The crystal structure of the beta polymorph of tripalmitin (1,2,3-trihexadecanoylglycerol, beta-PPP) has been determined by single-crystal X-ray diffraction. The molecules crystallize in space group P1; in an asymmetric tuning-fork conformation. This structure and the already-known crystal structures of beta-tricaprin (beta-CCC) and beta-trilaurin (beta-LLL) could be matched in an overlap model. Apart from a difference in chain length, the three structures are almost identical. The overlap model can be used to predict the crystal structure of the other members of the C(n)C(n)C(n)-type (n = even) TAG series reasonably accurately. This is demonstrated by predicting the crystal structure for beta-trimyristin (beta-MMM) and successively comparing the experimental and calculated X-ray powder diagrams.

Milk fat was fractionated by solvent (acetone) fractionation and dry fractionation. Based on their fatty acid and acyl-carbon profiles, the fractions could be divided into three main groups: high-melting triglycerides (HMT), middle-melting triglycerides (MMT), and low-melting triglycerides (LMT). HMT fractions were enriched in long-chain fatty acids, and reduced in short-chain fatty acids and unsaturated fatty acids. The MMT fractions were enriched in long-chain fatty acids, and reduced in unsaturated fatty acids. The LMT fractions were reduced in long-chain fatty acids, and enriched in short-chain fatty acids and unsaturated fatty acids. Crystallization of these fractions was studied by differential scanning calorimetry and X-ray diffraction techniques. In this study, the stable crystal form appeared to be the β′-form for all fractions. At sufficiently low temperature (different for each fraction), the β′-form is preceded by crystallization in the metastable α-form. An important difference between the fractions is the rate of crystallization in the β′-form, which proceeds at a much lower rate for the lowermelting fat fractions than for the higher-melting fat fractions. This may be due to the much lower affinity for crystallization of the lower-melting fractions, due to the less favorable molecular geometry for packing in the β′-crystal lattice.Milk fat is a natural product obtained from cream, and it forms the main constituent of butter. It has excellent organoleptic properties, which makes it an important ingredient in the bakery and confectionery industry. Despite these good qualifications, the market for milk fat has tended to decline in recent years due to its high price and limited functional properties. Melting characteristics and firmness vary with the season, breed of cow, stage of lactation, and the feed given to the cows. Moreover, the product diversity of milk fat is limited compared to that of margarine, for which a whole range of products exists for applications such as puff pastry, cookies, and cold-spreadable products.The physical properties of milk fat are determined by triglycerides, which are its main components. These triglycerides are composed of a large number of different fatty acids. This leads to a heterogeneous composition of triglycerides and a very broad melting range, which varies between approximately −40 and 35°C. Characteristic for milk fat is the occurrence of large amounts (approximately 25% on a molar basis) of short-chain fatty acids, of which butyric acid is the most important.Polymorphism is a common property of all triglycerides (1,2), including milk fat. The main types of polymorphic crystal forms in triglycerides are the γ-, α-, β′-, and β-forms (3-5). Of these main types, either the β′-or β-form is the stable form, depending on the molecular geometry of the triglyceride (6). The other forms are metastable, although they may persist for a long time. For milk fat, the β′-form is the most stable.The utilization range of milk fat can be broadened by separating it into fractio...

The crystal structures of beta-1,2,3-tritetradecanoylglycerol (beta-trimyristin or beta-MMM) and beta-1,2,3-trioctadecanoylglycerol (beta-tristearin or beta-SSS) have been determined from high-resolution synchrotron X-ray powder diffraction data. Grid search and Rietveld refinement have been used to determine and refine the structure, respectively. Both substances crystallize in space group P1; with Z = 2. The unit-cell parameters for beta-MMM are a = 12.0626 (6), b = 41.714 (1), c = 5.4588 (3) A, alpha = 73.388 (4), beta = 100.408 (5) and gamma = 118.274 (4) degrees. For beta-SSS the unit-cell parameters are a = 12.0053 (7), b = 51.902 (2), c = 5.4450 (3) A, alpha = 73.752 (5), beta = 100.256 (6) and gamma = 117.691 (5) degrees. Soft-distance restraints have been applied to the molecules during refinement. For beta-MMM the final R(p) value obtained is 0.053 and for beta-SSS the final R(p) value is 0.041.

The crystal structures of the beta' phase of CLC (1, 3-didecanoyl-2-dodecanoylglycerol) and MPM (1, 3-ditetradecanoyl-2-hexadecanoylglycerol) have been determined from single-crystal X-ray diffraction and high-resolution X-ray powder diffraction data, respectively. Both these crystals are orthorhombic with space group Iba2 and Z = 8. The unit-cell parameters of beta'-CLC are a = 57.368 (6), b = 22.783 (2) and c = 5.6945 (6) A and the final R value is 0.175. The unit-cell parameters of beta'-MPM are a = 76.21 (4), b = 22.63 (1) and c = 5.673 (2) A and the final R(p) value is 0.057. Both the beta'-CLC and beta'-MPM molecules are crystallized in a chair conformation, having a bend at the glycerol moiety. The zigzag planes of the acyl chains are orthogonally packed, as is typical for a beta' phase. Furthermore, unit-cell parameters of some other members of the C(n)C(n+2)C(n)-type triacylglycerol series have been refined on their high-resolution X-ray powder diffraction pattern. Finally, the crystal structures are compared with the currently known structures and models of triacylglycerols.

Alternation of melting points in the series of odd- and even-numbered monoacid triacylglycerols has been known for a long time, but hitherto little experimental evidence has been available to support existing theories. In this paper the melting point alternation of β-C n C n C n -type triacylglycerols is discussed, based on the crystal structures of β-C n C n C n (n = number of C atoms per hydrocarbon chain = 10, 12, 14, 16, 18 and n = 13, described in this paper). The crystal structure of β-1,2,3-tris(tridecanoyl)glycerol (β-C13C13C13) has been determined from high-resolution synchrotron X-ray powder diffraction data and is presented here. Grid search and Rietveld refinement have been used to determine and refine the structure, respectively. Like the even-numbered monoacid triacylglycerols, β-C13C13C13 is crystallized in an asymmetric tuning-fork conformation and its acyl chains are laterally packed, resulting in a layered structure. Within a molecular layer, the odd- and even-numbered monoacid triacylglycerols are identically packed, but the packing of adjacent molecular layers is different, clarifying the alternation of melting points.