Caporaso Nicola, Whitworth Martin B, Fisk Ian D
Campden BRI, Chipping Campden, Gloucestershire GL55 6LD, UK; Division of Food Sciences, University of Nottingham, Sutton Bonington Campus, LE12 5RD, UK.
Campden BRI, Chipping Campden, Gloucestershire GL55 6LD, UK.
Food Chem. 2018 Feb 1;240:32-42. doi: 10.1016/j.foodchem.2017.07.048. Epub 2017 Jul 12.
Hyperspectral imaging (HSI) combines Near-infrared (NIR) spectroscopy and digital imaging to give information about the chemical properties of objects and their spatial distribution. Protein content is one of the most important quality factors in wheat. It is known to vary widely depending on the cultivar, agronomic and climatic conditions. However, little information is known about single kernel protein variation within batches. The aim of the present work was to measure the distribution of protein content in whole wheat kernels on a single kernel basis, and to apply HSI to predict this distribution. Wheat samples from 2013 and 2014 harvests were sourced from UK millers and wheat breeders, and individual kernels were analysed by HSI and by the Dumas combustion method for total protein content. HSI was applied in the spectral region 980-2500nm in reflectance mode using the push-broom approach. Single kernel spectra were used to develop partial least squares (PLS) regression models for protein prediction of intact single grains. The protein content ranged from 6.2 to 19.8% ("as-is" basis), with significantly higher values for hard wheats. The performance of the calibration model was evaluated using the coefficient of determination (R) and the root mean square error (RMSE) from 3250 samples used for calibration and 868 used for external validation. The calibration performance for single kernel protein content was R of 0.82 and 0.79, and RMSE of 0.86 and 0.94% for the calibration and validation dataset, enabling quantification of the protein distribution between kernels and even visualisation within the same kernel. The performance of the single kernel measurement was poorer than that typically obtained for bulk samples, but is acceptable for some specific applications. The use of separate calibrations built by separating hard and soft wheat, or on kernels placed on similar orientation did not greatly improve the prediction ability. We simulated the use of the lower cost InGaAs detector (1000-1700nm), and reported that the use of proposed HgCdTe detectors over a restricted spectral range gave a lower prediction error (RMSEC=0.86% vs 1.06%, for HgCdTe and InGaAs, respectively), and increased R value (R=0.82 vs 0.73).
高光谱成像(HSI)结合了近红外(NIR)光谱学和数字成像技术,以提供有关物体化学性质及其空间分布的信息。蛋白质含量是小麦最重要的品质因素之一。众所周知,其含量会因品种、农艺和气候条件的不同而有很大差异。然而,关于批次内单粒小麦蛋白质变异的信息却知之甚少。本研究的目的是在单粒基础上测量全麦粒中蛋白质含量的分布,并应用高光谱成像技术预测这种分布。2013年和2014年收获的小麦样本来自英国的面粉厂和小麦育种者,通过高光谱成像技术和杜马斯燃烧法对单粒小麦的总蛋白质含量进行了分析。高光谱成像技术采用推扫式方法,在980 - 2500nm光谱区域以反射模式应用。单粒光谱用于建立偏最小二乘法(PLS)回归模型,以预测完整单粒小麦的蛋白质含量。蛋白质含量范围为6.2%至19.8%(“原样”基础),硬粒小麦的值明显更高。使用用于校准的3250个样本和用于外部验证的868个样本,通过测定系数(R)和均方根误差(RMSE)来评估校准模型的性能。单粒小麦蛋白质含量的校准性能在校准数据集和验证数据集中,R分别为0.82和0.79,RMSE分别为0.86%和0.94%,这使得能够对粒间蛋白质分布进行量化,甚至在同一粒内实现可视化。单粒测量的性能比通常对批量样本获得的性能要差,但对于某些特定应用来说是可以接受的。通过分离硬粒小麦和软粒小麦或基于放置方向相似的籽粒建立单独的校准,并没有显著提高预测能力。我们模拟了使用成本较低的铟镓砷探测器(1000 - 1700nm)的情况,并报告说在受限光谱范围内使用建议的碲镉汞探测器产生的预测误差更低(碲镉汞探测器和铟镓砷探测器的RMSEC分别为0.86%和1.06%),并且R值增加(R分别为0.82和0.73)。