High-yield enzymatic glycerolysis of fats and oils

Several triglyceride fats and oils were reacted with glycerol using lipase as catalyst. A batch system with magnetic stirring was used without the addition of any solvents or emulsifiers. In all cases a mixture of mono-, di- and triglycerides was obtained. However, the yield of monglyceride (MG) depended strongly on the reaction temperature: at higher temperatures approximately 30% MG was produced at equilibrium while at lower temperatures a yield of 65%–90% MG was obtained for most of the fats examined. The upper temperature limit below which a high MG yield could be attained was designated the critical temperature (T_c). The value of T_c depended on the fat type and was found to vary between 30°C and 46°C for naturally occurring hard fats. A high MG yield could not be obtained for fully hydrogenated tallow and lard under the conditions described here. Of the three liquid oils examined, rapeseed oil and olive oil had a T_c of 5°C and 10°C respectively whereas a high yield of MG could not be obtained with corn oil at 5°C or greater. The maximum yield of MG below T_c also depended on the fat type: the highest yields being obtained for olive oil (90%), palm stearin and milk fat (80%) and the lowest yield for palm oil (67%). In all cases a high yield of MG was accompanied by solidification of the reaction mixture. The effect of enzyme type on MG production was examined for palm oil and palm stearin and the effect of water concentration was examined for palm oil.     

脂肪酶促乌桕脂组分甘油解及其反应机理研究

Glycerolysis of Chinese vegetable tallow （CVT） fraction was investigated using a 1,3-specific lipase from Rhizopus arrhizus as catalyst. Based upon a binary gradient HPLC with an evaporative light-scattering detector （ELSD）, the contents of free fatty acids （FFA）, monoglycerides （MG）, diglycerides（DG） and triglycerides （TG） with their positional isomers during the glycerolysis were determined. The effects of water content and the ratio of glycerol to oil on the product distribution of glycerolysis were studied. Under the optimum reactant conditions： 250 units lipase per gram oil at 37℃ with 1：2 molar ratio of oil to glycerol in a solvent-free system, after 24 h reaction, the product consisted of 7.2% TG, 25.6% MG, 56.1% DG and 4.9% FFA （all by mass）. Furthermore, the mechanism of glycerolysis was discussed in detail.     

Studium der UV-Spektren oxydierter Fette III

Studies on the UV-Spectra of Autoxidized Fats III The author has determined the various properties of oxidized oils and fats with relation to the first maximum of extinction E₁ according the direct UV-method (E_1cm^1%). Following fats and oils were investigated: sunflower oil, rapeseed oil, peanut oil, soybean oil, corn oil, lard, butter, beef tallow and hardened edible fat.     

Spurennachweis von mehrfach verzweigten Fettsäuren in Fetten

Detection of Traces of Polybranched Fatty Acids in Fats A method for the detection and quantitative determination of saturated polybranched fatty acids in animal and vegetable fats is described. The method is based on gas-chromatographic determination of polybranched fatty acid methyl esters in the methyl esters which do not form urea adducts. The following amounts of polybranched fatty acids were determined in animal fats: whale oil 15 000 ppm., fish oil 6000 ppm., butter fat 4000 ppm., beef tallow 2000 ppm. and lard 110 ppm. In different vegetable oils and fats upto 200 ppm. of polybranched fatty acids were found. Not only the difference in total content of polybranched fatty acids but also differences in their percentage composition and retention volumes in gas-chromatograms were found. This method therefore offers the possibility of identification of some of the animal fats.     

