Synthesis of Wax Esters from Crude Fish Fat by Lipase of Burkholderia sp. EQ3 and Commercial Lipases

The lipase from Burkholderia sp. EQ3 was used to synthesize wax esters in comparison with commercial lipases. The supernatant of Burkholderia sp. EQ3 was collected from a liquid basal medium with 1 % fish oil after 12 h cultivation (1.90 U/ml of lipase activity). The crude lipase was prepared by acetone precipitation of the culture supernatant (4.70 U/mg and 9.40 purification folds). The crude fish fat obtained by hexane extraction of waste fat from the wastewater pond of a canned tuna factory and cetyl alcohol were used for wax esters synthesis. Five commercial lipases were screened in comparison with crude lipase from Burkholderia sp. EQ3 in wax esters synthesis. The optimum conditions for wax esters synthesis from crude fish fat using Novozyme 435 were enzyme 1 U, substrate molar ratio of crude fish fat to cetyl alcohol 1:2 (115.30 mg of crude fish fat and 66.67 mg of cetyl alcohol) in hexane at 37 °C and 200 rpm with 90.81 % (TLC–FID peak area) after one h of reaction. The optimum conditions for the synthesis by crude lipase from Burkholderia sp. EQ3 were crude lipase 40 U, substrate molar ratio of crude fish fat and cetyl alcohol 1:2 in isooctane at 30 °C and 200 rpm with 95.07 % (TLC–FID peak area) after 6 h of reaction. The synthesized wax esters were mainly composed of cetyl palmitate and cetyl oleate.     

Modification of Stearidonic Acid Soybean Oil by Immobilized Rhizomucor miehei Lipase to Incorporate Caprylic Acid

Immobilized sn-1,3 specific Rhizomucor miehei lipase (RML) was used to catalyze the incorporation of caprylic acid (C8:0) into high stearidonic acid (SDA, C18:4ω3) soybean oil (SDASO) to form structured lipids (SL). The effects of type of biocatalyst (Celite-, octyl-Sepharose-, and Duolite-immobilized RML) and reaction temperature (30, 40, 50, and 60 °C) on acidolysis and acyl migration were studied. Celite-immobilized RML (C-RML) at 50 °C maximized C8:0 incorporation and minimized acyl migration compared to other treatments. Optimal levels of substrate molar ratio (C8:0 to SDASO), incubation time, and enzyme load for SL synthesis by C-RML at 50 °C was determined by response surface methodology to be 6:1, 24 h, and 20 % weight of substrates, respectively. This optimum treatment was scaled-up in hexane or solvent-free reaction media using SDASO or an SDA-enriched acylglycerol mixture as substrate. This yielded various SL with C8:0 contents ranging from 17.0 to 32.5 mol% and SDA contents ranging from 20.6 to 42.3 mol%. When digested, these SL may deliver C8:0 for quick energy and SDA for heart health making them potentially valuable for medical and nutraceutical applications.     

Enzymatic modification of triacylglycerols of high eicosapentaenoic and docosahexaenoic acids content to produce structured lipids

Immobilized lipase, IM60, from Rhizomucor miehei was used as a biocatalyst for the incorporation of capric acid (C10:0) into fish oil originally containing 40.9 mol% eicosapentaenoic (20:5n-3) and 33.0 mol% docosahexaenoic (22:6n-3) acid. Acidolysis was performed with and without organic solvent. Pancreatic lipase-catalyzed sn-2 positional analysis was performed after enzymatic modification. Tocopherol analysis was performed before and after enzymatic modification. Products were analyzed by gas-liquid chromatography. After a 24-h incubation in hexane, there was an average of 43.0±1.6 mol% incorporation of C10:0 into fish oil, while 20:5 and 22:6 decreased to 27.8±2.2 and 23.5±1.3 mol%, respectively. The solvent-free reaction produced an average of 31.8±8.5 mol% C10:0 incorporation, while 20:5 and 22:6 decreased to 33.2±3.3 and 28.3±3.9 mol%, respectively. The effect of incubation time, substrate molar ratio, enzyme load, and added water were also studied. In general, as the enzyme load, molar ratio, and incubation time increased, mol% C10:0 incorporation also increased. The optimal mol% C10:0 incorporation was 41.2% at 48 h for the reaction in hexane and 46.4% at 72 h for the solvent-free reaction. The highest C10:0 incorporation (65.4 mol%) occurred at a molar ratio of 1:8 (fish oil triacylglycerols/capric acid) in hexane. For the solvent-free reaction, the optimal mol% C10:0 incorporation (56.1 mol%) occurred at a molar ratio of 1:6. An enzyme load of 10% gave the highest mol% C10:0 incorporation (41.4 mol%) in hexane; the highest incorporation (38.3 mol%) for the solvent-free reaction occurred at 15% enzyme load. Mol% incorporation of C10:0 declined with increasing amounts of added water. The optimal mol% C10:0 incorporation occurred at 1% added water (47.9 mol%) for the reaction in hexane, and at zero added water for the solvent-free reaction (21.8 mol%). Fish oil containing capric acid was successfully produced and may be nutritionally more beneficial than unmodified oil.     

