Influence of chemical interesterification on thermal behavior,microstructure, polymorphism and crystallization properties of canola oil and fully hydrogenated cottonseed oil blends

This work evaluated chemical interesterification of canola oil (CaO) and fully hydrogenated cottonseed oil (FHCSO) blends, with 20%, 25%, 30%, 35% and 40% (w/w) FHCSO content. Interesterification produced reduction of trisaturated and increase in monounsaturated and diunsaturated triacylglycerols contents, which caused important changes in temperatures and enthalpies associated with the crystallization and melting thermograms. It was verified reduction in medium crystal diameter in all blends, in addition crystal morphology modification. Crystallization kinetics revealed that crystal formation induction period and maximum solid fat content were altered according to FHCSO content in original blends and as a result of random rearrangement. Changes in Avrami constant (k) and exponent (n) indicated, respectively, that interesterification decreased crystallization rates and altered crystalline morphology. However, X-ray diffraction analyses showed randomization did not change the original crystalline polymorphism. The original and interesterified blends had significant predominance of β′ polymorph, which is interesting for several food applications.     

Synchrotron study on crystallization kinetics of milk fat under shear flow

A detailed synchrotron X-ray diffraction study on the kinetics of crystallization of anhydrous milk fat (AMF) and milk fat triacylglycerols (MFT) was done in a Couette cell at 17 °C, 17.5 °C and 20 °C under shear rates between 0 and 2880 s^?1. We observed shear-induced acceleration of the transition from phase α to β′ and the presence of crystalline orientation, but no effect of shear on the onset time of phase α was observed. A two stage regime was observed for the growth of phase β′. The first stage follows a series–parallel system of differential equations describing the conversion between liquid and crystalline phases. The second stage follows a diffusion-controlled regime. These mechanisms are consistent with the crystalline orientation, the growth of the crystalline domains and the observed displacement of the diffraction peak positions. The absence of the polar lipids explains the faster kinetics of MFT.     

Enzymatic interesterification of tripalmitin with vegetable oil blends for formulation of caprine milk infant formula analogs

The structure of triacylglycerols in vegetable oil blends was enzymatically modified, and the blends were incorporated into skim caprine milk to produce goat milk-based infant formula analogs, homologous to human milk. A modified lipid containing palmitic, oleic, and linoleic acids, resembling the composition of human milk fat, was synthesized by enzymatic interesterification reactions between tripalmitin and a vegetable oil blend containing a 2.5:1.1:0.8 ratio of coconut, safflower, and soybean oils. A commercial sn-1,3-specific lipase obtained from Rhyzomucor miehei, Lipozyme RM IM, was used as the biocatalyst. The effects of substrate molar ratio and reaction time on the incorporation of palmitic, oleic, and linoleic acids at the sn-2 position of the triacylglycerols were investigated. The fatty acid composition and sn-2 position of the experimental formulas were analyzed using gas chromatography. Results showed that the highest incorporation of palmitic acid was obtained at 12 h of incubation at 55°C with a substrate molar ratio of 1:0.4 of tripalmitin to vegetable oil blend. However, the modified milk interesterified for 12 h at a 1:1 molar ratio had a greater resemblance to human milk compared with the other formulas. The level of oleic acid incorporation at the sn-2 position increased with the molar ratio of tripalmitin to vegetable oil blend. It was concluded that, unlike the original goat milk and other formulas, the formulated caprine milk with a molar ratio of 1:1 and a 12-h incubation was similar to the fatty acid composition of human milk.     

Interactions of milk fat and milk fat fractions with confectionery fats

The objectives of this study were to provide a better understanding of the effects of triacylglycerol (TAG) and non-TAG components (minor lipids) of milk fat on phase and crystallization behavior of binary mixtures of palm kernel oil (PKO) and the physical properties of corresponding compound coatings. Binary mixtures of a fractionated PKO with the different milk fats were examined for melting profiles, crystallization kinetics, and crystalline microstructures, and polymorphic changes during storage. Compound coatings were made with equivalent binary fat mixtures and measured for hardness and bloom formation. Milk fat and milk fat fractions affected crystallization rates of fractionated PKO, depending on the melting point of the fat. High-melting components resulted in more rapid crystallization, whereas the original milk fat and low-melting components inhibited crystallization. The crystal structure (e.g., number, size, shape) of the PKO crystals was influenced significantly by the addition of milk fat fractions and was influenced by the presence or absence of the minor lipids in milk fat. Milk fat and milk fat fractions had a softening effect on fractionated PKO, which was apparent in the binary mixtures as well as the compound coatings. In general, as the solid fat content (at 25 degrees C) of the binary mixtures increased, the hardness of the respective coatings increased. This also was related to an increased rate of bloom formation during storage.     

