Parameters influencing cocrystallization and polymorphism in milk fat

Dry fractionation of milk fat is a common technique used to produce fat fractions with physical properties that are suitable for a variety of food and pharmaceutical products. During milk fat fractionation, the partial crystallization of triacylglycerols from the melt is the most important step. The efficiency of the separation of the crystals from the suspension is also important, but the crystallization itself influences the chemical composition and thereby determines the properties of the crystal fraction. At low supercooling, the crystallization kinetics are slow, and thus process time is increased. With increased kinetics due to a strong supersaturation, the chemical composition of the crystals is changed compared to crystals formed under slow kinetic conditions. This study shows to what extent controlled temperature and supercooling during milk fat crystallization influence crystal amount and the physical properties of the resulting fractions. Differences of the thermal characteristics of the crystal suspensions are directly detected by differential scanning calorimetry and nuclear magnetic resonance. At slow crystallization kinetics, the melting temperature range of the crystals in the suspensions is broader, and the resolution of the melting peak is higher. It is shown that compound crystals are formed when supercooling is performed, even if the supercooling takes place only for a short period of time. Controlled temperature conditions during crystallization govern larger differences in the fatty acid and triacylglycerol composition of the liquid and of the crystalline phases, compared to fractions crystallized under supercooling conditions, which contain a high amount of compound crystals.     

Dietary fat composition influences fatty acid composition of milk fat globule membrane in lactating cows

Milk fat globule membranes are derived directly from the apical plasma membrane of mammary epithelial cells. To evaluate the effect of dietary fat on mammary membranes, we determined the fatty acid composition of the milk fat globule membrane in lactating dairy cows fed diets supplemented with fats of different fatty acid composition, or infused intravenously with soy oil emulsion. A preliminary survey, using an abbreviated preparation procedure (membranes isolated at 48,000 x g-max for 15 min), yielded about 45% of the total membrane fatty acids that could be recovered by centrifuging at the same speed for 120 min, and showed that changes in fatty acid composition of membranes reflected dietary fatty acids to some extent. Dietary palmitic acid increased the content of 16:0 in the membranes. A high corn diet increased ruminal formation of t18:1, and its level increased to 12% of membrane fatty acids. Infusion of soy oil emulsion increased 18:2 membrane content, and decreased the levels of 18:1 and 20:4. All treatments decreased the ratio of unsaturated/saturated fatty acids as compared to controls, whereas the ratio of polyunsaturated/saturated fatty acids was increased by feeding a high corn diet or by infusing soy oil. The ratio of 18:2/c18:1 increased from 0.31 to 1.0 after infusing soy oil for 4 days. The fatty acids of membranes isolated upon 120-min centrifugation were slightly more saturated. The differences were not sufficiently large, however, to affect overall results significantly.     

Conjugated linoleic acid and chromium lower body weight and visceral fat mass in high-fat-diet-fed mice

More than half of the U.S. population has a body mass index of 25 kg/m² or more, which classifies them as overweight or obese. Obesity is often associated with comorbidities such as diabetes, cardiovascular diseases, and cancer. CLA and chromium have emerged as major dietary supplements that reduce body weight and fat mass, and increase basal metabolic rate in animal models. However, studies show that CLA induces insulin resistance in mice and in humans, whereas Cr improves insulin sensitivity. Hence, we designed the present study to examine the combined effect of CLA and Cr on body composition and insulin sensitivity in a Balb/c mice (n=10/group) model of high-fat-diet-induced obesity. CLA alone lowered body weight, total body fat mass, and visceral fat mass, the last of which decreased further with the combination of CLA and Cr. This effect was accompanied by decreased serum leptin levels in CLA-fed and CLA+Cr-fed mice, and by higher energy expenditure (EE) and oxygen consumption (OC) in CLA+Cr-fed mice. Serum levels of glucose, insulin, the pro-inflammatory cytokines, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6), as well as insulin resistance index (IRI), decreased with CLA, whereas CLA and Cr in combination had significant effects on insulin and IL-6 concentrations and IRI. In summary, CLA+Cr decreased body weight and fat mass in high-fat-diet-fed mice, which may be associated with decreased leptin levels and higher EE and OC.     

