Abstract:

The purpose of this study was to establish the optimal tenderization conditions using papain and composite
phosphate together for low-grade roast beef production. Response surface methodology (RSM) was used to model and
optimize responses. Three parameters including enzymatic specific activity, phosphate concentration and time were
selected as the main tenderization conditions. The responses were Warner-Bratzler shear force and sensory evaluation.
The experimental data were statistically analyzed for the establishment of quadratic regression models using the Design-
Expert 8.05 software. According to the results of RSM, the Warner-Bratzler shear force could be reduced remarkably by
using papain and composite phosphate, and higher water retention and sensory evaluation scores were achieved by properly
reducing papain dosage. The optimal tenderization parameters were determined as follows: papain activity, 9.44 U/g;
phosphate concentration, 18.35 mg/mL; and tenderization time, 9.09 h. Under these conditions, the shear force was
17.25 N and the sensory evaluation was 5.02. The predicted values were proved to coincide well with the measured values.
Accordingly, the developed regression models were reliable and could be used to predict the changes in shear force and
sensory evaluation.

Key words: low-grade beef, papain, composite phosphate, response surface methodology, combined tenderization