| Summary: | 酸价（acid value, AV）指示油脂中游离脂肪酸(free fatty acid, FFA)含量，是油脂和含油食品最重要的质量指标和安全指标之一。针对现行AV测定标准的酸碱中和滴定技术的共性与非特异性的局限，旨在给复杂基质样品的特异性定量FFA或AV提供新思路，综述了最具代表性的FFA特异性检测技术——铜皂络合比色法的近70年的研究进展。阐述了有机相溶解液的毒性与显色强度之间的矛盾化解历程、铜盐-吡啶水相染色液的演化史、FFA的铜皂络合物结构解析过程，以及从pH调控的经典络合显色理论到以吡啶与铜离子摩尔比为核心的络合显色理论的新发展。吡啶与铜离子摩尔比为\[1，3）的络合显色理论、具有增强显色强度和抑制乳化作用的乙酸盐-乙酸缓冲体系的中性染色液、低毒性溶剂替代传统高毒性苯的有机相溶解液，这三大创新使经典铜皂络合比色法突破了长期存在的试剂毒性与显色稳定性等瓶颈，成为复杂基质样品的特异性定量FFA或AV的理想方法。
Acid value(AV) indicates the content of free fatty acids(FFA) in oils and fats, which is one of the most important quality and safety indicators of oils and fats and oily foodstuffs. In view of the commonness and non-specificity limitations of the current acid-base neutralization titration techniques for AV determination standards, a new idea for the specific quantification of FFA or AV in complex matrix samples is aimed to offer. The research progress of cupric acetate-pyridine complexation colorimetry, the most representative technology for the specific determination of FFA in the nearly 70 years, was reviewed. The conflict resolution process between the toxicity of organic phase solution and color intensity, the evolution history of cupric acetate-pyridine colorimetric aqueous phase dyeing solution, the structure analysis process of cupric acetate-pyridine complex of FFA, and the new development of complexation color theory from the classical theory with pH regulation to the new theory with pyridine/copper ion mole ratio as the core were described. Pyridine/copper ions mole ratio \[1, 3) of the complexation color theory, acetate - acetic acid buffer′s neutral dyeing liquid with enhancement of color strength and inhibition of the emulsification, low toxic solvent instead of traditional high toxicity of benzene dissolved organic phase, three big innovation make the classic colorimetric method break through the bottleneck of toxicity and color stability etc., which is expected to be an ideal method for the specific quantification of FFA or AV in complex matrix samples.
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