鸡BF基因第2、3外显子序列及其多态性分析

目的分析鸡BF基因第2、3外显子序列及其多态性。方法从6羽霞烟鸡外周血淋巴白细胞(peripheral blood leukocytes,PBLs)中提取细胞DNA,以其为模板,经PCR法扩增BF基因的第2外显子、第2内含子和第3外显子,克隆至pGM-T载体上,构建重组质粒pGM-T-BF,并进行PCR、酶切和测序鉴定。利用生物信息学DNAStar软件将霞烟鸡与红原鸡第2、3外显子核苷酸及氨基酸序列进行多序列比对。结果经PCR、酶切及测序证明重组质粒pGM-T-BF构建正确。2种鸡BF基因序列的同源性可达88.6%~100%,第2、3外显子存在多态性变异位点91个,占总长度的17.04%,其中简约性信息位点66个,单变异位点25个;在编码相应的178个氨基酸残基中,多态变异位点49个,占总氨基酸残基数的27.53%,其中简约性信息位点37个,分单变异位点12个。结论鸡BF基因第2、3外显子呈高度多态性,且其多态性更多表现在氨基酸水平上。     

Gas recirculation rate and its influences on mass transfer in multiple impeller systems with various impeller combinations

Both the numerical and experimental approaches were used to study the effects of the gas recirculation and non‐uniform gas loading on the mass transfer rate for each impeller in a multiple impeller system. By combining the calculated gas velocity and local gas holdup, the gas recirculation rate around each impeller was estimated. The local mass transfer coefficients for systems equipped with various combinations of the Rushton turbine impeller (R) and pitched blade impeller (P) were determined by using the dynamic gassing out method. It is found that the Rushton turbine impeller has to be served as the lowest impeller in order to have a better gas dispersion and to give a higher overall K_La for a multiple impeller gas‐liquid contactor. The upper pitched blade impeller always enforces the circulating flow around the Rushton turbine impeller just beneath it and gives a higher overall average mass transfer rate. However, the system equipped with only the pitched blade impellers results in a much lower mass transfer rate than the other systems owing to the poor gas dispersion performance of the pitched blade impeller.     

Association of Apo E gene polymorphism with HDL level in Tehranian population

The prevalence of cardiovascular risk factors, especially low level of high density lipoprotein cholesterol (HDL‐C), is very high in Iran. The associations of apolipoprotein E (Apo E) polymorphism with lipid profile, especially high density lipoprotein (HDL) subfractions, were examined in Iranian population. A cross‐sectional study of 1030 subjects (452 men and 578 women) from the Tehran Lipid and Glucose Study (TLGS) was performed. Serum triacylglycerol, cholesterol, FBS, HDL‐C levels and its subfractions, Apo B and Apo A1 were determined and body mass index and blood pressure were measured. A segment of the mentioned gene was amplified by PCR and the polymorphisms were revealed by RFLP using HhaI restriction enzyme. Allele frequencies obtained for APOE*2, APOE*3, and APOE*4 were 5.77, 85.92, and 8.3%, respectively. The presence of the ε2 allele was significantly associated with increased serum HDL‐C levels and its subfractions both in men and women except HDL3 in men. The LDL/HDL ratio was significantly lower in female. The relations were significant even after adjustment for age, sex, and BMI but hypertension, smoking, and diabetes status decreased the effect of Apo E2 on HDL‐C and HDL subfractions. The observed genotype and allele frequencies were similar to those reported for other Caucasians samples. Apo E2 increased the level of HDL‐C, HDL subfractions, and decreased the LDL/HDL ratio. These findings highlight the important effect of variation in this gene on lipid levels.     

