Phân loại nguồn gốc địa lí và phân tích đồng thời các methylxanthine trong chè Việt Nam sử dụng phổ hồng ngoại phản xạ kết hợp với thống kê đa biến=Geographic origin classification and simultaneous determination of methylxanthines in vietnamese tea using chemometrics based on the near infrared reflectance spectroscopy

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Tác giả: Đức Thọ Bùi, Huế Trần Thị, Thảo Tạ Thị, Ri Nguyễn Văn

Ngôn ngữ: vie

Ký hiệu phân loại:

Thông tin xuất bản: Tạp chí Khoa học và Công nghệ - Đại học Nguyễn Tất Thành, 2019

Mô tả vật lý: tr.33

Bộ sưu tập: Metadata

ID: 487293

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Nghiên cứu này trình bày các kết quả phân loại nguồn gốc địa lí và xác định đồng thời ba methylxanthine (gồm caffeine, theobromine, theophylline) trong các mẫu chè Việt Nam dựa trên dữ liệu phổ hồng ngoại phản xạ kết hợp với thống kê đa biến. Phổ hồng ngoại được đo trong vùng 10000-4000cm-1 với khoảng cách đo 2cm-1. Thuật toán đa biến phân tích biệt thức kết hợp với bình phương tối thiểu từng phần (Partial Least Squares Discriminant Analysis (PLS-DA)) và phân tích cấu tử chính (Principal Component Analysis-Discriminant Analysis (PCA-DA) được sử dụng để phân loại nguồn gốc địa lí. Các mô hình cho phép dự đoán đúng tuyệt đối nguồn gốc của mẫu chè chưa biết thuộc vùng đại lí nào đã khai báo trong mô hình. Cũng dựa trên cùng dữ liệu phổ IR của mẫu, bằng thuật toán PLS có thể định lượng nhanh ba methylxanthine trong mẫu chè. Mô hình PLS được xây dựng dựa trên dữ liệu phổ của 24 mẫu chuẩn (là các mẫu chè có kết quả hàm lượng 3 methylxanthine được phân tích bằng HPLC). Phép xác định các methylxanthine trong 7 mẫu chè (dùng làm mẫu kiểm tra) cho thấy mô hình có độ chính xác cao. Hệ số tương quan (R2) của các kết quả hàm lượng theobromine, theophylline và caffeine tính được theo mô hình và hàm lượng xác định theo phương pháp HPLC lần lượt là 0,9582, 0,8894 and 0,9303. Nghiên cứu này chỉ ra rằng với một lần đo phổ hồng ngoại phản xạ, khi kết hợp với thống kê đa biến có thể xác định nhanh các thành phần chính trong chè, cũng như có thể phân loại nguồn gốc địa lí các mẫu.This paper reported the results of classification of geographic origin and simultaneous analysis of three methylxanthines (caffeine, theobromine, theophylline) in Vietnamese tea samples by the infrared reflectance spectrophotometry coupled with chemometrics. The spectral range was 10,000-4,000cm-1 and each spectrum was measured at 2 cm-1 intervals. For the purpose of geographic origin classification, this study used FT-NIR spectroscopy combined with Partial Least Squares Discriminant Analysis (PLS-DA), and Principal Component Analysis-Discriminant Analysis (PCA-DA). The ability to determine the origin of tea samples in the prediction set of PLS-DA model is 100%. Using the same IR spectral database combined with the partial least squares (PLS), three methylxanthines in tea samples are also quickly quantified. The PLS model based on the spectra of 24 tea samples in which the contents of 3 analytes were determined by high performance liquid chromatography- HPLC) were applied for simultaneous determination of caffeine, theobromine and theophylline in samples. The determination of methylxanthines in 7 tea samples in test set gave the good accuracy of the PLS model. The correlation coefficients (R2) in the prediction set were of 0.9582, 0.8894 and 0.9303 for theobromine, theophylline, and caffeine, respectively. This work demonstrated that infrared reflectance spectrophotometry combined with chemometrics could be applied to rapidly classify the geographic origin and simultaneous determination of main contents in green tea.

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