High-melting Milk Fat Fraction Research Articles

Engineering the nucleation of edible fats using a high behenic acid stabilizer

A stabilizer high in behenic acid (HBS) was used to control nucleation of edible fats. The addition of HBS led to an enhanced nucleation of anhydrous milk fat (AMF) and palm oil (PO) which had lower levels of high melting triacylglycerols (HMTs) (melting point >30°C, relative to the temperature used to crystallize samples) compared to other fats. With the addition of 1.5% HBS, there was an increase in crystallization onset temperatures and density of the microstructure in these two fats. Further studies were conducted to investigate the interactions between HBS and specific homogeneous triacylglycerols (TAGs) or a mixture of triacylglycerols. HBS displayed solid‐state incompatibility (eutectic behavior) with tripalmitin and tristearin, whereas it displayed compatibility (monotectic partial solid solution formation) behavior when mixed with the high‐melting milk fat fraction (HMF). This suggests two mechanisms for nucleation enhancement of HBS. One mechanism would involve surface nucleation on top of pre‐formed TAG surfaces, for tripalmitin and tristearin, while the other mechanism would involve additionally co‐crystallization with the nucleating agent, for the case of milkfat's HMF.Practical application: HBS may be used to accelerate the nucleation of PO, AMF, and HMF. A slow crystallization behavior of PO often leads to post‐hardening problems and a long α‐lifetime. Thus, HBS has a potential to solve these issues. Our results showed that HBS is more effective on fats with relatively low amounts of HMTs (20–50%). In addition, the nucleation enhancing mechanism of HBS was more effective in a mixture of TAGs, rather than in pure TAGs.High behenic acid stabilizers (HBS) are used to stabilize fat‐structured and oil‐rich food products. It is shown that HBS interacts with high‐melting triacylglycerols (HMTs) present in the fats and oils to be stabilized and reduces their free energy of nucleation, as shown in the graphical abstract. This leads to the formation of large numbers of smaller, stabilizing crystals in the system. Moreover, it also shown that HBS interacts differently with different HMTs. It displays incompatibility with tristearin and tripalmitin but displays compatibility with the high melting fraction of milkfat. A greater molecular compatibility is postulated to lead to greater stabilization.

Effects of Addition of a Palmitic Sucrose Ester on Low-Trans-Fat Blends Crystallization in Bulk and in Oil-in-Water Emulsions

The effect of addition of a highly hydrophobic emulsifier, the palmitic sucrose ester P-170, on isothermal crystallization behavior of a high-melting fraction of milk fat (HMF) and its mixtures with 20% or 40% sunflower oil (SFO), both in bulk and in emulsion systems, were studied by nuclear magnetic resonance (NMR) and by time-resolved in situ small-angle synchrotron X-ray scattering (SAXS). NMR studies showed that the effect of P-170 on the overall isothermal crystallization kinetics in bulk phase could be either acceleration or delay. The effect was strongly dependent on supercooling. For HMF, P-170 retarded crystallization at temperatures above 29.0 ± 0.2 °C, while below that temperature, it accelerated the process. For the blends of HMF with 20% or 40% SFO, the temperature at which the behavior changed was 27.0 ± 0.2 or 26.0 ± 0.2 °C, respectively. In emulsion systems, however, the effect was always acceleration for all temperatures selected. With the aid of SAXS, it was possible to study early stage of crystallization during real time and therefore to improve our understanding of the mechanism of P-170 action. The different effects caused by P-170, as described by SFC curves, were strongly related to the effects of P-170 on fat polymorphism, specially to the value of the time interval of coexistence of the α and β′ forms. These events took place at the very beginning of crystallization and thus could not be described by the traditional X-ray techniques used in previous studies of similar systems.