Physical properties of palm kernel olein-anhydrous milk fat mixtures transesterified using mycelium-bound lipase from Rhizomucor miehei

The transesterification activity of mycelium-bound lipase from Rhizomucor miehei on palm kernel olein:anhydrous milk fat (PKO:AMF) blends was investigated. Commercial immobilised R. miehei lipase preparation, Lipozyme IM60 (Novo Nordisk), was used as a comparison. Mixtures of PKO:AMF, at ratios of 100:0, 70:30, 60:40, 50:50 and 0:100, were transesterified using either enzyme in a solvent-free system. The triglyceride (TG) profile, slip melting point, solid fat content, melting thermogram and the polymorphic form of the unreacted and transesterified mixtures were evaluated. Results indicated that transesterification by either enzyme was able to produce an oil mixture with new TG profiles, generally lower slip melting points and solid fat contents. The melting thermograms from differential scanning calorimetry analysis indicated changes in the triglyceride's crystalline composition and an overall shift to lower melting TG. Although the catalytic activities were similar for both lipases, Lipozyme-catalysed mixtures produced higher degrees of transesterification (43–51%) than mycelium-bound lipase-catalysed (22–34%) mixtures. This study also demonstrated that the transesterified PKO:AMF mixture at 70:30 ratio completely melted at 25C, and this meets the melting criteria for fat used in ice cream formulation.     

Oxidation kinetics of soybean oil/anhydrous milk fat blends: A differential scanning calorimetry study

The oxidation kinetics of soybean oil (SBO)/anhydrous milk fat (AMF) blends was studied by differential scanning calorimetry (DSC). Lipid blends containing 0–100% of SBO in AMF at 10% intervals were analyzed. Samples were heated in the DSC at different heating rates (2.5, 5.0, 7.5, 10.0 and 12.5 °C/min) and oxidation kinetics parameters from the Arrhenius equation (activation energy, pre-exponential factor and oxidation rate constant) were calculated using the Ozawa–Flynn–Wall method. Results show a significant increase in the oxidation rate (k) with temperatures for 60–90% SBO blends. The increase in k with SBO addition was only significant for 240 and 250 °C. A significant correlation between the rate constant and the chemical composition of the samples was not observed. This behavior suggests possible interactions among fatty acids present in the blends.     

<Emphasis Type="Italic">Trans</Emphasis>-free margarine fat produced using enzymatic interesterification of rice bran oil and hard palm stearin

Trans-free interesterified fats were prepared from blends of hard palm stearin (hPS) and rice bran oil (RBO) at 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, and 80:20 weight % using immobilized Mucor miehei lipase at 60°C for 6 h with a mixing speed of 300 rpm. Physical properties and crystallization and melting behaviors of interesterified blends were investigated and compared with commercial margarine fats. Lipase-catalyzed interesterification modified triacylglycerol compositions and physical and thermal properties of hPS:RBO blends. Slip melting point and solid fat contents (SFC) of all blends decreased after interesterification. Small, mostly β′ form, needle-shaped crystals, desirable for margarines were observed in interesterified fats. Interesterified blend 40:60 exhibited an SFC profile and crystallization and melting characteristics most similar to commercial margarine fats and also had small needle-like β′ crystals. Interesterified blend 40:60 was suitable for use as a transfree margarine fat.     

Rheological and crystalline properties of trans-free model fat blends as affected by the length of fatty acid chains

Three structured fats were prepared by the total catalytic hydrogenation and random chemical transesterification using medium (coconut oil) and long (palmstearine, low and high erucic rapeseed oil) chain saturated fatty acids triglycerides. All three structured fats crystallized in β′ modification and had the same solid fat content profile. Hardness was dependent on the type of long chain fatty acid (palmitic, stearic and behenic) in structured fat. Molar ratio of medium:long chain fatty acids was 2:1. Model fat blends prepared on the base of these structured fats had the same solid fat content profile (at constant content of structured fat). Yield stress of the fat blends was dependent on the content and mainly on the composition of structured fat. None of the model fat blends crystallized in β modification. The substitution of the stearic–palmitic by stearic or by stearic–behenic acids in the structured fats appears possible.     

