Rice bran FFA determination by diffuse reflectance IR spectroscopy

Rice bran with FFA levels above 0.1% cannot be used as a food ingredient due to oxidative off-flavor formation. However, extracting high FFA oil from bran by in situ methanolic esterification of rice bran oil to produce methyl ester biodiesel produces greater yields relative to low-FFA rice bran oil. Therefore, high-FFA bran could be exploited for biodiesel production. This study describes an FTIR spectroscopic method to measure rice bran FFA rapidly. Commercial rice bran was incubated at 37°C and 70% humidity for a 13-d incubation period. Diffuse reflectance IR Fourier transform spectra of the bran were obtained and the percentage of FFA was determined by extraction and acid/base titration throughout this period. Partial least squares (PLS) regression and a calibration/validation analysis were done using the IR spectral regions 4000-400 cm⁻¹ and 1731-1631 cm⁻¹. The diffuse reflectance IR Fourier transform spectra indicated an increasing FFA carbonyl response at the expense of the ester peak during incubation, and the regression coefficients obtained by PLS analysis also demonstrated that these functional groups and the carboxyl ion were important in predicting FFA levels. FFA rice bran changes also could be observed qualitatively by visual examination of the spectra. Calibration models obtained using the spectral regions 4000-400 cm⁻¹ and 1731-1631 cm⁻¹ produced correlation coefficients R and root mean square error (RMSE) of cross-validation of R=0.99, RMSE=1.78, and R=0.92, RMSE=4.67, respectively. Validation model statistics using the 4000-400 cm⁻¹ and 1731-1631 cm⁻¹ ranges were R=0.96, RMSE=3.64, and R=0.88, RMSE=5.80, respectively.     

Free fatty acid formation and lipid oxidation on milled rice

Milled rice was stored at 37°C and 70% humidity and sampled regularly for 50 d. Rice surface lipid was extracted with isopropanol and analyzed for free fatty acids (FFA) and conjugated diene (CD) contents. Diffuse reflectance Fourier transform infrared (DRIFTS) spectra of the rice samples were also obtained. FFA and CD levels increased together during rice storage and exhibited three distinct phases. DRIFTS identified a decrease in intensity at 1746 cm⁻¹ (ester, −C=O) and increases in intensity at 1731 cm⁻¹ (aldehyde, −CO) and 1714 cm⁻¹ (fatty acid, −C=O) during storage, which correlated well with the chemical analysis data. DRIFTS spectral data were analyzed by a partial least squares regression method to identify spectral regions that correlate strongly with measured FFA and construct prediction models. Overall, the mid-infrared region (4000–400 cm¹) gave the best model (R=0.98, root mean square error of cross-validation=0.05) and also predcted the FFA content of milled rice well. The DRIFTS technique has potential for use in studying qualitative chemical changes on the milled rice surface lipids and for predicting FFA on milled rice.     

Detection of lard mixed with body fats of chicken, lamb, and cow by fourier transform infrared spectroscopy

Fourier transform infrared (FTIR) spectroscopy provides a simple and rapid means of detecting lard blended with chicken, lamb, and cow body fats. The spectral bands associated with chicken, lamb, and cow body fats and their lard blends were recorded, interpreted, and identified. Qualitative differences between the spectra are proposed as a basis for differentiating between the pure animal fats and their blends. A semiquantitative approach is proposed to measure the percent of lard in blends with lamb body fat (LBF) on the basis of the frequency shift of the band in the region 3009–3000 cm⁻¹, using the equation y=0.1616x+3002.10. The coefficient of determination (R ²) was 0.9457 with a standard error (SE) of 1.23. The percentage of lard in lard/LBF blends was also correlated to the absorbance at 1417.89 and 966.39 cm⁻¹ by the equations y=0.0061x+0.1404 (R ²=0.9388, SE=0.018) and y=0.004x+0.1117 (R ²=0.9715, SE=0.009), respectively. For the qualitative determination of lard blended with chicken body fat (CF), the FTIR spectral bands in the frequency ranges of 3008–3000, 1418–1417, 1385–1370, and 1126–1085 cm⁻¹ were employed. Semiquantitative determination by measurement of the absorbance at 3005.6 cm⁻¹ is proposed, using the equation y=0.0071x+0.1301 (R ²=0.983, SE=0.012). The percentage of lard in lard/GF blends was also correlated to the absorbance at 1417.85 cm⁻¹ (y=0.0053x+0.0821, with R ²=0.9233, SE=0.019) and at 1377.58 cm⁻¹ (y=0.0069x+0.1327, with R ²=0.9426, SE=0.022). For blends of lard with cow body fat (CBF) bands in the range 3008–3006 cm⁻¹ and at 1417.8 and 966 cm⁻¹ were used for qualitative detection. The equation y=−0.005x+0.3188 with R ²=0.9831 and SE=0.0086 was obtained for semiquantitative determination at 966.22 cm⁻¹.     

