The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

At what temperature does flour go rancid when milling?

Shyamala's picture
Shyamala

At what temperature does flour go rancid when milling?

Hello.  I recently just purchased the Vita-Mix dry container for milling grain.  I freeze the grain so the temperature doesn't get too high, but even so to get a fine/finer grind I have to mill for about 1 min 20 sec.  The flour seems quite warm.  I have taken the temperature of the flour immediately after grinding, but I have been unable to find at which temperature the enzymes break down.  Does anyone have any information on this? 

Yerffej's picture
Yerffej

Anything over 118 °F would be undesirable.  It is a matter of enzyme deterioration, any whole grain flour will eventually go rancid no matter how it was milled.

Jeff

BoyntonStu's picture
BoyntonStu

118 *F is the magic number for Raw Vegans.

suave's picture
suave

What on earth enzyme breakdown has to do with rancidity? 

Yerffej's picture
Yerffej

The original question contains the false premise that milling temperature cause rancidity.  Milling temperature directly affects the enzymes present in the grain and rancidity occurs when fats decompose.  But, Suave, you already know this.

Shyamala's picture
Shyamala

Thank you for your help.  I thought that might be the case.  It's tough to keep it below that when getting a fine grind in the Vita-Mix.  Any suggestions beyond freezing the grain?

Shyamala's picture
Shyamala

Suave.  You have brought up a good point.  Perhaps I am reasoning incorrectly.  Maybe the enzymes breaking down doesn't have anything to do with rancidity.  My question should have been when milling your own grains at what temperature is the flour comprimised in terms of its baking ability?

proth5's picture
proth5

Well, there's the $64,000 question.

Baking qualities start with the grain itself and can be impacted by many factors - including how the grain was tempered (if it was tempered), how finely both the endosperm and bran were milled, and how agressively the grain was milled.

Temperature after/during milling is actually a small concern for baking qualities.

If you are talking nutritional quality, then temperature may enter the discussion.

I'm going to post a link to an intriguing article reproduced from USA Today (OK, McNews - but not a complete rag)

http://www.measuresofsuccess.com/News+and+Press+Releases/Latest+News/663.aspx

This cites temperature up to 195F as attained in commercial milling processes.  These apparently do not sufficiently compromise baking qualities so that commercial millers avoid them.  I won't say that the above article is the source of absolute truth - but I know that grain can get warm coming off any mill and I don't see that as a major determinate of baking qualitites.

I would say that spelt can be a challenging grain to work with (having weak gluten) and that milling it in what is essentially a very powerful blender may not be route to the highest quality flour (That is, both bran and endosperm finely ground).

I am going to humbly suggest that if you are serious about milling your own flour, that you may wish to re think the Vita Mix as a flour mill and look into some of the excellent home flour mills avaialable to the home baker.

Rancidity has more to do with the oxidation of the fats in the wheat berry (the germ containing those fats) over time than enzymes.  Athough this oxidation will take place more quickly at higher temperatures (which is why many bakers refrigerate or freeze their whole grain flours) the temperature as the grain comes off the mill is probably not major concern for this.

suave's picture
suave

I can not boast first-hand experience with milling the way you do, but I read extensively on this topic and it appears that commercial millers prefer 90-95 F range, where they get the best yields.

proth5's picture
proth5

this is the temperature given in the article I cited for flour coming off a commercial rolling mill.  The 195F number was produced by a stone mill.

I've tried not to make my head hurt too much by overthinking my milling these days.  The flour doesn't get very warm and I find it difficult to control a lot of the variables anyway.

I think there is a lot of information floating around about commercial mills heating flour too much and the superiority of this or that way of doing things that is driven by agendas other than the search for truth...

Peace.

suave's picture
suave

I have read that article and let's just say that all things considered I was not overwhelmed by their scholarly effort.  It was more like "we tried a bunch of things without much rhyme and reason and that's we saw". 

proth5's picture
proth5

the source of all truth, to be sure - but intriguing nonetheless.  They do report correctly on the meaning of "stone ground", which is something I think more people should know.

And they got the temperature of the flour coming off a roller mill correct.

I'm a little dubious about the high temperature on all stone mills, though.

I guess I was referring to posts I have seen that have referenced "articles" saying that whole wheat flour becomes rancid immediately after milling - or that commercial mills heat flour to such high temperatures so as to destroy all the nutritional value (I mean - 95F too hot? The wheat gets at least as hot as that in a Kansas field - and then will still germinate.) I always think that there's an agenda behind those.

Shyamala's picture
Shyamala

Wow.  Thank you so much for the information.  My original querie has led to a blossoming of many other questions regarding home milling.  I am concerned with nutritional content and flour quality.  I suppose if you mill your own flour and begin the bread process as soon as possible then the milling temperature shouldn't be too much of a concern as it will be baked at a high temperature not too long after milling the grain.  If my reasoning is somewhat correct then the milling temperature is a bigger concern for store bought flours because it has more time to oxidize and therefore go rancid more quickly.  So proth5 am I understanding you correctly that the milling process and not temperature is what lends to baking quality in flour?  Thank you again everyone who helped answer my original querie and point out the specious reasoning in the question.