Thermal behavior of butterfat fractions and mixtures of tripalmitin and butterfat

The melting and crystallization behavior of blends of tripalmitin and butterfat were compared with that of butterfat fractions, which were prepared by dry fractionation and by solvent extraction. There were marked similarities in the behavior of the blends, the dry fractions and some solvent fractions. This similarity was not shared with the behavior of the hardest solvent fractions. The functionality or hard butterfat fractions seemed to derive from an enrichment in long-chain saturated triglycerides. Improved functionality could therefore be achieved equally well by blending or by fractionation. Blends of tripalmitin and butterfat could be used as model butterfat fractions, or as an alternative to butterfat fractions in some applications.     

Kinetics of butterfat crystallization

Fractionation of butterfat by melt crystallization is a commercial process in many countries for making butter fractions with varying melting, textural and flavor properties for use as food ingredients. However, the crystallization phenomena in this complex system are poorly understood and difficult to optimize and control. In this study, the crystallization kinetics of anhydrous butterfat were determined by cooling a melted sample to the final crystallization temperature in either a lab-scale (2 L) batch crystallizer or a pilot-scale (20 L) crystallization vessel. The butterfat was cooled sequentially from an initial temperature of 60°C to final temperatures of 30, 20 and 15°C at a constant cooling rate. Crystals formed at each temperature were separated by vacuum filtration, with the liquid cooled to the next crystallization temperature. Nucleation rates were determined by counting the number of crystals in a given volume of suspension during the course of crystallization. Crystal growth rates were obtained from image analysis of optical photomicrographs. Changes in viscosity, turbidity and mass of crystals also were determined. Effects of impeller velocity (75, 100 or 125 rpm) on the crystallization kinetics were determined. Nucleation and mass deposition rates increased while crystallization lag times decreased with increasing agitator velocities. Growth rates increased with agitator rpm at 20 and 15°C, but decreased with agitator rpm at 30°C, indicating different growth mechanisms. At 20 and 30°C, aggregation was the primary mechanism of crystal growth, whereas little aggregation was observed at 15°C. Crystallization at the larger scale, 20 L, showed only minor differences.     

Modeling of ta-C growth: Influence of the technological parameters

The structure of tetrahedral bonded amorphous carbon (ta-C) is determined by the energy of the impinging carbon ions, the angle of incidence, the substrate temperature and the deposition rate. Up to now modeling of the ta-C growth was concentrated on the energy effects by investigating the early stages of the ion impact and the short-time relaxation in the thermal spike. A new analytical model is presented, which emphasizes the role of long-time diffusion, driven by the stress induced drift towards the surface. In accordance with the experimentally found trends, the model allows the estimation of the sp³ content in dependence on the technological relevant deposition parameters ion energy, angle, temperature, rate and their distributions. This opens the way for the realistic simulation of ta-C growth in industrial coaters.     

关于生产精制元明粉的探讨

介绍了以山西运城南风自产芒硝为原料生产精制元明粉的几种工艺,以及国内外精制元明粉的市场及生产状况.精制工艺包括化学除杂法、原料优选法、重结晶法.结果表明,精制元明粉的生产过程实质是一个除杂、提纯过程：对于钙离子含量高的原料,可采用化学除杂法;对于氯离子含量高的原料,可采用氯离子富集法、冷冻法或洗涤法;镁离子较难去除,可采用水硝洗涤、冷冻法.     

Effects of thermal oxidation on the constitution of butterfat,butterfat fractions and certain vegetable oils

