EVALUATION OF REACTION CONDITIONS FOR CARBOXYMETHYLATION OF MUNG BEAN STARCH USING MONOCHLOROACETIC ACID

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Tác giả: Thi Thu Thao Ho, Nguyen Phuong Thanh Le, Thi Hong Thuy Le, Quynh Nhu Nguyen, Thanh Tung Nguyen, Thi Luong Nguyen, Thi Thao Nguyen, Van Khoi Nguyen

Ngôn ngữ: eng

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Thông tin xuất bản: Tạp chí Khoa học Công nghệ và Thực phẩm (Tên mới: Tạp chí Khoa học Đại học Công Thương), 2020

Mô tả vật lý: tr.37

Bộ sưu tập: Metadata

ID: 313021

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Carboxymethyl mung bean starch (CMS) was synthesized under different reaction conditions. The influence of sodium hydroxide concentration, monochloroacetic acid (MCA) concentration, type of organic solvent, reaction time, and temperature were evaluated for degree of substitution (DS). Optimal DS of 0.59 was obtained at 50 °C, 120 minutes in isopropanol-starch ratio of 7.5 mL/g. The ratio of sodium hydroxide and monochloroacetate acid moles to anhydroglucose unit (AGU) moles for the optimal DS were 2.4 and 1.5. Scanning electron microscope (SEM) of CMS particles showed the starch grain structure remains the same but the surface appeared many alveolar holes and no longer smooth as MS. Fourier transform infrared spectra (FTIR) of CMS and MS confirmed that carboxymethylation takes place on native starch molecules when the absorption band appears at a wavenumber of 1710 cm-1 corresponding to the vibrations of featured functional C=O group in CMS structure.Keywords: Carboxymethylation, carboxymethyl starch, monochloroacetic acid, mung bean, modified starch.Nghiên cứu này đánh giá các yếu tố ảnh hưởng đến quá trình carboxymethyl hóa tinh bột đậu xanh (MS) trong dung môi hữu cơ bằng tác nhân axit monocloaxetic (MCA) với sự tham gia của natri hydroxit. Các thông số khảo sát tối ưu sau thực nghiệm bao gồm: thời gian phản ứng 120 phút
nhiệt độ 50 °C
tỷ lệ mol MCA/AGU (đơn vị glucose) là 1,5
tỷ lệ mol NaOH/AGU là 2,4
tỷ lệ isopropanol (IPA)/tinh bột là 7,5 mL/g và dung môi sử dụng là IPA. Sản phẩm tinh bột đậu xanh carboxymethyl (CMS) tạo thành trong điều kiện tối ưu có độ thế (DS) là 0,59. Ảnh SEM của các hạt CMS xác định bằng kính hiển vi điện tử quét (SEM) cho thấy cấu trúc hạt tinh bột vẫn giữ nguyên nhưng bề mặt xuất hiện nhiều lỗ nhỏ và không còn mịn như hạt tinh bột đậu xanh tự nhiên. Phổ hồng ngoại biến đổi Fourier (FTIR) của CMS xuất hiện peak hấp thụ ở bước sóng 1710 cm-1 tương ứng với dao động nhóm C=O đã chứng tỏ quá trình carboxymethyl hóa diễn ra trên các phân tử tinh bột đậu xanh.Từ khóa: Axit monocloaxetic, carboxymethyl hóa, đậu xanh, tinh bột biến tính, tinh bột carboxymethyl.

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