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葵花籽油过氧化值激光诱导荧光快速检测技术研究

Laser Induced Fluorescence System for Assessment of PV of Sunflower Oil

  • 摘要: 葵花籽油极易被氧化产生多种自由基、有毒聚合物等,因此葵花籽油产销链中过氧化值现场实时检测技术及装置研发具有重要意义。以设计便携式检测装置为目的,搭建了基于激光诱导荧光光谱的食用油过氧化值快速检测系统,建立了葵花籽油过氧化值定量预测模型,并进行了外部实验验证。结果表明,基于自行搭建的检测系统采集的80个不同过氧化值葵花籽油原始光谱,经SG平滑加MSC预处理结合CARS算法筛选荧光特征波长后建立的过氧化值PLS定量预测模型效果最佳,R■和R■分别为0.999 5和0.997 2,校正集均方根误差和验证集均方根误差分别为0.008 8 g/(100 g)和0.022 7 g/(100 g)。同时选取10个未参与建模的葵花籽油样品对模型进行外部验证,预测值与理化测定值的R2为0.968 1,均方根误差为0.041 1 g/(100 g),在低于国标限0.25 g/(100 g)的残差绝对值均在0.08 g/(100 g)以下。结果表明,自行设计的激光诱导荧光检测系统可以较高的精度实现对葵花籽油过氧化值的快速检测,为后续便携式整机设计和食用油氧化预警系统构建提供技术支持。

     

    Abstract: With the aim to develop a rapid and nondestructive method to assess oxidation level of sunflower oil, fluorescence spectra were collected by a self-developed 365 nm laser induced fluorescence(LIF) system. Both thermal oxidation at 60℃ and room-temperature degradation were implemented to obtain sunflower oil with different peroxide values(PV). Fluorescence peaks at about 440 nm, 495 nm, 520 nm and 680 nm were identified. Sunflower oil with lower PVs had lower fluorescence intensities. A control part was designed in order to detect the fluorescence response at different spectral acquisition times. In contrast to the LIF spectra acquired from 10 s to 60 s(with a interval of 10 s), the spectra acquired at 1 s appeared to have the strongest response, and therefore it was used in the following part. After SG smoothing of the original LIF spectra, three different pre-processing methods were operated to correct the spectra. Top six normalized weights were extracted for evaluating the correlation between fluorophore in sunflower oil and PV. The peaks for hydroperoxides, chlorophyll and vitamin E had a very close association with the PV. The best partial least squares regression resulted in R■ of 0.999 5 and R■ of 0.997 2 and RMSEC of 0.008 8 g/(100 g) and RMSEP of 0.022 7 g/(100 g) for MSC pre-processing. The accuracy of the proposed LIF system was validated by using an independent set of samples with an R~2 of 0.968 1 and RMSE of 0.041 1 g/(100 g). The absolute residual values below the national standard limit were all below 0.08 g/(100 g). These findings demonstrated that the proposed LIF system could be used to detect PV of sunflower oil with high accuracy, thus providing technical support for subsequent design of portable device and construction of edible oil oxidation warning system.

     

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