Multivariate calibration of fourier transform infrared spectra for determining thiobarbituric acid-reactive substance content in palm oil

Fourier transform infrared (FTIR) spectra of palm oil samples between 2900 and 2800 cm⁻¹ and 1800 and 1600 cm⁻¹ were used to compare different multivariate calibration techniques for quantitative determination of their thiobarbituric acid-reactive substance (TBARS) content. Fifty spectra (in duplicate) of palm oil with TBARS values between 0 and 0.25 were used to calibrate models based on partial least squares (PLS) and principal components regression (PCR) analyses with different baselines. The methods were compared for the number of factors, coefficients of determination (R ²), and accuracy of estimation. The standard errors of prediction (SEP) were calculated to compare their predictive ability. The calibrated models generated three to eight factors, R ² of 0.9414 to 0.9803, standard error of estimation (SEE) of 0.0063 to 0.0680, and SEP of 1.20 to 6.67.     

Characteristics of Oil from Hulless Barley (<Emphasis Type="Italic">Hordeum vulgare</Emphasis> L.) Bran from Tibet

The bran of hulless barley (Hordeum vulgare L.) from Tibet was investigated. This paper reports on the physicochemical characteristics, lipid classes and fatty acids of the oil from the bran. The petroleum (60–90 °C) extract of hulless barley bran was found to be 8.1%. The investigated physiochemical parameters included density at 40 °C (0.96 g/cm³), refractive index at 40 °C (1.41), melting point (30.12 °C), acid value (11.6 mg KOH/g), peroxide value (19.41 μg/g), saponification value (337.62 mg KOH/g), iodine value (113.51 mg iodine/g) and unsaponifiable matter (4.5% of total lipids).The amount of neutral lipids in the crude oil was the highest (94.55% of total lipids), followed by glycolipids (4.20% of the total lipid) and phospholipids (1.25% of the total lipid). Linoleic acid (75.08% of total fatty acids) followed by palmitic acid (20.58% of total fatty acids), were the two major fatty acids in the oil. The results show that the oil from the hulless barley bran could be a good source of valuable essential fatty acids.     

Raman studies of structural rearrangements induced in human plasma lipoprotein carotenoids by malondialdehyde

Raman and resonance Raman spectra of plasma lipoproteins ± malondialdehyde were studied at concentrations which block the normal receptor-mediated uptake by cells. The strong resonance Raman bands at about 1010, 1162 and 1530 cm⁻¹, due to the presence of carotenoids in the lipoproteins, are envisaged as structural probes. High resolution resonance Raman spectra of the 1500–1600 cm⁻¹ region reveal multiple features suggesting the coexistence of several structural populations of β-carotene whose precise assignment is complex. When plasma lipoproteins are reacted with malondialdehyde, a complex change occurs in the resonance Raman banding of β-carotene in the 1500–1600 cm⁻¹ region. Malonaldehyde (MDA) also modifies the acoustical region (70–200 cm⁻¹ of low density lipoprotein (LDL) lipids. We suggest that malondialdehyde association with plasma lipoproteins alters the lipid structure via apoprotein or apoprotein/lipid associations.     