Use of enzymatic transesterified palm stearin-sunflower oil blends in the preparation of table margarine formulation

Palm stearin–sunflower oil (PS:SO) blends, formulated by mixing 40 to 80% palm stearin in increments of 10% (w/w), were subjected to transesterification catalysed by lipases from Pseudomonas sp. and Rhizomucor miehei (Lipozyme 1M 60). The physical properties of the transesterified products were evaluated by slip melting point (SMP), differential scanning calorimetry (DSC), solid fat content (SFC) and X-ray difflaction (XRD) analyses. SMP results indicate that Pseudomonas lipase caused a bigger drop in SMP (33%) in the PS–SO (40:60) blend than the R. miehei-lipase-catalysed reaction blend (13%). The Pseudomonas-catalyzed blends of PS-SO, at 40:60 and 50:50 ratios, showed complete melting at 37 and 40°C, respectively, while the R. miehei-catalyzed PS–SO blend at 40:60 ratio had a residual SFC of 3.9% at 40°C. Pseudomonas lipase also successfully changed the polymorphic form(s) in the unreacted PS–SO mixture from a predominantly β form to a predominantly β′ form in the transesterified blends. However, no changes in polymorphic forms were observed after transesterification with R. miehei lipase (as against to the unreacted PS–SO blends). These results suggest that the Pseudomonas lipase caused a greater randomization and diversification of fatty acids, particularly palmitic acids, in palm stearin with the unsaturated fatty acids from sunflower oil than did R. miehei lipase. Based on the physical characteristics, the Pseudomonas-catalyzed 40:60 and 50:50 PS:SO blends would be the two most suitable blends to be used as table margarine formulations.     

The cooling rate effect on the microstructure and rheological properties of blends of cocoa butter with vegetable oils

The elasticity (G′) and yield stress (σ¹) of blends of cocoa butter (CB) in vegetable oils (i.e., 30% CB/canola and 30% CB/soybean oil) crystallized at temperatures (T_Cr) between 9.5 °C and 13.5 °C and two cooling rates (1 °C/min and 5 °C/min) were determined, evaluating their relationship with parameters associated with the formation and structural organization of the crystal network [i.e., solid fat content (SFC), Avrami index, crystallization rate, fractal dimension (D)]. The results showed that T_Cr and cooling rate had a different effect for each blend on the three-dimensional organization of the crystal network, and on the proportion and size of β′ and β crystals. Thus, under low supercooling conditions at both cooling rates, the crystallized CB/canola oil blend was formed by a mixture of small β′ and large β crystals that provided high G′ and σ¹ at low SFC (i.e., 20.5–20.9%) and D (i.e., 1.66–1.72) values. The CB/soybean oil blend achieved similar G′ and σ¹ independent of cooling rate only at high supercooling. In this case, the crystal network was formed mainly by small β′ crystals with SFC (i.e., 25.4–26.3%) and D (i.e., 2.86–2.79) values higher (P < 0.05) than in the CB/canola oil blend at low supercooling.     

MELTING CHARACTERISTIC AND SOLID FAT CONTENT OF MILK FAT AND PALM STEARIN BLENDS BEFORE AND AFTER ENZYMATIC INTERESTERIFICATION

Melting characteristics and solid fat content of anhydrous milk fat (AMF), soft palm oil stearin (SPOs), hard palm oil stearin (HPOs) and their blends were studied by differential scanning calorimetry (DSC) and nuclear magnetic resonance (NMR) spectroscopy, respectively. Solid fat contents (SFC) determined by NMR were used to construct isosolid diagrams; these indicated the presence of an eutectic effect along the binary blends of AMF:SPOs which only could be observed at 5 and 10C. The effect was reduced after interesterification by sn-1,3-specific lipase. The modification also reduced the number of the distinct DSC melting peaks, demonstrating a better miscibility among the blended fats. A substantial decrease in DSC melting enthalpy of interesterified blends was found to be parallel to a decrease in SFC that was observed at 25–40C. Fatty acid composition showed that improved functionality of AMF may be due to an enrichment in long-chain saturated fatty acids contributed both by SPOs and HPOs.     