High-performance liquid chromatography with light-scattering detection and desorption chemical-ionization tandem mass spectrometry of milk fat triacylglycerols

The utility of reverse-phase high-performance liquid chromatography (HPLC), desorption chemical-ionization mass spectrometry (DCI-MS) and tandem mass spectrometry (MS/MS) for the characterization of triacylglycerols in complex mixtures has been further explored. Triacylglycerols of anhydrous bovine milk fat were separated by using two reversephase C₁₈ HPLC columns, and eluents were monitored with an evaporative light-scattering detector. Fifty-eight fractions were resolved and analyzed by positive ion isobutane DCI-MS. The formation of protonated molecules and of major fragments corresponding to the random loss of any one of the constituent fatty acids readily identified acyl carbon numbers and the number of double bonds within each fatty acid. MS/MS was only required when the original mass spectra indicated the presence of more than one triacylglycerol or of impurities in a fraction. Protonated molecules produced by DCI were fragmented using high energy collisional activation, and the resulting ions were detected by MS/MS. Odd-chain triacylglycerols were also readily distinguished using this methodology. The positive ion DCI and MS/MS techniques described here demonstrate the usefulness of this approach for the characterization of triacylglycerols in complex mixtures.     

Dietary conjugated linolenic acid in relation to CLA differently modifies body fat mass and serum and liver lipid levels in rats

The present study compared the effect of dietary conjugated linolenic acid (CLNA) on body fat and serum and liver lipid levels with that of CLA in rats. FFA rich in linoleic acid, α-linolenic acid, CLA, or CLNA were used as experimental fats. Male Sprague-Dawley rats (4 wk old) were fed purified diets containing 1% of one of these experimental fats. After 4 wk of feeding, adipose tissue weights, serum and liver lipid concentrations, serum tumor necrosis factor (TNF)-α and leptin levels, and hepatic β-oxidation activities were measured. Compared with linoleic acid, CLA and, more potently, CLNA were found to reduce perirenal adipose tissue weight. The same trend was observed in the weight of epididymal adipose tissue. CLNA, but not CLA, was found to significantly increase serum and liver IG concentrations. Serum FFA concentration was also increased in the CLNA group more than in the other groups. The activity of β-oxidation in liver mitochondria and peroxisomes was significantly higher in the CLNA group than in the other groups. Thus, the amount of liver TG exceeded the ability of hepatic β-oxidation. Significant positive correlation was found between the adipose tissue weights and serum leptin levels in all animals (vs. perirenal: r=0.557, P<0.001; vs. epididymal: r=0.405, P<0.05). A less significant correlation was found between adipose tissue weights and serum TNF-α level (vs. perirenal: r=0.069, P<0.1; vs. epididymal: r=0.382, P<0.05). Although the mechanism for the specific effect of CLNA is not clear at present, these findings indicate that in rats CLNA modulated the body fat and TG metabolism differently from CLA.     

Comparative effects of temperature exposure on mass and oxidative enzyme activity of brown fat in insectivores,tupaiads and primates

A study has been made to see if hyperplastic and biochemical responses similar to those which occur in temperature-exposed rodents also occur in insectivores, protoprimates and primates. Representative insectivores included the shrewsSuncus murinus andCryptotis parva. The representative prottoprimate wasTupaia chinensis. The representative primate wasMacaca mulatta. Both shrews show a striking thermogenic response in the brown fat with respect to increased specific activity of α-glycerophosphate oxidase and succinoxidase.Suncus also showed an increase in brown fat mass following cold exposure. In both shrews cold caused the brown fat to become darker in color.Cryptotis did not show a significant increase in brown fat mass, but this may be due to the fact that the cold exposure period was only four days. Thus the shrews appear to be rodent-like with respect to effects of cold on brown fat. In the Tupaiads the ratio of brown fat to body weight is not nearly as high as in rodents nor is there a striking hyperplasia with cold exposure. Thus the brown fat would seem to be of less importance to the Tupaiads than to rodents and shrews and the Tupaiads appear to be intermediate in this respect between the insectivores and the true primates. AdultMacaca, in spite of eight months of cold exposure at about 4–6 C, showed no hyperplasia of the brown fat and no increase in oxidative enzyme levels. Thus in adult primates so far studied, the evidence indicates that brown fat does not play an important role in homeothermy as it does in rodents. One of nine papers to be published from the Symposium “Brown Adipose Tissue,” presented at the AOCS-AACC Joint Meeting, Washington D. C. March, 1968     

