Dynamic crystallization of cocoa butter. I. characterization of simple lipids in rapid- and slow-nucleating cocoa butters and their seed crystals

Six cocoa butters with different crystallization induction times and their seed crystals were analyzed for simple lipid composition. The rapid-nucleating cocoa butter samples had higher concentrations of 1-palmitoyl-2-oleoyl-3-stearoylglycerol and 1,3-stearoyl-2-oleoylglycerol (SOS), and lower concentrations of the diunsaturated triacylglycerols, 1-palmitoyl-2,3-oleoylglycerol and 1-stearoyl-2,3-oleoylglycerol, as well as higher stearic acid concentrations within their diacylglycerol fractions when compared to the slow-nucleating samples. At the early stages of crystallization, under agitation conditions at 26.5°C, cocoa butters solidified into two fractions, high-melting and low-melting. The low-melting fractions were composed of polymorphs IV and V of cocoa butter, as indicated by the onset melting temperatures of the endotherms from differential scanning calorimetry. The high-melting fractions, which had wide melting ranges, had peak maxima of 38.5–52.2°C. Seed crystals isolated at the early stage of crystallization were characterized by high concentrations of complex lipids, saturated triacylglycerols, saturated fatty acid-rich diacylglycerols, and monoacylglycerols. The rapid-nucleating seed crystals had higher concentrations of SOS when compared to their respective cocoa butters. The slow-nucleating seed crystals did not exhibit this characteristic.     

Lipid composition of high-melting seed crystals formed during cocoa butter solidification

High-melting seed crystals which form during the early stages of cocoa butter solidification possess a lipid composition different than the cocoa butter from which the seed crystals were grown. Significantly large quantities of glycolipids, 11.1%, and phospholipids, 6.6–8.1%, were found in the high-melting seed crystals along with a dramatic decrease in the simple lipid class. The fatty acids comprising the simple lipid fraction of the seed crystals were considerably more saturated than the fatty acids present in the same fraction of the original cocoa butter. The increase in the degree of saturation was reflected in the triacylglycerol composition. Cocoa butter samples were predominantly monounsaturated triacylglycerols while the seed crystal samples were mainly trisaturated triacylglycerols. The elevated melting point (60–70°C) of the seed crystals was due to the presence of higher melting complex lipids as well as to the increase in saturated triacylglycerol species. As a result of the evidence provided, the high-melting seed crystal is indeed a distinct crystalline entity and not an additional polymorphic form of cocoa butter.     

Isolation and thermal characterization of high-melting seed crystals formed during cocoa butter solidification

Seed crystals which formed during early stages of cocoa butter solidification have been isolated and determined to have extremely high melting points. The melting points of the seed crystals generally exceeded 60°C, in contrast to cocoa butter, which melts between 30–35°C. In addition, the melting point of the seed crystals decreased as a function of crystal growth time. Evidence suggests that the high-melting seed crystal is not an additional polymorphic form of cocoa butter, but rather a distinct crystalline entity. Consequently, a unique compositional make-up is suspected as being responsible for the elevated melting point. A technique to separate seed crystals from the molten cocoa butter mass has been developed. The procedure has been shown not to alter the thermal and compositional properties of the isolated seed crystals.     

Triglyceride composition ofmadhuca butyraceae seed fat

Fatty acid and triglyceride compositions of phulwara butter (Madhuca butyraceae seed fat) have been determined by combination of the techniques of systematic crystallization at low temperatures, pancreatic lipase hydrolysis, and gas liquid chromatography of methyl esters. The percentages of individual fatty acids were found to be palmitic, 55.6; stearic, 5.2; oleic, 35.9; and linoleic, 3.3. The special characteristic of the phulwara butter is its content of POP, 52.5%; PLP, 4.9%; POSt, 8.6%; POO, 14.4% and PPP, 7.7% (P, palmitic; St. stearic; O, oleic; and L, linoleic). 2-Monoglycerides obtained by lipolysis of this fat and its least soluble fraction contained 13,0% and 29.3% saturated acids, respectively. Phulwara butter may be a potential source of palmitic acid for the pharmaceutical industry.     

Characterizing cocoa butter seed crystals by the oil-in-water emulsion crystallization method

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.     

