TAILIEUCHUNG - oil extraction and analysis phần 5

Chất lỏng siêu tới hạn khai thác (lâm trường) đang trở thành một phương pháp chuẩn bị mẫu quan trọng trong phân tích hóa học của sản phẩm thực phẩm, đặc biệt là đối với các chất béo và dầu béo. Lâm trường đã được sử dụng thành công trong hơn một thập kỷ trong phân tích các mẫu thực phẩm (1,2). Lâm trường dung môi phổ biến nhất là carbon | Chapter 5 Analytical Supercritical Fluid Extraction for Food Applications Tracy Doane-Weideman and Phillip B. Liescheski Isco Incorporated Lincoln NE 68504 Abstract In this review we explore the fundamental concepts of supercritical fluids and supercritical fluid extractions. Carbon dioxide and other solvents are discussed the solubility theory is introduced together with the calculation of the density of carbon dioxide. The state-of-the-art instrumentation is presented in terms of fundamental components. The most widely used application of analytical SFE is in the food industry and this review includes fats oils vitamins and pesticides in research and routine applications. Introduction Supercritical fluid extraction SFE is becoming an important sample preparation method in the chemical analysis of food products especially for fats and fatty oils. SFE has been used successfully for over a decade in analyses of food samples 1 2 . The most popular SFE solvent is carbon dioxide CO2 . Triglycerides cholesterol waxes and free fatty acids are quite soluble in supercritical CO2. The solubility of polar lipids such as phospholipids can be improved by augmenting the supercritical CO2 with a small addition of ethanol or other polar modifier solvent. Even though CO2 is considered a green-house gas it is ubiquitous in nature and can be retrieved from the environment and returned clean 3 . As a result SFE can still contribute positively to Green Chemistry. CO2 has the additional advantage of being nonflammable and less toxic than most organic solvents. For example petroleum ether which is commonly used in fat extractions can be easily detonated by static electricity and diethyl ether can form explosive peroxides. On the other hand some fire extinguishers use CO2 which is also commonly found in foods and drinks such as bread and carbonated drinks. Finally several common chlorinated solvents are banned by law and supercritical CO2 can be an alternative to these solvents. All of .

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