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Food Chemistry Division Lecture: Chemistry and analysis of anthocyanin pigments |
R. E. WROLSTAD, Dept. of Food Science & Technology, Oregon State Univ., 100 Wiegand Hall, Corvallis, OR 97331-6602 Anthocyanin pigments have received the attention of food chemists for years because of their importance to the color quality of fresh and processed fruits and vegetables. The current heightened interest in these compounds, however, is because of their possible health benefits. There is increasing experimental evidence that they may help reduce the risk of coronary heart disease and stroke, function as anti-carcinogens, and even help to improve cognitive behavior and prevent memory loss. Their bioactivity has stimulated development of anthocyanin-containing functional foods and nutraceuticals. The commercial sector is in particular need of standardized methods for measuring and reporting anthocyanin pigment content. The pH differential spectrophotometric method for total anthocyanins is very suitable for both research and quality control. Systematic methods for identification of anthocyanin pigments are well established, and over 300 anthocyanins have been identified in nature. Reverse phase HPLC with uv-visible diode array detection is the method of choice for tracking qualitative changes once identities have been established. Acid hydrolysis and saponification reactions in conjunction with HPLC are useful for identification, while the sensitivity of electro-spray mass spectroscopy (ESMS) makes it a powerful adjunct. For complete identification (site of glycosidic and acyl substitutions, nature of glycosidic linkage, sugar identification) NMR is needed. Very sensitive methods are required for investigating how anthocyanins are absorbed, transported, and metabolized in human and animal systems. Anthocyanin pigments are reactive substances and subject to degradation during extraction and isolation from food matrices and biological materials. The resonating, complex structures of anthocyanins are responsible for their attractive colors as well as their antioxidant properties. It is widely accepted that antioxidant activity is related to their biological properties.
Session 18, Chemistry and analysis of phytochemicals or plant bioactive materials
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