The Tinctorial Stability of Carthamin on Polysaccharides and Related Substances

Various saccharides and related substances were mixed with carthamin in aqueous solutions and their effects on red colour stability compared. At a low temperature range (5 °C), monoand disaccharides contributed to preservation of the carthamin red colouration. No monoand disaccharides could relieve carthamin from being bleached at a high temperature (30 °C). Among poly­ saccharides and their derivates (tested at 30 °C for 24 h in the dark), Avicel cel­ lulose was most effective for the retention of the red colour of carthamin (52 %). Chitin was also promising (41 %). CM-Cellulose, Sephadex G-15 and starch followed this (25, 17 and 13 %, respectively). The effects of alginic acid, chitosan, hyaluronic acid, agar and xylan were still further reduced (11, 8, 8, 7, and 5 % respectively). The adsorption of carthamin towards filter papers was investigated as a function of temperature, pH, buffer concentration and buffer types. To adsorb the red dye effectively, low temperature and high pH were found to be preferable. Buffer types were also contributive. Carthamin adsorption in citrate buffer at pH 4.5 with four different molar con­ centrations was not significant (24.7 -20.9 %), if compared with data without any buffer added (20.8 %). FT IR spectrometric analyses of carthamin adsorbed cellulose indicated that hydrogen bonding was involved in the carthamin/cellulose interaction. Based on the data, a hypothetical scheme to characterize a stable binding formation between carthamin and cellulose called the SAITO EFFECT was proposed.