The fatty acid composition of depot fat in childhood: II. A comparison of superficial and deep fat

The fatty acid composition of the triglycerides in samples of depot fat obtained from superficial abodominal wall and from deep properitoneal sites in children has been determined. Although no clear pattern was observed, differences in individual subjects could usually be demonstrated between composition at the two sites. Although the differences in most instances were relatively small, these findings provide further evidence aganist the concept of the uniform composition of human depot fat.     

Comparison of coconut water and a carbohydrate-electrolyte sport drink on measures of hydration and physical performance in exercise-trained men

Background  

Sport drinks are ubiquitous within the recreational and competitive fitness and sporting world. Most are manufactured and artificially flavored carbohydrate-electrolyte beverages. Recently, attention has been given to coconut water, a natural alternative to manufactured sport drinks, with initial evidence indicating efficacy with regard to maintaining hydration. We compared coconut water and a carbohydrate-electrolyte sport drink on measures of hydration and physical performance in exercise-trained men.     

The influence of chemical interesterification on the physicochemical properties of complex fat systems. 2. Morphology and polymorphism

Palm oil-soybean oil (POSBO) blends and lard-canola oil (LCO) blends were chemically interesterified with sodium methoxide. Changes in crystal morphology using polarized light microscopy and crystal polymorphic behavior using X-ray diffraction spectroscopy (XRD) were studied. Spherulitic crystalline particles, measuring 10–20 μm, were detected in palm oil (PO). These spherulitic particles were characterized by a dense core surrounded by a lower-density halo region. PO fat-crystal morphology was not greatly altered on addition of soybean oil (SBO), except for a gradual reduction in spherulite size as the amount of SBO in the blends was increased. Chemical interesterification (IE) did not alter PO or POSBO blend fat-crystal morphology significantly. Irregular particles and spherulites of different sizes and shapes were observed in lard, from small crystals to irregular, angular crystal aggregates. Changes in lard fat-crystal morphology due to the addition of canola oil (CO) were concentration-dependent. In general, spherulite diameter decreased with increasing CO addition. IE dramatically altered lard fat-crystal morphology—IE induced the formation of more symmetrical spherulitic crystalline particles, and the halo-to-core ratio was increased significantly. XRD spectroscopic analysis of POSBO blends revealed small changes in the long spacings of PO fat crystals with either blending or IE; all values were close to 45 ?. Short spacings of fat crystals in noninteresterified (NIE) POSBO blends suggested the predominance of β′ polymorphs. IE led to an increase in the proportion of the β polymorph in PO and POSBO blends. Long spacings of NIE lard fat crystals suggested the presence of a bilayer structure in their unit cells (45 ?). Dilution with ≥10% canola oil led to the appearance of a second reflection at 35 ?. β′ polymorphs were predominantly detected in NIE lard and NIE LCO blends. The β polymorph became more evident with increasing addition of CO. Fat crystals in IE lard and IE LCO blends displayed a single long-spacing reflection at 40 ?. IE of lard and LCO blends induced the formation of β polymorphs.     

Some differences in composition of covering fat,intermuscular fat,and intramuscular fat of meat animals

A method is described for rapid, reproducible extraction of total lipids from adipose and muscle tissues. The distribution of polyunsaturated fatty acids in the depot fats and intramuscular lipids in loin or rib roasts of pork, beef, lamb, and veal has been determined. The phosphatides of the muscle were found to contain a greater amount of polyunsaturated fatty acids than the neutral fats of the intramuscular lipids. American Meat Institute Foundation Journal Paper No. 225.     

