Near-infrared (NIR) hyperspectral imaging is a useful method for powdery food quality and safety evaluation. Due to the particularity of the powder, light penetration depth and adulterant particle size have an effect on detection of adulterants in wheat flour. In this study, wheat flour of different thickness was placed on talcum powder or benzoyl peroxide (BPO) of different particle sizes to study the light penetration depth. BPO of different particle sizes was also mixed in wheat flour to study the adulterant particle size effects. The results showed that, for talcum, the light penetration depth in wheat flour was 0.6 mm, and for BPO, the light penetration depth in wheat flour was 0.8–1 mm (depending on the particle size of BPO). In terms of the particle size effects, mixtures of wheat flour and BPO with particle sizes of 380–270 μm and 270–250 μm were found to have better adulterant detection results. It indicated that the difference of particle size of subsurface reference powder would affect the light penetration depth. Combined with the ideal “multi-layer effect” hypothesis, it is verified that the penetration depth of light and the particle size of adulterant affect the detection of adulterant in wheat flour.

近红外（NIR）高光谱成像是粉状食品质量和安全性评估的有用方法。由于粉末的特殊性，光的穿透深度和掺假粒径对小麦粉中掺假的检测有影响。在这项研究中，将不同厚度的小麦粉放在滑石粉或不同粒径的过氧化苯甲酰（BPO）上，以研究光穿透深度。还将不同粒径的BPO掺入小麦粉中，以研究掺假粒径的影响。结果表明，对于滑石粉，小麦粉的光穿透深度为0.6 mm，对于BPO，小麦粉的光穿透深度为0.8–1 mm（取决于BPO的粒径）。就粒度影响而言，发现小麦粉和BPO的混合物的粒径分别为380-270μm和270-250μm，具有更好的掺假检测结果。表明表面参比粉末粒径的不同会影响光的穿透深度。结合理想的“多层效应”假说，证实了光的穿透深度和掺假粉的粒径会影响小麦粉中掺假剂的检测。