Almonds, which is used in food, usually sweet. But there are bitter almonds, a close relative of sweet - their fruit in appearance almost indistinguishable. Just as walnut, bitter almonds will not pogradeci, but he is not lost in vain. First, it transforms the oil used in medicine, and, secondly, is used as an additive in the food industry, and when home cooking: from bitter almonds is much stronger flavor. The fragrance, which is called almond.
To distinguish bitter from sweet almonds in the same second, as will scrunch the nucleolus. But we will try to find and chemical differences. Not for analytical purposes - experience, perhaps, is too complex to apply it every time for recognition of almonds, and in order to understand some interesting details from the life of the Rosaceae, for this family and belongs to the almonds.
Thus, the experience. Clean a few kernels of almonds, remove the seeds dense shell and thoroughly mash them, adding 5-10 ml of water. Strain the resulting liquid, take about 10 drops of the filtrate and mix with a few drops of dilute (approximately 10%) sodium hydroxide solution. The reaction mixture should be alkaline, so add alkaline solution until, until you see a steady staining with a solution of phenolphthalein. Can be used for this purpose and self-made indicator.
The following operation: add a drop of a solution of ferrous sulfate FeSO4* 7H2O, heat the mixture to a boil, strain and add to the filtrate a few drops of hydrochloric acid. Now the reaction mixture must be acidic (repeat sample with indicator). And your last action: put a drop of solution of ferric chloride FeCl3. Now it will become clear what your almonds. If he was sweet, nothing will happen. But if it's bitter, then after adding ferric chloride will instantly fall beautiful blue precipitate, it is Prussian blue, substance composition Fe4[ Fe(CN)6]3.
Bitter almonds, which gave a beautiful color reaction, contains a complex substance called amygdalina. And in the same almond is the enzyme glucosidase, which is capable of decomposing amygdalin in the presence of water into simpler substances. After a complex chain of transformations, which for the sake of simplicity we omit, is formed ferrocyanide sodium Na4[ Fe (CN)6]. It with the last drop of ferric chloride and gives such a vivid colour.
But why sweet almond will not give such a reaction? There is no amygdalin. But the enzyme glucosidase there, and it can be used for another experience.
Bitter almond replace this time plum, peach or cherry pits: and plum, and peach, and cherry - also from the Rosaceae family, they have a lot in common with almonds. Including amygdalin in the seeds.
Remove the seeds from the seeds (but not subjected to heat - this should not be a bone of compote or jam; from frozen fruit or fresh - please). Mix them in with sweet almonds, add the water, strain the liquid and keep the experience as bitter almonds. Once you add at the end of the last drop of ferric chloride solution, the newly formed blue Prussian blue.
Amygdalin in this experience - from the seed of a cherry, peach or plum, and Deplete the enzyme from sweet almonds. So, by using different fruits, we finally obtained the same effect as that of bitter almonds.
Along the way is important. Doctors do not recommend to store too long homework cherry and plum, if they were not welded. All the danger - bones. When transformations amygdalin can be formed and harmful substances, although it takes a long time (fresh seeds safe).
Now, having understood what was happening, you can feel free to give advice. First, although it is troublesome, it is better for peace of mind to remove from the fruit seeds. And second: compotes and jams will not harm even with bones, because when heated, dissolved enzymes that decompose amygdalin. If you want to put the experience with boiled seeds - no color will not appear.