Application of FTIR Spectroscopy for the Determination of Virgin Coconut Oil in Binary Mixtures with Olive Oil and Palm Oil

Rapid Fourier transform infrared (FTIR) spectroscopy combined with attenuated total reflectance (ATR) was applied for quantitative analysis of virgin coconut oil (VCO) in binary mixtures with olive oil (OO) and palm oil (PO). The spectral bands correlated with VCO, OO, PO; blends of VCO and OO; VCO and PO were scanned, interpreted, and identified. Two multivariate calibration methods, partial least square (PLS) and principal component regression (PCR), were used to construct the calibration models that correlate between actual and FTIR-predicted values of VCO contents in the mixtures at the FTIR spectral frequencies of 1,120–1,105 and 965–960 cm⁻¹. The calibration models obtained were cross validated using the “leave one out” method. PLS at these frequencies showed the best calibration model, in terms of the highest coefficient of determination (R ²) and the lowest of root mean standard error of calibration (RMSEC) with R ² = 0.9992 and RMSEC = 0.756, respectively, for VCO in mixture with OO. Meanwhile, the R ² and RMSEC values obtained for VCO in mixture with PO were 0.9996 and 0.494, respectively. In general, FTIR spectroscopy serves as a suitable technique for determination of VCO in mixture with the other oils.     

Application of raman spectroscopy to monitor and quantify ethyl esters in soybean oil transesterification

Biodiesel (FA esters) has become very attractive as an alternative diesel fuel owing to its environmental benefits. Transesterification is the most usual and important method to make biodiesel from vegetable oils. This article investigates the potential for using Raman spectroscopy to monitor and quantify the transesterification of soybean oil to yield ethyl esters. The differences observed in the Raman spectra of soybean oil after transesterification were a peak at 2932 cm⁻¹ ( ), the displacement of the v _C=O band from 1748 to 1739 cm⁻¹, and the bands at 861 (v _R-C=O and v _C-C) and 372 cm⁻¹ (δ _CO-O-C). Uni- and multivariate analysis methods were used to build several analytical curves and then applied in known samples, treated as unknowns, to test their ability to predict concentrations. The best results were achieved by Raman/PLS calibration models (where PLS=partial least squares regression) using an internal normalization standard (v _=C-H band). The correlation coefficient (R ²) values so obtained were 0.9985 for calibration and 0.9977 for validation. Univariate regression analysis between biodiesel concentration and the increasing intensity of band or v _C=O displacement showed R ² values of 0.9983 and 0.9742, respectively. Although spectroscopic methods are less sensitive than chromatographic ones, the data obtained by spectroscopy can be correlated with other techniques, allowing biodiesel yield and quality to be quickly assessed.     

Genetic diversity for lipid content and fatty acid profile in rice bran

Rice (Oryza sativa L.) bran contains valuable nutritional constituents, which include lipids with health benefits. A germplasm collection consisting of 204 genetically diverse rice accessions was grown under field conditions and evaluated for total oil content and fatty acid (FA) composition. Genotype effects were highly statistically significant for lipid content and FA profile (P<0.001). Environment (year) significantly affected oil content (P<0.05), as well as stearic, oleic, linoleic, and linolenic acids (all with P<0.01 or lower), but not palmitic acid. The oil content in rice bran varied relatively strongly, ranging from 17.3 to 27.4% (w/w). The major FA in bran oil were palmitic, oleic, and linoleic acids, which were in the ranges of 13.9–22.1, 35.9–49.2, and 27.3–41.0%, respectively. The ratio of saturated to unsaturated FA (S/U ratio) was highly related to the palmitic acid content (r ²=0.97). Japonica lines were characterized by a low palmitic acid content and S/U ratio, whereas Indica lines showed a high palmitic acid content and a high S/U ratio. The variation found suggests it is possible to select for both oil content and FA profile in rice bran.     

