Polymorphic influences on the phase behavior of three types of binary mixtures of saturated monoacid triacylglycerols (TAGs), trilaurin/trimyristin (LLL/MMM), trilaurin/tripalmitin (LLL/PPP), and trilaurin/tristearin (LLL/SSS), were examined by small- and wide-angle X-ray scattering (SAXS/WAXS) using synchrotron radiation. The carbon numbers (C n ) for the fatty acid chains of the three TAGs are 12 (LLL), 14 (MMM), 16 (PPP), and 18 (SSS). In the LLL/MMM system, miscible phase behavior occurred in metastable α and β‘ forms, whereas the most stable β form exhibited a eutectic phase. On the other hand, LLL/PPP and LLL/SSS mixtures showed immiscible phases for α, β‘, and β forms. Therefore, the TAG binary mixtures were miscible in metastable polymorphs of α and β‘ forms when C n differed by 2, whereas the immiscible mixtures were constructed in all polymorphic forms when C n differed by 4 and 6.

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During the 4-day period of project observation, July 8-July 12, 1968, the "Baiu front" activity was prevailing almost steadily over the Far East. Therefore the averaged fields of various meteorological elements in the vicinity of "Baiu front" are examined. The most remarkable structure is found not in the thermal stratification but in the wind field with a low-level jet which is considerably ageostrophic. The existence of low-level jet stream seems to be deeply related with the precipitation and, therefore probably, with the connective activity. Along the concentrated zone of strongly baroclinic field, lower tropospheric disturbances of wave lengths less than 1,000km were generated and moved east-northeastwards successively, bringing a large amount of precipitation periodically at an interval of about 20 hours. The associated thermal field indicated the existence of indirect circulation, but, nevertheless, disturbances did develop. The energy conversion processes among three different scales of motion, i. e., general synoptic scale, intermediate scale (frontal disturbances) and small scale (convection) are studied. It is suggested that the kinetic energy of intermediate-scale disturbances is transformed from the kinetic energy of convective-scale motion.

The binary phase behavior of SOS (1,3-distearoyl-2-oleoyl-sn-glycerol) and SLS (1,3-distearoyl-2-linoleoyl-sn-glycerol) was examined by using DSC and conventional and synchrotron radiation X-ray diffraction. The solidsolution phases were observed in the metastable α and γ forms in all concentration ranges. Results indicated that the miscible γ form did not transform to the β′ form when the mixtures were subjected to simple cooling from a high-temperature liquid to a low-temperature solid phase. However, an α-melt-mediated transformation into β′ and β 2 resulted in the formation of immiscible phases in concentration ranges of SLS below 30%. By contrast, at SLS concentration ranges above 30%, the α-meltmediated transformation caused crystallization of only the γ form, and β′ and β 2 crystals did not appear. These results show that the specific interactions between SOS and SLS are operative in the phase behavior of the mixture states of SOS and SLS.The phase behavior of TAG mixtures is one of the major factors that determines the macroscopic properties of fat products, such as mouthfeel, appearance, and rheology, together with fat polymorphism, crystal size, morphology, and crystal network formation (1-8).Real fat systems of both vegetable and animal origin are multicomponent systems containing different kinds of FA moieties. The complex features of real fat systems are due to fat polymorphism as well as the mixing behavior of different TAG. The physical analysis of real fat systems usually starts with understanding the individual TAG molecules and subsequently moves on to understanding the mixed systems. The best approach for the latter task usually starts with studying binary mixture systems of different TAG and extends to ternary and multicomponent mixture systems. Therefore, many studies of binary phase behavior have been performed for different combinations of TAG mixtures (9-15).In the phase behavior of binary mixture systems, three typical phases can occur: a solid-solution phase, a eutectic phase, and molecular compound formation. The general tendency in the relationship between molecular interactions and phase behavior may be summarized as follows: (i) The two components (A and B) can exchange places with one another in the crystal lattice in all concentration ratios (solid-solution phase); (ii) no solubilities will exist in the lattices of crystals A and B, respectively (eutectic phase); and (iii) highly specific interactions can give rise to the formation of molecular compounds. In the particular case of the mixture of tristearin/tripalmitin (SSS/PPP) (16,17), metastable α and β′ forms were shown to exhibit continuous solid solutions, yet a eutectic nature was revealed in the most stable β form. For PPP/1,3-dipalmitoyl-2-oleoyl-sn-glycerol (POP) mixtures (18,19), eutectic phases were observed in the metastable α and β′ forms and in the most stable β form as well. Recent studies on phase behavior have revealed various types of binary mixtures of TAG that form molecular compounds: 1,3-distearoyl-2-oleoyl-sn...

Polymorphic transformation behavior of sub-α 1 , sub-α 2 , α, and γ in 1,3-distearoyl-sn-2-linoleoyl-glycerol (SLS) has been studied with X-ray diffraction, differential scanning caloremetry, and Fourier-transform infrared spectroscopy. Synchrotron radiation X-ray beam was employed to observe rapid transformation processes from the sub-α and α forms to the γ form. The chain length structures were double in sub-α 1 , sub-α 2 , and α, whereas γ was of triple chain-length structure. The subcell packing was pseudohexagonal for the two sub-α forms, hexagonal for the α form, and parallel type for the γ form. In comparison with 1,3-distearoyl-sn-2-oleoyl-glycerol (SOS), the occurrence behavior of sub-α, α, and γ of SLS was the same as that of SOS. However, the absence of β' and β was unique for SLS. The chain-chain interactions between the linoleoyl moieties may stabilize the γ form, prohibiting the transformation into β' or β forms. The presence of two cis double bonds may cause this stabilization, revealing the disordered chain conformation of the unsaturated chains.