沙棘油脂肪酸、sn-2位脂肪酸及甘三酯的测定与分析

采用超临界CO_2萃取得到沙棘籽油和沙棘全果油,并采用气相色谱和超高效液相色谱-飞行时间质谱对其脂肪酸、sn-2位脂肪酸及甘三酯组成进行测定与分析。结果表明:沙棘籽油中亚油酸、亚麻酸和油酸的含量较多,分别为38.71%、25.66%和20.68%,这3种脂肪酸也是其主要的sn-2位脂肪酸,含量分别为46.46%、25.49%和23.02%;LOL(13.65%)、OLO(12.06%)和LLn O(11.23%)是沙棘籽油的主要甘三酯类型;沙棘全果油中棕榈油酸(36.86%)、棕榈酸(27.27%)和油酸(18.00%)的含量较高,主要的sn-2位脂肪酸为棕榈油酸(45.57%)和油酸(32.06%);沙棘全果油的主要甘三酯为POPo(14.38%)、PoOPo(13.77%)和OPO(12.06%)。     

Triacylglycerol composition of protected designation of origin cheeses during ripening. Authenticity of milk fat

Triacylglycerol (TAG) composition by carbon number in 2 protected designation of origin cheeses, Mahón (cheese from cow milk) and Manchego (cheese from ewe milk) that were manufactured by 3 different producers was analyzed during cheese ripening using gas chromatography with a short capillary column. The TAG composition at different times during cheese ripening was also analyzed in cheeses from different batches produced at the same plant. Lipolysis levels in the Mahón and Manchego cheeses during ripening were low; free fatty acid values ranged from 2,500 to 4,000 ppm at the end of ripening. The TAG composition did not change significantly during ripening. The TAG values obtained from each cheese sample were substituted into the multiple regression equations that have been proposed to detect foreign fats in milk fat. The values obtained using the equations for bovine (proposed by the European Union) and ovine milk (proposed by our laboratory) were within the normal range. Accordingly, these equations can be considered useful for detecting foreign fat in these cheeses during the ripening period contemplated during this study.     

A rapid method for enzymatic synthesis and purification of the structured triacylglycerol, 1,3-dilauroyl-2-oleoyl-glycerol

A rapid method for synthesis and purification of the structured triacylglycerol (TAG), 1,3-dilauroyl-2-oleoylglycerol (LaOLa), has been developed. A fraction containing 70% LaOLa was obtained by enzymatic transesterification between triolein and lauric acid using Lipozyme IM, which has 1,3-regioselectivity on the glycerol moiety of TAG. The fraction was passed through a Bond Elut SI Column to remove mono-and diacylglycerols produced during the transesterification. The TAG fraction thus obtained was applied to a reversed-phase column, eluted with acetonitrile/tetrahydrofuran (8:2, vol/vol) to separate different TAG species. The LaOLa fraction obtained by this method was of greater than 99% purity. The concentrations of total fatty acids and fatty acids bound to the sn-2 position of this LaOLa fraction were determined by gas-liquid chromatography after hydrolysis by pancreatic lipase, to confirm the purity of stereospecific isomers in this fraction. The final purity of LaOLa was found to be greater than 95%, which was in good agreement with the result obtained by high-performance liquid chromatography using a Lichrosorb Si60 argentated column.     

Polymorphism of pos. I. occurrence and polymorphic transformation

Polymorphic behavior of 1,3-rac-palmitoyl-stearoy 1-2-oleoylglycerol, 99.9% purity (POS) was examined by X-ray diffraction (XRD), differential scanning calorimetry (DSC), solubility measurements and optical microscopy in comparison with 1,3-dipalmitoyl-2-oleoylglycerol (POP) and 1,3-distearoyl-2-oleoylglycerol (SOS). Melt crystallization and solvent crystallization were examined for the occurrence of metastable and stable polymorphs. The number of independent polymorphs was four; α,δ, pseudoβ′ andβ. The lowest melting form, α, was identical to that commonly observed in POP and SOS lowest melting forms. As to the highest melting form,β, the XRD shortspacing pattern was identical toβ ₁ of POP and SOS. This is consistent with crystal habit:β single crystals of POS showed the same shape as those of β₁ of POP and SOS. However, the melting point ofβ (POS), 35.9°C, was lower than those ofβ ₁ of POP, 36.7°C, and of SOS, 43.0°C. Correspondingly, solubility ofβ of POS was lower than that of β₁ of POP below about 13°C, but higher above 13°C. POS did not possessβ ₂ , which is the second stable form in POP and SOS. Two forms of6 and pseudoβ′ occurred, the latter being more stable. The structural properties ofδ showed thatδ is not identical toγ previously observed in POP and SOS. Transformation behavior from the metastable to stable polymorphs of POS showed some differences from those of POP and SOS. Presented at the AOCS annual meeting in Cincinnati, Ohio, in May 1989.     

Sn-1,3-specific Interesterification of Soybean Oil with Medium-chain Triacylglycerol Catalyzed by Lipozyme TL IM

abstract The structured lipids are produced through sn-1,3-specific interesterification of soybean oil with medium-chain triacylglycerol (MCT) in continuous reactions catalyzed by Thermomyces lanuginos...     