Lipase-catalyzed incorporation of oleic acid into melon seed oil

The ability of lipase PS30 (Pseudomonas sp.) to modify the fatty acid profile of melon seed oil by incorporation of oleic acid (18:1n-9) was investigated. The transesterification was carried out in hexane in an orbital shaking water bath at 55°C for 24 h with methyl oleate (70% pure) as acyl donor. Oleic acid content increased from 13.5% to 53%, and linoleic acid (18:2n-6) content decreased from 65% to 33%. The incorporation of oleic acid into melon seed oil by Pseudomonas sp. lipase helped balance the fatty acid profile of the oil in terms of monounsaturated (18:1n-9) and essential fatty acids (18:2n-6).     

Comparative Effects of Sandalwood Seed Oil on Fatty Acid Profiles and Inflammatory Factors in Rats

The aim of the present study was to investigate the effect of sandalwood seed oil on fatty acid (FA) profiles and inflammatory factors in rats. Fifty male Sprague–Dawley rats were randomly divided into five different dietary groups: 10 % soybean oil (SO), 10 % olive oil (OO), 10 % safflower oil (SFO), 10 % linseed oil (LSO) and 8 % sandalwood seed oil blended with 2 % SO (SWSO) for 8 weeks. The SWSO group had a higher total n-3 polyunsaturated fatty acids (PUFA) levels but lower n-6:n-3 PUFA ratios in both adipose tissue and liver than those in the SO, OO and SFO groups (p < 0.05). Although the SWSO group had a much lower 18:3n-3 level (4.51 %) in their dietary lipids than the LSO group (58.88 %), the levels of docosahexaenoic acid (DHA: 22:6n-3) in liver lipids and phospholipids of the SWSO group (7.52 and 11.77 %) were comparable to those of the LSO group (7.07 and 13.16 %). Ximenynic acid, a predominant acetylenic FA in sandalwood seed oil, was found to be highly incorporated into adipose tissue (13.73 %), but relatively lower in liver (0.51 %) in the SWSO group. The levels of prostaglandin F_2α, prostaglandin E₂, thromboxane B₂, leukotriene B₄, tumor necrosis factor-α and interleukin-1β in both liver and plasma were positively correlated with the n-6:n-3 ratios, suggesting that increased n-6 PUFA appear to increase the formation of pro-inflammatory cytokines, whereas n-3 PUFA exhibit anti-inflammatory activity. The present results suggest that sandalwood seed oil could increase tissue levels of n-3 PUFA, DHA and reduce the n-6:n-3 ratio, and may increase the anti-inflammatory activity in rats.     

Concentration of Stearidonic Acid in Free Fatty Acids Form from Modified Soybean Oil by Selective Esterification with Dodecanol

The concentration of stearidonic acid (SDA, 18:4 n-3) in free fatty acids (FFA) formed by selective esterification with dodecanol (lauryl alcohol) was studied. For this purpose, modified soybean oil (initial SDA content, ~23 %) was converted into its corresponding FFA by chemical hydrolysis. In a second step, the resulting FFA were esterified with dodecanol. Process variables such as the type of biocatalyst (lipase), substrate molar ratio and amount of lipase were evaluated. The best SDA concentration (58 %) and recovery (94 %) were attained by performing the esterification reaction for 4 h, with 1:1 molar ratio (dodecanol:FFA), and 5 % (w/w) Candida rugosa lipase as biocatalyst. It was observed that SDA was concentrated in the unesterified fraction.     