To evaluate the thermal oxidative behavior of butterfat in comparison to selected vegetable oils, samples of winter and summer butterfat, liquid and solid butterfat fractions, and selected vegetable oils were heated at 185 C in the presence of air (30 ml/min) for 8 and 16 hr. The resultant heated fats and oils, as well as the methyl esters of their fatty acids, were examined by gel permeation chromatography. The results indicated that butterfat is much more stable to thermal oxidation than canola, sunflower and soybean oils. This was evidenced by a substantially higher content of both dimeric and higher oligomeric triglycerides in the vegetable oils than in any of the butterfat samples after both 8 and 16 hr of heating. The corn oil also exhibited a high degree of stability to thermal oxidation after 8 hr of heating. The 16 hr corn oil data, however, was less certain due to the presence of a very viscous and dark colored material which could not be removed from the oxidation flask; this was believed to contain highly polymerized oil and was not observed with any of the other samples. There were some differences in the inter- and intramolecular polymerization of the butterfat fractions compared with each other and with whole butterfat. With the winter butterfat samples, after 8 hr of thermal oxidation, both the solid and liquid butterfat fractions exhibited more stability toward intermolecular polymerization than did the whole butterfat. After 16 hr of heating the ratio of trimeric and higher oligomeric triglycerides to dimeric triglycerides increased with increasing degree of unsaturation of the butterfat and with increased time of heating. Similar trends were observed with regard to the degree of intramolecular polymerization. Presented at the AOCS meeting in Philadelphia in May 1985.     

Volatile compounds produced by irradiation of butterfat

Anhydrous butterfat was irradiated at 6 megarads in a special glass reaction flask, and the headspace and total condensate samples were examined by wide-range (−180C to 125C) gas chromatography combined with mass spectrometry. The nature and amounts of volatile compounds were not greatly influenced by whether the butterfat was irradiated under oxygen or under vacuum, nor (apart fromn-alkanoic acids) by storage for 1 and 9 weeks. Carbon dioxide was produced in greatest amount. Of the remaining compounds, aliphatic hydrocarbons predominated both in number and amount. Aliphatic oxygenated compounds including carbonyl compounds were isolated in relatively small amounts. The following compounds were identified positively: C_1–13 n-alkanes; C_4–9 2-methylalkanes; C_2–14 alk-l-enes; C_2–9 alk-l-ynes; C_2–5 n-alkanoic acids; C_1–5 n-alkan-l-ols and propan-2-ol; C_2–8 n-alkanals and 2-methylbut-2-enal; C_3–5,7 alkan-2-ones; C_1–4 n-alkyl formates, vinyl and isoamyl formate, methyl acetate and methyln-hexanoate; and carbon dioxide. Visiting Scientist from Division of Dairy Research, C.S.I.R.O., Highett, Victoria, Australia.     

The effect of the composition of butterfat on its susceptibility of oxidation

Summary There is considerable variation in the stability of the butter fat toward oxidation where it is obtained from different cows and from an individual cow at different periods. The stability of butterfat toward oxidation bears an inverse relation to the unsaturation of the fat. The fat from cows receiving grass as part of their ration is less saturated and more susceptible to oxidation. It appears that the amount of linoleic acid rather than the oleic acid governs the stability of butterfat. The results point to the presence of protective substances in milk in increased amounts when cows are on grass which prevent the development of oxidized flavors in the milk. There is no relation between the carotene content, as evidenced by the color of the fat, and the stability of the fat toward oxidation. The refractive index of butterfat varies in direct proportion to the iodine number of the fat. A Paper Presented at the Tenth Fall Meeting of the American Oil Chemists’ Society, Chicago, October 8–9, 1936. Published with the permission of the Director of the Wisconsin Agricultural Experiment Station.     

Adulterated butterfat: Fatty acid composition of triglycerides and 2-monoglycerides

Beef tallow and cottonseed oil were mixed with a pure butterfat in the ratios of 2%, 4% and 6% to obtain admixtures of beef tallow with butterfat and cottonseed oil with butterfat. The hydrolysis of individual triglycerides was carried out using the lipase to obtain 2-monoglycerides. The results indicated that butterfat had a higher percentage of C14:0 and C16:0 acids than found in the triglycerides and 2-monoglycerides of beef tallow and cottonseed oil. Beef tallow contained a higher proportion of C18:0 and C18:1 acids than butterfat and cottonseed oil triglycerides or 2-monoglycerides. Cottonseed oil had a higher percentage of C18:2 acid located in triglyceride or 2-monoglyceride than found in butterfat or beef tallow triglycerides and 2-monoglycerides. The analysis of the samples of butterfat containing 2%, 4% and 6% beef tallow revealed that the addition of beef tallow to butterfat affected the fatty acid composition of butterfat triglycerides and 2-monoglycerides with C18:0 and C18:1 acids; the effect was increased with increasing percentages of beef tallow. The addition of cottonseed oil to butterfat in the ratios of 2%, 4% and 6% affected the fatty acid composition of butterfat triglycerides and 2-monoglycerides. It was found that both C18:1 and C18:2 increased as the added cottonseed oil percentages increased.     

