Abstract: Linoleate isomerase can catalyze the chemical reaction from linoleic acid to conjugated linoleic acid, while the latter shows many physiological activities. However, linoleate isomerase activity assay differs from literature to literature. Enzyme activity assay of linoleate isomerase of Lactobacillus acidophilus was studied in this paper, so as to provide some reference to study the enzyme activity during the process of enzyme purification. Optimum reaction conditions for linoleate isomerase activity were determined by single-factor test and orthogonal test, as follows: crude enzyme 0.10ml, linoleic acid 0.70ml, Tween-80 2.00ml, reaction temperature 37℃, and reaction time 3h.

Key words: Lactobacillus acidophilus, linoleate isomerase, enzyme activity mensuration