Daily on a table of each of us dozens of various food products are replaced by a kaleidoscope. Unfortunately, by sight it is not always possible to claim with confidence that in the presented food there is a protein. If you care for the health and with special care select the list of useful proteinaceous products, then you need to know a way of high-quality definition of protein in products. And will help you with it simple performed by biuretovy reaction.
It is required to you
- - product for the analysis;
- - 10% sodium hydroxide (NaOH);
- - sulfate of copper (CuSO4) 1%;
- - measured glass with division in 1 ml or a test tube;
- - water;
- - pipette;
- - transparent container.
Instruction
1. Take the studied product and crush by cutting and grinding to a condition of gruel. For example, pound an egg yolk a spoon, and crush meat in the blender. If you take obviously liquid food product, for example, broth, then can safely pass the first step.
2. In in advance prepared measured glass it is placed the weight received in the first step of 0.5 ml and we part with water before division in 1 ml. It will also become our studied solution. If in the first point you took liquid food product (broth, compote), then to part with water it there is no need, just measure 1 ml of a product a measured glass or a test tube.
3. We add in a separate transparent container (test tube) to 1 ml of the studied solution 1 ml of 10% of solution of sodium hydroxide (NaOH). In house conditions any means perfectly will be suitable for a clearing of pipes, the component necessary for us always is its part and costs kopeks. Be careful during the work with this substance: at hit on skin causes serious chemical burns.
4. By the pipette it is added to solution 2-3 drops 1% of solution of sulfate of copper (CuSO4). It is possible to get it in household shops, in supermarkets department a garden/kitchen garden as in practice copper vitriol is used for fight against diseases of plants.
5. We mix contents of a transparent container (test tube). We watch closely solution coloring change. If protein - is present at a biological product or medicine, then its peptide communications form with copper ions in the alkaline environment complex connections which color we also will explain in the following step.
6. We interpret change of color of the studied solution. If proteins are present – we will see violet coloring. In that case biuretovy reaction to high-quality definition of protein in food will be considered as positive. However, it is worth paying attention and to a liquid shade, it dolzhn to become red or blue.