The effect of scanning angle on measured reflectance and tenderness prediction in beef longissimus thoracis steaks.

摘要

NIR spectroscopy has been used to quantify the tenderness and sensory attributes of meat. Effects of scanning angle on visible NIR (VNIR) spectral reflectance and the ability of reflectance spectra to predict tenderness of longissimus thoracis (LT) steaks were determined. 2 experiments were conducted to evaluate the effect of scanning angle configuration on steak reflectance. The first experiment included 60 steaks from 2 quality grades, aged for either 7 or 14 days, which were randomly assigned to 2 treatments in which steak angles with respect to the light and sensor were changed. In the second experiment, 16 steaks from the 2 quality grades were scanned at 6 different angles. Warner-Bratzler shear force (WBSF) was measured as a quantitative measure of tenderness. There were marked amplitude differences of up to 50% in the average reflectance spectra between the 2 treatments in experiment 1, and up to 200% difference between the reflectance spectra when the steak was tilted from 30 degrees counterclockwise to 30 degrees clockwise. First derivatives of the reflectance spectra also showed marked differences with respect to scanning angle. Chemometric models on VNIR spectra could predict only 19% of the variability in tenderness when the scanning angle was not considered. However, when individual models were developed for each scanning angle-ageing group, models accounted for 20 to 86% of the variability in tenderness. Results suggest that scanning angle is an important factor affecting the accuracy of reflectance-based tenderness models.