Effect of pH and temperature on the stability of the natural dye from the roselle flower (Hibiscus sabdariffa L.) and its application in flavored milk

In recent years, global trends indicate consumer interest in functional foods. Thus, there is a trend to replace the use of artificial colors with natural colors that, in addition to being attractive to consumers, provide benefits to the biological functions of the human organism. The objective of this research was the solvent extraction of a natural dye from the roselle flower, its identification and evaluation of its behavior at different pH and temperatures. In addition, its application in flavored milk was evaluated sensorially. The anthocyanins located in the roselle flower were extracted by fragmentation and milling. The separation of pigments was carried out with ethanol (96%v/v) for 72 h. The qualitative tests of identification, physics and chemistry revealed the presence of anthocyanins (delphinidin 3-glucoside and cyanidin 3-glucoside). The pigments present in roselle flower are relatively stable with temperature. However, at temperatures above 80 °C a gradual degradation occurs. At different pH values, two visible absorption points are shown at 519.6 and 320.4 nm, which correspond to the two characteristic bands of anthocyanins. The milk flavored and dyed with roselle extract had a shelf life of 7 days in refrigerated storage and was sensorially accepted by consumers, but the color was unattractive.