Determination of alpha beta-unsaturated aldehydes formed from deteriorated deep fried oils and food in large scale cooking.

为了测定油脂自氧化或热氧化过程中过氧化氢二次生成的反应性低分子α-β-不饱和醛的含量，研究了一种新的测定方法。由于这些不饱和醛不稳定，用2，4-DNPH作稳定剂，用最不稳定的醛-4-羟基-2-反式-壬烯醛(HNE)作为萃取剂，考察了提取溶剂和与2，4-DNPH反应的条件。初步的高效液相色谱柱(ODS柱，乙腈/水/四氢呋喃70：29：1，检测波长：350 nm)中HNE的回收率极高，达99.38%。这些α-β-不饱和醛的9个肼类化合物可以用线性梯度高效液相色谱法(ODS柱，乙腈：水：四氢呋喃，60：39：LTO 90：9：1，30min，检测：UV 350 nm)进行分离，并以庚烯醛为内标计算各醛的量。在当地市场上购买的8种植物油，在2 0 0ﾟC的热块浴中加热5h，用这种新方法测定这些醛。这些不饱和醛在玉米油和红花油中的总含量为1200mug/ml，而在紫苏油和烘烤芝麻油中的不饱和醛总量为600mug/mloil。

To determine the amount of reactive low molecular alpha beta-unsaturated aldehydes, which were secondary formed from peroxides in autoxidation or thermal oxidation of oils and fats, a new method was investigated.As these unsaturated aldehydes were unstable, they were stabilized with carbonyl reagent, 2,4-DNPH.With the hydrazone of 4-hydroxy-2-trans-nonenal (HNE), which was the most unstable aldehyde, extracting solvent and some reactive conditions with 2,4-DNPH were examined. The extremely high recovery of hydrazone of HNE during the processes was obtained as 99.38% in preliminary HPLC examination (ODScolumn, acetonitrile/H_2O/ THF 70 : 29 : 1, detect : uv 350nm). The nine hydrazones of these alpha beta-unsaturated aldehydes were able to separate by linear gradient HPLC (ODS column, acetonitrile : H_2O : THF from 60 : 39 : lto 90 : 9 : 1 by 30min, detect : uv 350nm) and to calculate the amount of each aldehyde by heptenal, as an internal standard. The eight vegetable oils, which were purchased in some local markets, were heated in hot block bath at 200ﾟC,for 5 hours and dtermined these aldehydes by this new method. The total amout of these unsaturated aldehydes was 1200mug/ml oil in corn and safflower oils, on the other hand, 600 mug/mloil in perilla and roasted sesame oils.These results were shown that the reactive and toxic in vivo aldehydes produced from deteriorated edible oils were separated and determined with high sensitiveness by linear gradient HPLC.