Chemoenzymatic Method for Producing Stearidonic Acid Concentrates from Stearidonic Acid Soybean Oil

The aim of this study was to produce stearidonic acid (SDA, 18:4n-3) omega-3 concentrates from 25 % SDA soybean oil (SDASO) by enzymatic acidolysis. Substrates were prepared by chemical and enzymatic hydrolysis of SDASO. A 62 % SDA free fatty acid mixture (SDA-FFA) was obtained by low temperature crystallization of the chemical hydrolyzate while partial hydrolysis of SDASO by non-immobilized lipase AY 30 (Candida rugosa) yielded a 51 % SDA acylglycerol mixture (SDA-GLY). Reaction conditions for acidolysis between SDA-FFA and SDA-GLY were optimized using response surface methodology (RSM). Incorporation of SDA into SDA-GLY by immobilized Lipozyme RM IM (Rhizomucor miehei) and non-immobilized Lipomod 34P-LO34P (C. cylindracea [rugosa]) lipases were modeled under varying levels of the substrate molar ratio (S _r ), temperature (T), and time (t). Optimal conditions for production of a 60 % SDA concentrate were predicted to be S _r  = 4.8, T = 65 °C and t = 8 h for Lipozyme RM IM and S _r  = 5.0, T = 43 °C and t = 48 h for Lipomod 34P-L034P. The model was verified experimentally by gram scale synthesis under optimal conditions which resulted in the production of 59.98 and 58.98 % SDA concentrates (≥96 % triacylglycerols) by Lipozyme RM IM and Lipomod 34P-L034P, respectively.     

Optimization of Lipase-Catalyzed Fractionation of Two Conjugated Linoleic Acid (CLA) Isomers

The separation of two isomers of conjugated linoleic acid is highly significant since each exhibits different biochemical properties. The aim of this study was to investigate and optimize several factors affecting the esterification of l-menthol with the c9,t11-CLA isomer in an organic solvent-free system using lipase from Candida rugosa (Lipase AY-30). D-optimal design with 5 factors and 3 levels were employed to evaluate the effects of synthesis parameters; reaction time (8–24 h), temperature (30–50 °C), enzyme content (2–20 U/ml), substrate molar ratio of conjugated linoleic acid oil to l-menthol (2:1–1:2) and pH (6–8) on esterification of c9,t11-CLA with l-menthol. Based on the analysis of the residual amount of c9,t11-CLA in the free fatty acid fraction after just one-step esterification, the optimum synthesis conditions were as follows: reaction time 23.12 h, temperature 32.65 °C, enzyme amount 135.40 U, molar ratio of CLA oil to l-menthol at 1:1.7 and pH at 7.7; the lowest purity of c9,t11-CLA in free fatty acid fraction based on the total content of c9,t11 and t10,c12-CLA isomers was 8.6 %.     

Optimized Production of MLM Triacylglycerols Catalyzed by Immobilized Heterologous <Emphasis Type="Italic">Rhizopus oryzae</Emphasis> Lipase

Response surface methodology was used to model and optimize the acidolysis of virgin olive oil with caprylic (C8:0) or capric (C10:0) acids, aimed at the production of low caloric triacylglycerols (TAG) of MLM type, in solvent free media, catalyzed by the heterologous Rhizopus oryzae lipase (r-ROL) immobilized in Eupergit^® C. This lipase was produced in the methylotrophic yeast Pichia pastoris Mut^s phenotype (experiments with C10:0) or a Mut⁺ phenotype (experiments with C8:0), under different operational conditions. The r-ROL used in experiments with C10:0 presented a hydrolytic activity about 5 times of that presented by r-ROL used in acidolysis with C8:0. The experiments were carried out following a central composite rotatable design, as a function of the molar ratio (MR) medium chain fatty acid/TAG (1.6–4.4) and temperature (25–55 °C). Convex surfaces described by second order polynomials as a function of MR and temperature were well fitted to fatty acid incorporation values. After 24-h reaction, the predicted maximum incorporation of caprylic (15.5 mol%) or capric (33.3 mol%) acids in olive oil occurs at 37 and 35 °C, respectively, and at C8:0/TAG of 2.8:1 or C10:0/TAG of 3:1. These predicted optima were experimentally validated. Fermentation conditions used in r-ROL production highly affected hydrolytic activity and to a lesser extent interesterification activity.     

