Improving the crystallization and melting characteristics of cocoa butter substitute by blending with krabok seed fat.

This work investigated the crystallization and melting behavior of a commercial cocoa butter substitute (CBS) blended with 10-80% (by weight) of a hard lauric fat called krabok seed fat (KSF). The aim was to find CBS-KSF blends with improved crystallization and melting characteristics from that of the CBS. It was found that the addition of 10-80% KSF to CBS improved the melting properties of the CBS. However, 10-20% KSF resulted in too high solid fat content (SFC) values at the body temperature (37 °C) which would lead to waxy mouth feel. Adding 30-40% KSF resulted in better melting profiles than 10-20% KSF with SFC values < 3% at 37 °C and SFC curves most similar to cocoa butter. However, 40% KSF led to a significant decrease in the crystallization rate from that of CBS and a significant increase in the average crystal size. With 60-80% KSF, although the blends melted completely at the body temperature, their crystallization rates were significantly reduced. All CBS-KSF blends crystallized into ß' structure. Therefore, the addition of 30% KSF to the CBS is recommended for industrial use to obtain compound chocolate with improved quality. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-022-05513-1.

Rice bran wax effects on cocoa butter crystallisation and tempering.

The effects of up to 5 wt% rice bran wax (RBX) on the crystallisation, tempering and storage stability of cocoa butter (CB) and a model dark chocolate were assessed. Presence of RBX significantly accelerated tempering and the formation of the desirable form V polymorph in CB. The form V to VI transition in both CB and chocolate was slowed in the presence of RBX during temperature-cycling, with addition of 1 wt% wax effectively reducing the extent of bloom formation in model chocolate following two weeks of temperature-cycling from 25 to 29 °C. Overall, this study has shown that RBX may be considered a viable seed material to accelerate tempering of CB and retard fat bloom in chocolate.

Temperature-dependent properties of fat in adipose tissue from pork, beef and lamb. Part 1: microstructural, thermal, and spectroscopic characterisation.

We investigated the temperature-dependent microstructure and thermal properties of back fat adipose tissue from pork, beef and lamb. Microstructural characterisation via electron, confocal and light microscopy showed that the back fats were structurally similar and consisted of fat dispersed as discrete units within a protein matrix akin to a closed cell foam. Differential scanning calorimetry showed distinct fat melting profiles for each of the tissues, which were ascribed to differences in fatty acid profile. Fat crystal organisation, melting and re-solidification signatures unique to each adipose tissue were found via X-ray diffraction and Raman spectroscopy. Overall, we found that the temperature-dependent microstructure of adipose fat was intricately linked to the fat phase melting behaviour, and importantly, to its protein matrix at elevated temperatures. Such understanding is necessary to provide the required insights to effectively replicate the functionality of adipose tissue using plant-based materials.

Temperature-dependent properties of fat in adipose tissue from pork, beef and lamb. Part 2: rheology and texture.

Matching the texture of fat in plant-based meat alternatives requires an in-depth understanding of the rheology of animal adipose tissue which, to-date, remains under-studied. Here, we characterised the small and large deformation behaviour of back fat from pork, beef, and lamb, with the underlying goal being the establishment of the temperature-dependent structure-function relationship governing the texture and rheology of adipose tissue. The dynamic rheological behaviour of the back fats was characterised via frequency and amplitude sweeps and large amplitude oscillatory strain (LAOS), as well as texture analysis via puncture tests. At 20 °C, prior to heating, the small and large deformation properties of adipose tissue were dominated by the solid fat phase within the adipose cells. Upon heating to 80 °C, with the fat phase molten, the protein network underpinning the structure of the back fats conferred elastic behaviour to the tissues, and the now-molten oil partly leaked from the adipocytes into the surrounding interstitial space. Upon re-cooling, a bicontinuous network of fat crystals and protein contributed to back fat rheology. Large deformation rheology revealed animal species-specific differences. Prior to heating, pork back fat was characterised by soft yielding behaviour while beef and lamb back fat showed abrupt yielding and intra-cycle strain stiffening. Post-heating, lamb showed the highest stiffness, compared to pork and beef, as well as non-linearities in its stress-strain relationship obtained via LAOS. Such fundamental understanding is essential to provide the required insights to replicate the functionality of adipose tissue using plant-based materials.

