TAG composition of ewe's milk fat. Detection of foreign fats

The TAG composition of 45 samples of ewe's milk, collected throughout the year from five Spanish breeds, was analyzed according to their carbon number by using short capillary column GC. The TAG content had a bimodal distribution with maxima at C₃₈ (12.8%) and C₅₂ (8.4%). The TAG composition did not vary significantly with respect to the time of year of sampling but was affected by the breed. Multiple regression equations based on TAG content are proposed to detect foreign fats in ewe's milk fat. Analysis of known mixtures of lard, palm oil, and cow's milk fat with ewe's milk fat have experimentally confirmed the accuracy of the equations.     

Numerical and experimental methodology for the development of a new membrane prototype intended to microfiltration bioprocesses. Application to milk filtration

In tangential flow filtration, the non-uniform TransMembrane Pressure (TMP) on the membrane length produces a non homogeneous filtration cake, initiates process selectivity changes and modifies the permeate quality. The purpose of this study is to create a tubular ceramic membrane prototype with a more uniform TMP, intended to filtration of fouling fluids. The principle of this membrane structure is to waterproof the external membrane surface to limit flow circulation in the porous support of the membrane. The production was controlled by sizing «permeation vents». This development was achieved using a CFD modelling tool interacting with experiments. A preliminary modelling study was made with water. This work was afterwards applied to the industrial process of casein micelle separation from skim milk. The influence of operating conditions on the membrane hydrodynamics was highlighted. The modelling results were experimentally confirmed, with a discrepancy smaller than 3% and a reproducible water permeability of 2.3 L h⁻¹ bar⁻¹ for 1 mm-wide vent (TMP = 1 bar, T = 20 °C). Then, milk filtration experiments showed a production ratio milk/water equal to 1/2. The permeate quality parameters were studied and the fouling phenomena were taken into account. A parametric study led to the sizing of a final prototype. Its efficiency was experimentally evaluated.     

Triglyceride analysis by consecutive liquid-liquid partition and gas-liquid chromatography.Ephedra nevadensis seed fat

The triglyceride composition ofEphedra nevadensis seed fat, which contains 16 different fatty acids, has been analyzed by a combination of liquid-liquid partition and gas-liquid chromatography. Triglycerides were first separated by liquid-liquid partition chromatography. The recovered fractions were then analyzed by gas-liquid chromatography to determine the molecular weights of the triglycerides present. Consecutive separation by these two techniques resolved this complex seed fat into 30 different triglyceride groups. A method for preparative liquid-liquid partition chromatography of triglycerides is described in detail. Highly unsaturated triglyceride mixtures are easily resolved on the basis of “partition number” by using a hexadecane/nitroethane partition system. Presented at the AOCS Meeting, Chicago, October, 1967.     

Aqueous lipid phases of relevance to intestinal fat digestion and absorption

The phase behavior of monoglyceride/water systems, with oleic and linoleic acid as the dominating fatty acid residues, was investigated. Increased solubilization of triglycerides (oil) or oleic acid in the cubic liquid-crystalline phase formed by monoglyceride and water resulted in the formation of a reversed hexagonal liquid-crystalline phase followed by an L2-phase. The liquid-crystalline phases have different dispersion properties compared to each other in dilute micellar bile salt solutions. The cubic phase is found to be easily dispersed. The relevance of aqueous lipid phases other thah micellar is discussed in relation to intestinal lipid digestion and absorption.     

Feeding encapsulated oils to increase the polyunsaturation in milk and meat fat

Journal of the American Oil Chemists' Society - Methods of preparing encapsulated, or protected vegetable oil supplements for feeding ruminant animals to increase the polyunsaturation in milk...     

Solid immiscibility in milk fat fractions and methods to determine their occurrence

In this work, the occurrence of solid phase immiscibility during the fractionation process of milk fat is documented. It is shown that solid phase immiscibility occurs in normal fractionation procedures, upon crystallisation at low temperatures and in particular on further fractionation of narrow melting fractions. This phenomenon results in distinct phases of crystallisation. In some cases, the initial phase yields intermediate solid levels independent of increasing supersaturation. The subsequent increase of solids content is solely a contribution of a second, independent crystallisation event. Furthermore, it could be shown that the induction time for the second crystallisation event is not influenced by the presence or absence of the first triacylglyceride group. These results clearly indicate the independence of the crystallisation of the different immiscible fractions in terms of kinetics and thermodynamics. The different processes during the crystallisation process are monitored simply by viscosimetry.     