Physicochemical and thermal characterization of seed oil from Mexican mamey sapote <Emphasis Type="Italic">(Pouteria sapota)</Emphasis>

The aim of this research was to perform a physicochemical characterization of native mamey sapote seed oil [Pouteria sapota (Jacq.) H.E. Moore and Stearn]. Mamey sapote seed oil showed good oxidative stability as it had low peroxide, free fatty acid, and p‐anisidine values. The main fatty acids present in the oil were palmitic, stearic and oleic acid, constituting five major triacylglycerides families: PLP, POP, StOO, POSt and StOSt. Crystallization and melting points of the oil were ?37.7 and 23.84 °C, respectively. The oil had higher SFC when the temperature was lower than 10 °C. X‐ray diffraction patterns showed that prolonged storage times lead to the formation of β crystals. Micrographs showed granular crystals (91–105 μm), with needle edges similar to cocoa butter. In addition, mamey sapote seed oil can be used in confectionery products or as a possible substitute for cocoa butter to improve and obtain good‐quality products.     

Bloom Formation on Poorly-Tempered Chocolate and Effects of Seed Addition

Bloom on chocolate with different levels of cocoa butter seed addition was investigated. When insufficient cocoa butter seed crystals were added to give proper temper, the chocolate developed bloom as dark brown spheres in lighter color areas, similar to that seen in bloom on untempered chocolate. These dark colored spheres overlapped and the lighter color areas disappeared with increasing seed amount added. The relationship between seed amount and lighter color area (bloom), as quantified by image analysis, showed that over 270 ppm seeds (fat basis) were needed to accomplish good tempering. The cocoa butter crystallization behavior with various amounts of seed was observed by light microscopy. Too few seeds caused sparse β crystallization and massive β′ crystallization, which explains the appearance of poorly tempered chocolate bloom. As seed amount increased, β crystallization of cocoa butter took less time to reach the upper level of solid fat content and the size became smaller. In addition, DSC analysis was carried out to study crystallization and melting behavior of cocoa butter with different seed amounts. Higher levels of added seeds resulted in greater amounts of β crystal formation and the crystallization temperature increased, which meant crystallization occurred earlier. These results showed that the mechanism of bloom formation on poorly tempered chocolate (insufficient seeds) is due to sufficient time and space for phase (particles and fat) separation as the stable polymorphs grow.     

Phospholipid composition of guinea pig lung lavage

Phospholipids from guinea pig lung lavage were analyzed. The total lavage phospholipid content was 2.65+0.67 mg, per gram of lung, which accounted for 85% of the total lipids in lung wash. Phosphatidylcholine (PC) accounted for over 60% of the total phospholipids. The other phospholipids factions, in order of pedominance, were phosphatidylinositol (PI), phosphatidylserine (PS), sphingomyelin (SPH), phosphatidylethanolamine (PE), phosphatidylglycerol (PG) and lysophosphatidyl-choline (LPC). Disaturated phosphatidylcholine (DSPC) comprised 80% of the total PC, and it contained ostly palmitic acid. The DSPC content of the lung lavage fluid per square meter of alveolar surface area was 5.76±0.42 mg.     

Generation of phospholipid artefacts during extraction of developing soybean seeds with methanolic solvents

The major phospholipids of soybean cotyledons during development were phosphatidylcholine (45–55%), phosphatidylethanolamine (24–28%), and phosphatidylinositol (15–18%) when the tissue was steam-killed prior to extraction of the lipids. The only other phospholipids of any significance (4–6%) was identified as phosphatidylglycerol. Phosphatidic acid was a minor constituent (<1%), and neither N-acyl phosphatidylethanolamine norbis-phosphatidic acid were detected in appreciable (>0.1% of the total lipid phosphorus) quantities. When fresh cotyledons were rapidly homogenized in mixtures of chloroform and methanol or in methanol alone, phosphatidylmethanol was formed in variable amounts (0–20% of the total phospholipid), and when cotyledons were soaked in methanol prior to homogenizing, phosphatidylmethanol became the major phospholipid, accounting for up to 75% of the total lipid phosphorus. Phosphatidylmethanol was formed by the phospholipase D-catalyzed transphosphatidylation of phosphatidylcholine and phosphatidylethanolamine during extraction.     