A critical evaluation of Raman spectroscopy for the analysis of lipids: Fatty acid methyl esters

The work presented here is aimed at determining the potential and limitations of Raman spectroscopy for fat analysis by carrying out a systematic investigation of C₄−C₂₄ FAME. These provide a simple, well-characterized set of compounds in which the effect of making incremental changes can be studied over a wide range of chain lengths and degrees of unsaturation. The effect of temperature on the spectra was investigated over much larger ranges than would normally be encountered in real analytical measurements. It was found that for liquid FAME the best internal standard band was the carbonyl stretching vibration ρ(C=O), whose position is affected by changes in sample chain length and physical state; in the samples studied here, it was found to lie between 1729 and 1748 cm⁻¹. Further, molar unsaturation could be correlated with the ratio of the ρ(C=O) to either ρ(C=C) or δ(H−C=) with R ²>0.995. Chain length was correlated with the δ(CH₂)_tw/ρ(C=O) ratio, (where “tw” indicates twisting) but separate plots for odd- and even-numbered carbon chains were necessary to obtain R ²>0.99 for liquid samples. Combining the odd- and even-numbered carbon chain data in a single plot reduced the correlation to R ²=0.94–0.96, depending on the band ratios used. For molal unsaturation the band ratio that correlated linearly with unsaturation (R ²>0.99) was ρ(C=C)/δ(CH₂)_sc (where “sc” indicates scissoring). Other band ratios show much more complex behavior with changes in chemical and physical structure. This complex behavior results from the fact that the bands do not arise from simple vibrations of small, discrete regions of the molecules but are due to complex motions of large sections of the FAME so that making incremental changes in structure does not necessarily lead to simple incremental changes in spectra.     

Characterization of edible oils,butters and margarines by Fourier transform infrared spectroscopy with attenuated total reflectance

The combination of attenuated total reflectance (ATR) and mid-infrared spectroscopy (MIRS) with statistical multidimensional techniques made it possible to extract relevant information from MIR spectra of lipid-rich food products. Wavenumber assignments for typical functional groups in fatty acids were made for standard fatty acids: Absorption bands around 1745 cm⁻¹, 2853 cm⁻¹, 2954 cm⁻¹, 3005 cm⁻¹, 966 cm⁻¹, 3450 cm⁻¹ and 1640 cm⁻¹ are due to absorption of the carbonyl group, C−H stretch, =CH double bonds of lipids and O−H of lipids, respectively. In lipid-rich food products, some bands are modified. Water strongly absorbs in the region of 3600–3000 cm⁻¹ and at 1650 cm⁻¹ in butters and margarines, allowing one to rapidly differentiate the foods as function of their water content. Principal component analysis was used to emphasize the differences between spectra and to rapidly classify 27 commercial samples of oils, butters and margarines. As the MIR spectra contain information about carbonyl groups and double bonds, the foods were classified with ATR-MIR, in agreement with their degree of esterification and their degree of unsaturation as determined from gas-liquid chromatography analysis. However, it was difficult to differentiate the studied food products in terms of their average chainlength.     

Lipid Components of North American Wild Rice (<Emphasis Type="Italic">Zizania palustris</Emphasis>)

The content and composition of fatty acids, sterols, tocopherols, and γ-oryzanol in wild rice (Zizania palustris) grown in North America were compared with those in regular brown rice (Oryza sativa L.). The lipid content of wild rice ranged from 0.7 to 1.1%, compared with 2.7% in regular brown rice. The lipids of wild rice comprised mainly linoleic (35–37%) and linolenic (20–31%) acids. Other fatty acids included palmitic (14.1–18.4%), stearic (1.1–1.3%), and oleic (12.8–16.2%). Wild rice lipids contained very large amounts of sterols, ranging from 70 g/kg for a Saskatchewan sample to 145 g/kg for Minnesota Naturally Grown Lake and River Rice. The main sterols found in an unsaponified fraction were: campesterol (14–52%), β-sitosterol (19–33%), Δ⁵-avenasterol (5–12%), and cycloartenol (5–12%). Some of sterols, γ-oryzanols, were present as the phenolic acid esters; the amount ranged from 459 to 730 mg/kg in wild rice lipids. The largest amounts of tocopherols and tocotrienols, 3682 and 9378 mg/kg, were observed in North Western Ontario wild rice samples, whereas the lowest were 251 mg/kg in an Athabasca Alberta sample and 224 mg/kg in regular long-grain brown rice. The α isomer was the most abundant among tocopherols and tocotrienols. The results of this study showed that wild rice lipids contain large amounts of nutraceuticals with proven positive health effects.     