Application of silica gel-sintered plate to thin layer lipid chromatographic analysis

The merits and disadvantages of using the silica gel-sintered plate for lipid chromatographic analysis were investigated in detail. The commercially available sintered plate could be used repeatedly, employing the reconditioning procedure which involved chromic-sulfuric acid treatment and subsequent activation. The reconditioned sintered plate has now been used successfully 20 times, for lipid analysis without any deterioration of the excellent resolution power for complex lipid mixtures for all the solvent systems. Since the sintered plate is sturdy, the chromatogplate could be immersed directly in the liquid reaction mixture, so that spots on the chromatogram could be seen and impregnated plates prepared simply. The sintered plate was found to be much more economical than the silica gel-coated plate. Presented in part at the Japan Oil Chemists' Society 20th Annual Meeting, Tokyo, November 1972 The following abbreviations are used in this paper: TLC, thin layer chromatography; PA, phosphatidic acid; PS, phosphatidylserine; PC, phosphatidylcholine; LPC, lysophosphatidylcholine; PI, phosphatidylinositol; SPM, sphingomyelin; PE, phosphatidylethanolamine; PG, phosphatidylglycerol; CL, cardiolipin; CMH, ceramide-monohexoside; CDH, ceramide-dihexoside; CTH, ceramide-trihexoside; NL, neutral lipid.     

Lipid class separation by HPLC combined with GC FA analysis: Comparison of seed lipid compositions from different <Emphasis Type="Italic">Brassica napus</Emphasis> L. varieties

A reliable HPLC method was established to evaluate the lipid composition of useful plants modified by breeding techniques. This study focused on the polar lipid distribution and polar lipid FA compositions of four rapeseed varieties. Structure and quantity of the distinct lipid classes were compared by HPLC using ELSD followed by a GC FA analysis. A baseline separation of 14 lipid classes could be achieved within one step by using an eluent gradient of hexane, tert-methylbutyl ether, isopropanol, acetonitrile, chloroform, triethylamine, acetic acid, and water supplemented with ammonium sulfate with a polyvinyl alcohol column. After automatic fractionation, the FA compositions of the distinct lipid classes were characterized by a subsequent complementary GC FA analysis through direct acetylchloride methylation. The rape varieties analyzed showed diversity in polar lipid content and distribution, dominated by PC, PE, PI, monoglycosyldiacylglycerols, and phytosterols. Extensive variations were detected in FA within the lipid classes of rape varieties with predominantly oleic acid, linoleic acid, and α-linolenic acid observed followed by palmitic acid and gondoic acid. Oleic acid was mainly connected to PC and linoleic acid to PE, whereas α-linolenic acid and γ-linolenic acid were predominantly linked to PI in all varieties.     

Thermal analysis of palm mid-fraction,cocoa butter and milk fat blends by differential scanning calorimetry

Commercial samples of anhydrous milk fat (AMF), Ivory Coast cocoa butter (CB) and palm mid-fraction (PMF) were blended in a ternary system. The melting characteristics of the blends were studied by differential scanning calorimetry (DSC). Results suggest that in the studies of interaction involving more than two fats, partial area (A_i) under the melting peak should be converted to partial enthalpy (ΔH_i) rather than to solid fat index. The ΔH values of the blends decreased as the amount of AMF was increased and increased as the amount of CB was increased. In general, the effect of PMF was less pronounced compared to the effect of the other two fats. Eutectic effects within the ternary system could be detected by measuring the deviation of melting enthalpy by DSC, and from the corresponding values that were calculated for the thermodynamically ideal blends. The deviation reached a maximum when the amount of AMF was about 33%. On the binary line of CB/PMF, the eutectic effect was maximum at about 50–75% PMF. The interaction effect in the system was more noticeable at 30 and 20°C than at lower temperatures. Evaluation at 30°C was preferred because both the effect of AMF in the ternary system and the effect of PMF on the binary line were more readily observed.     

Application of response surface methodology for the optimization of supercritical carbon dioxide extraction and ultrasound-assisted extraction of Capparis spinosa seed oil

Caper (Capparis spinosa) seed oil growing wild in Iran was extracted using supercritical CO₂ and ultrasound-assisted extraction methods. The experimental parameters of SFE and UAE were optimized using a rotatable central composite design. The highest yield for SFE was obtained at a pressure of 355 bar, temperature of 65 °C, modifier volume of 140 μL, static and dynamic extraction time of 10 and 35 min, respectively, and for UAE was gained at solvent volume of 23 mL, sonication time of 45 min and temperature of 40 °C. This resulted in a maximum oil recovery of 25.1% and 27.9% for SFE and UAE, respectively. The extracts with higher yield from both methods were subjected to transesterification and GC–MS analysis. SFE and UAE processes selectively extracted the fatty oils with high percentage of omega-6 and omega-9-fatty acids. The major components of the extracted oils from both methods were linoleic, oleic, its positional isomer cis-vaccenic and Palmitic acid.     

