the 1:1 (w/w) concentration ratio of POP and OPO, giving rise to two monotectic phases of POP/compound and compound/OPO in juxtaposition. β_C has a long-spacing value of 4.2 nm with a double chainlength structure and the melting point of 31.9°C. A structural model of the POP-OPO compound is proposed, involving the separation of palmitoyl and oleoyl chain leaflets in the double chainlength structure. In the polymorphic occurrence of the POP-OPO mixtures, the POP fraction transformed from α to β′ with no passage through γ, then transformed to β. The presence of OPO in POP promoted the β′–β transformation of POP during the melt-mediated crystallization.

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Minato A., Yano J., Ueno S., Smith K., Sato K., FT-IR study on microscopic structures and conformations of POP-PPO and POP-OPO molecular compounds, Chemistry &  Physics of  Lipids, 1997, 88, 63-71

The microscopic structures and conformations of the molecular compounds of POP–PPO and POP–OPO were examined using microprobe polarized Fourier transform infrared (FT–IR) spectroscopy. The two molecular compounds are formed in a double chain length structure due to specific acyl–acyl interactions through oleic acid moieties, yet peculiar differences were observed between the two molecular compounds. The subcell structure of β form of the POP–PPO compound was T_||, whose b_S-axis was approximately parallel to the unit cell b-axis. The olefinic conformation were neither of skew-cis-skew′ type nor of skew-cis-skew type. On the other hand, two subcell structures were assumed for β form of the POP–OPO compound: (a) the palmitoyl leaflet forms the T_|| subcell and the oleoyl leaflet O′_||, or (b) the two leaflets are both of T_|| subcell in which the directions of subcell axes of the palmitoyl and oleoyl chains are different. The olefinic conformation of the β form of the POP–OPO compound revealed the skew-cis-skew′ type. It was assumed that steric hindrance between the palmitoyl and oleoyl chains resulted in the formation of the molecular compounds of two types of double chain length structure: (a) complete separation of the palmitoyl and oleoyl chain leaflets as revealed in the POP–OPO compound, and (b) one leaflet of the palmitoyl chains and other leaflet of the palmitoyl-oleoyl mixed acid chains in the POP–PPO compound. The olefinic conformation of the POP–PPO compound was largely deformed compared to that in the PPO–OPO compound.

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Minato A., Ueno S., Smith K.W., Amemiya Y., Sato K., Thermodynamic and kinetic study on phase behaviour of binary mixtures of POP and PPO forming molecular compound systems, Journal of Physical Chemistry B, 1997, 101, 3498-3505

The phase behavior of PPO (sn-1,2-dipalmitoyl-sn-3-oleoylglycerol) and POP (sn-1,3-dipalmitoyl-sn-2-oleoylglycerol) binary mixture was examined using differential scanning calorimetry, conventional and synchrotron radiation X-ray diffraction (XRD), and highly pure samples. A molecular compound, β_C, was formed at the 1:1 concentration ratio of PPO and POP, giving rise to two monotectic phases of PPO/compound and compound/POP in a juxtapositional way. β_C has a long spacing value of 4.1 nm of double chain length structure. In the PPO/compound region, the DSC melting peak increased with increasing PPO concentration, whereas the DSC melting peak increased with increasing POP concentration in the compound/POP region. The melting point of β_C was lowest at 31.2 °C. Time-resolved XRD study unveiled the formation of molecular compounds in metastable forms, α_C and β’_C, having the same PPO/POP concentration ratio as β_C. α_C and β’_C exhibited monotectic phases with corresponding metastable forms of the pure components. In α_C, two hexagonal packing XRD short spacing peaks were obtained for α_C, corresponding to a differently packed hexagonal subcell of two leaflets. A structure model of the PPO/POP molecular compound is proposed, involving separation of palmitoyl chain leaflet and palmitoyl−oleoyl mixed-acid chain leaflet in the double chain length structure. This model justifies the structure of β_C of SOS/SSO proposed by Engstrom (Engstrom, L. J. Fat Sci. Technol. 1992 94, 173−181), in which the saturated and unsaturated chains are packed in the same leaflet of the double chain length. The present work additionally proved that the formation of the molecular compound was present in the α_C and β’_C metastable forms, as directly proved by dynamic X-ray diffraction study using synchrotron radiation.

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Duurland F., Smith K.W., Novel Non-Temper Confectionery filling fats using asymmetric triglycerides, Lipid Technology, 1995, 7, 6-9

Smith K.W., Perkins J.M., Jeffrey B.S.J., Phillips D.L., Separation of molecular species of cis- and trans-triacylglycerols in trans-hardened confectionery fats by silver-ion High-Performance Liquid Chromatography, Journal of the American Oil Chemists’ Society, 1994, 71 (11), 1219-1222

Silver-phase high-performance liquid chromatography (HPLC) on silver nitrate-loaded silica achieves incomplete separation of major triacylglycerol (TAG) classes present in trans-hardened fats. The ”ChromSpher Lipids” silver loaded cation exchange HPLC column has been found to yield good separations of trans hardened TAG, with molecular species well resolved. Separations comparable to those previously possible for nonhardened fats are now possible for trans-hardened fats. The separation is on the basis of number and type (i.e. cis/trans) of double bonds only; the position of the double bond along the acyl group appears not to influence the separation significantly. The analysis of a palm fraction, hardened to a slip melting point of 37°C and chemically randomized, is presented as an example. This technique offers a new approach to understanding and controlling the hydrogenation and processing of trans-hardened fats.

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Cebula D.J., Smith K.W., Differential scanning calorimetry of confectionery fats Part II.  Effects of blends and minor components, Journal of the American Oil Chemists’ Society, 1992, 69 (10), 992-998

Differential scanning calorimetry (DSC) measurements of the crystallization and melting phenomena of typical confectionery fats are presented. The results show the sensitivity and reproducibility with which DSC data can be used to classify the types of confectionery fat. Calculations of the reproducibility of crystallization and melting parameters obtained from DSC are presented. In addition, the effects are shown on the thermograms of progressive changes in formulation to a typical cocoa butter equivalent. Further, the effects brought on by the presence of minor components, such as trisaturated triglycerides and other polar materials, which are common in confectionery fats, are described and quantified.

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Cebula D.J., Smith K.W., Talbot G., DSC of confectionery fats, pure triglycerides. Effects of cooling and heating rate variation, The Manufacturing Confectioner, 1992, 72 (9), 135-139

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Cebula D.J., Smith K.W., Differential scanning calorimetry of confectionery fats pure triglycerides effects of cooling and heating rate variation, Journal of the American Oil Chemists’ Society, 1991, 68 (8), 591-595

Differential scanning calorimetry (DSC) measurements of the crystallization and melting phenomena of pure forms of the three principal triglycerides present in cocoa butter and related confectionery fats are presented. The results are used to exhibit the usefulness of the DSC technique for potential application in quality control of these types of material, but also as a warning of the difficulties in interpretation of data. The results also serve as a reference for future use in DSC studies of similar materials.

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Cebula D.J., Dilley K.M., Smith K.W., Continuous tempering studies on model confectionery systems, The Manufacturing Confectioner, 1991, 71 (5),
131-136

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