The effect of Initial pH and Storage Temperature on the Stability of Betacyanin Dye Extract from Globe amaranth (Gomphrena globosa L.)

Abstract

Globe amaranth is a flower that can be used as a natural dye. The flower has a high betacyanin. This study  aimed to determine the effect of initial pH and the temperature in stability extent of globe amaranth dye extract,  with determined the initial pH and globe amaranth flower temperature with the maximum stability of dye  extract during the retention. This experiment used a complete randomized design with two factors. The first  factor was the initial pH that consist of pH 4, pH 5, and pH 6. The second factor was the storage temperature  consist of temperature 4±1ºC and temperature 28±2ºC. The data were analyzed through analysis of variance  in determined the effect of each factors. The results showed the initial pH had significant effect on betacyanin  levels and value of brightness level (L*), redness level (a*), and yellowish level (b*) during the storage of  globe amaranth dye extract. The temperature had significant effect on betacyanin levels and the value of  brightness level (L*), value of the level of redness (a*) on the third and fourth weeks, and a significant effect  of yellowish (b*) only on the first and third weeks, a significant effect of yellowness (b*) on the fourth week.  The interaction of two treatments had significant effect in every week on betacyanin levels and the value of the  brightness level (L*) on the first and second weeks, the value of the level of redness (a*) on the second week,  and significant effect of the yellowish level (b*) on third and fourth weeks. The dye extract from the globe  amaranth was stable at initial pH 4 with (4±1ºC) cold temperature during the storage. During the control  retention of globe amaranth dye extract within four weeks caused a decrease on betacyanin levels 34.76%, redness level value (a*) 61.85%, and it was an increase of brightness level (L*) 70 ,91%, the value of yellowish  level (b*) 67.21%.