Iron antimony oxide selective oxidation catalysts – an inelastic neutron scattering study

The inelastic neutron scattering spectra of allyl iodide (3-iodopropene, CH₂=CHCH₂I) and allylpalladium chloride, and allyl iodide dosed onto activated iron(III) oxide and iron antimonate catalysts at room temperature have been determined to characterise the adsorbed allyl species. The spectra are energy loss vibrational spectra in the range 16–4000 cm⁻¹. Allyl iodide is not decomposed on the surface and interacts through the localised C = C bond, more strongly with iron antimonate than with iron(III) oxide. This revised version was published online in August 2006 with corrections to the Cover Date.     

Rapid Determination of Free Fatty Acid in Extra Virgin Olive Oil by Raman Spectroscopy and Multivariate Analysis

We introduce a visible Raman spectroscopic method for determining the free fatty acid (FFA) content of extra virgin olive oil with the aid of multivariate analysis. Oleic acid was used to increase the FFA content in extra virgin olive oil up to 0.80% in order to extend the calibration span. For calibration purposes, titration was carried out to determine the concentration of FFA for the investigated oil samples. As calibration model for the FFA content (FFA%), a partial least squares (PLS) regression was applied. The accuracy of the Raman calibration model was estimated using the root mean square error (RMSE) of calibration and validation and the correlation coefficient (R ²) between actual and predicted values. The calibration curve of actual FFA% obtained by titration versus predicted values based on Raman spectra was established for different spectral regions. The spectral window (945–1600 cm⁻¹), which includes carotenoid bands, was found to be a useful fingerprint region being statistically significant for the prediction of the FFA%. High R ² and small RMSE values for calibration and validation could be obtained, respectively.     

Determination of free fatty acids in crude palm oil and refined-bleached-deodorized palm olein using fourier transform infrared spectroscopy

A rapid direct Fourier transform infrared (FTIR) spectroscopic method using a 100 μ BaF₂ transmission cell was developed for the determination of free fatty acid (FFA) in crude palm oil (CPO) and refined-bleached-deodorized (RBD) palm olein, covering an analytical range of 3.0–6.5% and 0.07–0.6% FFA, respectively. The samples were prepared by hydrolyzing oil with enzyme in an incubator. The optimal calibration models were constructed based on partial least squares (PLS) analysis using the FTIR carboxyl region (C=O) from 1722 to 1690 cm⁻¹. The resulting PLS calibrations were linear over the range tested. The standard errors of calibration (SEC) obtained were 0.08% FFA for CPO with correlation coefficient (R ²) of 0.992 and 0.01% FFA for RBD palm olein with R ² of 0.994. The standard errors of performance (SEP) were 0.04% FFA for CPO with R ² of 0.998 and 0.006% FFA for RBD palm olein with R ² of 0.998, respectively. In terms of reproducibility (r) and accuracy (a), both FTIR and chemical methods showed comparable results. Because of its simpler and more rapid analysis, which is less than 2 min per sample, as well as the minimum use of solvents and labor, FTIR has an advantage over the wet chemical method.     

Relationship between residue quality,decomposition patterns,and soil organic matter accumulation in a tropical sandy soil after 13 years

The objectives of this study were to investigate decomposition patterns and soil organic matter (SOM) accumulation of incorporated residues (10 Mg ha⁻¹ year⁻¹) of different quality, and identify microbiological parameters sensitive to changes in SOM dynamics, in a 13-year-old field experiment on a sandy soil in Northeast Thailand. Mass loss was fastest in groundnut stover (high N), followed by rice straw (high cellulose) and tamarind (intermediate quality), and slowest in dipterocarp (high lignin and polyphenol) following a double exponential pattern. The decomposition rate k ₁ (fast pool) was positively correlated with cellulose (r = 0.70*) while k ₂ (slow pool) was negatively related to lignin (r = −0.85***) and polyphenol (r = −0.81**) contents of residues. Residue decomposition was sensitive to indigenous soil organic nitrogen (SON), particularly during later stages (R ² = 0.782**). Thirteen years’ addition of tamarind residues led to largest soil organic carbon (SOC) (8.41 Mg ha⁻¹) accumulation in topsoil (0–20 cm), while rice straw yielded only 5.54 Mg ha⁻¹ followed by the control (2.72 Mg ha⁻¹). The highest SON (0.78 Mg N ha⁻¹) was observed in the groundnut treatment. Increases in SOC were negatively correlated with cellulose content of residues (r = −0.92***) and microbial respiration (CO₂-C) losses, while SON was governed by organic N added. During later decomposition stages, there was a high efficiency of C utilization (low qCO₂) of decomposer communities especially under tamarind with the lowest qCO₂ and CO₂-C evolution loss. This study suggests that N-rich residues with low cellulose and moderate lignin and polyphenol contents are best suited to improve SOM content in tropical sandy soils.     

