麦芽炒制过程中近红外在线监测模型的建立及“炒香”终点判断研究

Establishment of near-infrared on-line monitoring model and determination of endpoint in frying process of Hordei Fructus Germinatus

炒麦芽一直沿用"炒黄炒香"的入药传统,而"炒黄炒香"终点的判断一直是炒制研究的重点与难点。该实验建立指标成分与NIRS之间的定量校正模型用于快速检测总还原糖、总氨基酸、总黄酮、A_(420)及含水量,并提出基于"成分变化率"的炒制终点判断方法。以近红外光谱仪采集不同炒制时间样品光谱,建立基于近红外光谱的定量分析模型,并对光谱预处理、建模波段等参数进行优选;采用HCA,PLS-DA研究成分与"炒香"的关系,确定炒制终点。所建立的校正模型性能良好,采用所建模型进行在线分析,预测结果与实际测定值相关系数均大于0.9,预测相对偏差小于10%;HCA方法将在不同炒制时间的麦芽分为4类,PLS-DA分析表明总还原糖对区分不同炒制时间的麦芽具有显著的贡献率,当总还原糖的变化率为80%时,即可判断"炒香"终点的到达。结果表明,近红外光谱可快速准确地测定麦芽不同炒制时间样品中总还原糖、总氨基酸、总黄酮、A_(420)及含水量,并可判断"炒香"工艺终点,为中药炒制工艺的评价及终点判断提供新的研究方法。

Hordei Fructus Germinatus has been always used by ＂ stir-frying＂ as a traditional medicine and the endpoint judgment of ＂ fragrant＂ and ＂ yellow＂ has been the focus and difficulty in frying process research. In this study,a quantitative calibration model between index components and NIRS was established in order to rapidly detect the contents of reducing sugar,total amino acids,total flavonoids,A_（420） and moisture; besides,an endpoint judgment method of frying process was put forward based on the ＂ component change rate＂. Near-infrared spectra of samples with different frying time were collected,and a quantitative analysis model based on near-infrared spectroscopy was established to optimize the parameters such as spectral pretreatment and modeling band. HCA and PLS-DA were used to study the relationship between component and ＂ stir-frying＂,and the endpoint of frying process was determined. The established calibration model had a good performance that the correlation coefficients between the predicted results and the actual measured values were both more than 0. 9,with predicted relative deviations less than 10%. Hordei Fructus Germinatus with different frying time was divided into 4 categories by HCA analysis. PLS-DA analysis showed that total reducing sugar had a significant contribution to distinguishing the Hordei Fructus Germinatus of different frying time. When the change rate of total reducing sugar was 80%,it could judge that the endpoint of frying had been obtained. Results showed that NIRS could not only quickly and accurately determine the contents of reducing sugar,total amino acid,total flavonoid,A_（420） and moisture in Hordei Fructus Germinatus samples of different frying time,but also judge the endpoint of frying in the process. This study provided a new method for the evaluation and endpoint judgment of ＂ stir-frying＂ process in research of traditional Chinese medicine.