Two Triacylglycerol Lipases Are Negative Regulators of Chilling Stress Tolerance in Arabidopsis

Cold stress is one of the abiotic stress conditions that severely limit plant growth and development and productivity. Triacylglycerol lipases are important metabolic enzymes for the catabolism of triacylglycerols and, therefore, play important roles in cellular activities including seed germination and early seedling establishment. However, whether they play a role in cold stress responses remains unknown. In this study, we characterized two Arabidopsis triacylglycerol lipases, MPL1 and LIP1 and defined their role in cold stress. The expression of MPL1 and LIP1 is reduced by cold stress, suggesting that they may be negative factors related to cold stress. Indeed, we found that loss-of-function of MPL1 and LIP1 resulted in increased cold tolerance and that the mpl1lip1 double mutant displayed an additive effect on cold tolerance. We performed RNA-seq analysis to reveal the global effect of the mpl1 and lip1 mutations on gene expression under cold stress. The mpl1 mutation had a small effect on gene expression under both under control and cold stress conditions whereas the lip1 mutation caused a much stronger effect on gene expression under control and cold stress conditions. The mpl1lip1 double mutant had a moderate effect on gene expression under control and cold stress conditions. Together, our results indicate that MPL1 and LIP1 triacylglycerol lipases are negative regulators of cold tolerance without any side effects on growth in Arabidopsis and that they might be ideal candidates for breeding cold-tolerant crops through genome editing technology.     

Feeding increasing amounts of ruminally protected choline decreased fatty liver in nonlactating,pregnant Holstein cows in negative energy status

The objectives were to determine the optimal feeding amount of choline in a ruminally protected form to reduce the triacylglycerol (TAG) concentration in liver and to increase TAG in blood plasma of dairy cows. Pregnant, nonlactating multiparous Holstein cows (n = 77) were blocked by body condition score (3.59 ± 0.33) and assigned to treatment at 64 ± 10 d before calculated calving date. Dietary treatments were top-dressing of 0, 30, 60, 90, or 120 g/d of ruminally protected choline (RPC; Balchem Corp., New Hampton, NY) ions to supply the equivalent of 0, 6.5, 12.9, 19.4, and 25.8 g/d of choline ions. Diets were formulated to exceed nutrient requirements for maintenance and pregnancy and fed in ad libitum amounts for the first 5 d. From d 6 to 15, cows were restricted to consume approximately 31% of their net energy requirements to simulate early lactating cows in negative energy balance. Methionine intake was maintained throughout each 15-d period. Liver was biopsied at 5 and 14 d and analyzed for TAG and glycogen. Blood was sampled on d 5 and 14 and plasma analyzed for glucose, insulin, cholesterol, β-hydroxybutyrate, long-chain fatty acids, and haptoglobin. On d 14, a mixture of saturated long-chain fatty acids, ground corn, and dried molasses (50:37:13) was offered (908 g, as-is basis) 10 h after the single daily feeding. Blood samples were collected for 19 h and plasma analyzed for TAG and cholesterol to assess apparent absorption of dietary fat. Mean dry matter intake and energy balance decreased from means of 9.5 to 3.3 kg/d and from 0.6 to ?9.2 Mcal of net energy for lactation/d during the ad libitum and restricted feeding periods, respectively. Plasma concentrations of the lipid-soluble choline biomolecules, namely total phosphatidylcholines, total lysophosphatidylcholines, and sphingomyelin, increased with choline supplementation. Feed restriction increased plasma concentrations of β-hydroxybutyrate and free long-chain fatty acids, whereas those of glucose, insulin, and total cholesterol decreased. During feed restriction, concentration of hepatic TAG and plasma haptoglobin decreased linearly, whereas concentration of hepatic glycogen tended to increase quadratically with increasing intake of RPC. After fat supplementation, mean plasma concentration of TAG increased by an average of 21% with intake of RPC ions, peaking at intakes of ≥6.5 g/d of RPC ion. In summary, feeding RPC ions to cows in negative energy balance had increasing lipotropic effects on the liver when consumed up to 25.8 g/d, whereas feeding only 6.5 g/d increased concentrations of hepatic glycogen and TAG in the blood.     

Fatty acid and triacylglycerol composition and thermal behaviour of fats from seeds of Brazilian Amazonian Theobroma species

Raw materials for cocoa butter substitutes, replacements or equivalents depend mostly on the unsteady supply from wild stands of plants, while there is no current supply of Neotropical origin. Seed fats from Theobroma species (T cacao, T bicolor, T grandiflorum, T obovatum, T subincanum, T speciosum, T sylvestre and T microcarpum, plus the closely related species Herrania mariae) were analysed for fatty acid and triacylglycerol composition by gas and liquid chromatography respectively, for iodine value, for melting point by open capillary tube and for solid fat content (SFC) by nuclear magnetic resonance. All Theobroma species had significantly lower palmitate levels than T cacao, except for T sylvestre and T speciosum, T microcarpum presented highly unsaturated fat (C18:2), while H mariae had high levels of arachidate. Fats from T sylvestre and T speciosum had a similar iodine value to T cacao and a higher melting point. No fat from the other species presented a similar melting profile to cocoa butter. T sylvestre and T bicolor were the most similar to T cacao but had a higher SFC at human body temperature. T sylvestre and T speciosum seed fats had more POP than cocoa butter. Fats from seeds of T speciosum, T sylvestre and T bicolor could be recommended as cocoa butter substitutes, while fats from species of the section Glossopetalum could be employed in products requiring fats with a lower melting point. © 2002 Society of Chemical Industry