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Teach you to judge the good or bad of food
2017/7/1 10:38:32

Although people do not want to buy food, cooking this complex, but involving food safety matters, it should be more careful. In addition to refiningFireOnce outside, sometimes a simple chemical experiment can obviously help consumers judge the safety of food.

Beautiful fresh lotus root is the beauty

Since the fall, lotus has become a frequent dish on the family table. Many people go to the market to buy fresh lotus root, are accustomed to buying clean and beautiful appearance. In fact, the lotus root comes from the mud, and the surface silt is not easily washed away. In order to wash, and make fresh lotus root appearance is good, illegal traders will choose sodium bisulfite or sulfite to wash. Originally, such substances can be used for food bleaching and corrosion protection, belong to food additives, but absolutely prohibited for fresh food. Such practices are abusive and excessive use of food additives.

National senior food inspector, senior nutrition lecturer Li Guangping introduced, judging whether the lotus root was washed by sulfite, the way is to find some barium salt. In order to make the effect more obvious, you can first wash the lotus root, filter out the lotus root water, in which drip barium salt. If the water suddenly produces a white floc, it means that the water washing the lotus root contains sulfate or sulfite ions.

Food "whitening" repeated

Konjac, pig, squid, squid, chicken feet, white core shutter...... These foods sold in the market share a common feature - being easily washed by caustic soda. As long as the food is soaked by caustic soda, the color is whiter than paper. The experiment is to determine the key food phenolphthalein reagent is whitening. In the laboratory, is a special indicator phenolphthalein alkali, alkali instantly becomes pink, encountered thick lye soon receded to colorless red. Phenolphthalein is insoluble in water and soluble in alcohol, so usually prepared into alcohol solution using phenolphthalein. When the phenolphthalein reagent drops into the water or water solution of neutral, acidic, there will be a white haze, this is because the alcohol soluble in water, so that the reagent water insoluble precipitate phenolphthalein. On the people side, phenolphthalein not be able to find, but Phenolphthalein Tablets is very easy to buy in pharmacies, mainly used for the treatment of intractable constipation.

The chemical constituents of caustic soda are sodium hydroxide, which are soluble in water. The cleaning of food from the market to buy food, cleaning the water filtered was dripped into phenolphthalein, if the food had been soaked in caustic soda, water color will instantly change if there is no powder, caustic soda ingredients will have white floc. Simple methods, can also take a Phenolphthalein Tablets directly on the food, although phenolphthalein is insoluble in water, but can also be slightly soluble, instant color.

Therefore, Li Guangping prompted consumers, in the purchase of such caustic soda "beauty" food, the first to observe the appearance, not red, do not buy. The smell, whether white or blind pig, chemical taste will be completely covered by its meat smell. Third touch feel, the meat itself should have greasy feeling, being soaked after caustic soda will have a slippery feel. Finally, if Phenolphthalein Tablets home, can be placed directly into a piece of food, can make residues appear immediately the prototype of caustic soda.

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