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Trans fat is a unsaturated fatty acid with trans configuration and separated double bonds. Analytical methods have been introduced to analyze trans fat content in foods including infrared (IR) spectroscopy, gas chromatography (GC), Fourier transform-infrared (FT-IR) spectroscopy, reverses-phase silver ion high performance liquid chromatography, and silver nitrate thin layer chromatography. Currently, FT-IR spectroscopy and GC are mostly used methods. Trans fat content in 6 vegetable oils were analyzed and processing effects including baking, stir-frying, pan-frying, and frying on the formation of trans fat in corn oil was evaluated by GC. Among tested vegetable oils, corn oil has 0.25 g trans fat/100 g, whereas other oils including rapeseed, soybean, olive, perilla, and sesame oils did not have detectable amount of trans fat content. Among cooking methods, stir-frying increased trans fat in corn oil whereas baking, pan-frying, and frying procedures did not make changes in trans fat content compared to untreated corn oils. However, the trans fat content was so low and food label can be declared as ‘0’ trans based on the regulation of Ministry of Food ad Drug Safety (MFDS) (< 2 g/100 g edible oil).

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Summary A simple spectroscopic method using 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) was developed to simultaneously monitor the contents of free radical scavenging antioxidants (FRSs) and oxidised lipid products during oxidation through selection of proper solvents. Validation of the DPPH method was conducted in a stripped oil matrix, and practical applicability of the method was tested with heated oils. The absorbance of DPPH in isooctane simultaneously reflected the changing amounts of both FRSs and oxidised lipid products, whereas the absorbance in methanol mainly reflected changes in FRSs. Total polar materials (TPMs) were found to be representative of oxidised lipid products, which reacted with DPPH in isooctane better than in methanol. Validation parameters including accuracy, precision, linearity, limit of detection and limit of quantification were determined using α‐tocopherol as a model for FRSs and TPMs for oxidised lipid products. The DPPH protocol in isooctane and in methanol is useful for assessing the degree of oxidation in heated oils through comparing the contents of FRSs and oxidised lipids.

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The research aims to describe the micro-machining characteristics in a high-speed magnetic abrasive finishing, which is applicable for achieving the high surface accuracy and dimensional accuracy of fine ceramic bars that are typically characterized by strong hardness and brittle susceptibility. In this paper, the high-speed magnetic abrasive finishing was applied to investigate how the finishing parameters would have effects on such output parameters as surface roughness, variation of diameters, roundness, and removed weight. The results showed that, under variants of diamond abrasives sizing between (1, 3 and 9 µm), 1 µm showed comparatively good values as for surface roughness and roundness within shortest processing time. When the optimal condition was used, the surface roughness Ra and roundness (LSC) were improved to 0.01 µm and 0.14 µm, respectively. The tendency of diameter change could be categorized into two regions—stable and unstable. The finding from the study was that the performance of ultra-precision processing linear controlling was possibly achievable for the stable region of diameter change, while linearly controlling diameters in the workpiece.