Interesterification kinetics of triglycerides and fatty acids with modified lipase inn-hexane

The kinetics of lipase-catalyzed interesterification of triglycerides and fatty acids in organic media was studied. First, the lipase Saiken 100,Rhizopus japonicus, was modified by surfactant to form an enzyme precipitate in aqueous solution, which was well dispersed in organic solvents. This modified lipase catalyzed the interesterification of tripalmitin and stearic acid. The enzyme has 1,3-positional specificity and does not distinguish between stearic and palmitic acids. The kinetic model developed to describe the interesterification reaction system is based on mass balance of two consecutive second-order reversible reactions. The reaction rate constant, k, was determined by solving the differential rate equations of the reaction system and by expressing the value of k as a function of concentrations of the substrates with time. The model gave satisfactory results. The best value of the specific reaction rate constant k* that fits all experimental data was 1.2 · 10⁻⁵ [L²/(mmol · mg biocatalyst · h)] under the reaction conditions in this study.     

Effect of interesterification on the structure and physical properties of high-stearic acid soybean oils

Triglyceride structures of genetically modified soybean oils high in stearic acid were determined by high-pressure liquid chromatography, and their physical properties were assessed by dilatometry and dropping point. In their natural state, these oils lack sufficient solids at 10–33°C to qualify as margarine oils. However, after random interesterification, soybean oil containing 17% stearic acid shows a solid fat index (SFI) profile and dropping point closely matching those of a liquid margarine oil. Other oils, with stearic acid contents in the range of 20–33%, showed appreciable SFI values at 10°C but lacked sufficient solids at 21.1–33.3°C. After random interesterification, these oils also exhibited SFI profiles suitable for soft tub margarine, and their drop points increased from 18–19°C to 36–38°C.     

Industrial validation of fourier transform infrared trans and lodine value analyses of fats and oils

A Fourier transform infrared (FTIR) edible oil analysis package designed to simultaneously analyze for trans content, cis content, iodine value (IV), and saponification number (SN) of neat fats and oils by using calibrations based on pure triglycerides and derived by application of partial-least-squares (PLS) regression was assessed and validated. More than 100 hydrogenated rapeseed and soybean samples were analyzed by using the edible oil analysis package as well as the newly proposed modification of the AOCS IR trans method with trielaidin in a trans-free oil as a basis for calibration. In addition, ∼1/3 of the samples were subsequently reanalyzed by gas chromatography (GC) for IV and trans content. The PLS approach predicted somewhat higher trans values than the modified AOCS IR method, which was traced to a combination of the inclusion of trilinolelaidin in the calibration set and the effects of baseline fluctuations. Eliminating trilinolelaidin from the triglyceride standards and the use of second-derivative spectra to remove baseline fluctuations produced excellent concurrence between the PLS and modified AOCS IR methods (mean difference of 0.61% trans). Excellent internal consistency was obtained between the IV and cis and trans data provided by the edible oil analysis package, and the relationship was close to that theoretically expected [IV=0.86 (cis + trans)]. The IV data calculated for the GC-analyzed samples matched the PLS IV predictions within 1 IV unit. The trans results obtained by both IR methods were linearly related to the GC data; however, as is commonly observed, the GC values were significantly lower than the IR values, the GC and IR data being related by a slope factor of ∼0.88, with an SD of ∼0.80. The concurrence between the trans data obtained by the two FTIR methods, and between the FTIR and GC-IV data, as well as the internal consistency of the IV, cis and trans FTIR predictions, provides strong experimental evidence that the edible oil analytical package measures all three variables accurately. Co-Director, McGill IR Group.     

Surface tension of fatty acids and triglycerides

Surface tension as a function of temperature was measured for four fatty acids (lauric, myristic, palmitic, and oleic) and two triglycerides (tricaprylin and tripalmitin). These surface tension measurements were performed using a K12 vers. 3.1 (Krüss GmbH) tensiometer at temperatures from 20 (or the melting point of each substance) to 90°C. The constants for a van der Waals-type correlation as well as for a linear equation are presented. Both equations are quite accurate, presenting mean deviations not exceeding 0.570%. Such correlation constants are valuable in the design or evaluation of processing equipment, especially that involving gas-liquid contact such as distillation and stripping columns, deodorizers, reactors, and equipment for physical refining.     

Organotypic co-culture system to study plant extract bioactivity on hepatocytes

Natural plant extracts are complex mixtures of molecules that have to be uptaken and metabolized, at least by the intestinal barrier, before they reach their body targets. This paper evaluates the feasibility of using a co-culture system to assay the bioactivity of plant extract on hepatic cells closest to the in vivo situation. Caco-2 cells, mimicking intestinal barrier roles, were grown on inserts on a monolayer of HepG2 hepatocytes for 24 h. The co-culture induced some adaptations, but the Caco-2 cells showed no differences in their abilities to filter and metabolize grape-seed derived extract (GSPE) components. The co-culture clearly reproduced the ability of a procyanidin extract to decrease the triglyceride secretion of hepatocytes, a proven in vivo effect. This system mimics a human physiological system that is useful for assaying the bioactivity of extracts and may be able to be used for developing new functional foods.     