Factors Affecting Initial Retention of a Microencapsulated Sunflower Seed Oil/Milk Fat Fraction Blend

AbstractTo study the effect of emulsion stability, particle size, emulsifier, and crystalline fat in the oil phase on initial retention of a low‐trans fat encapsulated in a trehalose matrix, six emulsions were prepared. The six emulsions were formulated with 20 wt% trehalose solution as the aqueous phase, a lipid phase either with no crystalline fat, sunflower seed oil (SFO), or with a crystalline phase, a 40% SFO in high‐melting fraction of milk fat (HMF) blend, and sodium caseinate (NaCas), a 50 wt% blend of the palmitic sucrose esters (SE) P‐170 and P‐1670, or a 50 wt% blend of NaCas/SE as stabilizers. Particle size did not change or it changed only slightly during the freeze thaw or freeze drying process when the fat phase was SFO. However, when a crystalline phase was present, the volume‐weighted mean diameter (D4,3) increased dramatically for SE and NaCas/SE stabilizers. Encapsulation properties were determined by the counteracting effects of particle size and distribution, the presence of crystalline material in the droplets and interactions between interface components, fat phase and trehalose. In addition, retention was less related to emulsion stability. The emulsions selected for this study were stable for at least 30 h which was enough for obtaining a high degree of encapsulation.

Polymorphism and growth behavior of low‐trans fat blends formulated with and without emulsifiers

AbstractPolymorphism and growth behavior of blends of a high‐melting fraction of milk fat (HMF) and sunflower oil (SFO) formulated with and without the addition of sucrose esters (SE) P‐170, P‐1670, and S‐170 were studied by pulsed 1H NMR spectroscopy, X‐ray diffraction, and polarized light microscopy. The effect of SE on the solid content maximum (Smax) or crystallization rate was observed only at low supercooling (values of ΔT below 15°C). The Avrami kn decreased as n values increased, indicating that SE inhibited growth and impeded nucleation. Addition of SFO modified the polymorphic behavior of milk fat, most likely owing to the increase in the C54 fraction (mostly 18∶1 cis) in crystals composition. P‐170 and S‐170 modified the polymorphic behavior of HMF when it crystallized in the α‐form or in blends with up to 40% SFO at all crystallization temperatures (Tc) selected. Addition of P‐170 and S‐170 favored crystallization in the β′‐form, and the appearance of the β‐form was delayed. P‐1670 had no effect on polymorphism. When HMF and the blends were crystallized under dynamic conditions, addition of P‐170 and S‐170 markedly decreased crystal sizes. P‐1670, however, showed no effect on microstructure.

Influence of high-melting milk fat fraction on quality and fat bloom stability of chocolate

The aim of this paper was to define the optimal concentration of a high-melting milk fat fraction with a suitable precrystallization temperature time regime in order to obtain chocolate which would have satisfactory sensory characteristics and an increased fat bloom stability. The precrystallization was performed in a laboratory crystallizer, that is in a modified Brabender pharinograph, which measures the rheological characteristics of the precrystallized fluid chocolate mass with a milk fat fraction. The experiments were performed according to the factorial plan 32 (two factors on three levels). Hardness as well as solid fat content of chocolate was measured by instrumental methods. The optimal sensory quality of chocolate was achieved by adding 1–3% of the milk fat fraction and under the 25 °C precrystallization temperature. These samples of chocolate showed the highest fat bloom stability.

Effects of Glycerol and Tween 60 on the Crystallization Behavior, Mechanical Properties, and Microstructure of a Plastic Fat

The addition of 0.10% glycerol or Tween 60 increased the yield force of a 70:30 (w/w) mixture of triolein/HMF (high-melting fraction of milkfat) at 5 °C. Further increases in glycerol or Tween 60 caused a decrease in yield force. Solid fat content (SFC) versus time profiles at 30 °C (glycerol) and 28 °C (Tween 60) allowed for the determination of Avrami rate constants of crystallization (k) and Avrami exponents (n). Higher Avrami constants and lower Avrami indices (higher rate of crystal growth), smaller crystallites, and a shorter induction time of nucleation were observed in samples containing 0.10% Tween 60 relative to the control and 0.50% Tween 60. A 0.10% glycerol addition, on the other hand, yielded opposite results. The increase in hardness induced by small additions of Tween 60 could be attributed to decreases in crystallite size at constant SFC and fractal dimension. The increase in hardness induced by small additions of glycerol could only be attributed to increases in the crystal-melt interfacial tension, at constant SFC and fractal dimension, despite increases in crystallite size.

Effect of sucrose ester addition on nucleation and growth behavior of milk fat-sunflower oil blends.