Optical activity of butterfat and vegetable oils

Optical activities of oils freshly expressed from viable seeds of rape, soybean and peanut show no change in rotation with time; neither do oils extracted from these materials by diethyl ether, as previously reported by other workers. Similarly, no evidence for racemization of butterfat isolated immediately after milking could be found. On removal of the steroids present, by chromatography on Celite impregnated with digitonin, and removal of the mono- and diglycerides by chromatography on alumina, butterfat maintained the highest degree of optical activity compared to most of the vegetable oils studied. This residual activity of butterfat tends to substantiate preferential location of short chain fatty acids on the 1 or 3 position of the triglycerides. ARS, USDA.     

Crystal morphology of mixtures of tripalmitin and butterfat

Blends of butterfat and tripalmitin are of interest for use as moisture barriers in edible films. Tripalmitin was blended with butterfat in the ratios 100:0, 90:10, 80:20, and so on through to 10:90 and 0:100. Crystal morphologies of squash and smear preparations were determined by polarizing light microscopy. Samples were stored at 19–22°C and re-examined after 6 d and after 30 d. Morphology was strongly dependent on composition and the presence of a coverslip. Morphology was less dependent on polymorphic form and age. Barrier properties depend more strongly on morphology than on polymorphic form.     

Racemic lactones from butterfat: An advanced approach that includes stereodifferentiation

A new method was developed to obtain lactones from butterfat. The application of lipases and capillary gas-liquid chromatography with chiral phases for the separation of γ-lactone enantiomers resulted in elucidation of the racemic composition of γ-lactones from butterfat. The seasonal distribution of lactones in butterfat was determined.     

Quantitative gas liquid chromatographic analysis of butterfat triglycerides

Gas liquid chromatographic triglyceride separation by carbon number, and integration of the area response obtained in the hydrogen flame ionization detector, has permitted the calculation of the following molar proportions for the various triglyceride types in a blended butterfat sample: C₂₄ 0.5, C₂₅ 0.08, C₂₆ 0.57, C₂₇ 0.18, C₂₈ 0.81, C₂₉ 0.17, C₃₀ 1.15, C₃₁ 0.2, C₃₂ 3.1, C₃₃ 0.34, C₃₄ 5.41, C₃₅ 1.0, C₃₆ 10.6, C₃₇ 1.2, C₃₈ 12.8, C₃₉ 1.15, C₄₀ 10.7, C₄₁ 1.0, C₄₂ 6.1, C₄₃ 0.58, C₄₄ 5.15, C₄₅ 0.6, C₄₆ 5.8, C₄₇ 1.0, C₄₈ 6.45, C₄₉ 1.47, C₅₀ 8.5, C₅₁ 1.43, C₅₂ 6.95, C₅₃ 1.05, C₅₄ 4.0. The validity of these estimates was verified by similar determinations performed on molecular distillates of butterfat and on butterfats with known amounts of added saturated and unsaturated long chain triglycerides. The fatty acid carbon recoveries estimated on the basis of the observed triglyceride peak proportions were of the order of 95% or better. A comparison of the experimentally determined triglyceride type distributions with those calculated on the basis of a completely random fatty acid arrangement for the blended and the molecularly distilled samples showed considerable differences, the most apparent of which was the greater proportion of both short and long chain triglycerides consistently predicted for the random population. On the basis of these studies, it is suggested that butterfat possesses a non-random fatty acid distribution which is reflected in its triglyceride type distribution. Presented at the AOCS meeting in Toronto, Canada, 1962     

The metabolism of native and randomized butterfat chylomicrons in the rat is similar

