Abstract
The anthocyanin pigments of cultivated strawberries were extracted with 0.1% methanolic HCl and two purified fractions were obtained by cation-exchange chromatography and mass paper chromatography. They were identified as pelargonidin-3 -monoglucoside and cyanidin-3-monoglucoside respectively by spectral analysis and by detections of aglycones and sugars.
Then the degradation of the pelargonidin-3-monoglucoside was studied in pure pigment solution at pH 2.2, 5.0 and 8.0. By heating pH 2.2 solution at 100°C for 10 minutes, absorbancy of the pigment solution decreased to 91% of the original, and at pH 5.0 the pigment solution changed to dull pink, but absorbancy of 500 mμ recovered to 89% of the original when it was brought back to pH 2.2 after heating.
By irradiating pH 2.2 sample with ultra-violet rays for 2 hours, absorbancy of the pigment solution decreased to 19% of the original, and the irradiation on pH 5.0 sample changed the absorption spectrum of the pigment solution, but 40% of the original absorbancy recovered after it was brought back to pH 2.2. The destruction of pigment at pH 8.0 did not recover even after it was brought back to pH 2.2.
