The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Why is the Internal temperature going down?

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kolobezka's picture
kolobezka

Why is the Internal temperature going down?

I was taught to always aim for internal temperature to reach 98°C (208°F) for any kind of bread to assure its microbiologic safety. I've never had problems with that until I recently started to test a new recipe. 

1.step sourdough: 10% dark rye (I'm now using freshly ground) + 10% water - ferment overnight

2.step sourdough: 45% dark rye + 45% water - ferment 6-8 hours

Final dough: 45% mixed flours (e.g. whole spelt and all purpose) + 10-15% water + 4% olive oil + 1-2% honey + 1% salt + caraway seeds and bread spice

The final dough goes directly to pans and proofs for 45 - 90 minutes, depending on room temperature.

I bake it as all other breads: 15 minutes 230°C (446°F) with steam, then 40-50 minutes 200°C (392°F). Lowering the temperature is a must with my Bosh oven, which has quite strong upper heat.

The problem with this bread is that after 50-55 minutes the internal temperature is about 91-95°C (196-203°F). Than I take the loafs out of the pans and put back to oven directly on the rack (as quickly as possible). After another 10 minuts of baking the internal temperature hardly reaches 90°C (194°F). Why is the temperature dropping?

ananda's picture
ananda

Hi kolobezka,

Not sure I can help with the temperature readings going down, but want to re-assure you that the bake profile you describe seems fine to me.   If you are baking your loaf in excess of an hour and it is recording a core temperature of 95*C, then to me, it is baked, unless you are scaling in excess of 1300g, which, I suspect is not the case.

Even in the plant bakeries I visit 96*C is the target core temperature to benchmark at.   More than that and they start jumping about weight loss in the finished loaf, but you are right to be concerned to achieve the proper reading to demonstrate safe practice, and ensure your loaf is properly baked.

Do you really need to take the loaves out of their tins?   If so, maybe place them on a solid metal baking sheet rather than just a rack?

All good wishes

Andy

kolobezka's picture
kolobezka

Thanks Andy

I usually bake 3 loafs at a time - 3 x 500 g flour (or 3 x about 850 g dough).

No, I don't have to take the bread out of the pans. But as the internal temperature is slightly under 95°C even after 55 minutes of baking, I thought it would help. Do you thing cold baking sheet would be better than the hot rack?

I've never read a concrete study about what the safe internal temperature should be. All Czech textbooks say 98°C. Proper baking is really important. I want my bread to keep 1 week at least (and it does!, and even much more).

As a rule of thumb the final weight for most of my breads = flour x 1,5

zdenka

ananda's picture
ananda

Hi zdenka,

Have you any space in your oven to pre-heat the metal sheet before you decant the loaves onto it from tins?

I take it you don't use an oven stone?   My thinking is there is no solidity to the heat in your oven; it is just a gentle supply controlled by thermostat.

I work on around 15 - 20% moisture loss for the sort of hydration you are using here during baking.

In assessing baking, I use the time factor as the first check...and you are baking over an hour here.   The loaf is baked!   Core temperature is a back up check now, if you are at 95*C that is quite satisfactory.

The most important reason why your laf keeps a week is because of the level of rye sourdough in the formula!

Take care

Andy

kolobezka's picture
kolobezka

Thanks for your suggestions Andy.

You may be right - the oven temperature stability may be poor without the stone. But it would probably regain the temperature as it lost it, wouldn't it? I do not use stone when baking in pans - my oven has strong upper heat but quite week lower heat. I have observed insufficient browning when putting pans on the stone (BTW for this bread I use 2 black pans and 1 pyrex).

I'll try keeping the loafs in the pans and also putting them on a preheated sheet (but doubt a little that it will keep the temperature while manipulating with the open oven)

Do you think 95°C is enough to assure the microbiological safety? I'm not sure that time is the only criterium. It depends on the baking temperature, type of dough ..., doesn't it? The moisture loss here was around 15% - I use this as a secondary indicator when the core temperature seems like never achieving 98°C.

I often bake breads with 10 - 20% rye sourdough and they keep a week as well (rather more - my friends tested 2 weeks. I usually freeze for convenience). Same for occasional breads with commercial yeast (with preferment). I consider durability (shelf-life)  one of the most important criteria for a good bread - hence emphasis on proper baking and internal temperature.