Reportedly’ randomly rearranging the position of fatty acids (FA) in butterfat triacylglycerol (TAG) by interesterification’ thereby lowering the proportion of saturated FA in the sn-2 position’ reduces its hypercholesterolemic and hypertriglyceridemic properties when fed to humans. The aim of this work was to determine if these reductions in plasma cholesterol and TAG could be explained by an improved rate of clearance from the plasma of chylomicrons composed of randomized butterfat’ using a rat model. Acute chylomicron clearance studies demonstrated no differences in fractional clearance rates of cholesteryl esters and TAG from the plasma of rats infused with chylomicrons produced from gastric feeding of either native (NBF) or randomized (RBF) butterfat. Although there was a 14% decrease in the level of saturated FA occupying the sn-2 position of TAG in RBF compared with NBF’ this difference became negligible (∼5%)’ following digestion of the fat and subsequent repackaging of TAG into chylomicrons. These observations suggest that the previously observed reduction in hypercholesterolemic properties of randomized butterfat in rat is unlikely to be explained by improved clearance of chylomicron TAG.     

工艺因素对轻烧白云石活性度的影响

为考察白云石轻烧工艺对轻烧白云石活性的影响,为实际白云石轻烧生产提供最佳轻烧条件,以河南卫辉白云石为主要原料,研究了其粒度(分别为5±2、10±2、20±2、50±5和(100±5)mm)、轻烧温度(分别为1 100、1 200、1 250℃)和保温时间(分别为1、2、3 h)对白云石轻烧料活性度的影响。研究结果表明,白云石的粒度、轻烧温度和保温时间对轻烧白云石的活性度有较大影响,其最佳工艺条件为:粒度(20±2)mm,轻烧温度1 200℃,保温时间2 h。     

Environment and colour: The technological interface

Technology and colour are viewed as interfaces between the environment, humans and human activity. Examples are provided of ways of facilitating and improving access to and use of colours by commercial users of colour coatings through improvements in the accuracy of measuring and displaying colour. By analogy, the task of providing effective interfaces within the coatings industry, between the coatings industry and the environment and between the coatings industry and the public and political domain are discussed. Examples of information shortfalls are cited to illustrate how distortions arise. Examples of more effective, integrated technological, organisational and political interfacing are culled from the author's experiences.     

Volatile compounds produced by copper-catalyzed oxidation of butterfat

Anhydrous butterfat treated with copper and stored under vacuum at 38C in the dark for 9 weeks yielded the C_5–8 n-alkanes, acetic acid and the C_4,5,7,9 alkan-2-ones. The same butterfat stored under oxygen for 1 week yielded the C_1,2,3,5-7 n-alkanes, the C_2,4–6,8 alk-l-enes, the C_7,8 alk-l-ynes, the C_2–6 n-alkanoic acids, ethanol, the C_2–7 n-alkanals, 3-methylbutanal and 4-methylpentanal, the C_1–4 n-alkyl formates, ethyl acetate and propionate,n-propyl acetate and propionate, and butanone. Both treatments yielded carbon dioxide. All samples including those not treated with copper yielded butane-2,3-dione. Visiting Scientist from Division of Dairy Research, C.S.I.R.O., Highett, Victoria, Australia.     

无水乙醛肟的制备

乙醇肟是生产农药灭多威的中间体,也是重要的有机合成试剂和分析试剂[1]。用于有机合成的乙醛后有时必须要求无水（如：与酰氯和异氰酸酯的反应）,而目前国内市场提供的乙醇肟为含量40％左右的水溶液,不能满足需要,为此,我们对无水乙醛股的制备做了研究。无水乙醛肟可由相应乙醛肟水溶液制备。乙醛肟水溶液由盐酸羟胺或硫酸羟胺与乙醛反应而得。本文用盐酸羟胺和乙醛反应所得已醛肟水溶液经萃取、分离、蒸馏制备无水乙酸肟,取得了较好的结果。1实验部分1.1试剂与仪器．乙醛为分析纯;盐酸羟胺、氢氧化钢和二氯甲烷均为化学纯。CR－3…     

无水乙醛肟的制备

乙醛肟是生产农药灭多威的中间体,也是重要的有机合成试剂和分析试剂[1]。用于有机合成的乙醛肟有时必须要求无水(如：与酰氯和异氰酸酯的反应),而目前国内市场提供的乙醛肟为含量40％左右的水溶液,不能满足需要,为此,我们对无水乙醛肟的制备做了研究。