Solid phase enzymatic glycerolysis of beef tallow resulting in a high yield of monoglyceride

A mixture of mono-, di- and triglycerides was obtained when beef tallow was reacted with glycerol using lipase enzyme as a catalyst. The reaction was carried out batchwise in a small vessel with agitation by magnetic stirring. The yield of monoglyceride (MG) was greatly influenced by the reaction temperature—at higher temperatures (48–50°C) a yield of approximately 30% MG was obtained, while at lower temperatures (38–46°C) a yield of approximately 70% MG was obtained. A sharp transition was observed between the high and low yield equilibrium states. The temperature at which this transition occurred is called the critical temperature (T_c) and was found to be 46°C in the case of tallow. During the course of the reaction, when approximately 40% MG had been synthesized, the reaction mixture became solid but the reaction continued until approximately 70% MG had been synthesized. A yield of 70% MG also was obtained with tallow at 42°C when a glycerol/tallow mole ratio ranging from 1.5 to 2.5 was used. The free fatty acid content at equilibrium depended on the water concentration in the glycerol phase and varied from 0.5% to 11.0% when the water content ranged from 0.6% to 12.5%. Above 8% water content, the yield of MG was reduced. Of the commercially available lipases that were investigated, lipase fromPseudomonas fluorescens orChromobacterium viscosum resulted in the highest yield of MG.     

Detection of lard and randomized lard as adulterants in refined-bleached-deodorized palm oil by differential scanning calorimetry

A study was conducted to assess the use of differential scanning calorimetry (DSC) for detecting the presence of lard/randomized lard as adulterants in refined-bleached-deodorized (RBD) palm oil. Lard extracted from the adipose tissues of pig was chemically interesterified using sodium methoxide as catalyst. DSC thermal profiles of both genuine lard and randomized lard were compared with those of other common animal fats such as beef tallow, mutton tallow, and chicken fat. Lard and randomized lard were then blended with RBD palm oil in two series, in proportions ranging from 0.2 to 20%, and DSC analyses were obtained. The DSC cooling profiles of adulterated RBD palm oil samples showed an adulteration peak corresponding to lard/randomized lard in the low-temperature region. This peak was confirmed as an indicator of the presence of lard in RBD palm oil since similar experiments carried out using other common animal fats such as mutton tallow, beef tallow, and chicken fat showed that the lard adulteration peak could be distinctly identified. Using this method, a detection limit of 1% lard/randomized lard was reached (P<0.0001).     

Physical and chemical properties of randomly interesterified blends of soybean oil and tallow for use as margarine oils

Refined, unhydrogenated soybean oil and edible beef tallow were interesterified with sodium methoxide. This was done as an alterna-tive to hydrogenation for the production of plastic fats for use as margarine oils. Using 0.5% sodium methoxide at 80 C, interesterifi-cation was complete in 30 min as determined by lipase hydrolysis. A blend of 60% soybean oil and 40% edible beef tallow was found to have physical characteristics (melting point, solid fat index) similar to those of commercial tub margarine oils. The level of poly-unsaturated fatty acids was slightly lower and the level of saturated fatty acids slightly higher than the commercial margarine oils. Iodine value andtrans fatty acid determinations indicated no dis-cernible effect on the degree of unsaturation or the level of isomeric fatty acids by the interesterification process. The interesterified blend did contain 3.0%trans fatty acids which were originally present in the tallow. Oxidative stability of the interesterified oils was estimated by peroxide value determinations over several days on samples stored at 60 C. Experimental blends treated with 0.1% citric acid had poorer stability than the partially hydrogenated margarine oils; however, 0.01% BHA significantly delayed oxidation of the experimental samples. Presented at the JOCS/AOCS annual meeting, 1979, San Francisco. Paper No. 6797, Journal Series, Nebraska Agricultural Experiment Station.     

Enzymic hydrolysis of animal fats in organic solvents at temperatures below their melting points

Lipase fromCandida rugosa catalyzed the hydrolysis of inedible beef tallow and pork lard (edible and inedible) in the presence of organic solvents at temperatures below the melting point of the fat. Reactions were carried out at 50% substrate with 180 lipase units per gram of fat in a two-liter reactor. In the presence of isooctane (5-10%) beef tallow yielded 94% hydrolysis in 24 hr both at 37° and 31°C. Edible pork lard yielded 97% hydrolysis under these conditions and at temperatures as low as 25°C, while inedible lard gave hydrolysis intermediate between the other two fats.     