Production of Cocoa Butter Substitute via Enzymatic Interesterification of Fully Hydrogenated Palm Kernel Oil, Coconut Oil and Fully Hydrogenated Palm Stearin Blends.

This research synthesized structure lipids (SL) from blends of fully hydrogenated palm kernel oil (FHPKO), coconut oil (CNO) and fully hydrogenated palm stearin (FHPS) by enzymatic interesterification (EIE)using rProROL, an sn-1,3-specific lipase from Rhizopus oryzae, as a catalyst. Five physical blends of FHPKO:CNO:FHPS were prepared with the following wt. ratios: 40:10:50, 50:10:40, 60:10:30, 70:10:20 and 80:10:10. The EIE reactions were carried out at 60℃ for 6 h in a batch-type reactor using rProROL 10% wt. of the substrate. It was found that EIE significantly modified the triacylglycerol compositions of the fat blends resulting in changes in the crystallization and melting behavior. In particular, SL obtained from EIE of blend 70:10:20 exhibited high potential to be used as a cocoa butter substitute (CBS) because it showed similar solid fat content curve to the commercial CBS and crystallized into fine spherulites and desirable ß' polymorph.

Production of cocoa butter equivalent from blending of illipé butter and palm mid-fraction.

Cocoa butter equivalent (CBE) was prepared from illipé butter (IB) and palm mid-fraction (PMF) blends in different wt ratios. The solid fat content (SFC), compatibility, crystallization/melting thermograms and crystal microstructure of the blends were studied. Softening occurred with IB/PMF blends due to eutectic formation and resulted in blend 75/25 (IB/PMF) exhibiting SFC profile and crystallization/melting behavior comparable to CB and hence it was selected to be used as a CBE. The CBE was fully compatible with CB and displayed similar polymorphic structure (ß2) and isothermal crystallization curve to CB. When it was used to partially replace CB in chocolate (5 %wt of the finished product), the hardness, SFC and the bloom formation behavior of the chocolate were not significantly different from the chocolate made with CB. Overall, the 75/25 blend met all criteria to be considered as CBE, hence, it can be used as an alternative to commercially available CBE.

Synthesis of cocoa butter alternatives from palm kernel stearin, coconut oil and fully hydrogenated palm stearin blends by chemical interesterification.

BACKGROUND: Chemical interesterification (CIE) is one of the important technological processes for the production of zero-trans fats. The aim of this study was to produce trans-free cocoa butter alternatives (CBAs) from palm kernel stearin (PKS), coconut oil (CNO) and fully-hydrogenated palm stearin (FHPS) blends via CIE using sodium methoxide as a catalyst. The physicochemical properties, crystallization and melting behavior, solid fat content (SFC), crystal morphology and polymorphism of the structured lipids (SLs) obtained and the corresponding physical blends (PBs) were characterized and compared with commercial CBAs. RESULTS: After CIE, randomization of fatty acid distribution within and among triacylglycerol (TAG) molecules of PKS, CNO and FHPS resulted in a modification in TAG compositions of the PKS/CNO/FHPS blends and improved the properties and crystallization behavior of the blends. SFC and slip melting points of all SLs decreased from those of their respective PBs. In particular, SLs obtained from CIE of blends with 60-70% wt. PKS (blend ratios 60:10:30 and 70:10:20) exhibited the melting characteristic, SFC curves, crystal morphology and polymorphic form most similar to the commercial CBAs. In addition, these blends melted almost completely at body temperature, an improvement from that of the commercial CBAs. CONCLUSION: SLs obtained from CIE of blends with 60-70% wt. PKS has high potential to be used commercially as trans-free CBAs for the confectionery industry. © 2021 Society of Chemical Industry.

The Effect of Polyglycerol Esters of Fatty Acids on the Crystallization of Palm Olein.

This research investigated the effect of polyglycerol ester of fatty acids (PGE) on the crystallization of palm olein (POL). Three PGEs were studied: two solid-state PGEs (PGE1105 and PGE1117) and one liquid-state PGE (PGE1155). The addition of 0.5-5% wt. PGEs influenced the crystallization kinetics of POL and this depended on the type and concentration of the emulsifiers. During cooling down with a cooling rate of 5℃/min, the samples containing PGE1105 and PGE1117 started to crystallize at higher temperatures when compared with POL but the crystallization began at lower temperatures for the samples containing PGE1155. All samples with added PGEs exhibited lower solid fat content than that of POL after 12 h of crystallization time. The number of crystals decreased with an increase in the crystal size with PGE addition but there was no effect on polymorphism. Overall, the results suggested that PGE1105 and PGE1117 enhanced the early stages of POL crystallization possibly via the template effects but suppressed the later stages, whereas PGE1155 delayed the whole process of POL crystallization. The application of POL is often limited by its tendency to get cloudy at low temperatures during long-term storage. Based on the results, 1-5% wt. PGE1155 could be used to delay or prevent the crystallization of POL at low temperatures.

