dissoorecedure, do you think your ese instead of buming it off through the ashin

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dissoorecedure, do you think your ese instead of buming it off through the ashing process. If you had used the for the inorganic mineral tests would have been any different? Justify your aniswe mineral testing involves dissolving the organic 5 Another method of preparing food sampies for mineral testing involves 6 Saits ofen are used as adstives or presenathes in canned foods A can of beans was analyzed for minerals using the tests described in this lab. The results were as follows: Na* Zn2 | |Orange-yellow flame! No violet in fame Red coor coudy write coir charge No color charge n upper layer on these data alone, circle all of the compounds below that are possible additives or preservatives used in the can of beans. Puzz a Potassium odide b Calcium carbonate c Sodium chloride d Zinc axide e Iron (0) sulfate Sodium bisulfite I Zinc citrate i Sodium bicarbonate k Calcium sulfate lon Sodium phosphate mCopper (0) oxide n Elemental iron Silioon dioxide EPotassium chloride Obje After ce Iden com nam Nan its c Dos

Explanation / Answer

5. The dry ash or dry oxidation procedure for mineral content testing in food samples involves simple defatting and demoisturization followed by heating the ground sample to very high temperatures in a furnace to convert all organic matter into gaseous states as carbon dioxide, water, nitrogen oxides and sulphur oxides leaving only minerals as oxides or nitrides or such in the crucible as only these can withstand the temperatures of the experiment without decomposition of forming gaseous products that take off the minerals too.

In the acid digestion procedure, the organic matter is digested by treating it with oxidizing acids like nitric acid or perchloric acid and then heating the sample. This ensures that all the organic matter is made water soluble by the strongly oxidizing conditions which converts the organic matter into nitrates or alcohols or carbonyls or acids. However a major problem in this technique is that while digestion, the organic matter will also get charred and form an insoluble black sticky substance which is a result of the high oxidative stress applied on the food sample by acids and heating. These charred solids will have a certain quantity of the minerals in them but those will be sequestered inside the char making it impossible to be available for acid digestion and mineral content determination thus giving a negative error in the estimation through this method.

The only way to minimize this charring to add the acid(s) very slowly and carefully with vigorous and continous stirring. Also, after the complete addition of the oxidant, the sample should be heated gradually again with vigorous stirring regulating the temperature spontaneously as and when charring appears.

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