Crystallization,Physicochemical Properties,and Oxidative Stability of the Interesterified Hard Fat from Rice Bran Oil,Fully Hydrogenated Soybean Oil,and Coconut Oil through Lipase-Catalyzed Reaction

Interesterified hard fat (IEHF) was produced from fully hydrogenated soybean oil (FHSBO) and rice bran oil (RBO) with different molar ratio (RBO/FHSBO = 1:1, 1:2, and 1:3). For interesterification, Lipozyme TL IM (10% of total substrates) was used as a biocatalyst. Further, coconut oil (CO; 40 wt.% on total weight of RBO and FHSBO) was also added in all reactants for providing medium chain fatty acid. After interesterification, the obtained IEHF and physical blend (before interesterification) with same molar ratio were carried out for comparing the physical properties, (i.e., solid fat content, melting and crystallization behavior, and polymorphic forms). From DSC results at 25 °C, solid fat content of the IEHF with different molar ratio (RBO/FHSBO = 1:1, 1:2, and 1:3) were 33.9%, 58.8%, and 72.1%, respectively, whereas physical blends at same molar ratio showed 66.2%, 71.6%, and 74.8%. Besides, short spacing β crystal polymorphic form was observed in the physical blend while only β′ crystal form was observed in IEHF, in which β′ polymorphic form is a desirable for the production of shortenings and margarines. In Rancimat test for oxidative stability, IEHF showed significantly lower induction time than the physical blend. When the catechin (200, 400, and 800 ppm) was added to the IEHF, induction time was significantly increased to 21.4, 34.1, and 44.3 h, respectively. In this study, IEHF from this study may have a potential functionality for the shortenings and margarines.     

Crystallization behavior of milk fat obtained from linseed-fed cows

Milk with an increased content of unsaturated fatty acids was obtained by incorporating 60% of extruded linseed into the concentrate of cows. Two groups of Holstein cows (3 animals/group) were fed a concentrate (control or linseed enriched) together with the same roughage diet (ad libitum). After an adaptation period of 3 wk, evening and morning milk samples were collected every 7 d for 3 wk. Milk was decreamed and anhydrous milk fat (AMF) was isolated from the fat fraction by using the Bureau of Dairy Industries method. The objective of this study was to investigate if the crystallization mechanism of milk fat changed when the content of unsaturated fatty acids was increased. Therefore, the crystallization behavior of a milk fat enriched with unsaturated fatty acids was compared with that of a control milk fat. Nonisothermal crystallization was investigated with differential scanning calorimetry, and 1-step and 2-step isothermal crystallization behaviors were investigated using pulsed nuclear magnetic resonance, differential scanning calorimetry, and x-ray diffraction. A higher content of unsaturated fatty acids in AMF resulted in an increased proportion of low melting triglycerides. These triglycerides lowered the solid fat content profile, particularly at refrigerator temperatures. Furthermore, they induced some changes in the crystallization and melting behaviors of milk fat compared with a control AMF, although no fundamental changes in the crystallization mechanism could be revealed. Even though a lower melting point could be observed for milk fat with a higher content of unsaturated fatty acids, a similar degree of supercooling was needed to initiate crystallization, resulting in a shift in onset temperature of crystallization toward lower temperatures. In addition, slower crystallization kinetics were measured, such as a lower nucleation rate and longer induction times, although crystallization occurred in a similar polymorphic crystal lattice. During melting, a shift in offset temperature toward lower temperatures could be observed for the 3 melting fractions of AMF in addition to a higher proportion of low melting triglycerides. These results demonstrate that a higher content of unsaturated fatty acids has some effect on the crystallization behavior of milk fat. This knowledge could be used to produce dairy products of similar or superior quality compared with conventional products by intervening in the production process of dairy products.     

Insights into the mechanism of the formation of the most stable crystal polymorph of milk fat in model protein matrices

The effect of incorporation and presence of various ingredients in a model sodium caseinate-based imitation cheese matrix on the polymorphism of milk fat was comprehensively described using powder x-ray diffraction, differential scanning calorimetry, and microscopy. With anhydrous milk fat (AMF) in bulk used as control, the embedding of AMF as droplets in a protein matrix was found to result in a greater extent of formation of the β polymorph than AMF alone and AMF homogenized with water and salts solution. The use of other protein matrices such as soy and whey protein isolate gels revealed that the nature of the protein and other factors associated with it (i.e., hydrophobicity and molecular structure) do not seem to play a role in the formation of the β polymorph. These results indicated that the most important factor in the formation of the β polymorph is the physical constraints imposed by a solid protein matrix, which forces the triacylglycerols in milk fat to arrange themselves in the most stable crystal polymorph. Characterization of the crystal structure of milk fat or fats in general within a food matrix could provide insights into the complex thermal and rheological behavior of foods with added fats.     

