No abstract

Chicken fat in an emulsion prepared with mechanical shearing and high pressure homogenization (HPH) was hydrolyzed using Candida cylindracea lipase. A homogenization pressure of 50 MPa, which can generate smaller droplets and higher hydrolysis efficiency than mechanical shearing, was fixed to prepare the emulsion for hydrolysis optimization. Response surface methodology (RSM) was applied to study the effect of temperature, enzyme loading, shaking rate and reaction time on the hydrolysis process. The results showed that all three-second-order polynomial models adequately fitted the experimental data. Additionally, hydrolysis parameters for the optimal yields of free oleic and linoleic acids were also obtained using the desirability function: a temperature of 38°C, an enzyme loading of 0.48% (g/g fat basis), a shaking rate of 100 rpm and a reaction time of 80 min. Under the optimal conditions, the yields of free oleic and linoleic acids were predicted as being 0.470 and 0.118 g/g fat with recoveries of 94.6 and 93.7%, respectively. During the hydrolysis process, the particle size increased with concomitant boosting of the degree of hydrolysis and the stability of the emulsion system was gradually undermined by this reaction process.