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甲醛合次硫酸氢钠,俗称吊白块.又名雕白粉、易溶于水,温度稍高或遇酸、碱即可分解为甲醛、二氧化硫,是一种禁用于食品的工业漂白剂,在食品中不得检出.但有不少面食经营户利用吊白块能够漂白增鲜而用来制作“精粉”馒头,使市售馒头异常洁白,如果食用,对人体可造成一定的危害.目前国内尚无测定食品中吊白块的标准方法,我们采用水蒸汽蒸馏,吊白块分解为甲醛与二氧化硫,甲醛馏出,与变色酸在酸性溶液中呈紫色.依据颜色深浅,比色定量.此法灵敏度高,结果准确可靠.
Formaldehyde sodium bisulfate, commonly known as hanging white block. Also known as carving white powder, soluble in water, the temperature is slightly higher or in case of acid, alkali can be decomposed into formaldehyde, sulfur dioxide, is a banned food industrial bleach, Food may not be detected.But there are many pasta business households use hanging white block can be bleached fresh and used to make “flour” steamed bread, the bread exceptionally white, if consumed, can cause some harm to the human body. There is no standard method for determining the amount of white lumps in foodstuffs in our country. We use steam distillation, white lumps to decompose into formaldehyde and sulfur dioxide, formaldehyde distillate, and chromogenic acid to purple in acidic solution. This method of high sensitivity, accurate and reliable results.