Lipase-catalyzed glycerolysis of olive oil in organic solvent medium: Optimization using response surface methodology

Enzymatic glycerolysis of olive oil for mono- (MG) and diglycerides (DG) synthesis was investigated. Several pure organic solvents and co-solvent mixtures were screened in a batch reaction system. The yields of MG and DG in co-solvent mixtures exceeded those of the corresponding pure organic solvents. Batch reaction conditions of the glycerolysis reaction, the lipase amount, the glycerol to oil molar ratio, the reaction time, and temperature, were studied. In these systems, the high content of reaction products, especially MG (55.8 wt%) and DG (16.4wt%) was achieved at 40 °C temperature and 0.025 g of lipase with relatively low glycerol to oil molar ratio (2: 1) within 4 h of reaction time in isopropanol/tert-butanol (1: 3) solvent mixture. Glycerolysis reaction was optimized with the assistance of response surface methodology (RSM). Optimal condition for reaction conversion was recommended as lipase amount 0.025 g, glycerol to oil molar ratio 2: 1, reaction time 4 h and temperature 40 °C.     

Umesterung und Hydrierung der Schlachttierfette

Interesterification and Hydrogenation of Animal Fats. Directed and indirected interesterification of fats alters the distribution of fatty acids in triglycerides and thus changes the physical properties, such as melting behaviour, crystallization and plasticity. Slight refining (hydro-refining) improves the stability of fats. Industrial processes and their possible applications, either individually or in combination, for the modification of animal fats (lard and beef tallow) are reviewed. These processes enable better utilization of animal fats.     

Chemical and enzymatic interesterification of a beef tallow and rapeseed oil equal‐weight blend

A mixture of beef tallow and rapeseed oil (1:1, wt/wt) was interesterified using sodium methoxide or immobilized lipases from Rhizomucor miehei (Lipozyme IM) and Candida antarctica (Novozym 435) as catalysts. Chemical interesterifications were carried out at 60 and 90 °C for 0.5 and 1.5 h using 0.4, 0.6 and 1.0 wt‐% CH₃ONa. Enzymatic interesterifications were carried out at 60 °C for 8 h with Lipozyme IM or at 80 °C for 4 h with Novozym 435. The biocatalyst doses were kept constant (8 wt‐%), but the water content was varied from 2 to 10 wt‐%. The starting mixture and the interesterified products were separated by column chromatography into a pure triacylglycerol fraction and a nontriacylglycerol fraction, which contained free fatty acids, mono‐, and diacylglycerols. It was found that the concentration of free fatty acids and partial acylglycerols increased after interesterification. The slip melting points and solid fat contents of the triacylglycerol fractions isolated from interesterified fats were lower compared with the nonesterified blends. The sn‐2 and sn‐1,3 distribution of fatty acids in the TAG fractions before and after interesterification were determined. These distributions were random after chemical interesterification and near random when Novozym 435 was used. When Lipozyme IM was used, the fatty acid composition at the sn‐2 position remained practically unchanged, compared with the starting blend. The interesterified fats and isolated triacylglycerols had reduced oxidative stabilities, as assessed by Rancimat induction times. Addition of 0.02% BHA and BHT to the interesterified fats improved their stabilities.     

On the glyceride composition of animal fats

Summary In agreement with comments of Hilditch but in contrast with certain other statements in the literature it is concluded that lard, beef tallow, and mutton tallow are non-random in distribution of fatty acid chains among their glycerides. From thermal and x-ray diffraction techniques applied to S₃, S₂U, SU₂, and U₃ fractions of these fats and to the various products of complete hydrogenation it is concluded that lard is composed largely of 2-palmityl glycerides as proposed by Hilditch while the tallows are composed largely of 1-palmityl glycerides.     