FADS1 gene polymorphism(s) and fatty acid composition of serum lipids in adolescents

Polyunsaturated fatty acids (PUFA) influence many physiological functions. Associations have been found between single nucleotide polymorphisms (SNP) in the FADS1 (Fatty acid desaturase 1) gene and the relative abundance of PUFA in serum lipids. This study examines the relationship between two SNPs in the FADS1 gene (rs174546, rs174537) and the fatty acid (FA) composition of serum lipids in adolescents (13–18 years). We used DNA samples (670 children; 336 girls and 334 boys) from the Childhood Obesity Prevalence and Treatment (COPAT) project. Genomic DNA was extracted from peripheral blood leukocytes in whole blood samples. For genotype analysis, TaqMan SNP Genotyping assays (Applied Biosystems) were used. Fatty acid composition of serum lipids was assessed using gas chromatography. The T-statistic and regression were used for statistical evaluations. Minor allele T carriers in both SNPs had significant lower level of palmitic acid (16:0, phospholipids) and arachidonic acid (20:4[n-6], phospholipids) in both sexes. In girls, we found a significant positive association between minor allele T carriers and eicosadienoic acid (20:2[n-6], cholesteryl esters) in both SNPs. Being a minor allele T carrier was significantly positively associated with dihomo-γ-linolenic acid (20:3[n-6], phospholipids) in boys in both SNPs. SNPs (including rs174546, rs174537) in the FADS gene cluster should have impacted desaturase activity, which may contribute to different efficiency of PUFA synthesis.     

A carbohydrate-rich diet reduces LDL size in QQ homozygotes for the Gln192Arg polymorphism of the paraoxonase 1 gene

Paraoxonase 1 (PON 1) is an esterase with antioxidant properties that is present in HDL. Gln192Arg polymorphism (also named Q192R or Q/R) of the PON 1 gene that encodes this protein defines two alleles (Q and R). The R allele has been associated with higher cardiovascular risk. LDL size and susceptibility to oxidation also have been identified as cardiovascular risk factors. Our objective was to determine whether genetic variations in the Gln192Arg polymorphism influence LDL size and susceptibility to oxidation after the consumption of diets with different fat content. In our experiments, the participants (n=98), underwent three 4-wk diets—one, saturated fat-enriched (SAT); another, monounsaturated fat-enriched (MONO); and a third, carbohydrate-enriched (CHO). We observed that LDL were smaller in the QQ group after the CHO diet vs. the SAT (P<0.01) and MONO diets (P<0.03). No differences in LDL size were found in QR/RR subjects. When we analyzed lag time of oxidation of LDL, we found that when carriers of the R allele (QR/RR) received the MONO diet, the lag period of LDL oxidation was longer as compared with the CHO diet. Otherwise, we found no differences in QQ homozygotes when we evaluated the lag time of oxidation of LDL after the three diets. These results suggest that the Gln192Arg polymorphism of the paraoxonase gene influences LDL size and susceptibility to oxidation in response to diet.     

生物柴油--快速发展中的油脂化工新产品

简述了我国目前石油化工和煤化工的情况以及我国发展生物柴油的重要性。回顾了世界生物柴油作为一种工业产品的发展史。指出了我国目前发展生物柴油所存在的问题,并对我国开发生物柴油新产品进行了分析。提出了开发生物柴油的必要性及重要性,以及生物柴油广泛的市场前景。     

Heat and mass transfer in spouted beds - A review

The considerable literature on spouting which has accumulated since the inception of this fluid-solid contacting technique fifteen years ago is critically reviewed with reference to heat and mass transfer. The relatively meagre basic data on both surface-to-bed and fluid-to-particle heat transfer, as well as particle-to-fluid mass transfer, are interpreted wherever possible, in the light of understanding gained from more exhaustive information available on the hydrodynamics of the system. Contradicitions are noted and in some cases reconciled. Conclusions are drawn as to the relative merits of various correlations. Design equations for heating or cooling of solids for both batch and continuous systems are formulated and a new theoretical model to describe wall-to-bed heat transfer is proposed.