Exploratory chemometric analysis for the characterisation of Tunisian olive cultivars according to their lipid and sterolic profiles

This study aims to evaluate some Tunisian olive genetic resources using fatty acid, triacyglycerol and sterolic compositions and to classify the cultivars according to their fruit genotype and to their respective geographical origin (North, Centre and South). manova results showed that the studied cultivars presented highly significant differences regarding all the variables (P < 0.01). The most discriminant variables of fatty acids are C17:1 (F = 98.468), C16:0 (F = 92.994), C18:1 (F = 60.865), C18:1/C18:2 (F = 44.632) and C18:2 (F = 40.167); those of triacylglycerols are POP (F = 123.34), LLL (F = 122.944), LnLO (F = 98.363), POO (F = 93.357) and LOO (F = 90.42), while sitostanol (F = 289.171), campestanol (F = 192.792) and campesterol (F = 160.724) have the higher discriminant power among sterol compounds. Principal component analysis (PCA) was performed on the data of each chemical parameter to explore their usefulness for the discrimination of eleven monovarietal olive oils. Best differentiations among cultivars were obtained with triacyglycerol and sterolic compositions. The spatial distribution of the different oil samples using all the collected data showed a good discrimination among olive cultivars. A strong resolution between the samples according to the geographical origin was obtained by means of factorial discriminant analysis (FDA) (λ = 0.002). Comparisons of the distances between classes were statistically significant (Fisher tests; P < 0.0001), and 90.91% of cross‐validated grouped cases are correctly classified. The obtained results could become an important tool for sorting out oils to a single cultivar or to a specific geographical area.     

Hydrolysis of palm oil catalyzed by macroporous cation-exchanged resin

Hydrolysis of palm oil was studied using four types of commercial H⁺-exchanged resin with acidity in the region of 5×10⁻³ eq g⁻¹ but with different pore volumes, specific surface areas, and pore diameters. The reaction was carried out in a stirred batch reactor in the liquid phase with continuous steam injection for up to 14 h. The rate of hydrolysis did not depend on total pore volume and specific surface area but did depend on pore diameter. On exchanging H⁺ with La³⁺, Co²⁺, and Na⁺, the rate of reaction decreased markedly and was dependent on the degree of exchange, demonstrating that hydrolysis was catalyzed by H⁺ sites. The activation energy for the hydrolysis of the triglycerides was estimated to be 240 kJ mol⁻¹. A procedure to estimate the rates of the different stages of hydrolysis and hence the individual rate constants of the forward and reverse reactions is described. The procedure yielded reasonable parameters for the reaction at 155°C up to 6 h of reaction time, when about 75 mol% of triglycerides was hydrolyzed.     

Calculating the lodine value for marine oils from fatty acid profiles

The iodine values of marine oils were directly calculated from fatty acid profiles by using reacting ratios (calculation factors) between I₂ (iodine) and either the fatty acids bound to a triglyceride or the free fatty acids. A total of 20 factors were incorporated from C14:1 to C24:1, placed into an Excel® spreadsheet, and used to calculate the iodine values. The calculated values were then compared to the oil’s iodine value obtained by the traditional titration method. The results indicate that this method can be used to obtain the iodine value of marine oils directly from the oil’s fatty acid composition, thus giving two results from one analysis.     

Modulated temperature differential scanning calorimetry for examination of tristearin polymorphism: 2. Isothermal crystallization of metastable forms

The transformations of tristearin were examined by modulated temperature differential scanning calorimetry (MTDSC) in order to examine the utility of this technique. Tristearin has been used as a model polymorphic system, showing metastable phases and complicated transformation routes occuring at relatively slow rates. The β′-forms generated by thermal treatment under modulation do not differ significantly from those generated by the corresponding treatment without modulation. While the total heat flow thermograms are similar, the deconvoluted reversing component shows that annealing, especially at 63°C, has a significant effect on the crystal size and perfection of the solid phases formed. MTDSC also enables the melting of β′ to be separated from the simultaneous crystallization of the β form as evidenced in the c _p component. Quantitative interpretations about such systems cannot be drawn from MTDSC at this point in time.     

Acorn (<Emphasis Type="Italic">Quercus</Emphasis> spp.) fruit lipids: Saponifiable and unsaponifiable fractions: A detailed study

The composition of the oils extracted from the acorn fruit of three species of Mediterranean oaks, Quercus ilex L., Q. suber L., and Q. faginea L., was characterized. Both major and minor components, including FA, TG, sterols, methyl sterols, triterpenic and aliphatic alcohols, tocopherols, and hydrocarbons, were identified by standard methods and MS. High-resolution GLC and HPLC were used for quantification. The FA profile, together with the equivalent carbon numbers and TG carbon numbers, was compared with data for other edible vegetable oils. Oil yield, expressed as wet weight, was 5% (w/w). Sterol content was remarkable for the three species (8,563–11,420 mg/kg), with β-sitosterol being the most abundant (80%). Oils were also high in tocopherol, with a wide variation between species (165–456 mg/kg) but with γ-tocopherol predominating in all three oils (90% of the total tocopherol content). Also, high terpenic alcohol contents were found (1527–2984 mg/kg), with dammaradienol and β-amyrin being the most abundant (33–60% of the total alcohol content). Bioactive properties and industrial applications of this underutilized native product are also discussed.