Abstract:

Egg yolk was inoculated with a mixed culture of three strains with high cholesterol-reducing capacity and kept
in a thermostatic oven in order to maximize cholesterol reduction. Direct saponification-colorimetry method was used to
measure the reduction rate of cholesterol. The fermentation conditions were optimized using an orthogonal array design as
follows: fermentation temperature, 40 ℃; fermentation time, 24 h; inoculum amount, 3%; bile salt concentration, 3 g/L; and
the proportion of mixed strains, 1:2:1 (Streptococcus thermophilus:Lactobacillus acidophilus:Bifidobacterium). Under these
conditions, the cholesterol in egg yolk was reduced by 31.5%.

Key words: mixed Lactobacillus, egg yolk, cholesterol degradation, colorimetric method