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Whole Wheat Flour got bitter after few months

Malik's picture

Whole Wheat Flour got bitter after few months

Hi everyone,

I am flour miller, these days I am working on extending the shelf life of wheat flour, for that I made some Whole wheat flour in my mills and staked its bags for few time. Its been more than 2 months and now there is no difference in color and smell, but its got bitter in taste.

Can anyone please advice me regarding this and the reasons of getting bitter.



charbono's picture

I don't see how it could get bitter.  However, it could get rancid, depending on storage temperature.


Malik's picture

Thanks for your response dear,

Actually I have packed it in airtight plastic bags. I kept checking these every 15 days, it wasnt bitter before now, there is no bad smell or bad color yet. Even no bitter taste when uncooked, it gets bitter when making flatbread.

Please advice what is the reason.


pmccool's picture

Was the flour milled in a stone mill or roller mills?  If roller mills, was the germ separated from the bran and the endosperm?

What variety of wheat was used to make the flour?

What is the temperature in the flour storage location?  What is the humidity level (approximately)?

What sort of bags are used for storing the flour?  Plastic?  Fabric?  Paper?

Is there anything else stored nearby which could have been absorbed by the flour?

My first guess, like charbono's, would have been that the oils in the wheat germ had gone rancid, which does produce a bitter flavor.  However, rancid flour also has a bitter odor.  Since you don't detect a change in the flour's odor, that would seem to argue against rancidity. 

There is the possibility that some other substance in the vicinity of the flour could have been absorbed by the flour, so long as that "something" is itself odorless but produces a bitter flavor.  Or perhaps there is a mold growing in the flour that is not yet visible but is detectable due to the flavor it produces.  Or....who knows what.


Malik's picture

Dear thanks for your response.

It was milled in roller mill and germ and endosperm was seperated. It was milled from common wheat with the extraction ratio of 10% bran and 90% flour.

Temp in storage area is 35c to 43c and humidity level is .

Flour is stored in plastic bag sealed with heat sealer.

There is no other stuff is stored nearby.

One thing which I observed is that when I stored the flour  bags they seems have some air in it like air pocket, but now bags look like that the air is vaccumed and plastic bags are shrinked due to absense of air.

Please give me some advice..

charbono's picture

Way too warm!