The effects of addition of the sucrose esters (SE) P-1670, P-170, and S-170 to a high-melting fraction of milk fat (HMF) and its blends with sunflower oil (SFO) on nucleation and growth were studied by laser polarized light turbidimetry and polarized light microscopy (PLM). The three SE delayed nucleation of HMF at the temperatures selected. P-1670 did not modify average crystal size after 3 h at crystallization temperature (T(c)) or crystal size distribution and modified crystallization kinetics only slightly. P-170 and S-170, however, markedly diminished crystal size and narrowed crystal size distribution. Activation free energies of nucleation at equivalent supercooling, calculated using the Fisher-Turnbull equation, significantly increased with addition of SE. According to these results, among the mechanisms described in the literature for fats or emulsions, the cocrystallization hypothesis is the one that better described the effects of sucrose esters on crystallization behavior in these systems.

Effect of Sucrose Esters and Sunflower Oil Addition on Crystalline Microstructure of a High‐melting Milk Fat Fraction

ABSTRACT: The effects of sunflower oil (SFO) and the sucrose esters (SE) P‐1670, P‐170, and S‐170 on crystalline microstructure of a high‐melting milk fat fraction (HMF) was studied by polarized‐light microscopy (PLM) and confocal laser scanning microsopy (CLSM). The addition of SFO markedly diminished crystal size and delayed crystallization kinetics, as observed in PLM images. Addition of P‐1670 modified crystallization behavior only slightly. Addition of P‐170 and S‐170, however, markedly diminished crystal size and led to more transparent crystals, with lower amount of solids in each crystal. These results show that the microstructural properties of HMF were modifed by addition of SFO and by addition of SPE with low HLB.

Effects of Sucrose Esters on Isothermal Crystallization and Rheological Behavior of Blends of Milk‐fat Fraction Sunflower Oil

ABSTRACT: Crystallization kinetics and rhelogical behavior of blends of high‐melting milk‐fat fraction (HMF) and sunflower oil (SFO) with and without addition of the sucrose esters P‐170, S‐170, and P‐1670 were investigated. Addition of sucrose esters delayed crystallization, as was evidenced by the longer induction times of crystallization (t) and the lower maximum solid fat content (Smax). Values of penetration force and time corresponding to the 1st peak of curves force compared with time also diminished with addition of SFO. When sucrose esters were added, a solid fat content greater than 10% at the 1st crystallization temperature was necessary to give a stronger structure that could be noticed as higher yield point.

Effect of cooling rate on crystallization behavior of milk fat fraction/sunflower oil blends

AbstractThe effect of cooling rate (slow: 0.1°C/min; fast: 5.5°C/min) on the crystallization kinetics of blends of a highmelting milk fat fraction and sunflower oil (SFO) was investigated by pulsed NMR and DSC. For slow cooling rate, the majority of crystallization had already occurred by the time the set crystallization temperature had been reached. For fast cooling rate, crystallization started after the samples reached the selected crystallization temperature, and the solid fat content curves were hyperbolic. DSC scans showed that at slow cooling rates, molecular organization took place as the sample was being cooled to crystallization temperature and there was fractionation of solid solutions. For fast cooling rates, more compound crystal formation occurred and no fractionation was observed in many cases. The Avrami kinetic model was used to obtain the parameters kn and n for the samples that were rapidly cooled. The parameter kn decreased as supercooling decreased (higher crystallization temperature) and decreased with increasing SFO content. The Avrami exponent n was less than 1 for high supercoolings and close to 2 for low supercoolings, but was not affected by SFO content.

Identifying key structural indicators of mechanical strength in networks of fat crystals

The mechanical properties of edible fats can be influenced by a series of factors, including the amount of solids, the polymorphism of the solid-state, as well as the microstructure of networks of polycrystalline particles created upon crystallization. This work demonstrates that for binary mixtures of the high-melting fraction of milk fat (HMF) with cocoa butter as well as for mixtures of HMF with the middle-melting fraction of milk fat, changes in the storage shear modulus ( G′) are mostly controlled by the solid fat content (SFC), and the material’s microstructure. The SFC, in turn is a function of the phase behavior of the mixtures in the solid state. Experimental techniques used in the characterization of the different levels of structure are presented in this work. A model developed to explain mechanical properties of these materials taking into account all levels of structure is proposed. The polymorphism of the solid state did not seem to influence the mechanical properties of the fats, indicative of this material being structured as a network of weakly-attractive polycrystalline particles. Moreover, the mass fractal dimension of the network was closely related to the polymorphism of the solid state.

Effect of cooling rate on nucleation behavior of milk fat--sunflower oil blends.