Assessment of rheological methods to study crystallization of palm oil fractions.

This study provides an evaluation of the use of rheology to characterize soft, semi-hard, and hard fats in relation to determine the crystallization onset, crystallization behavior, as well as microstructure development using either a plate-plate or a starch pasting cell (SPC). The results from this study demonstrate that when applying rheology to study fat crystallization, the results must be interpreted with care. The application of a plate-plate geometry allowed for sensitive evaluation of the initial nucleation phase, which was not possible with an SPC. Both geometries could provide information on crystallization behavior in terms of one-step or two-step crystallization. However, in the late stage of the crystallization process, when the fat crystals form a strong network, the SPC could not describe differences in the rheology of the fat-crystal network, which was a possibility by the use of a plate-plate geometry. Thus, oscillatory rheology with a suitable geometry can be used to evaluate the entire crystallization process.

The Effect of Hard Lauric Fats on the Crystallization Behavior of Cocoa Butter Substitute.

This work investigated the crystallization and melting behavior of cocoa butter substitute (CBS) blended with two hard lauric fats: fully hydrogenated palm kernel oil (FHPKO) and krabok seed fat (KSF). The aim was to find a way to increase the heat resistance of CBS for the production of heat-resistant compound chocolate (HRCC). Adding FHPKO to CBS increased the crystallization rate with a decrease in crystallization induction time but did not increase the heat resistance. In contrast, all KSF-CBS blends exhibited higher heat resistance than CBS and crystallized into ß' form, a preferred polymorph for fats used in compound chocolate. Only the blends with 10-60% KSF melted completely at the body temperature, indicating that they would leave no waxy mouthfeel, but the blends with 30 and 40% KSF exhibited a significant decrease in the crystallization rate compared to the original CBS. Therefore, the KSF-CBS blends with 10, 20 and 60% KSF are recommended for future use as fats for HRCC production.

Oleogelation of emulsified oil delays in vitro intestinal lipid digestion.

Oleogelation is shown to delay the in vitro digestion of soybean oil (SBO) dispersed within an oil-in-water (O/W) emulsion. Rice bran wax (RBX) was used as an oleogelator at concentrations of 0, 0.25, 0.5, 1 and 4 wt% of the emulsions. All emulsions, which contained 1 wt% whey protein and 20 wt% oil and were prepared via hot homogenization, were kinetically stable against phase separation during the experimental timeframe (4 weeks), except at 4 wt% RBX where wax crystals 3-5 µm in length appeared within the dispersed oil phase, and which resulted in some emulsion instability. Rheological and thermal analysis of the emulsions and their corresponding SBO-RBX blends showed that the RBX led to formation of rigid oil droplets. Both in vitro gastric and intestinal digestion resulted in extensive oil droplet coalescence in all emulsions. Free fatty acid (FFA) release profiles showed that dispersed phase oleogelation delayed intestinal lipid digestion, with this effect enhanced up to 1 wt% RBX. A further increase to 4 wt% increased the rate of lipid digestion, which was ascribed to emulsion instability resulting from growth of intra-droplet RBX crystals.

Structure and rheology of oleogels made from rice bran wax and rice bran oil.