Simultaneous determination of quality parameters of biodiesel/diesel blends using HATR-FTIR spectra and PLS, iPLS or siPLS regressions

Partial least-squares (PLS), interval partial least squares (iPLS) and synergy partial least squares (siPLS) regressions were used to simultaneous determination of quality parameters of biodiesel/diesel blends. Biodiesel amount, specific gravity, sulfur content and flash point were evaluated using spectroscopic data in the mid-infrared region obtained with a horizontal attenuated total reflectance (HATR) accessory. Eighty-five binary blends were prepared using biodiesel and two types of diesel, in concentrations from 0.2 to 30% (v/v). Fifty-seven samples were used as a calibration set, whereas 28 samples were used as an external validation set. All samples were characterized using the appropriated standard methods. The specific gravity values at 20 °C were in the range of 848.2-866.2 kg/m³. Flash point values lay between 47.0 and 79.5 °C. Sulfur content values varied from 312 to 1351 mg/kg. Raw spectra of the samples were corrected by multiplicative scatter correction (MSC) and were pre-processed using a mean-centered procedure. Algorithms iPLS and siPLS were able to select the most adequate spectral region for each property studied. For all the properties studied, the siPLS algorithm produced better models than the full-spectrum PLS, selecting the most important bands. The quantification of biodiesel was performed using two spectral regions between 650-1909 cm⁻¹ and 2746-3165 cm⁻¹, and an excellent correlation coefficient of R² = 0.9996 was obtained. The specific gravity was determined from the spectral region from 650 to 1070 cm⁻¹, which yielded a very good correlation coefficient of R² = 0.9987. The sulfur content was evaluated from the spectral regions of 1070-1491 cm⁻¹ and 2746-3165 cm⁻¹. A very good correlation coefficient of R² = 0.9995 was obtained, regardless of whether the samples were formulated with metropolitan or countryside diesel. Finally, the flash point was determined from the spectral region between 756 and 968 cm⁻¹ and a very good correlation coefficient of R² = 0.9982 was obtained.     

Decolorization of Rice Bran Oil Using Modified Kaolin

Measurements show that kaolin from Ranong, obtained from a major deposit in southern Thailand, can be modified to produce a material that is suitable for decolorizing rice bran oil. Its sorption properties were determined after various physical and chemical modifications of this kaolin. Physical modification was achieved by grinding via a planetary ball mill (300 rpm for 1 h), and this was followed by chemical treatment using sulfuric or oxalic acids. The optimum decolorization capacity (~80%) was achieved by using 2 M sulfuric acid. With oxalic acid, the best results were obtained with 0.7 M, but these were slightly lower than those obtained with 2 M sulfuric acid. Compared to the original kaolin sample, the specific surface area of the modified clay increased from ~13 to ~244 cm² g⁻¹, and the total pore volume from 0.06 to 0.43 cm³ g⁻¹. The pore size distribution curves show that most pores are in the mesoporous region with their diameters between 3.0–4.5 nm, and are suitable for adsorption of pigment molecules that are present in rice bran oil. Desorption and spectroscopic studies suggest that both electrostatic and chemical processes are involved in the interaction between pigments and active sites on the clay surface.     

