Abstract
Research was undertaken to determine if relectance (interactance) measured with a portable fiver optic probe (Colormet) can be used to assess porcine fat quality. Soft fat generally had lower interactance than hard fat, p<0.05 from 400 to 700 nm, although interactance spectra of hard and soft fat were similar in shape. At $4^{\circ}C$, interactance from 450 nm to 700 nm at the inner layer of backfat was correlated (p<0.01) with subjective soft fat score (r = 0.06 to 0.70), and with the refractive index (r = -0.62 to -0.65) and melting point (r = 0.59 to 0.60) of heat-extracted lipid. Colormet interactance $L^*$ at $4^{\circ}C$ was correlated (p<0.01) with soft fat score (r = 0.72), refractive index (r = -0.66) and melting point (r = 0.61). Interactance decreased as the temperature of the fat was increased from 22 to $44^{\circ}C$ (p<0.01). Soft fat had lower interactance than fats that were slightly soft, slightly hard and hard at 4, 22 and $40^{\circ}C$, although softness and temperature may interact to affect interactance. These results indicate that soft porcine fat may be detected easily by fiber-optic spectrophotometry.