Structural and rheological properties of oleogels consisting of 0.5-25 wt% rice bran wax (RBX) in rice bran oil (RBO) were explored. RBX was an efficient, thermoreversible oleogelator capable of structuring RBO at concentrations as low as 0.5 wt% RBX. A qualitative temperature-composition phase diagram showed that oleogels containing higher concentrations of RBX were expectedly the most resistant to melting. In oleogels at higher RBX concentrations, polarized light microscopy revealed the presence of a network of interlinked, long aspect ratio wax crystal needles up to 50 µm long. Upon heating, RBX crystals did not undergo any structural transition, based on the constant short spacings at ~ 4.16 and ~ 3.73 Å, indicative of an orthorhombic subcell, and d001 long spacing at 74-76 Šthat persisted until RBX fusion. This long spacing was ascribed to the presence of wax esters consisting of long-chain saturated fatty acids (C24 and C22) esterified to C28 - C34 saturated fatty alcohols. During cooling from 90 to 20 °C, the increase in oleogel viscosity resulting from the RBX liquid-solid phase transition was corroborated by DSC-based crystallization onset and enthalpy data. Similarly, elastic moduli and hardness both rose with increasing RBX concentration. This study, which demonstrated that RBX can structure RBO with distinct concentration-dependent properties, serves as the foundation for the development of oleogel-based approaches to saturated and trans fats replacement in processed foods.

Characterization of Coconut Oil Fractions Obtained from Solvent Fractionation Using Acetone.

This work was aimed to study the solvent fraction of coconut oil (CNO). The fatty acid and triacylglycerol compositions, solid fat content (SFC) and the crystallization properties of CNO and its solid and liquid fractions obtained from fractionation at different conditions were investigated using various techniques. CNO was dissolved in acetone (1:1 w/v) and left to crystallize isothermally at 10°C for 0.5, 1 and 2 h and at 12°C for 2, 3 and 6 h. The solid fractions contained significantly lower contents of saturated fatty acids of ≤ 10 carbon atoms but considerably higher contents of saturated fatty acids with > 12 carbon atoms with respect to those of CNO and the liquid fractions. They also contained higher contents of high-melting triacylglycerol species with carbon number ≥ 38. Because of this, the DSC crystallization onset temperatures and the crystallization peak temperatures of the solid fractions were higher than CNO and the liquid fractions. The SFC values of the solid fractions were significantly higher than CNO at all measuring temperatures before reaching 0% just below the body temperature with the fraction obtained at 12°C for 2 h exhibiting the highest SFC. On the contrary, the SFC values of the liquid fractions were lower than CNO. The crystallization duration exhibited strong influence on the solid fractions. There was no effect on the crystal polymorphic structure possibly because CNO has ß'-2 as a stable polymorph. The enhanced SFC of the solid fractions would allow them to find use in food applications where a specific melting temperature is desired such as sophisticated confectionery fats, and the decreased SFC of the liquid fractions would provide them with a higher cold stability which would be useful during extended storage time.

Crystallization kinetics of cocoa butter in the presence of sorbitan esters.

Cocoa butter crystallization in the presence of sorbitan mono- and triesters or canola oil was investigated. Solid-state surfactant esters accelerated early-stage cocoa butter solidification while suppressing later growth. Sorbitan tristearate showed the strongest effect, followed by sorbitan monostearate and sorbitan monopalmitate. Liquid-state surfactants suppressed cocoa butter crystallization at all time points, with sorbitan trioleate showing a stronger effect than sorbitan monooleate, which behaved in a similar fashion to canola oil. Via DSC, the palmitic and stearic-based surfactants only associated with cocoa butter's high-melting fraction, with the oleic acid-based surfactants and canola oil showing little influence. All sorbitan esters had little effect on polymorphism, whereas canola oil accelerated the form II-to-III-to-IV transition. The palmitic and stearic-based surfactants greatly reduced cocoa butter crystal size whereas the oleic acid-based surfactants and canola showed no notable effect. Overall, sorbitan esters impacted cocoa butter crystallization kinetics, though this depended on surfactant structure and concentration.

Trans-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 ß' 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 ß' crystals. Interesterified blend 40:60 was suitable for use as a transfree margarine fat.

Lauric fat cocoa butter replacer from krabok (irvingia malayana) seed fat and coconut oil.

Lauric fat cocoa butter replacer (LCBR) was produced from a blend of krabok seed fat (KSF) and coconut oil (CO). Four fat blends with different ratios of KSF/CO (20/80, 40/60, 60/40 and 80/20 (%wt)), CO, KSF and a commercial LCBR (C-LCBR) were characterized using various techniques. It was found that blend 60/40 exhibited SFC curve and crystallization/melting behavior most similar to that of C-LCBR. The blend met the requirements to be considered as LCBR and has potential as an alternative to commercial LCBR that are being used nowadays and hence it was recommended as LCBR (called R-LCBR). The polymorphic behavior of both C-LCBR and R-LCBR was investigated and both fats displayed mainly short spacing pattern associated with ß' polymorph, a required polymorph for LCBR. The compatibility between R-LCBR and CB was investigated by mixing the R-LCBR with CB in different proportions and softening due to the eutectic effect was observed in the mixed fats. This limits the proportion of CB and the R-LCBR in compound coatings to no more than 5% of CB in the total fat phase.