FA composition and regiospecific analysis of Acer saccharum (sugar maple tree) and Acer saccharinum (silver maple tree) seed oils

GC analysis was performed to determine regiospecific distribution and FA composition in seed oils of the Aceraceae species, Acer saccharum and A. saccharinum. The oil content in the seeds was low at 5.0% in A. saccharum and 5.8% in A. saccharinum, and the main FA were linoleic (30.8 and 29.4%), oleic (21.3 and 27.6%), palmitic (10.1 and 10.5%), and cis-vaccenic (9.4 and 7.9%) acids, respectively. In addition, both oils contained long-chain monoenes of the n−9 and n−7 groups, including 11-eicosenoic, 13-docosenoic, 15-tetracosenoic, 13-eicosenoic, and 15-docosenoic acids, whereas γ-linolenic acid accounted for 0.8% of total FA in A. saccharum, and 0.5% in A. saccharinum. Regiospecific analysis, performed using the methodology of dibutyroyl derivatives of MAG, indicated that linoleic, oleic, and linolenic acids were mainly esterified at the internal position of TAG in both seed oils, whereas long-chain monoenes of the n−7 group were almost exclusively esterified on the external positions.     

Determination of mixtures in vegetable oils and milk fat by analysis of sterol fraction by gas chromatography

A rapid gas-chromatographic (GC) procedure was developed for the analysis of the total sterol fraction of vegetable oils, milk fat or mixtures, to detect possible admixtures of sunflower with olive oil and the addition of vegetable oils to milk fat. The method, which employs alkali-catalyzed transesterification with KOH/methanol, was compared with saponification procedures with and without transformation of sterols into silyl derivatives prior to analysis. Repeatability of the method was assessed, and the coefficient of variation was 6.0 and 8.0% for β-sitosterol in olive and sunflower oils, respectively. Recovery of β-sitosterol ranged from 92.6 to 95.8 for both oils. The GC method assayed in this work requires little analysis time and eliminates the need for saponification, extraction, and derivatization steps. It offers good repeatability and recovery and is thus well suited to routine use.     

Unified methodology for thermal energy efficiency improvement: Application to Kraft process

A unified methodology that can be used to identify the interactions between the utilities systems and the process, as well as their impacts on the implementation of energy efficiency measures is presented. It takes into account steam and water systems to analyze the process and formulate energy enhancement measures. It has been applied to an operating Kraft mill in Eastern Canada. The methodology consists of five stages: base-case process definition and characterization, pre-benchmarking, systems interactions analysis, implementation strategy and post-benchmarking. A simulation focused on the energy and water systems is first developed and used as basis of the analysis. The pre-benchmarking characterizes the current energy efficiency of the process by three techniques: energy and exergy content indicators, comparison to the current industrial practice and establishing targets for minimum energy and water requirements determined by the Thermal Pinch and Water Pinch methods. The systems interactions are analyzed to develop complementary energy efficiency measures by applying several energy enhancing techniques. A three-phase strategy is proposed to implement the identified measures. The application of the unified methodology results in an eco-friendly process that does not require fossil fuel for steam production and generates revenues by producing green electricity from biomass. In the case study presented, very significant energy gains have been proposed (26.6% steam requirement reduction and 33.6% fresh water intake reduction).     

The flavor potential of milk fat. A review of its chemical nature and biochemical origin

Actual and potential flavors are among the most important attributes of milk fat. In some dairy products (milk, cream, ice cream, uncul-tured butter) the aim is to retain the faint pleasant flavor associated with the fat of fresh milk. However in cooking, baking, and many processed food applications the object is to gen-erate buttery, creamy, cheesy, and caramel-like flavor qualities from milk fat. Although the ulti-mate chemical characterization of all these fla-vors has not been achieved, the existing infor-mation is reviewed in this paper. Some recent findings concerning the biological variability and significance of the lactone and ketone flavor po-tential of milk fat are also presented. A scheme which outlines means for more effectively utiliz-ing the flavor capabilities of milk fat is included. 1 Authorized for publication on December 1, 1966 as Paper No. 3198 in the Journal Series of the Pennsylvania Agricultural Experi-ment Station. 2 Presented at the AOCS Meeting, Philadelphia, October 1966.     

