Enhanced photostability of monascus pigments derived with various amino acids via fermentation.
The photostability of 18 amino acid derivatives from monascus pigment was tested under various physical and chemical conditions. Under sunlight, the half-life of derivatives was increased to 1.45-5.58 h, corresponding to a 6-25-fold improvement over a control red pigment (0.22 h). The degradation of pigment derivatives followed a first-order reaction, and the pigment stability increased with an increasing concentration while it decreased with both an increase and decrease in pH from 7. The stabilities of derivatives decreased in descending order in hexane, ethanol, propanol, methanol, ethyl ether, distilled water, chloroform, and acetonitrile. Pigment stability under UV light (365 nm) showed a pattern similar to stability after exposure to sunlight. After 30 days of incubation at 30 degrees C, more than 80% of the initial derivative contents remained while only 29% of the control red remained. The differences in degradation patterns that control red gradually changed to brown whereas the phenylalanine derivative remained a weak red were confirmed by HPLC analysis.
Jung
Heeyong
H
Department of Biotechnology, College of Engineering, Yonsei University, Seoul 120-749, South Korea.
Kim
Chulyoung
C
Shin
Chul Soo
CS
D000596:Amino Acids / Q000737:chemistry*; D003116:Color; D004355:Drug Stability; D005285:Fermentation; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D032741:Monascus / Q000737:chemistry*; D010860:Pigments, Biological / Q000737:chemistry*; D013472:Sunlight; D013696:Temperature
D000596:Amino Acids; D010860:Pigments, Biological