The effect of cooling rate on the crystallization behavior of mixes of high-melting milk fat fraction (HMF) and sunflower oil (SFO) was studied by following nucleation with laser-polarized turbidimetry. The initial crystals were photographed, and their thermal and polymorphic behaviors, as well as chemical composition, were investigated by calorimetry, X-ray diffraction, and capillary gas chromatography. Activation energies of nucleation were calculated using the Fisher-Turnbull equation. Despite small differences in Mettler dropping points for different ratios of SFO to HMF, induction times were significantly different between samples and were shorter at a slow cooling rate for the same supercooling. Rapidly cooled samples required more time at crystallization temperature to crystallize than slowly cooled samples because molecular organization prior to nuclei formation took place under different conditions. Regardless of cooling rate or composition, all crystals were in the beta' polymorph. However, morphology, thermal behavior, and chemical composition showed differences with cooling rate. Activation free energies of nucleation were of the same order of magnitude as those published for hydrogenated SFO.

Physical Characteristics of Frozen Desserts Made with Cream, Anhydrous Milk Fat, or Milk Fat Fractions

Vanilla ice creams (10% fat) were prepared with or without emulsifier and by substituting anhydrous milk fat, a low melting milk fat fraction, and a very high melting milk fat fraction for cream. Viscosity of the ice cream mixes was affected by the source of milk fat and the addition of emulsifier. Ice cream mixes that were made with a very high melting milk fat fraction had the highest solidified fat, and mixes made with a low melting milk fat fraction had the lowest solidified fat. Rates of solidification were faster in the presence of emulsifier. The amount of adsorbed protein at the surface of fat globules in ice cream mixes in the presence of emulsifier was higher than when no emulsifier was used. The use of the very high melting milk fat fraction led to decreased adsorption of protein. More fat was agglomerated in ice cream made with emulsifier than in ice cream without emulsifier. Hardness of the ice creams made with different milk fat sources were not significantly different. Ice cream made with emulsifier was significantly harder than ice cream made without emulsifier. Meltdown of the samples made with the very high melting fraction was slower than meltdown of ice creams made with other milk fat sources. The results suggested that frozen dessert could be made using low melting and very high melting milk fat fractions in place of cream and that the ice cream made with the very high melting fraction was especially practical for use in warm climates.

Effect of Milk Fat Fractions on the Sensory Evaluation of Frozen Desserts

Consumer panels compared sensory attributes of vanilla ice cream (10% fat) made with cream anhydrous milk fat, a low melting milk fat fraction, and a very high melting milk fat fraction with and without an emulsifier. Samples were compared immediately after manufacture and after 3 mo of storage. Flavor, texture, and overall acceptability of the samples differed. Ice cream made with cream had the highest score for flavor acceptability, followed by ice cream made with the very high melting fraction. The ice cream made with the low melting fraction had the lowest score. These differences in flavor were attributed to the differences in peroxide values between anhydrous milk fat and its fractions. Texture scores between the samples made with cream and those made with very high melting fraction were not different. Also, texture scores between the sample made with anhydrous milk fat and that made with a low melting fraction were not different. The overall scores of the samples made with cream were higher than that of samples made with anhydrous milk fat and its fractions. No differences were observed in the flavor, texture, and overall acceptability of the samples made with or without an emulsifier. A very high melting milk fat fraction can be probably used as a substitute for cream in ice cream manufacture.

Viscoelastic properties of edible lipids

The viscoelastic natures of beeswax, candelilla wax, carnauba wax and a high-melting milkfat fraction were compared by estimating their relaxation parameters from stress relaxation data. A generalized Maxwell model consisting of one spring element and two Maxwell elements best described the stress relaxation of all lipids tested. The stress responses over both the compressive and relaxation portions of a stress relaxation test were considered. Cone penetration tests were used as a comparison to the stress relaxation tests. Candelilla wax and carnauba wax behaved similarly as hard and elastic materials which resisted deformation. Beeswax and the milkfat fraction, on the other hand, were significantly more viscous, less elastic, and more easily deformed.

Establishing the Presence of Distearyl Triglycerides in a High-Melting Fraction of Milk Fat Using Silicic Acid Chromatography1,2

Establishing the Presence of Distearyl Triglycerides in a High-Melting Fraction of Milk Fat Using Silicic Acid Chromatography1,2