National Institute of Lasers and Optronics (NILOP), Lehtrar Road, Islamabad, Pakistan.
Barani Agricultural research Institute (BARI), Chakwal, Pakistan.
J Fluoresc. 2020 Jul;30(4):939-947. doi: 10.1007/s10895-020-02538-7. Epub 2020 Jun 6.
The olive oil production in Pakistan has recently been started with the cultivation of exotic cultivars that are successfully adapted at Barani Agriculture Research center (BARI), Chakwal, Pakistan in Potohar valley. Therefore, characterization of extra virgin olive oil (EVOO) from this agro-climatic region is mandatory in establishing its biochemical profile and thermal stability. Seventeen monovarietal EVOOs extracted from these cultivars were analysed using synchronous fluorescence spectroscopy (SFS) and subjected to heating at 115, 150 and 170 °C for 15 min to identify their thermal stability. SFS emission spectra differentiated EVOOs on the basis of phenolic compounds that are denatured at high temperature, further chlorophyll contents also decreased with increasing temperature. The strong emission at ca. 351 nm, suggested to be vanillic acid, 391-471 nm for blue green region (BGR) assigned to other phenolic compounds and two peaks at 672 and 723 nm for chlorophyll became the bases for grouping through Hierarchical clustering. Most of the EVOOs were stable at 150 °C but showed denatured spectra at 170 °C, the only EVOO extracted from Spanish cultivar Arbequina was found to have moderate fluorescence emission from both vanillic acid and BGR that are more likely to impart oxidative stability even after heating at 170 °C, also confirmed by lowest values of specific extinction co-efficient (K and K). Moreover, variation in phenolic contents of Arbequina EVOO was observed with different harvesting stages and the early harvested olives produced more thermally stable oil as compared to late harvested olives. Arbequina oil grown in Pakistan can be better suited for cooking at high temperatures, moreover can be blended with other monovarietal EVOOs to enhance the nutritional benefits and thermal stability.
巴基斯坦最近开始种植外来品种来生产橄榄油，这些品种在巴基斯坦 Potohar 山谷的巴拉尼农业研究中心（BARI）成功适应了巴兰农业。因此，有必要对该农业气候区的特级初榨橄榄油（EVOO）进行特征描述，以确定其生化特征和热稳定性。从这些品种中提取的 17 种单品种 EVOO 使用同步荧光光谱（SFS）进行分析，并在 115、150 和 170°C 下加热 15 分钟，以确定其热稳定性。SFS 发射光谱根据在高温下变性的酚类化合物区分 EVOO，随着温度的升高，叶绿素含量也降低。在 ca.351nm 处的强发射，推测为香草酸，在 391-471nm 处的蓝绿色区域（BGR）归因于其他酚类化合物，在 672nm 和 723nm 处的两个峰为叶绿素，成为通过层次聚类进行分组的基础。大多数 EVOO 在 150°C 下稳定，但在 170°C 下显示出变性光谱，唯一从西班牙品种 Arbequina 提取的 EVOO 表现出香草酸和 BGR 的中等荧光发射，这更有可能赋予即使在 170°C 加热后仍具有氧化稳定性，这也通过最低的特征消光系数（K 和 K）得到证实。此外，Arbequina EVOO 的酚类含量随不同的收获阶段而变化，早期收获的橄榄产生的油更热稳定，与晚期收获的橄榄相比。在巴基斯坦种植的 Arbequina 油更适合高温烹饪，此外还可以与其他单品种 EVOO 混合，以提高营养价值和热稳定性。