Thermal behavior of fat droplets as related to adsorbed milk proteins in complex food emulsions. A DSC study

The thermal behavior of hydrogenated palm kernel oil-in-water emulsions, which differed in their milk-protein composition, was studied in parallel with other characteristic parameters such as the aggregation/coalescence of fat droplets, and the proportion of adsorbed proteins at the oil/water interface. DSC was applied to monitor the crystallization and melting behavior of nonemulsified and emulsified fat samples. Comparison between nonemulsified and emulsified fat samples showed that in emulsified samples the initial temperature of fat crystallization and the temperature of the completion of melting were invariably lower and slightly higher, respectively. Furthermore, in complex food emulsions the supercooling temperature needed to initiate fat crystallization and the variation in its growth rate in the cooling experiment were dependent on the amount and nature of the adsorbed proteins. Our results indicate that the total replacement of milk proteins by whey proteins affected the fat crystallization behavior of emulsified fat droplets, in parallel with changes in their protein surface coverage and in their physical stability against fat droplet agglomeration.     

NMR chemical shift reagents. Application to structural determination of lipid derivatives

Chemical shift reagents (csr) markedly expand the nuclear magnetic resonance spectra of lipid derivatives thus providing considerably more structural information than it has hitherto been possible to obtain. Preferred csr are rare earth complexes of europium (III) and praseodymium (III) with certain anionic ligands. The use of csr with methyl oleate is described here.     

Fasting and postprandial lipid response to the consumption of modified milk fats by guinea pigs

The objective of the present study was to investigate the effect of three modified milk fats with different melting profiles on fasting and postprandial lipid responses and on fecal fat content in guinea pigs. We hypothesized that the consumption of modified milk fat with a high m.p. results in reduced fasting and postprandial lipid responses compared with that of modified milk fat fractions with lower m.p. To test this hypothesis, male Hartley guinea pigs were fed isoenergetic diets containing 110 g of fat/kg, either from one of the three modified milk fats with high (HMF), medium (MMF), or low melting profiles (LMF), or from one of the two reference fats as whole mil fat (MF) or a fat blend similar to that of nonhydrogenated soft margarine (MA) for 28 d. Food intake (P<0.05) and body weight gain (P<0.05) were reduced in the animals fed the HMF diet compared with the other groups. In the fasting state, plasma LDL cholesterol was highest in animals fed the LMF diet, intermediary in those fed the MMF and MF diets, and lowest in those fed the HMF and MA diets (P<0.05). Postprandially, the areas under the 0- to 3-h curves for the changes in plasma TG were lower in the HMF group than in the MA- and LMF-fed guinea pigs (P<0.05). The fecal fat content was higher (P<0.05) in the HMF group compared to the other milk fat groups. The present results suggest that modified milk fats can impact food intake, body weight gain, fasting cholesterolemia, and postprandial triglyceridemia, and these changes may be attributed to an altered fat absorption.     

Fluorescent products of lipid peroxidation: II. Methods for analysis and characterization

The effects of pH and of the metal chelator, europium (Tric[2,2,6,6-tetra-methyl-3,5-heptanedionate]), upon fluorescence of lipid peroxidation products were tested, and fluorescence decay times and fluorescence polarization values were determined. Measurements of fluorescence intensity showed that the fluorescence of these compounds was quenched at basic pH and that it was restored by adjustment of pH to neutrality. Metal chelator decreased the fluorescence intensity 8–15%. pH Effects and metal coordination effects are useful for analysis and characterization of these fluorescent products. Fluorescence polarization and fluorescence decay times are also useful analytical techniques for characterization of fluorescent products.     

Rapid transesterification and mass spectrometric approach to seed oil analysis

Fatty acid composition of seed oil is determined in less than one hr using a quantitative one-vial technique. The method of analysis requires alcoholic solutions of sodium methoxide mild enough for epoxy and polyunsaturated oils. Separation and characterization of component fatty acids were accomplished by high resolution gas chromatography-mass spectrometry. Using this method,Vernonia galamensis seed oil is shown to contain 79–80% vernolic (cis-12,13-epoxy-cis-9-octadecenoic) acid.Amaranthus cruentus, a West African vegetable crop, is shown to contain 17.3% palmitic acid, 3.2% stearic acid, 22.7% oleic acid, 54.7% linoleic acid and 2.1% linolenic acid.