Dear Simon,

The buffering capacity of foods plays a pivotal role in food breakdown during gastric digestion. The ability of foods to resist changes in pH alters the acidity of the stomach, influencing acid secretion, enzyme function, and chyme viscosity. All of these properties directly influence the stomach’s ability to break down foods. Therefore, such kind of foods are obviously valuable...

visit following link... Hope you will find what you seek

http://www.bartek.ca/pdfs/Newsletter/BufferCapacity2004IFT.pdf

http://orbit.dtu.dk/files/102243053/Buffer_capacity_poster.pdf

Article Study on the buffering capacity of wort

http://www.istocar.bg.ac.rs/images/V21_I5-6/V21_I5-6_51.pdf

Dear Simon, your question is vague and to a large extent misleading. Buffer or buffering capacity is not a pH range as your food has (pH 2-12). It is a chemical expression that refers to the amount of acids or bases a substance can receive without undergoing any drastic (significant) change in pH. Every food has its prevailing pH which I am sure is not a range but specific for the food. Available proteins are very relevant mediators of buffering capacity. If your food changes pH so drastically as you claim, then the buffering capacity is very low or non-existent. Please rephrase the question and let us know exactly what the problem is. Cheers.

Dear Maurice, thank you for your answer. Let me put it another way:

When I mix 5g of my food in 50 mL solution of pH 2, the pH quickly goes to a value of 6.5. The same happens if the initial pH of the solution is 3, 4, 5, ... 12. I understand now that buffering capacity is not the appropriate concept I should use to talk about this but I thought that maybe this behaviour would have some value for a food, what is your opinion ?