Preparation of Highly Pure n-3 PUFA-Enriched Triacylglycerols by Two-Step Enzymatic Reactions Combined with Molecular Distillation

Highly pure n-3 polyunsaturated fatty acids (PUFA)-enriched triacylglycerols (TAG) have attracted considerable attention due to their nutritional benefits and pharmacological effects. In this study, an alternative approach to the conventional method for the synthesis of highly pure n-3 PUFA-enriched TAG by using a multi-step process was reported. First, glyceride mixtures were synthesized through Novozym 435 [Novozymes A/S (Bagsvaerd, Denmark)] catalyzed esterification of n-3 PUFA-enriched FA and glycerol. Second, partial glycerides in the resulting glyceride mixtures were hydrolyzed to FA by immobilized partial glycerides-selective lipase from Malassezia globosa. The purity of TAG reached 99.84% under the optimized conditions: buffer solution of pH 6.0, water content of 100% (w/w, with respect to the oil mass), enzyme loading of 120 U/g (U/w, with respect to oil mass) and reaction temperature of 30 °C. During hydrolysis, the immobilized SMG1-F278N exhibited good reusability and TAG purity of over 94% was maintained after being used for six cycles. Subsequently, purification of TAG was accomplished by molecular distillation at low temperature (150 °C) and highly pure (99.85%) TAG with 88.73% n-3 PUFA was obtained. The final glyceride mixtures with low acid, peroxide and anisidine value were promising products for medical and dietetic purposes. Compared with the conventional one-step synthesis of n-3 PUFA-enriched TAG by enzymatic esterification or glycerolysis or the two-step method by combined transesterification and ethanolysis, this improved process allows for higher purity of n-3 PUFA-enriched TAG and significant reduction in reaction time.     

Acidolysis Reaction of Terebinth Fruit Oil with Palmitic and Caprylic Acids to Produce Low Caloric Spreadable Structured Lipid

The lipase (Lipozyme IM from Rhizomucor miehei) catalyzed acidolysis reaction of terebinth (Pistacia terebinthus L.) fruit oil with caprylic and palmitic acid in hexane was investigated in a batch system. The effect of reaction conditions and relationship among them were analyzed and optimized by response surface methodology with a four-factor five-level central composite rotatable experimental design. The four major factors chosen were enzyme load (10–20 wt%), reaction time (12–20 h), reaction temperature (45–60 °C) and substrate mol ratio (TO:PA:CA, 1:2.3–4.1:1.15–2.05). Optimum reaction conditions for reaction time, temperature, enzyme load and substrate mole ratio were 12 h, 45 °C, 10 wt% and 1:4.1:2.05, respectively. The maximum yield of desired triacylglycerols (TAG) obtained at these optimum conditions was 50.87 %. Produced structured lipid had a caloric value which was 1.5 % lower than that of terebinth fruit oil. Its solid fat content was found comparable with commercially available margarines. The relative activity of lipase was well maintained in up to 10 repeated cycles.     

Lipase-Catalysed Enrichment of γ-Linolenic Acid from Evening Primrose Oil in a Solvent-Free System

The enrichment of γ-linolenic acid (GLA) was carried out in a solvent-free system by lipase-catalysed esterification of free fatty acids from evening primrose oil (EPO-FA) and 1-butanol (BtOH). The lipase employed to conduct this study was a free preparation of Candida rugosa. Variables evaluated were: substrate molar ratio (1:4, 1:6, 1:8, 1:10 and 1:12, EPO-FA:BtOH), temperature (10, 20, 30, 40, 50 and 60 °C), and enzyme loading (5, 10, 15 and 20 %, based on the total weight of substrates). GLA was highly enriched in the non-esterified fatty acid fraction since C. rugosa showed very low selectivity for this fatty acid. We were able to increase the content of GLA to ca. 70 wt.% under the following optimal conditions: 30 °C, 10 % enzyme loading and a 1:10 molar ratio (EPO-FA:BtOH), after 24 h. An additional set of experiments was conducted whereby the amount of water was controlled by addition of molecular sieves to the reaction mixture. The latter experiments produced a higher GLA concentrate (83.74 wt.%), under the optimal conditions described above and by adding 10 % molecular sieves (based on the total weight of substrates) after 36 h.     