Seeding effects on solidification behavior of cocoa butter and dark chocolate. I. Kinetics of solidification

Effects of seeding of fat crystals on the crystallization kinetics of cocoa butter and dark chocolate were examined with a rotational viscometer. The seed crystals employed were cocoa butter, 1,3-distearoyl-2-oleoylglycerol (SOS), 1,3-dibehenoyl-2-oleoylglycerol (BOB) and 1,2,3-tristearoylglycerol (SSS). The seed powders were prepared by pulverization below —50°C, the dimensions being in a range from 20–70 μm. Particular attention was paid to the influence of polymorphism of the seed crystal. We found that all of the above seed materials accelerated the crystallization, the degree of acceleration being in a following order; SOS (β ₁) > cocoa butter (Form V) > SOS (a mixture ofβ’ andβ ₂) > BOB (β ₂) > BOB (pseudo-β’) > SSS (β). Precise measurements of the crystallization kinetics showed that the most influential factors in the seeding effects are the physical properties of the seed materials—above all, thermodynamic stability, and similarity in the crystal structure to cocoa butter are the most determinative.     

Lipid composition of murraya koenigii seed

Total seed lipids extracted fromMurraya koenigii (Linn), Rutaceae amounted to 4.4% of the dry seed. The total lipids consisted of 85.4% neutral lipids, 5.1% glycolipids and 9.5% phospholipids. Neutral lipids consisted of 73.9% triacylglycerols, 10.2% free fatty acids and small amounts of diacylglycerols, monoacylglycerols and sterols. At least five glycolipids and seven phospholipids were identified. Sterylglucoside and acylated sterylglucoside were major glycolipids, while digalactosyldiacylglycerol, monogalac-tosyldiacylglycerol and monogalactosylmonoacylglycerol were present in small quantities. The phospholipids consisted of phosphatidylethanolamine, phosphatidylcholine, lysophosphatidylethanolamine and lysophosphatidylcholine as major phospholipids and minor quantities of phosphatidylinositol, phosphatidylglycerol and phosphatidic acid. The fatty acid composition of these different neutral lipids, glycolipids and phospholipids were determined.     

A comparative study of the lipid composition of isolated rat sertoli and germinal cells

The lipid composition of enriched preparations of sertoli cells and of germinal cells, isolated from the testes of mature rats, has been investigated. Sertoli cells contained a much lower content of phospholipids (in particular, much less phosphatidylcholine and phosphatidylethanolamine) and a higher content of triacylglycerols than did germinal cells. In addition, the Sertoli cells had a higher ratio of esterified to unesterified cholesterol than did germinal cells. Total lipids of Sertoli cells contained considerably lower levels of palmitic and docosa-4,7,10,13,16-pentaenoic acids and higher levels of stearic and oleic acids than did the total lipids of germinal less palmitic and docosa-4,7,10,13,16-pentaenoic acids, more stearic and oleic acids and also more arachidonic acid than did the corresponding lipid classes of the germinal cells. Minor differences between cell types were also noted for the content of palmitoleic, linoleic, docosa-7,10,13,16-tetraenoic, docosa-4,7,10,13,16,19-hexaenoic and tetracosa-9,12,15,18-tetraenoic acids.     

Dynamic crystallization of cocoa butter. II. Morphological,thermal, and chemical characteristics during crystal growth

After an induction period, crystallization of cocoa butter under dynamic conditions at 26.5°C occurs in two stages, primary and secondary. The primary stage involves nucleation, crystal growth, aggregation, and sintering. Crystals formed during the primary stage were slightly or non-birefringent, and had long, irregular-shaped filaments. The secondary stage was initiated by the formation of spherulites. Total crystallization time may depend upon the crystal growth rate in the primary stage and the time that coca butters take to form the spherulitic crystals in the secondary stage. After the spherulitic crystals formed, the crystal growth rates were rapid. Cocoa butters crystallized into two fractions during the primary and secondary stages. The low-melting fractions had onset melting temperatures similar to those of polymorphs IV and V of cocoa butter. The high-melting fractions, which were observed at the latter stages of crystallization, had differential scanning calorimetry endotherms with peak maxima at approximately 34–36°C (Form VI). The concentrations of 1,3-stearoyl-2-oleoylglycerol (SOS) in the crystals during growth were higher than those in the original cocoa butter. As crystallization progressed, crystals increased in their proportions of SOS in the triacylglycerol fraction. Concentrations of the C₁₈ free fatty acids were lower during early crystallization as compared to the original cocoa butter.     

