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RISS 인기검색어
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- 발행기관 : American Oil Chemists' Society (검색결과 5 건)
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Effects of Deuterium Oxide on the Oxidative Stability and Change of Headspace Volatiles of Corn Oil
Kim, J.,Kim, M. J.,Lee, J. AOCS AMERICAN OIL CHEMISTS' SOCIETY 2014 Journal of the American Oil Chemists' Society Vol.91 No.4
Effects of deuterium oxide and deuterium oxide-free water on the oxidative stability and formation of headspace volatiles were determined for corn oils to evaluate the role of moisture as an active influential factors during lipid oxidation. Mixtures of corn oil and water with different ratios of deuterium oxide were prepared, and the mixtures were stored at 60 A degrees C for 2 days. Headspace oxygen contents, conjugated dienoic acid (CDA) values, and p-anisidine values (p-AV) were analyzed as a measure of oxidative stability, and headspace volatiles were analyzed by solid phase microextraction and a gas chromatography mass selective detector to determine the involvement of deuterium in volatiles. Deuterium oxide accelerated the rate of lipid oxidation in corn oil compared to oils with deuterium-free water based on the results of headspace oxygen content, CDA, p-AV, and total volatile content. Fragmented mass to charge ratios (m/z) of 73.1/72.1 for d (1)-pentane/pentane and 57.0/56.0 for d (1)-2-propenal/2-propenal from samples containing deuterium oxide were significantly higher than those from deuterium oxide-free water, implying that moisture participated to form volatiles in corn oil oxidation under air-tight condition. Deuterium oxide appeared to accelerate the rate of lipid oxidation in corn oils and participated to form volatiles from oils during oxidation.
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Kim, S.,Kim, I. H.,Akoh, C. C.,Kim, B. H. AOCS AMERICAN OIL CHEMISTS' SOCIETY 2014 Journal of the American Oil Chemists' Society Vol.91 No.5
This study aimed to optimize the lipase-catalyzed transesterification of high oleic sunflower oil (A) with a mixture of ethyl palmitate and ethyl stearate (B) to produce cocoa butter equivalents with a weight ratio of 1-palmitoyl-2-oleoyl-3-stearoyl-rac-glycerol (POS) to total symmetric monounsaturated triacylglycerols (SMUT) that is similar to that of cocoa butter by response surface methodology. The reaction was performed in a continuous packed bed reactor, using 0.45 g of Lipozyme RM IM as the biocatalyst. The effects of temperature (Te), residence time (RT), substrate molar ratio (SR, B/A), and water content (WC) of the substrates on the composition of reaction products were elucidated using the models established. Optimal reaction conditions for maximizing total SMUT and POS contents while minimizing the levels of diacylglycerol formation and acyl migration were: Te, 60 A degrees C; RT, 28.5 min; SR, 8.5; WC, 300 mg/kg. The contents of total SMUT, POS, and diacylglycerol in the reaction products and the content of palmitoyl and stearoyl residues at the sn-2 position of triacylglycerols in the products were 52.0, 25.1, 9.4, and 4.8 %, respectively, under these conditions. Successful scale-up of the reaction was achieved under the optimal conditions, using 5 g of the lipase. A silver-ion high performance liquid chromatography analysis showed that the products obtained by the larger scale reaction contained 49.1 % total SMUT and 6.1 % of their positional isomers.
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Ahn, Jinsoo,Oh, Shin-Ae,Suh, Yeunsu,Moeller, Steven J,Lee, Kichoon American Oil Chemists' Society 2013 Lipids Vol.48 No.3
<P>Adipose triglyceride lipase (ATGL), catalyzing the initial step of hydrolysis of triacylglycerol (TAG) in adipocytes, has been known to be inhibited by G0/G1 switch gene 2 (G0S2). In this study, we report the porcine G0S2 cDNA and amino acid sequences as well as the expression level of porcine G0S2. The porcine G0S2 mRNA was abundantly expressed in adipose tissue and liver among various tissues. In adipose tissue, porcine G0S2 expression was 16-fold higher in the fat cell fraction than the stromal vascular fraction. The G0S2 level increased significantly during adipogenesis in vitro and in vivo. These data indicate that G0S2 expression is closely associated with lipid accumulation and adipogenesis. Considering G0S2 as an inhibitor of cell proliferation, the relatively low levels of G0S2 in preadipocytes and adipose tissues of fetal and neonatal pigs compared to adipocytes and adipose tissues of adult pigs may allow the fast cell proliferation rates. Further studies showed that a short-term 24-h fast down-regulated G0S2 expression and increased ATGL expression in adipose tissue; however, a long-term calorie restriction for 8?days had no influence on the level of G0S2 but increased ATGL expression. Therefore, porcine G0S2, which is both a negative regulator of ATGL-mediated lipolysis and cell proliferation in adipose tissue, can be down-regulated in vivo by a short-term 24-h fast followed by increased ATGL-mediated lipolysis.</P>
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Wang, T,Lee, S B,Hwang, J H,Lim, J N,Jung, U S,Kim, M J,Kang, H S,Choi, S H,Lee, J S,Roh, S G,Lee, H G American Oil Chemists' Society 2015 Lipids Vol.50 No.5
<P>cis-9, trans-11 Conjugated linoleic acid (CLA) is one of the most extensively studied CLA isomers due to its multiple isomer-specific effects. However, the molecular mechanisms of cis-9,trans-11 CLA synthesis in ruminant mammary gland are still not clearly understood. This process may be mediated, to a certain extent, by trans-11 C18:1 regulated by stearoyl-CoA desaturase-1 (SCD1) and/or its syntrophic proteins. This study aimed to investigate the effects of TVA on SCD1-mediated cis-9,trans-11 CLA synthesis in MAC-T cells and its potential molecular mechanism. Results showed that trans-11 C18:1 was continually taken up and converted into cis-9,trans-11 CLA in MAC-T cells during the 4-h incubation of 50?μM trans-11 C18:1. SCD1 protein expression increased more than twofold at 2?h (P?<?0.01) and 2.5?h (P?<?0.05) before decreasing to less than half of the normal level at 4?h (P?<?0.05). One up-regulated (RAS guanyl releasing protein 4 isoform 1 [RASGRP4]) and six down-regulated proteins (glucosamine-6-phosphate deaminase 1 [GNPDA1], triosephosphate isomerase [TPI1], phosphoglycerate mutase 1 [PGAM1], heat shock protein beta-1 [HSPB1], annexin A3 [ANXA3], thiopurine S-methyltransferase [TPMT]) were found in MAC-T cells treated with trans-11 C18:1. Of these seven identified proteins, the presence of GNPDA1 and PGAM1 was verified in several models. More trans-11 C18:1 was taken up after PGAM1 knockdown by small interfering RNA (siRNA). In conclusion, our data suggested that PGAM1 may have a negative relationship with SCD1 and seemed to be involved in cis-9, trans-11 CLA synthesis by facilitating the absorption of trans-11 C18:1 in the bovine mammary gland.</P>
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