Production of MLM-Type Structured Lipids Catalyzed by Immobilized Heterologous <Emphasis Type="Italic">Rhizopus oryzae</Emphasis> Lipase

This work aims to produce triacylglycerols (TAG) containing a medium-chain fatty acid (M) at positions sn-1,3 and a long-chain fatty acid (L) at sn-2 position, i.e. TAG of MLM type, by acidolysis of virgin olive oil with caprylic (C8:0) or capric (C10:0) acids, catalyzed by 1,3-selective Rhizopus oryzae heterologous lipase (rROL) immobilized in Eupergit^® C and modified sepiolite. This lipase was produced by the methylotrophic yeast Pichia pastoris. Reactions were performed at 25 and 40 °C, for 24 h, either in solvent-free or in n-hexane media, at a molar ratio 1:2 (olive oil:free fatty acid). Higher incorporations of C8:0 (21.6 mol%) and C10:0 (34.8 mol%) into the TAG were attained in solvent-free media, at 40 °C, when rROL immobilized in Eupergit^® C was used. In organic media, at 40 °C, only 15.9 and 14.1 mol%, incorporation of C8:0 or C10:0 were, respectively observed. Lower incorporations were attained for both acids (3.4–7.0 mol%) when native ROL (nROL) in both supports and rROL in modified sepiolite were used. rROL in Eupergit^® C maintained its activity during the first four or three 23-h batches, respectively when C8:0 (half-life time, t _1/2 = 159 h) or C10:0 (t _1/2 = 136 h) were used, decreasing thereafter following a time delay model.     

Macroporous carbon aerogel as a novel adsorbent for immobilized enzymes and a support for the lipase-active heterogeneous biocatalysts for conversion of triglycerides and fatty acids

A macroporous carbon aerogel (MCA) was produced by in situ synthesis of multi-walled carbon nanotubes (CNTs) via catalytic high-temperature decomposition of ethylene over the supported Fe:Co catalyst. A three-dimensional framework of ball-shaped MCA granules was formed by chaotic interlacing of growing CNTs and mechanical strength of the granules was high enough for their promising application in heterogeneous processes, in particular, bioconversion of fatty acids. The macroporous carbon aerogel was investigated as a novel support for adsorptive immobilization of an enzyme—Thermomyces lanuginosus lipase, followed by preparation of the lipase-active heterogeneous biocatalysts. It was found that the efficient and tight adsorption of the lipase on MCA occurred due to hydrophobic interactions. The amount of the lipase adsorbed in one dense adsorptive layer was equal to 110 mg per 1 g of the carbon aerogel. The lipase adsorbed in the 1st adsorptive layer possessed the maximum activity, 700–800 U/mg. The lipase-active heterogeneous biocatalysts were studied in the periodic processes of hydrolysis of emulsified triglycerides (tributyrin), interesterification of vegetable oil with ethyl acetate, and esterification of fatty acids (butyric C4:0, capric C10:0, and stearic C18:0) with isopentanol. It was found that T. lanuginosus lipase lost significantly its enzymatic activity during adsorption on the carbon aerogel; possible causes of the negative effect of such immobilization were discussed. The specific activity of the adsorbed lipase, as well as activity and stability of the biocatalysts depended foremost on the type of the reaction performed. The maximum activities of the biocatalysts were determined to be approximately 75·10³ and 2.5 U/g in tributyrin hydrolysis (aqueous media) and esterification of fatty acid (non-aqueous media), respectively. Stability of the biocatalysts was very high in the esterification reaction due to accumulation of essential water inside MCA. The lipase-active biocatalysts carried out the synthesis of isopentyl caprinate in organic solvents (hexane?+?diethyl ether) for several 100 h at 40 °C.     

