Dipartimento di Ingegneria Industriale, Università degli Studi di Parma, viale Usberti, 181/A, I-43124 Parma, Italy.
J Sci Food Agric. 2011 Jan 30;91(2):198-206. doi: 10.1002/jsfa.4165.
The use of differential scanning calorimetry (DSC) for assessing the deterioration effect of microwave heating on vegetable oils, and on olive oils in particular, has been partially explored in literature. The aim of this work was to evaluate the potential of DSC to discriminate among microwaved extra virgin olive oils (EvOo from different olive cultivar and origin), according to changes on thermal properties (upon cooling and heating) and traditional oxidative stability indices (peroxide, p-anisidine and TOTOX values).
An elevated value of lipid oxidation was reached by the most unsaturated EvOo sample (9.5% of linoleic acid) at 6 min of microwave treatment. Free acidity significantly increased (0.42%) only for the oil sample with the highest water content (874 mg kg(-1) oil) at the longest time of treatment. Crystallisation enthalpies significantly decreased and the major exothermic peak shifted towards lower temperature, leading to enlargement of the transition range in all samples due to the formation of weak and mixed crystals among triacylglycerols and lipid degradation products. On the contrary, thermal properties upon heating appeared to similarly vary among samples.
The analysis of DSC thermal properties upon cooling seemed to clearly discriminate among different EvOo samples after microwaving. The relation between changes of thermal properties and oxidation parameters should be further studied using additional oxidative stability indices on a larger set of oil samples, due to the complexity of EvOo composition.
文献中已经部分探讨了使用差示扫描量热法（DSC）来评估微波加热对植物油（特别是橄榄油）劣化效果的影响。本工作旨在评估 DSC 鉴别经微波处理的特级初榨橄榄油（EvOo，来自不同橄榄品种和产地）的潜力，方法是根据热特性（冷却和加热时）和传统氧化稳定性指标（过氧化物值、对茴香胺值和 TOTOX 值）的变化来进行。
在 6 分钟的微波处理下，最不饱和的 EvOo 样品（亚油酸含量为 9.5%）达到了较高的脂质氧化值。仅在处理时间最长、含水量最高（874mgkg(-1)油）的油样中，游离酸度显著增加（0.42%）。结晶焓显著降低，主要放热峰向低温移动，导致所有样品的相变范围扩大，这是由于甘油三酯之间形成了弱混合晶体和脂质降解产物。相比之下，加热时的热特性似乎在样品之间也有类似的变化。
经微波处理后，通过冷却时 DSC 热特性的分析似乎可以清楚地区分不同的 EvOo 样品。由于 EvOo 成分复杂，应使用更多的氧化稳定性指标在更大的油样组上进一步研究热特性变化与氧化参数之间的关系。
