Effects of Microwave Heating on the Molecular Species of Soybean Triacylglycerols

Microwave heating of whole soybeans resulted in an apparent increase of the total lipids. Molecular species of triacylglycerols were isolated from total lipids by a combination of silicic acid column chromatography and AgNO₃-thin layer chromatography (TLC). Fifteen molecular species of triacylglycerols were still found in whole soybeans following heat treatment. Microwave heating for about 5 min did not change all molecular species of soybean triacylglycerols nor cause a loss of unsaturated heat fatty acids. However, heat treatment for 8 min significant decrease not only in molecular species containing more than four double bonds, but also in the amount of diene and triene present in a triacylglycerol.     

Effects of Microwave Treatment on the Trypsin Inhibitor and Molecular Species of Triglycerides in Soybeans

Whole soybeans at different moistures (8.6, 24.3, and 49.7%) were heated by exposure to microwaves at frequency of 2,450 MHz. The trypsin inhibitor in soybeans at 24.3% moisture, soaked for 1 hr, was completely inactivated after treatment for 4 min, which was shorter than the heating period (6 min) needed for unsoaked soybeans. However, the trypsin inhibitor in soybeans at 49.7% moisture, soaked for 5 hr, was not completely inactivated even after heating for 12 min. The loss of molecular species of soybean triglycerides containing more than four double bonds in a triglyceride was less for soaked soybeans than for soybeans before soaking (8.6% moisture).     

Use of an aggregation model as an observer

An aggregation model can be used to reconstruct the state variables of a plant. The necessary and sufficient conditions for the existence of such an aggregation model are given. This model can be seen as a degenerate case of a conventional observer, and can be constructed more easily. The use of this in a feedback system can be seen as generalization of a pole-zero cancellation technique in classical design methods.     

Precise Determination of the 3CaO·SiO2 Cells and Interpretation of Their X-Ray Diffraction Patterns

The cell dimensions of pure triclinic 3CaO·SiO₂ and monoclinic 3CaO·SiO₂ solid solution (54CaO·16SiO₂·Al₂O₃·MgO) were determined and the powder diffraction patterns were indexed by the method of precise measurement of the spacings. The lattice constants are expressed in terms of triclinic or monoclinic cells corresponding to pseudo-orthorhombic cells derived from Jeffery's trigonal cell. The apparent lattice constants for pure 3CaO·SiO₂ are a = 12.195 a.u., b = 7.104 au., c = 25.096 a.u., α= 90°, β= 89°44'γ= 89°44'; for 54CaO·16SiO₂.-Al₂O₃MgO, a = 12.246 a.u., b = 7.045 a.u., c = 24.985 a.u., β= 90°04'. Precise lattice constants of Jeffery's monoclinic lattice for 54CaO.-16SiO₂-Al₂O₃·MgO are derived as a = 33.091 a.u., b = 7.045 a.u., c = 18.546 a.u., β= 94°08'. High-temperature X-ray patterns showed that pure triclinic 3CaO·SiO₂ transformed to a monoclinic form at about 920°C. and then to a trigonal form at about 970°C. Monoclinic 54CaO.16SiO₂·Al₂O₃–MgO transformed to trigonal at about 830°C. These transitions were reversible and reproducible and were accompanied by only slight deformation of the structure forms.     

Microwave Heating Effects on Relative Stabilities of Tocopherols in Oils

The relative stabilities of individual tocopherols during microwave heating were investigated in fatty acid esters and tocopherol-stripped vegetable oils. The rate of tocopherol loss during heating was less from the highly unsaturated ethyl esters or vegetable oils than from ethyl laurate or olive oil. However, changes in chemical properties of the substrates depended on degree of unsaturation of esters and oils. The stability of tocopherols during microwave heating was δ > β > γ > α, and the order did not change with differences in the type of ethyl esters of fatty acids or oils.     

Microwave Heating Affects Composition and Oxidative Stability of Sesame (Sesamum indicum) Oil

The effects of microwave heating on antioxidative components and lipid quality of sesame seeds were studied. Amounts of antioxidative components were 576, 18, and 8 mg/kg oil for γ-, δ-, and α-tocopherols; 6,824, 5,642, and 54 mg/kg oil for sesamin, sesamolin, and sesamol, respectively. During microwave treatments, concentrations of tocopherols, sesamin and sesamolin gradually decreased, and ca. 20% of these dominant components was lost after 30 min heating. However, microwave treatments for 16 to 20 min, which would be optimal to prepare sesame oil with better quality, still retained over 85% of the antioxidative components (with few exceptions) and caused no significant chemical changes in lipids.     

Microwave Energy Effects on Quality of Some Seed Oils

Effects of microwave heating were investigated on chemical properties of seed oils in relation to tocopherol contents. For assessing quality of oils (linseed, soybean, corn, olive, and palm) during microwave treatments, peroxide, thiobarbituric acid, carbonyl and anisidine values were determined. As the amount of polyunsaturated fatty acids in oils increased the index for the chemical properties increased. After 8-10 min heating the amount of tocopherols decreased substantially in linseed, olive and palm oils, whereas that in corn and soybean oils was still ca. 90%. Thus, the reduction in tocopherols in oils is not necessarily in agreement with chemical properties of the oils.     

Lamb wave device using PbZrO3-based ceramic substrate

A Lamb wave device using a PbZrO₃ abased piezoelectric ceramic substrate and its application to an oscillator are described. The Lamb wave device which is practically in single-mode operation uses the zeroth-order symmetrical (S₀ ) mode. A delay line oscillator is composed of the S₀ mode device, an amplifier and an electrically controllable phase shifter, whose oscillation frequency varies with the applied voltage. The oscillator has fine frequency modulation characteristics in a wide frequency range from DC to 100 kHz. The device performance is useful for FM signal processing or voltage sensing.     

Effects of Microwave Energy on the Tocopherols of Soybean Seeds

The effects of microwave heating on the tocopherols of soybeans were studied in relation to chemical changes in the lipids. The amounts of α-, β-, γ-, and δ-tocopherols in the soybeans before microwave treatment ranged from 6.2 to 13.0, 2.7 to 4.5, 60.0 to 76.8, and 45.7 to 57.9 mg/100 g lipid, respectively, γ- and δ-Tocopherol concentrations gradually decreased, and as much as 40% of the tocopherols originally present in the soybeans was lost after 12 min heating. However, microwave treatment of soybeans for 6 min, which would be optimal to prepare full-fat soyflour without a burnt odor, retained ca. 90% of the individual tocopherols with a few exceptions and caused no significant difference in the chemical changes of the lipids.     

Microwave Roasting Effects on Acyl Lipids in Soybeans (Glycine max. L.) at Different Moisture Contents

The effects of microwave roasting on acyl-lipids of soybeans were studied iti relation to moisture. During microwave treatments, triacylglycerols were hydrolyzed randomly, due to differences of moisture contents, but remained > 72% of total lipids after 20 min roasting. Phospholipids containing amino group decreased substantially (P < 0.05) in low moisture soybeans. Formation of browning substances was inhibited by increasing moisture contents. Differences (P < 0.05) in fatty acid distributions occuired (with few exceptions) when soybeans were microwaved for 12 min or more. Microwave treatments for soybeans should depend on moisture contents.