Untersuchungen über die Fettverwertung der Regenbogenforelle (Salmo gairdnerii,R.) VI: Vergleichender Einsatz von 18 unterschiedlichen Futterfetten in einer gereinigten Diät

Investigations about Fat Utilization of the Rainbow Trout (Salmo gairdnerii, R.) VI: Comparative Use of 18 Different Feeding Fats in a Purified Diet In the submitted work the usability of different feeding fats as source of energy in rations for rainbow trouts is reported. In comparison to 10% of sunflower oil in a standard diet the same amount of examined fats (maize germ oil, rice oil, lard, Novitol-30) with a share of less than 3% of essential linolenic acid (18:3, n-3) produced a just so good utilization. Only olive oil with an unbalanced high content of oleic acid decreased significantly. If a share of 6–7% in 18:3, n-3, fatty acids was contained in the feeding fat (rape seed oil poor in erucic acid and rich in erucic acid, raw and refined soya bean oil, refined soya fatty acids) the utilization increased significantly. The best result was achieved by addition of refined soya fatty acids with 15% 18:3, n-3, or red perch oil with a share of 17% 20:5, n-3 and 22:6, n-3. If beef tallow and especially micronized hardened fatty acids were used whose melting point was far beyond 40°C, a significant decrease in utilization was noticed. These fats proved to be less suitable as source of energy in rations for rainbow trouts. The same good characteristics of utilizations as with soya bean oil and rape seed oil were found in case of use of mixed animal fats, though no essential fatty acids were contained. An explanation could not be found. Linseed oil came off badly, though a surplus of essential fatty acids 18:3, n-3 was contained. The high rate of oxidations of the three fold unsaturated linolenic acid and as result a lacking absorption might be the cause.     

A rapid and quantitative procedure for the preparation of methyl esters of butteroil and other fats

A simple and convenient method for the quantitative preparation of methyl esters of fatty acids from glyceride fats and oils is described. The procedure, using potassium methylate as catalyst and a heating interval of 2 min at 65C in a closed vial, is applicable to fats containing both low and high molecular weight fatty acids such as butteroil. The methyl esters of samples ranging from a few mg to 30 mg are isolated by CS₂ extraction and a TLC technique. A similar procedure using sulfuric acid in methanol as catalyst is described for the conversion of free fatty acids to methyl esters. For the routine analysis by GLC of fats and oils such as lard, tallow, soybean, cottonseed oil or butteroil, no isolation of the methyl ester is required. A CS₂ extraction carried out in the reaction vial allows the GLC analysis immediately after the reaction period (2 min). Presented at the AOCS Meeting, Philadelphia, October 1966. E. Utiliz. Ees. Dev. Div., ABS, USDA.     

A continuous process for the glycerolysis of soybean oil

A continuous process for the glycerolysis of soybean oil with pure and crude glycerol, the co-product from the transesterification of soybean oil, was investigated in a pilot plant. The process was equipped with a static and a high-shear mixer. The experimental studies explored the effects of variations in mixing intensity, temperature, reactant flow rates, and reactant stoichiometry on the formation of MG and DG. The developed process resulted in high conversion of TG to MG. The most favorable conditions were 230°C, 40 mL/min total flow, 25 min of reaction time, 2.5∶1 molar ratio of glycerol/soybean oil, and 3600 rpm for the reactions involving crude glycerol where the concentrations of MG and DG in the product were about 56 and 36 wt%, respectively. Under similar conditions, glycerolysis of pure glycerol resulted in 58% MG and 33% DG. In general, higher temperatures and mixing intensities favored the conversion of TG to MG and DG. Reaction temperature had a greater influence on the extent of the reaction than mixing. The formation of MG approached equilibrium for nearly all cases under investigation.     