Enrichment of Refined Olive Oil with Palmitic and Docosahexaenoic Acids to Produce a Human Milk Fat Analogue

Refined olive oil was enriched with palmitic acid (PA) and docosahexaenoic acid (DHA) via lipase-catalyzed acidolysis reaction using Novozym 435 in hexane. The enrichment reaction was optimized by response surface methodology. Three independent variables, reaction time (12, 18, and 24 h), temperature (55, 60, and 65 °C), and substrate molar ratio (refined olive oil:DHA single cell oil free fatty acid:PA 1:1:6, 1:1:9, and 1:1:12) and three responses, total PA and DHA incorporation, and PA content at the sn-2 position were investigated. Results showed that PA was incorporated into the triacylglycerols(TAGs) of refined olive oil at up to 55.79 mol % while incorporation of PA at the sn-2 position and total DHA were found to be up to 33.63 and 3.54 mol %, respectively. Second-order models were generated for each of the three responses. A Chi-square test verified that the predicted values from the models were not significantly different from the observed ones. The prediction power of the models was further confirmed by a solvent-free scale-up reaction. The produced structured lipids have the potential to be used in infant formula.     

Hydrolytic Activity of Castor Bean Powder: Effect of Gum Arabic,Lipase and Oil Concentrations

Lipase activity from castor bean seed powders was evaluated in hydrolysis reactions at 37 °C. The effects of different concentrations of lipase powder (LP), substrate (high oleic sunflower oil, O) and surfactant (gum arabic, A) on lipase activity (R) were assessed using experimental designs. Considered variable bounds were: 0.05–0.15 g_LP, 0.07–0.20 oil:aqueous phase (w/w) and 0–0.025 g gum arabic/mL. All variables had significant effects on the transformed response, R ^1/2. The most important result was the negative effect of gum arabic in lipase activity, even when high oil concentrations were used. Experimental lipase activities involved in this work were within 0.32–16.90 mmol_FFA/g_oil·g_LP·h. Using 0.05 g_LP and 0.20 oil:aqueous phase (w/w) without gum arabic, the activity of 20.47 ± 7.19 mmol_FFA/g_oil·g_LP·h was reached.     

Immobilization of Candida antarctica lipase onto cellulose acetate-coated Fe2O3 nanoparticles for glycerolysis of olive oil

Candida antarctica lipase was covalently immobilized onto the surface of cellulose acetate-coated Fe₂O₃ nanoparticles. The characterizations of immobilized lipase were examined by Fourier transform infrared spectrophotometer (FTIR) and field emission gun-scanning electron microscopy (FEG-SEM). The immobilized lipase was assayed for production of monoglycerides (MG) and diglycerides (DG) by glycerolysis of olive oil in a solvent medium. The effect of various reaction conditions on the MG and DG production such as reaction time, temperature, the molar ratio of glycerol to oil and amount of immobilized lipase was investigated. The optimum condition for MG and DG production was found at 50 °C temperature and 0.025 g of lipase with the molar ratio of glycerol to oil 1.5: 1 in 5 h of reaction time. The effect of substrate concentration on enzymatic activity of the free and immobilized lipase showed the best fits to the Lineweaver-Burk plots. The K _m and V _max values of immobilized lipase were found to be 25mM and 0.58mM/min, whereas that for free lipase was 52.63mM and 1.75mM/min, respectively. The activation and deactivation energy was found to decrease for immobilization of lipase on cellulose acetate-coated Fe₂O₃ nanoparticles.     