Distribution of cholesterol in milk fat fractions

Milk fat was fractionated into liquid (m.p. congruent to 12 degrees C), intermediate (m.p. congruent to 21 degrees C) and solid (m.p. congruent to 39 degrees C) fractions by three different processes--melt crystallization, short-path distillation and supercritical CO2 extraction--and the cholesterol content of these fractions determined. Cholesterol was enriched in the liquid fractions from all three processes, in particular about 80% of the cholesterol being found in the liquid fraction obtained by short-path distillation. The basis of migration of cholesterol into various milk fat fractions was explained by its affinity to various triglycerides (melt crystallization) and by vapour pressure and molecular weight (short-path distillation). It was more complex in the supercritical CO2 extraction process; the interplay of cholesterol affinity toward CO2 and its molar volume, and its vapour pressure enhancement under applied pressure play a role.     

Microstructure and texture of white fresh cheese made with canola oil and whey protein concentrate in partial or total replacement of milk fat

A control white fresh cheese was prepared from milk containing 24 g milk fat (MF) L⁻¹, and nine white fresh cheese-like products were made by partial or complete substitution of milk fat by whey protein concentrate (WPC) and/or canola oil (CO) emulsified with an emulsifiers blend (EB) made of polyoxyethylene sorbitan monostearate (P), sorbitan monostearate (S) and glycerol monostearate (G) in 0.5:0.2:0.3 ratio. The textural characteristics and microstructure of the cheeses were assessed by Instrumental Texture Profile Analysis and Scanning Electron Microscopy. Polynomial models were obtained that estimated the composition and texture characteristics of the cheeses as function of the MF, EB (indirectly CO) and WPC concentrations in the cheese milk. CO incorporation promoted an open microstructure in the cheese, while WPC favoured a close and compact network made of short linking strands of milk proteins.MF, EB and WPC contributed positively to all the textural characteristics of the cheeses.     

Effect of plant oils and camelina expeller on milk fatty acid composition in lactating cows fed diets based on red clover silage

Five multiparous Finnish Ayrshire cows fed red clover silage-based diets were used in a 5 × 5 Latin square with 21-d experimental periods to evaluate the effects of various plant oils or camelina expeller on animal performance and milk fatty acid composition. Treatments consisted of 5 concentrate supplements containing no additional lipid (control), or 29 g/kg of lipid from rapeseed oil (RO), sunflower-seed oil (SFO), camelina-seed oil (CO), or camelina expeller (CE). Cows were offered red clover silage ad libitum and 12 kg/d of experimental concentrates. Treatments had no effect on silage or total dry matter intake, whole-tract digestibility coefficients, milk yield, or milk composition. Plant oils in the diet decreased short- and medium-chain saturated fatty acid (6:0-16:0) concentrations, including odd- and branched-chain fatty acids and enhanced milk fat 18:0 and 18-carbon unsaturated fatty acid content. Increases in the relative proportions of cis 18:1, trans 18:1, nonconjugated 18:2, conjugated linoleic acid (CLA), and polyunsaturated fatty acids in milk fat were dependent on the fatty acid composition of oils in the diet. Rapeseed oil in the diet was associated with the enrichment of trans 18:1 (Δ4, 6, 7, 8, and 9), cis-9 18:1, and trans-7,cis-9 CLA, SFO resulted in the highest concentrations of trans-5, trans-10, and trans-11 18:1, Δ9,11 CLA, Δ10,12 CLA, and 18:2n-6, whereas CO enhanced trans-13-16 18:1, Δ11,15 18:2, Δ12,15 18:2, cis-9,trans-13 18:2, Δ11,13 CLA, Δ12,14 CLA, Δ13,15 CLA, Δ9,11,15 18:3, and 18:3n-3. Relative to CO, CE resulted in lower 18:0 and cis-9 18:1 concentrations and higher proportions of trans-10 18:1, trans-11 18:1, cis-9,trans-11 CLA, cis-9,trans-13 18:2, and trans-11,cis-15 18:2. Comparison of milk fat composition responses to CO and CE suggest that the biohydrogenation of unsaturated 18-carbon fatty acids to 18:0 in the rumen was less complete for camelina lipid supplied as an expeller than as free oil. In conclusion, moderate amounts of plant oils in diets based on red clover silage had no adverse effects on silage dry matter intake, nutrient digestion, or milk production, but altered milk fat composition, with changes characterized as a decrease in saturated fatty acids, an increase in trans fatty acids, and enrichment of specific unsaturated fatty acids depending on the fatty acid composition of lipid supplements.     

