Objective: To establish an objective and quantitative method for the determination of optimum processing time of Atractylodis Macrocephalae Rhizoma stir-fried with bran

and to provide scientific basis for the standardization of processing technology of Atractylodis Macrocephalae Rhizoma and improving quality standards of this decoction pieces.At the same time

this study can provide reference for establishment of determining processing time of other Chinese medicinal decoction pieces.Method: Based on the principle of colorimetric analysis

the color space parameters of L*

a* and b* (L* indicates brightness

a* indicates red and green color value

and b* indicates yellow and blue color value) were introduced

and CM-5 color difference meter was used for objective quantification of color of Atractylodis Macrocephalae Rhizoma stir-fried with bran.SPSS 21.0 statistical software was used to establish mathematical discrimination model and bilateral 90% reference range of different processing time of this decoction pieces.Result: A mathematical discriminant model based on color space parameters of L* and b* for different processing time of Atractylodis Macrocephalae Rhizoma stir-fried with bran was established (the coincidence rate was 100%) and bilateral 90% reference range was determined.The optimum processing time of this decoction pieces was 12 min

discriminant function (1) was processing time=0.675×L*+0.972×b*-49.365

the range of function values was 10.103 6-16.051 4;discriminant function (2) was processing time=0.884×L*-0.998×b*-11.277

the range of function values was -6.366 0-0.496 7.The bilateral 90% reference range is L* of 44.127 8-47.661 2 and b* of 30.674 5-34.112 3.Conclusion: Based on the color change can achieve the objective quantification discriminant of optimum processing time of Atractylodis Macrocephalae Rhizoma stir-fried with bran.