Full Length Research Paper

Application of response surface methodology optimization for the production of caffeic acid from tobacco waste

Jun Wang¹, Dingqiang Lu^{1, 2}*, Hui Zhao¹, Xiuquan Ling¹, Ben Jiang¹ and Pingkai Ouyang¹

¹College of Life Science and Pharmaceutical Engineering, Nanjing University of

Technology, Nanjing 210009, P.R. China.

²Jiangsu Provincial Institute of Material Medica, Nanjing 210009, P.R. China.

*Corresponding author. E-mail: ludingqiang@njut.edu.cn. Tel: 86-25-8328-5202.

Accepted 31 December, 2008

Caffeic acid (CA) was widely applied in food and pharmaceutical industries as an important natural antioxidant. In the present study, the main caffeoylquinic acids (CQAs) in tobacco waste were analyzed by HPLC-PAD-ESI-MS/MS, and used as raw material for producing CA which preparation process was optimized by response surface methodology (RSM). The research results indicated the main ingredients of CQAs in tobacco waste were identified as three isomers containing chlorogenic acid (5-caffecylquinic acid, 5-CQA), cryptochlorogenic acid (4-caffecylquinic acid, 4-CQA) and neochlorogenic acid (3-caffecylquinic acid, 3-CQA), respectively. The production of CA produced by alkaline hydrolysis of the CQAs extract from tobacco waste was effectively enhanced by RSM. NaOH was selected as catalyst through screening of four different alkalis. Three hydrolysis reaction parameters for production of CA were optimized as follows by using central composite rotatable design (CCRD) of RSM: pH value 13.5, reaction temperature 85^oC and reaction time 10 min. The adequately high R² value 0.9275 and F score 7.105 indicated the statistical significance of the model. The conversion rate of CA after optimization was 43.46% while the predicted value was 44.92%. In conclusion, hydrolysis conditions optimization to enhance CA production from tobacco waste can be easily and effectively done by RSM; the developed production process of CA indicated CQAs in tobacco waste are potential raw material for producing CA.

Key words: Caffeic acid, caffeoylquinic acids (CQAs), hydrolysis reaction parameter optimization, response surface methodology, tobacco waste, HPLC-PAD-ESI-MS/MS.