Distribution of (n-9) and (n-7) Isomers of Monounsaturated Fatty Acids in Indian Mustard (Brassica juncea)

The seed oils of 19 Indian mustard varieties were analyzed for fatty acid composition using GC–MS, reporting the presence of n-7 isomers of C18:1, C20:1 and C22:1 fatty acids. n-7 isomers namely cis-vaccenic (C18:1), 11, eicosenoic(C20:1) and 13-cis-docosenoic (C22:1) acids ranged from 0.61 to 1.73, 1.04 to 1.69 and 0.58 to 1.17 %, respectively. The average values of C20:1(n-7) was highest (1.36) amongst the three acids. Nervonic acid was also reported in the range of 0.69 to 2.52 %. The ratios of (n-7)/(n-9) ranged from 6.22 to 14.62, 12.38 to 27.35 and 2.01 to 3.24 % for C18:1, C20:1 and C22:1 fatty acids, respectively. The variety RLM-619 had the lowest elongation ratio (ER) as 0.44 and the highest desaturation ratio (DR) as 0.41 indicating higher efficiency of the desaturation pathway than for other varieties. The oleic desaturation ratio (ODR) values varied from 0.68 (Basanti) to 0.75 (GM-2) with a mean value of 0.72 and linoleic desaturation ratio from 0.40 (Basanti) to 0.49 (Pusa Bold) with a mean value of 0.45. Palmitoleic acid showed positive correlation with C18:1(n-7), C20:1(n-7), C20:2, C22:0, C22:1(n-7), C24:1, (n-7)/(n-9) ratio of C18:1 and C22:1 and a positive trend with ER but a significant negative correlation with C18:3, DR and ODR. The results indicated that palmitoleic acid is an important intermediate component in the synthesis of long chain (n-7) fatty acids.     

Physicochemical Properties and Minor Lipid Components of Soybean Germ

This study aimed to determine and to compare the main phytochemicals from soybean and soybean germ of different Chinese varieties. The results indicate that the soybean germ contains low protein (38.19 %), lipids (10.98 %), and crude fiber (7.47 %) compared with soybean. Specific gravity, refractive index, and saponification values of soybean germ oil were comparable to those of soybean oil. However, unsaponifiable matter of the germ oil was significantly higher (6.982 %) than soybean oil (1.072 %). The tocopherol contents in soybean germ oil ranged as follows: γ-tocopherol, 176.39 mg/100 g oil; δ-tocopherol, 57.29 mg/100 g oil; α-tocopherol, 50.67 mg/100 g oil; and β-tocopherol, 8.15 mg/100 g oil. The main sterols in soy germ oil were β-sitosterol (1,681.90 mg/100 g oil), crevesterol (358.02 mg/100 g oil), stigmasterol (189.62 mg/100 g oil), and brassicasterol (3.70 mg/100 g oil). Furthermore, soybean germ oil seemed to be an important source of triglyceride, fatty acids, and particularly the fatty acids in the sn-2 position of triacylglycerol. The important nutritional value of all these phytochemicals makes soybean germ and particularly germ oil sources of functional molecules and additives for the food industry.     

Antioxidant Activity of Sesamol in Soybean Oil Under Frying Conditions

Antioxidant activity of sesamol was investigated in soybean oil using a miniaturized frying experiment with potato cubes fried at 180 °C. Oxidation of soybean oil was determined by gel permeation chromatography for polymerized triacylglycerols and by ¹H-NMR spectroscopy for reactions at reactive sites of soybean oil molecules including olefinic, bisallylic and allylic protons during frying. Sesamol showed lower antioxidant activity than 0.02 % (w/w) tert-butylhydroquinone (TBHQ) at the same molar concentration. Higher concentrations of sesamol provided better antioxidant effects indicating that no prooxidant activity occurred. Sesamol in this frying test showed better results than 0.02 % TBHQ when the concentration was as high as 0.66 % by weight. An HPLC experiment showed that the concentration of sesamol decreased sharply during frying. Thermogravimetric analysis indicated that sesamol is highly volatile and easily oxidizes when exposed to air. To overcome this problem, two multiple addition methods were evaluated in which sesamol was added portion by portion every hour. The multiple additions of divided portions of 0.66 % (w/w) sesamol maintained the concentration of sesamol at the minimum of 0.04–0.06 % throughout the frying process and showed improved antioxidant activity compared to one single addition of 0.66 % sesamol at the beginning of frying. One of the multiple addition methods showed 28, 18, 59, and 27 % less polymerized triacylglycerols and losses of olefinic, bisallylic and allylic protons, respectively, than 0.02 % TBHQ after 8-h frying. This study shows that sesamol can be used as an alternative for synthetic antioxidants for frying oil.