A Review of Optical Nondestructive Visual and Near-Infrared Methods for Food Quality and Safety

Figure 2

NIR spectra of water and oil measured at different path lengths. (a) Water spectra when the path length is 1, 2, 5, or 10 mm. (b) Water spectra when the path length is 0.2 mm. (c) Vegetable oil spectra when the path length is 1, 8, or 22 mm. The shape and level of measured spectra depend on the path length.

(a) Water measured at 1, 2, 5, and 10 mm path length

(b) Water measured at 0.2 mm path length

(c) Vegetable oil measured at 1, 8, and 22 mm path length