Phospholipid Composition of Karanja (Pongamia glabra) Seeds

The Karanja (Pongamia glabra) seed kernels were extracted with a solvent mixture of chloroform and methanol (2:1, v/v). The extract was dissolved in chloroform and precipitated with acetone. Acetone insolubles (0.78% wt. of the kernels) contained 2.9 percent of phosphorus. Major constituent phospholipids were identified as phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol by spraying with characteristic spray reagents on thin-layer chromatograms (TLC) and by comparing the Rf values with those of standards and literature values. A quantitative TLC method using a colorimetric determination of phosphorus without acid digestion was used for studying the phospholipid composition of the acetone insolubles. The composition was found to be phosphatidylcholine, 43.1%; phosphatidyl-ethanolamine, 18.8%, phosphatidylinositol, 33.3% and unidentified, 4.8%. The fatty acid composition of the individual phospholipids is also reported.     

Fatty acid and molecular species composition of rat brain phosphatidylcholine and-ethanolamine from birth to weaning

The fatty acid composition of diacyl phosphatidylcholine and phosphatidylethanolamine from the brain of rats 3, 6, 9, 12, 15, 18, and 21 days old were determined. In phosphatidylcholine, the relative amounts of stearic and oleic acid increased from 25% to 33% while the relative amounts of myristic, palmitic, and palmitoleic decreased from 65% to 50% during this time period. The same pattern was seen in phosphatidylethanolamine with stearic and oleic increasing from 38% to 49% and the shorter chain acids decreasing from 17% to 13%. The polyunsaturated fatty content of phosphatidylcholine was approximately 10% and increased slightly during the first 3 weeks, while the polyunsaturated content of phosphatidylethanolamine decreased from 44% to 37%. The molecular species composition of phosphatidylcholine and phosphatidylethanolamine was determined in brains of rats 3, 6, and 9 days old. The relative amounts of the molecular species remained nearly constant during this time period with phosphatidylcholine containing 35% saturated, 40% monoenoic, 6% dienoic, 11% tetraenoic, 2% pentaenoic, and 5% hexaenoic. Phosphatidylethanolamine contained 1% saturated, 8% monoenoic, 3% dienoic, 40% tetraenoic, 9% pentaenoic, and 37% hexaenoic species. Analysis of the fatty acid composition of the molecular species reveals that in phosphatidylcholine the polyunsaturated fatty acids 20∶4 and 22∶6 are predominately paired with 16∶0, while in the phosphatidylethanolamine these two unsaturated fatty acids are paired with 18∶0. Furthermore, dipalmitoyl phosphatidylcholine accounts for approximately 25% of the total molecular species of that lipid.     

The absorption of fatty acids by functional bovine mammary cells

Freshly dispersed bovine mammary cells rapidly absorbed long chain fatty acids from the culture medium. Differences in the rates of absorption were observed, i.e., palmitic > stearic > oleic > myristic > linoleic acid. The preponderance of the fatty acids absorbed were esterified into triglycerides (>75%) and the remainder were mostly incorporated into phospholipids. The cells secreted triglycerides into the culture medium. Of the phospholipid classes, phosphatidylcholine always contained most of the radioactivity in all experiments with labeled fatty acids. These observations are related to the metabolism of mammary cells in vivo.     

Variations in fat content and lipid class composition in ten different mango varieties

The kernels of 10 different mango varieties were extracted. The physico-chemical characteristics and lipid class composition of fats were studied. The fat content of mango kernels grown under the soil and climatic conditions of Bangladesh varied from 7.1% to 10%, depending on the variety. The total lipid extracts were fractionated into lipid classes by a combination of column and thin layer chromatography (TLC). The hydrocarbon and sterol esters varied from 0.3% to 0.7%, triglycerides from 55.6% to 91.5%, partial glycerides from 2.3% to 4% and free sterol from 0.3% to 0.6%. Free fatty acids amounted to 3.0–37% as oleic; glycolipids were 0.6–1.2% and phospholipids 0.11–0.8%. The fatty acid composition of triglyceride (TG) fractions was analyzed by gas liquid chromatography (GLC). Palmitic acid varied from 7.9 molar % to 10.0 molar %, stearic from 38.2% to 40.2%, oleic from 41.1% to 43.8%, linoleic from 6.0% to 7.6%, linolenic from 0.6% to 1.0% and arachidic acid from 1.7% to 2.6%. TLC revealed the presence of lyso-phosphatidylcholine, phosphatidylcholine, phosphatidylinositol, phosphatidylethanolamine and phosphatidic acid in the phospholipid fraction.     