Fumigant and Contact Toxicities of Monoterpenes to <Emphasis Type="Italic">Sitophilus oryzae</Emphasis> (L.) and <Emphasis Type="Italic">Tribolium castaneum</Emphasis> (Herbst) and their Inhibitory Effects on Acetylcholinesterase Activity

A comparative study was conducted to assess the contact and fumigant toxicities of eleven monoterpenes on two important stored products insects—, Sitophilus oryzae, the rice weevil, and Tribolium castaneum, the rust red flour beetle. The monoterpenes included: camphene, (+)-camphor, (−)-carvone, 1-8-cineole, cuminaldehyde, (l)-fenchone, geraniol, (−)-limonene, (−)-linalool, (−)-menthol, and myrcene. The inhibitory effect of these compounds on acetylcholinesterase (AChE) activity also was examined to explore their possible mode(s) of toxic action. Although most of the compounds were toxic to S. oryzae and T. castaneum, their toxicity varied with insect species and with the bioassay test. In contact toxicity assays, (−)-carvone, geraniol, and cuminaldehyde showed the highest toxicity against S. oryzae with LC₅₀ values of 28.17, 28.76, and 42.08 μg/cm², respectively. (−)-Carvone (LC₅₀ = 19.80 μg/cm²) was the most effective compound against T. castaneum, followed by cuminaldehyde (LC₅₀ = 32.59 μg/cm²). In contrast, camphene, (+)-camphor, 1-8-cineole, and myrcene had weak activity against both insects (i.e., LC₅₀ values above 500 μg/cm²). In fumigant toxicity assays, 1-8-cineole was the most effective against S. oryzae and T. castaneum (LC₅₀ = 14.19 and 17.16 mg/l, respectively). Structure-toxicity investigations revealed that (−)-carvone—, a ketone—, had the highest contact toxicity against the both insects. 1-8-Cineole—, an ether—, was the most potent fumigant against both insects. In vitro inhibition studies of AChE from adults of S. oryzae showed that cuminaldehyde most effectively inhibited enzyme activity at the two tested concentrations (0.01 and 0.05 M) followed by 1-8-cineole, (−)-limonene, and (l)-fenchone. 1-8-Cineole was the most potent inhibitor of AChE activity from T. castaneum larvae followed by (−)-carvone and (−)-limonene. The results of the present study indicate that (−)-carvone, 1,8-cineole, cuminaldehyde, (l)-fenchone, and (−)-limonene could be effective biocontrol agents against S. oryzae and T. castaneum.     

Modification of epoxidized soybean oil for lubricant formulations with improved oxidative stability and low pour point

To produce soybean oil-based lubricants with good oxidative stability and low pour point, epoxidized soybean oil (SBO) was chemically modified. Epoxidized SBO was reacted with various alcohols in the presence of sulfuric acid as a catalyst to give a ring-opened intermediate product. In this step, the epoxy group was transformed to the functional group of-CH(OR¹)CH(OH)-(where the R¹=methyl, 1-butyl, 2-butyl, 1-hexyl, cyclohexyl, 2,2-dimethyl-1-propyl, or 1-decyl). The ¹H nuclear magnetic resonance spectra of the products indicated that transesterification was accompanied by the ringopening reaction except when the bulky 2,2-dimethyl-1-propanol was used. Acid anhydride was used to esterify the hydroxy groups in the ring-opened product. This resulted in a fluid that is a lubricant candidate with the functional group of −CH(OR¹)CH(OCOR²)−. Pour point studies of the resulting products showed that the pour points varied with the substituents, R¹ and R². Products with R¹=CH₃(CH₂)₅₋ and R²=CH₃(CH₂)₂₋, (CH₃)₂CH−, or CH₃(CH₂)₄-showed the lowest pour points (−39, −39, and −45°C, respectively) when 1% of pour point depressant was added. For the oxidative stability test, two products, in which R¹, R²=CH₃(CH₂)₅₋, (CH₃)₂CH− and R¹, R²=CH₃(CH₂)₅₋, CH₃(CH₂)₄₋, were chosen for a modified Penn State micro-oxidation test. In the oxidative stability test, the products gave 69–71% of oxidative evaporation and 10–17% of tetrahydrofuran-insoluble deposits in 3 h at 175°C. The amounts of deposits were much lower than those of soybean oil (96%) and epoxidized SBO (83%) and even less than those of most petroleum-based lubricant basestocks (3–93%).