Addition of olein from milk fat positively affects the firmness of butter

Butter is highly valued for its characteristic flavor and aroma; however, it has the disadvantage of unsatisfactory spreadability at low temperatures. The functional characteristics of butter can be modified by changing its composition or physical structure. The objective of this study was to evaluate the effect of olein on structure and composition of butter. Olein was obtained by two stage dry fractionation process of the anhydrous milk fat (AMF) and added to commercial cream prior to butter manufacture. The fractions were characterized for triacylglycerols composition, solid fat content, crystallization isotherm, and thermal behavior. Butter was manufactured using commercial cream or cream containing 50% olein. Butter samples were characterized for physicochemical composition, instrumental color, crystallization parameters, and firmness after 1 and 7 days of storage at 10 °C. The firmness of butter subjected to room temperature was also evaluated. Butter containing olein differed significantly from the control and had darker yellow color, higher crystallization time, and lower solid fat content after 120 min at 15 °C, and hence lower firmness after 1 and 7 days of refrigerated storage. Although lower firmness was observed over time for all samples at room temperature, butter containing olein exhibited lower firmness after both 1 and 7 days, thus suggesting changes in organization of solid fat crystal network in the liquid fat. The addition of olein to butter allowed obtaining a softer product, with more intense color and possible nutritional benefits due to the medium chain triglycerides and higher carotene levels.     

Aeration of low fat dairy emulsions: Effects of saturated–unsaturated triglycerides

Three dairy emulsions containing 10 wt% anhydrous milk fat (AMF), alone or in mixture with its low or high melting temperature fraction (olein- or stearin-rich fraction, respectively), were aged at 4 °C for 24 h and then submitted to a whipping test at this temperature. We observed that the AMF/olein emulsion presented less crystalline fat content, and a higher ability for air incorporation than the other two emulsions. In addition, air bubbles formed in the AMF/olein-rich emulsion presented a more uniform size distribution, a smaller proportion of bubbles higher than 50 μm, and they appeared to be coated with a thicker layer of fat droplets. These results indicated that foam-structure forming properties in reduced milk fat emulsions can be enhanced by lowering the proportion of saturated triglycerides.     

The effect of butter grains on physical properties of butter-like emulsions

Milk fat exists as globules in its natural state in milk. The potential of using globular fat to modulate the rheological properties and crystallization behavior in butter-like emulsions was studied in the present work. We conducted a comparative study of butter-like emulsions, with a fat phase consisting of 0, 10, 25, 50, or 100% anhydrous milk fat (AMF), the remaining fat being butter grains, and all samples containing 20% water, to obtain systematic variation in the ratio of globular fat. All emulsions were studied over 4 wk of storage at 5°C. By combining small and large deformation rheology, we conducted a detailed characterization of the rheological behavior of butter-like emulsions. We applied differential scanning calorimetry to monitor thermal behavior, confocal laser scanning microscopy for microstructural analysis, and low-field pulsed nuclear magnetic resonance spectrometry to measure solid fat content. By combining these techniques, we determined that increasing the fraction of globular fat (by mixing with butter grains) decreases the hardness of butter-like emulsions up to an order of magnitude at d 1. However, no difference was observed in thermal behavior as a function of butter grain content, as all emulsions containing butter grains revealed 2 endothermal peaks corresponding to the high (32.7°C ± 0.6) and medium (14.6°C ± 0.1) melting fractions of fatty acids. In terms of microstructure, decreasing the amount of butter grains in the emulsions resulted in formation of a denser fat crystal network, corresponding to increased hardness. Moreover, microstructural analysis revealed that the presence of butter grains resulted in faster formation of a continuous fat crystal network compared with the 100% AMF sample, which was dominated by crystal clusters surrounded by liquid oil. During storage, hardness remained stable and no changes in thermal behavior were observed, despite an increase in solid fat content of up to 5%. After 28 d of storage, we observed no difference in either microstructural or rheological properties, indicating that formation of primary bonds occurs primarily within the first day of storage. The rheological behavior of butter-like emulsions is not determined solely by hardness, but also by stiffness related to secondary bonds within the fat crystal network. The complex rheological behavior of milk fat-based emulsions is better characterized using multiple parameters.