Investigation of Biosubjects with Diffuse Reflectance Spectroscopy.

A portable spectrometric apparatus using a diffuse reflectance spectroscopy (DRS) scheme, comprising visible and near-infrared (NIR) spectrometers, was assembled to investigate the biosubjects. In this work, we measured the direct visible DRS of the various products including kiwi, banana, lemon, apple, avocado, and peppers of different colors; as a result, each biological item exhibited a distinctive DRS curve characteristic of the specific product. However, inspecting the time-dependent variations of the visible DRS for the apple slice exposed to air is difficult. Instead, the oxidation process of the sliced apple could be monitored with near-infrared absorption with DRS, which successfully characterized the dehydration stages of the fruit. Considering that hydration and dehydration pathways for bio-objects involve the same water molecule, we further proofed that the NIR absorption with DRS skill could effectively monitor the hydration levels of human skin following the application of a moisturizing mask. Our results confirm that DRS is a promising tool for applications in biochemistry, medical diagnosis, and healthcare.