Mix uniformity is a critical quality control point in food manufacturing. Process analytical technology (PAT) provides new technological opportunities for fulfilling and perhaps replacing conventional sampling methods by proposing spectroscopic analyzers for measuring blend homogeneity. Many spectroscopic analyzers have been used in powder blending processes. Light-induced fluorescence (LIF) is the most rapid and consistent underutilized PAT. An experiment was conducted to evaluate the effects of DL-methionine concentration, moisture content (MC) and bulk density (BD) on LIF responses. Fluorescent responses to powder mixtures comprising 0.05−0.50% w/w fluorescent active pharmaceutical ingredient (API) were reported. Approximate density ranges of 6.5−20% w/w for MCs and 0.55−0.65 g/ml for animal food were also evaluated. Results indicated that DL-methionine concentration and MC were statistically significant factors affecting the LIF response, but the effect of BD was not statistically significant. DL-methionine concentration from 0.05% to 0.50% caused a linear increase of LIF signals with y = 41.04x + 715.8, R² = 0.990 fitted to the data. Increasing MC from 6.5% to 20% w/w caused decreasing LIF although y = -45.50x + 1037 could not explain LIF variation versus MC because of low coefficient of determination (R² = 0.851).