AbstractThe reflectance spectrum of beta‐carotene dissolved in ethanol in front of barium sulphate powder was measured with a portable fibre‐optic spectrophotometer based on a xenon flash unit and a photodiode array. Maximum absorbance (minimum reflectance) was from 470 to 490 nm. The same result was found with white adipose tissue in place of barium sulphate. Samples of subcutaneous adipose tissue from 13 cattle were measured. With a range from white to pale yellow adipose tissue, the maximum divergence of reflectance spectra was at 460 nm. With a range from pale to lemon yellow, the maximum divergence was at 410 nm. Reflectance spectra of adipose tissue had evidence of absorbance from 410 to 420 nm and at 540 and 580 nm, which might have been caused by residual oxyhaemoglo