Crystallization Kinetics of Cocoa Fat Systems: Experiments and Modeling

Isothermal crystallization kinetics of unseeded and seeded cocoa butter and milk chocolate is experimentally investigated under quiescent conditions at different temperatures in terms of the temporal increase in the solid fat content. The theoretical equations of Avrami based on one-, two- and three-dimensional crystal growth are tested with the experimental data. The equation for one-dimensional crystal growth represents well the kinetics of unseeded cocoa butter crystallization of form α and β′. This is also true for cocoa butter crystal seeded milk chocolate. The sterical hindrance due to high solids content in chocolate restricts crystallization to lineal growth. In contrast, the equation for two-dimensional crystal growth fits best the seeded cocoa butter crystallization kinetics. However, a transition from three- to one-dimensional growth kinetics seems to occur. Published data on crystallization of a single component involving spherulite crystals are represented well by Avrami’s three-dimensional theoretical equation. The theoretical equations enable the determination of the fundamental crystallization parameters such as the probability of nucleation and the number density of nuclei based on the measured crystal growth rate. This is not possible with Avrami’s approximate equation although it fits the experimental data well. The crystallization can be reasonably well defined for single component systems. However, there is no model which fits the multicomponent crystallization processes as observed in fat systems.     

Sal olein and mahua olein for direct edible use

Vegetable butter oleins are obtained as by-products during the fractionation process employed for making cocoa butter substitutes from sal and mahua. Outlets for these olein portions would not only ensure total utilization of these nontraditional oils, but would also provide an extension of edible oil supplies. The normal analytical characteristics and fatty acid compositions of the olein portions obtained from sal and mahua fats were investigated under appropriate conditions of time and temperature. Sal olein was found to be rich in stearic (33.5–34.0%) and oleic acids (49.1–50.0), whereas mahua olein contained palmitic (18%), stearic (21%) and oleic (38%) acids. Projections from Schaal oven stability studies indicated that even without an antioxidant addition, the oleins could be stored for 4–5 months, and with 0.01% tertiary butyl hydroquinone, the storage life could be prolonged to over one year. Deep-fat frying experiments indicated that the oleins showed a slow buildup rate of total polar material and are quite suitable for such use.     

Characterization of pili nut (Canarium ovatum) oil: Fatty acid and triacylglycerol composition and physicochemical properties

The fatty acid and triacylglycerol composition of pili nut (Canarium ovatum) oil and fractions were analyzed by gas chromatography and reversed-phase high-performance liquid chromatography, respectively. The oil obtained by solvent extraction was low in polyunsaturated fatty acids and high in saturates. The polyunsaturated fatty acid (18∶2 and 18∶3) contents were less than 11%, whereas palmitic (16∶0) and stearic acid (18∶0) were 33.3 and 10.9%, respectively. The saturated fatty acid level of the low-melting fraction oil was reduced from 44.4 to 35.5% and the total unsaturated fatty acid levels were increased from 55.6 to 65% by fractional crystallization. Triacylglycerol analysis showed that the high-melting fraction (HM) from pili nut oil consisted of POP, POS, and SOS+SSO (P=palmitic acid, O=oleic acid, and S=stearic acid) in the proportion of 48.6, 38.8, and 8.7%, respectively. The physicochemical properties of the HM fraction were studied using differential scanning calorimetry and pulsed nuclear magnetic resonance. The results showed that the melting range and solid fat content of the HM fraction were very similar to those isolated from cocoa butter and olive oil. The content of POP played an important role in determining the melting range of the HM fraction. It is suggested that this HM fraction may have applications as a cocoa butter substitute in confectionery products.