用于从羊肌肉制备脂肪酸甲酯的酸性和碱性催化剂的比较，重点关注共轭亚油酸。

Comparison of acidic and alkaline catalysts for preparation of fatty acid methyl esters from ovine muscle with emphasis on conjugated linoleic acid.

作者信息

Murrieta C M, Hess B W, Rule D C

机构信息

Department of Animal Science, University of Wyoming, Laramie, WY 82071-3684, USA.

出版信息

Meat Sci. 2003 Sep;65(1):523-9. doi: 10.1016/S0309-1740(02)00244-9.

DOI:10.1016/S0309-1740(02)00244-9

PMID:22063245

Abstract

Methanolic reagents containing acidic catalysts, HCl (0.5 M, 1 h, 80° C) or BF(3) (14%, 1 h, 80° C), or alkaline catalysts, KOH (0.2 M, 15-60 min, 50° C) or NaOCH(3) (0.5 M, 15-60 min, 50° C), were compared for use in preparation of fatty acid methyl esters for GC analysis of total lipids from freeze-dried semitendinosus muscle of lambs fed a 3.6% linoleate diet. Lipid preparations were in duplicate and included a total lipid extract, as well as direct transesterification and direct saponification of freeze-dried muscle. For the total lipid extracts, the weight% of 18:2 cis-9, trans-11 (CLA) with BF(3) (1.15) was 14.0% lower (P=0.001) than with either KOH (1.32) or NaOCH(3) (1.36); however, with HCl (1.25) CLA was intermediate (P=0.02). Concentrations of CLA (mg/g tissue) were similar (P ⩾0.44) within acidic or alkaline catalysts, but were 18.1% higher (P ⩽0.01) with KOH (2.56) and NaOCH(3) (2.52) than with HCl (2.01) or BF(3) (2.12). For direct transesterification, weight% of CLA was similar (P=0.55) with KOH (1.34) and NaOCH(3) (1.33), but each was 11.9% greater (P=0.003) than with HCl (1.18) and 19.1% greater (P=0.005) than with BF(3) (1.08). Concentrations of CLA after direct transesterification were greatest (P ⩽0.04) with KOH (3.31), followed by HCl (2.89, P=0.04), BF(3) (2.42, P ⩽0.004), and lowest (P ⩽0.002) with NaOCH(3) (2.21), indicating differences in efficiency of direct transesterification. Weight% of CLA in semitendinosus muscle, ranked highest to lowest, was lambs fed 3.6% linoleate (P ⩽0.003) > lambs fed 3.8% oleate (P ⩽0.01) > lambs fed a non-fat supplemented control diet (P ⩽0.01) when either BF(3) (saponified lipids) or KOH (direct transesterification) was used. Thus, dietary treatment effects on muscle CLA were not affected by catalyst. For the muscle of high-linoleate, high-oleate, and control lambs, CLA was 20.2, 13.9 and 0.0% higher, respectively, with KOH than BF(3), indicating that degradation of CLA by acidic catalysts decreased with lower starting amounts of CLA.

摘要

比较了含有酸性催化剂（0.5 M HCl，80℃，1小时或14% BF₃，80℃，1小时）或碱性催化剂（0.2 M KOH，50℃，15 - 60分钟或0.5 M NaOCH₃，50℃，15 - 60分钟）的甲醇试剂在制备脂肪酸甲酯中的应用，用于气相色谱分析饲喂3.6%亚油酸日粮的羔羊冻干半腱肌中的总脂质。脂质制备重复进行，包括总脂质提取物，以及冻干肌肉的直接酯交换和直接皂化。对于总脂质提取物，使用BF₃（1.15）时18:2顺-9，反-11（共轭亚油酸，CLA）的重量百分比比使用KOH（1.32）或NaOCH₃（1.36）时低14.0%（P = 0.001）；然而，使用HCl（1.25）时CLA处于中间水平（P = 0.02）。在酸性或碱性催化剂中，CLA的浓度（mg/g组织）相似（P⩾0.44），但使用KOH（2.56）和NaOCH₃（2.52）时比使用HCl（2.01）或BF₃（2.12）时高18.1%（P⩽0.01）。对于直接酯交换，使用KOH（1.34）和NaOCH₃（1.33）时CLA的重量百分比相似（P = 0.55），但均比使用HCl（1.18）时高11.9%（P = 0.003），比使用BF₃（1.08）时高19.1%（P = 0.005）。直接酯交换后CLA的浓度以KOH（3.31）最高（P⩽0.04），其次是HCl（2.89，P = 0.04）、BF₃（2.42, P⩽0.004），以NaOCH₃（2.21）最低（P⩽0.002），表明直接酯交换效率存在差异。当使用BF₃（皂化脂质）或KOH（直接酯交换）时，半腱肌中CLA的重量百分比从高到低依次为：饲喂3.6%亚油酸的羔羊（P⩽0.003）>饲喂3.8%油酸的羔羊（P⩽0.01）>饲喂无脂肪补充对照日粮的羔羊（P⩽0.01）。因此，日粮处理对肌肉CLA的影响不受催化剂影响。对于高亚油酸、高油酸和对照羔羊的肌肉，使用KOH时CLA分别比使用BF₃时高20.2%、13.9%和0.0%，表明随着CLA起始量降低，酸性催化剂对CLA的降解作用减弱。