苋菜红作为酸碱指示剂的研究

以红苋菜为原料提取苋菜红色素,测定苋菜红水溶液的变色pH值范围为7.6～9.6,与酚酞相同,且变色灵敏,可以替代酚酞用作酸碱滴定指示剂.用苋菜红和酚酞作为食品酸味剂和膨松剂分析指示剂的实验结果表明,苋菜红指示酸碱滴定终点变色明显,与酚酞相当.苋菜红指示剂宜现用现配,若制成浸膏在无水乙醇密封下避光避热可长期保存.苋菜红指示剂具有安全性和实用价值.

The research of amaranth red pigment acting as acid-base indicator

Red pigment is extracted from red amaranth.The pH value scope for color variation of amaranth red pigment is determined as 7.6~9.6,as same as that of phenolphthalein,and its color variation is sensitive to pH value,which indicates that it may be substitute for phenolphthalein acting as acid-base indicator.When amaranth red pigment is used as indicator for analysis of food sour matters and the swelling agent,the color transformation of end point of acid-base titration is obvious and its effect is comparable with that of phenolphthalein.It had better prepare the amaranth red pigment just when it is needed.If made into extracts under the conditions of airtighting with anhydrous alcohol and avoiding light and hot,it can be kept in storage over a long period of time.Amaranth red pigment has security and practical value.