Blending of mango kernel fat and palm oil mid-fraction to obtain cocoa butter equivalent.

Cocoa butter equivalent (CBE) was produced from a blend of mango kernel fat (MKF) and palm oil mid-fraction (PMF). Five fat blends with different ratios of MKF/PMF (90/10, 80/20, 70/30, 60/40 and 50/50 (%wt)) and pure MKF, PMF and cocoa butter (CB) were characterized. Similar to CB, all fat blends contained palmitic (P), stearic (S) and oleic (O) acids as the main fatty acid components. The triglyceride compositions of all blends were significantly different from CB. However, blend 80/20, which contained higher content of SOS, similar content of POP and lower content of POS compared to CB, exhibited a slip melting point, crystallization and melting behavior most similar to CB and hence it was recommended as CBE. The chosen CBE was then mixed with CB in a ratio of 1:5.64 (wt), mimicking that of typical dark chocolate where 5 % of CBE is added to the finished product. The crystallization behavior, the crystal morphology and bloom behavior of the mixture was investigated and was found to be not significantly different from CB.

Studies of fatty acid composition, physicochemical and thermal properties, and crystallization behavior of mango kernel fats from various Thai varieties.

Mango kernel fat (MKF) has received attention in recent years due to the resemblance between its characteristics and those of cocoa butter (CB). In this work, fatty acid (FA) composition, physicochemical and thermal properties and crystallization behavior of MKFs obtained from four varieties of Thai mangoes: Keaw-Morakot (KM), Keaw-Sawoey (KS), Nam-Dokmai (ND) and Aok-Rong (AR), were characterized. The fat content of the mango kernels was 6.40, 5.78, 5.73 and 7.74% (dry basis) for KM, KS, ND and AR, respectively. The analysis of FA composition revealed that all four cultivars had oleic and stearic acids as the main FA components with ND and AR exhibiting highest and lowest stearic acid content, respectively. ND had the highest slip melting point and solid fat content (SFC) followed by KS, KM and AR. All fat samples exhibited high SFC at 20℃ and below. They melted slowly as the temperature increased and became complete liquids as the temperature approached 35°C. During static isothermal crystallization at 20°C, ND displayed the highest Avrami rate constant k followed by KS, KM and AR, indicating that the crystallization was fastest for ND and slowest for AR. The Avrami exponent n of all samples ranged from 0.89 to 1.73. The x-ray diffraction analysis showed that all MKFs crystallized into a mixture of pseudo-ß', ß', sub-ß and ß structures with ß' being the predominant polymorph. Finally, the crystals of the kernel fats from all mango varieties exhibited spherulitic morphology.

Characterization of physicochemical and thermal properties and crystallization behavior of krabok (Irvingia Malayana ) and rambutan seed fats.

Fatty acid composition, physicochemical and thermal properties and crystallization behavior of fats extracted from the seeds of krabok (Irvingia Malayana) and rambutan (Nephelium lappaceum L.) trees grown in Thailand were studied and compared with cocoa butter (CB). The krabok seed fat, KSF, consisted of 46.9% lauric and 40.3% myristic acids. It exhibited the highest saponification value and slip melting point but the lowest iodine values. The three fats displayed different crystallization behavior at 25°C. KSF crystallized into a mixture of ß' and pseudo-ß' structures with a one-step crystallization curve and high solid fat content (SFC). The fat showed simple DSC crystallization and melting thermograms with one distinct peak. The rambutan seed fat, RSF, consisted of 42.5% arachidic and 33.1% oleic acids. Its crystallization behavior was more similar to CB than KSF, displaying a two-step crystallization curve with SFC lower than that of KSF. RSF solidified into a mixture of ß' and pseudo-ß' before transforming to ß after 24 h. The large spherulitic microstructures were observed in both KSF and RSF. According to these results, the Thai KSF and RSF exhibited physicochemical, thermal characteristics and crystallization behavior that could be suitable for specific applications in several areas of the food, cosmetic and pharmaceutical industries.