Guess it may be a substance that can react with oxygen at room temperature to prevent food from oxidative deterioration.
Looking for materials
1. Deoxidation preservative, also known as free oxygen absorbent, free oxygen remover or deoxidizer, is a substance that can absorb oxygen. When food is sealed and packaged, at the same time, substances that can remove oxidation in the packaging are put in to remove free oxygen and dissolved oxygen in the packaging container, so as to prevent food from going moldy and deteriorating due to oxidation. The most commonly used deoxidizers are iron-based deoxidizers and sulfite deoxidizers.
3 cases of iron-based deoxidizer formula (according to Japanese patent literature).
(1) 15g cast iron powder +3g NaCl+4g diatomite +2g activated carbon+water.
(2) Mix iron powder, NaCl, activated carbon and lime milk in the ratio of 100: 0.4: 19.5: 7.5.
⑶ Mix 4 g iron powder +2 g water +2 g activated carbon ++ 1 g NaCl.
(The above content is taken from Shandong Teacher Education Network:
/Blog/Article/805 1 1 . aspx)
2. Deoxidation preservative is a chemical reaction between iron and oxygen. As catalysts, water and salt can effectively absorb oxygen in food packaging bags and promote the reaction itself.
Chemical reaction formula: 4Fe+3O2+6H2O=4Fe(OH)3.
3. Diatomite is composed of amorphous silica, containing a small amount of Fe2O3, CaO, MgO, Al2O3 and organic impurities. Diatomite is fine, loose, light, porous, absorbent and breathable, and is a poor conductor of heat, electricity and sound. Melting point 1650 ~ 1750℃, good chemical stability, insoluble in any strong acid except hydrofluoric acid, soluble in strong alkali solution.
Experimental scheme
A bag of deoxidizing and antistaling agent in a brand almond packaging bag was selected as the experimental sample.
1. Observe the color and state of the deoxidizing preservative, and divide the deoxidizing preservative into four parts for experiment.
2. Dissolve the first deoxidizing preservative in water, observe the color of the supernatant, determine its pH value, and drop silver nitrate solution and dilute nitric acid to see if precipitation occurs. (If chloride ion can be determined, add flame reaction to determine sodium ion. )
3. Take the second deoxidizing preservative, add excessive hydrochloric acid, and observe whether it produces bubbles and can be completely dissolved in hydrochloric acid, and observe the color of the solution after the reaction. After standing, add chlorine water and potassium thiocyanate solution to the supernatant and observe the color.
4. Take the third deoxidizing preservative, add enough sodium hydroxide solution to observe whether it dissolves, and then add enough hydrochloric acid to the supernatant to observe whether there is white precipitation.
5. Take the fourth deoxidizing preservative, heat it in a large test tube, put it into clarified limewater with a single hole plug with a catheter, and observe the phenomenon.
Experimental inquiry
experimental procedure
Experimental phenomenon
Experimental conclusion
1. Take a bag of deoxidizing preservative, open it and observe its color and state. Divide it into four parts.
The powder is a mixture of colorless transparent particles, brown powder and black powder.
Colorless particles may include sodium chloride and diatomaceous earth, brown powder may be iron hydroxide generated after iron powder absorbs oxygen and water, and black powder may include iron powder and charcoal powder.
2. Take the first part of the deoxidizer in the test tube, add 2 mL of distilled water respectively, shake it well, let it stand, and measure the pH value of the supernatant with pH test paper. Dropping silver nitrate solution and dilute nitric acid into the supernatant.
The pH value of the solution is 7. Adding silver nitrate solution dropwise to the clear solution produces white precipitate, but the precipitate does not dissolve after adding dilute nitric acid dropwise.
It contains no acidic or alkaline substances. Chloride ions exist in the solution. (Confirm the existence of sodium chloride and supplement the flame reaction) The flame reaction is yellow, indicating the existence of sodium chloride.
3. Take the second part of deoxidizer in the test tube and add enough dilute hydrochloric acid. Observe the phenomenon. After standing, chlorine water and potassium thiocyanate solution were added to the clear solution after the reaction, and the color of the solution was observed.
Many tiny bubbles are produced and last for a long time. There are still insoluble substances after standing, and the color of the solution is light green.
The solution turns red.
It contains iron powder and substances insoluble in water and acid.
4. Take the third deoxidizing preservative, add excessive sodium hydroxide solution, and observe whether it dissolves. Then take the supernatant, add enough dilute hydrochloric acid, and observe the phenomenon.
There are still insoluble solids in sodium hydroxide solution, and the solution is colorless.
There was no obvious phenomenon after dropping hydrochloric acid.
Deoxidation preservative does not contain diatomite.
5. Take the fourth deoxidizing preservative, heat it in a large test tube, put it into clarified limewater with a single hole plug with a catheter, and observe the phenomenon.
Clear limewater becomes turbid.
Insoluble substance is charcoal powder, which is heated in air to produce carbon dioxide.
Interpretation and conclusion
Through exploratory experiments, it can be concluded that the main components of deoxidation preservative are iron powder, sodium chloride and charcoal powder.
Reflection and evaluation
In this inquiry experiment, we used scientific research methods, from asking questions, guessing hypotheses, searching information on the Internet, and designing the inquiry process, which have been repeatedly scrutinized and verified by students. In the process of inquiry experiment, we did not use any high-tech means, but chose the material identification scheme commonly used in middle schools, which not only conforms to our teaching practice, but also improves our practical operation ability, and conforms to the new curriculum concept of "giving students more opportunities to actively experience the inquiry process, developing scientific attitudes and methods in the process of knowledge formation, connection and application, and gradually forming the consciousness and ability of lifelong learning in the inquiry practice of' doing science'". The concept of.