There is hardly any nutritional component of grain remain unaffected by pH changes....

The organic acids such as glutamic, oxalic, malic, tartaric, shikimic and fumaric acids etc. can affect the pH of grains

Kindly check http://www.phsystem.guide/grain_food_values.htm

Also check https://ifst.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2621.2011.02886.x

I will take a look.

Thank you very much Chinaza.

Acidity

Dear Andres Silva,

The major contributing factor responsible are the organic acids present in the wheat flour which because of their high solubility contributes in a major way to decide the pH of the dough(once you add water to flour).

Further the soluble portion of mineral components of wheat flour are also having some influence.

pH would attain a certain stabilized value due to buffering action of soluble amino acids and water soluble proteins such as albumines and other fractions particularly globulines would also play a deciding role in the whole process of buffering action.

Further, the water that is used in making dough may also have some influence such as hard water or soft water. Generally the total hardness of potable water that is also used for cooking food is in the range of 50 to 100 ppm of calcium carbonate but in certain places water having more hardness is also very common.

Also some contribution from soluble polysacharide gums of wheat and other grains including pentosans, pectins and henmicelloses need to be considered.

Important consideration is that of the pH of the dough rather than that of the grain

as such.

Regards,

Thank you for replying dear Arun

Indeed the organic acids would affect the pH level of grains by reducing it when dissolved in water. However,

Question: in order to change the pH, how amino acids would increase the pH level when solely dissolved in water, considering they are amphoteric?

Dear Andres,

OK Fine.

I got your query now.

In flour there will be certain praportion of free amino acids already present.

Amino acids are amphoteric and that is the reason they contribute to bufferring action and pH stabilization to a certain extent.

In addition to this some naturally occurring phosphates and citrates would also play their own contributions.

However, as you allow the dough to stand for some time(half an h to 1 h) at ambient temperature the proteases present in wheat floor will start acting on their substrates and will be responsible for certain degree of protein hydrolysis to occur thereby releasing more free amino acids than that were present earlier at zero time.

Obviously these newly released amino acids are going to influence the pH to a new value which is expected to be different than that at zero time.

Ambient temperature will have significant influence in the whole process.

In cold climate these changes will be very slowly.

In my country where temperatures could be in the range of 37-40 in many places (particularly in summer) and which might reach as high as 50 degree Celcius also(places like western Maharashtra) this effect is quite significant.

Regards,

Dear Andres,

Also you should think in terms of the difference in the iso-electric pH of various amino acids.

To what extent each one of the amino acid is ionized will decide the overall pH of the system after the equilibrium is attained at any given time.

Due to proteolytic action more amino acids are released and which particular types are available like acidic, basic and neutral(as far as their side chains are concerned)after a certain degree of hydrolysis at any given point of time after floor is made into dough.

Regards,

Thank you for the explanation. There occur significant changes in pH during the kneading process.

However, what would the amino acids affect the pH level considering the pH determination?

That is, in an aqueous solution, a fraction of a whole grain flour is added. After a stirring time, the pH is registered.

Interestingly, different nutritional components would influence the pH level, among them, the organic acids, amino acids and minerals, as you stated. But, in addition of organic acids which decrease the pH, which food components would increase the pH level in contact with water?

Dear Andres,

The basic amino acids such as glutamine and arginine.

Certain phosphate salts and other components of mineral matter which contribute to the 'alkalinity of water soluble ash'(which are water soluble components of the grain mineral matter).

Regards,

Dear Andres,

If you want to confirm about the veracity of my answer, I would ask you to carry out small experiment.

Take 3-4 different wheat varieties both from hard and soft type.

Analyse the total ash and alkalinity of water soluble ash of all incinerated mineral matter from each sample.

Then prepare a dough by adding standardised quantity of water into accurately known weight of wheat flour on dry weight basis.

Then find out pH of the slurry/dough at zero time and another observation after say kneading/standing for say half an hour.

You would find that if all other factors are constant/not much different for various wheat samples then the sample which is having higher value in terms of alkalinity of water soluble ash would register higher pH both at zero time and may be after an incubation for 30 minutes or so.

Regards,

Hello

There are some enzymes on raw grain that could act on the maduration of the grain changing the pH on the system.