Iodide reaction times of peroxyhemiacetals (PHAs) in the peroxide value titration; implications for the testing of citrus oils,Flavour and Fragrance Journal

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Iodide reaction times of peroxyhemiacetals (PHAs) in the peroxide value titration; implications for the testing of citrus oils
Flavour and Fragrance Journal ( IF 2.1 ) Pub Date : 2019-11-07 , DOI: 10.1002/ffj.3542
Michael J. Calandra ₁ , Ying Wang ₁ , Courtney Beckett ₁

Affiliation

Limonene and linalool are major components in many essential oils, and both may autoxidize under certain conditions to form terpene hydroperoxides (THPs), which are reported to be sensitizers that may cause allergic contact dermatitis. This laboratory previously reported that peroxyhemiacetals (PHAs) may be present in some citrus oils, formed by reaction of THPs with endogenous aldehydes. It was also shown that PHAs can dissociate back to the corresponding THPs in polar solvation environments. Because of this potential for reversion to THPs, the analysis of PHAs is important in the context of measuring peroxide values in products. The fragrance industry currently utilizes iodometric titration to monitor THP levels in many raw materials; the currently accepted method requires that THPs in the sample are allowed to oxidize excess added iodide to molecular iodine for a one‐minute reaction time. The iodine generated is then titrated with thiosulfate to give the peroxide value. This paper reports on the iodide reaction time required for PHAs to be quantitatively measured by such an iodometric titration technique, and on the implications to citrus oil raw material testing.

中文翻译：

过氧滴定法中过氧半缩醛（PHA）的碘化物反应时间；对柑桔油测试的意义

柠檬烯和芳樟醇是许多精油中的主要成分，它们在一定条件下都可能自氧化形成氢过氧化萜烯（THPs），据报道它们是可能引起过敏性接触性皮炎的敏化剂。该实验室先前曾报道过，THP与内源性醛反应生成的某些柑橘类油中可能存在过氧半缩醛（PHA）。还表明，在极性溶剂化环境中，PHA可以解离回相应的THP。由于具有转化为THP的潜力，因此在测量产品中的过氧化物值的背景下，PHA的分析非常重要。目前，香料行业利用碘量滴定法来监测许多原材料中的THP水平。目前公认的方法要求样品中的THP允许在一分钟的反应时间内将过量添加的碘化物氧化为分子碘。然后将生成的碘用硫代硫酸盐滴定，得到过氧化物值。本文报道了通过这种碘量滴定技术定量测量PHA所需的碘化物反应时间，以及对柑桔油原料测试的影响。

更新日期：2019-11-07

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