Physical analyses of gel-like behavior of binary mixtures of high- and low-melting fats

Gel-like fat mixtures of high-melting (HM) and low-melting (LM) fats were formed by means of rapid cooling and subsequent heating. No “non-fat” ingredients such as emulsifiers, water, or waxes were added to the mixtures. The gel-like fats having solid fat content (SFC) values below 2.0 wt% formed crystal networks of HM-fats that entrapped the liquid oil fraction of LM-fats. In a search for optimal fat combinations exhibiting gel-like behavior, fully hydrogenated rapeseed oil with a high amount of behenic acid (FHR-B), fully hydrogenated rapeseed oil with a high amount of stearic acid (FHR-S), tristearoylglycerol (SSS), triarachidonoyl-glycerol (AAA), and tribehenoylglycerol (BBB) were examined as the HM-fats. For LM-fats, sal fat olein (SFO), cocoa butter (CB), palm super olein (PSO), and olive oil were examined. The following results were obtained: (i) the gel-like behavior was observed in mixtures of FHR-B/SFO and FHR-B/CB with initial concentrations of FHR-B of 1.5–4.0 wt%. (ii) Rapid cooling to T _c (crystallization temperature) from 70°C and subsequent heating to T _f (final temperature) were necessary to reveal the gel-like behavior, whereas simple cooling without a cooling/heating procedure did not form the gel-like fat mixture. (iii) Optimal values of T _c and T _f were related to the m.p. of the LM-fat and HM-fat, respectively. (iv) Temperature variations of SFC as well as X-ray diffraction spectra showed that the melt-mediated transformation from α to β of the HM-fat crystals was a prerequisite to reveal the gel-like behavior. Consequently, the fat mixture revealing the gel-like behavior might be called β-fat gel.     

The effect of various dietary factors on the size distribution of lymph fat particles in rat

By means of cellulose acetate electrophoresis and measurement of radioactivity, lipoproteins (d≤1,006) of lymph collected from rats fed a diet containing fats added to labeled fatty acids for 20–24 hr, have been separated into two kinds differing in their size. Fats with different saturated and unsaturated fatty acid content were tested: corn oil, lard, mutton tallow, tripalmitin, corn oil-lard mixture, and randomized palmitic-linoleic triglycerides. Factors studied were: (a) increased amounts of these fats given alone or included in a test meal; (b) added amounts of nutrients (other than fats) in the test meal; (c) adaptation to a diet containing 20% fat for 10 days. The major part of the labeled lymph lipid was always transported by the smaller particles. Size distribution of lymph fat particles was influenced by some of the factors studied. Generally, unsaturated fats produced higher amounts of larger particles.     

Rapid densitometric determination of triglyceride groups by argentation thin layer chromatography

A method has been developed for the quantitative thin layer chromatographic determination of the triglyceride groups, differing in unsaturation, based on densitometry of the charred bands. Complete separation was achieved by continuous development in an open glass jar. The need for correction coefficients was avoided through addition of bromine to the double bonds prior to charring in the presence of sulphuryl chloride. The accuracy and precision of the method were evaluated on a standard mixture and on sunflower oil, olive oil, lard, cocoa butter, and beef tallow. The method is applicable for triglyceride group analysis of the most common fats and oils which contain saturated, monoene, and diene acids.     

Influence of cabbage juices on oxidative changes of rapeseed oil and lard

The influence of white cabbage on oxidative and thermooxidative changes of plant fats (rapeseed oil) and animal fats (lard) was determined by an array of standard tests. The fats were heated at 100 °C for 6 h in a model system mimicking normal cooking conditions in the presence or absence of fresh cabbage juice (FCJ) or sauerkraut juice (SJ). After thermal processing of fats in the presence of cabbage juices, regardless of the kind, the formation of oxidized triacylglycerols (TAG) was decreased by about 40% compared to fats heated alone. Juices also inhibited the formation of TAG dimers and polymers. Such parameters as peroxide value, extinction coefficient at 232 nm (E^1%_1cm), and losses of polyene fatty acids revealed the protective effect of cabbage juices as well; however, in this case FCJ displayed a much stronger antioxidant effect than SJ. The protection was more visible for lard which contains much lower amounts of natural antioxidants.