I really appreciate your help!

zdenka

gerhard's picture
gerhard

I don't know if this is true but I think when you take the temperature you have lot of moisture in the steam phase, after removing it maybe some of the vapour has condensed, it takes a fair amount of energy to make the condensed steam into a vapour again.

Just my thoughts not neccessarily what is happening

Gerhard

Nickisafoodie's picture
Nickisafoodie

I typically bake to about 94C - 95C  (201-203F) internal and never had a problem with any ills of any sort, or off flavors.   At higher temps I find the interior of the bread can be on the dryer side.   

Is there any literature or studies that you are aware of that I should read on this?  If I haven't gotten sick yet in 10 years and hundreds of loaves, I'm inclined to keep all as is...  My finished loaves are about 92% of the starting weight.

Thanks, input from professional bakers?

kolobezka's picture
kolobezka

Thanks for sharing your experience. 98°C is what I was told by professionals here but without a link to any concrete studies. I'd also appreciate some more details about that.

ananda's picture
ananda

Hi zdenka, Nick,

Rather than reaching for my copy of Pyler on this, I will write about what I have observed and analysed in UK plant bakeries concerning this matter.

Zdenka my comment about the time factor is meant to emphasize it is the FIRST check to carry out when assessing baking: how long has the loaf been in the oven?   Then adding in factors like the original dough hydration and the oven temperature give the bigger picture.

Core temperature is then a second check.   However it is crucial test, and one the plant bakers incoroporate into their HACCP system to demonstrate food safety compliance.   Plant bakers in the UK expect to achieve 96*C and will accept 95*C.   Less than 95 is insufficient for them to be confident of HACCP compliance.   My thought on this is that even at that temperature they are being super-cautious, as nearly all pathogenic bacteria is killed off at temperatures of 63*C!

Plant bakers would be unhappy at allowing core temperatures to rise above 96*C for precisely the reason Nick has identified.   The loaf will be too dry.   This does not only affect the final eating quality, but is also likely to leave the bakers open to heavy fines, as the bread will be underweight.   The original scaling weight is set quite precisely so that the baker can expect a cooled and wrapped loaf to weigh very close to 800g [ or 400g ] every time.   Plant bakers have exceptionally good cooling systems which mean the loaf core temperature will be reduced to c.10*C within 90 minutes.   Again, this is integral to their HACCP system.   We obviously do not have the same means to cool our bread.   Additionally, a denser rye loaf will take longer to cool.

Nick if you can achieve 92% finished weight on original scaling weight you are doing very well indeed.   Plant bakers would be very happy with 93%.   When I worked in-store as a baker, we weighed loaves straight from the oven and expected them to be 10% over the target weight when they were cooled and wrapped!

I hope this sheds a bit more light for you, but my opinion is the professional Czech bakers' words are leading you to over-baking in this instance.   It is quite possible that Gerhard's ideas are correct, so if you just bake to core temperature, the loaf is way over-baked.   Time in the oven is your first reference; a theme I always start with when teaching students, and constantly return to it too.

Best wishes

Andy

kolobezka's picture
kolobezka

Hmmm. Your detailed explanation is really helpful. But you are certainly right that bad bacteries will die at around 65°C and mold would survive 100°C anyway...

However, there are some experiments lead by consumers (well, it's not peer reviewed science, but it's reality) showing very short shelf life od commercial bread, even of those prepared with traditional methods. I wonder if unsufficient baking time could contribute to that.

There might be some in English but I just remember one in Czech that appear recently HERE (hope Google translate will be understandable).

zd

Mini Oven's picture
Mini Oven

I remember reading somewhere (cookbook?) that when even taking a peek, it lengthens the baking time by at least 5 minutes, then add to that if needed.  Constantly checking on baked goods can really mess up bake times.  I think the reason for putting glass doors in ovens was to prevent this inconsistency.  Opening the door to remove bread pans I imagine would take more, at least 10 minutes for the oven to recoup and then start warming up the bread to the point before opening.

 Meanwhile, if the loaf is rather wet, the evaporation process (no longer blocked by the pan) around the loaf could actually cool it until it reaches a certain dryness.  (Architecture, cooling effect of evaporating pools used to cool building in hot arid climates) And the bread is missing the metal pan, a good heat conductor unless it is shiny and reflecting heat away from the baking bread. (the reason for removing the pan?)  I have also noticed it takes time for a pale bread to brown when flipped out of a shiny pan, even in a mini oven.  But keep the oven door closed and after that initial lag in temperature, it browns fast!  Try looking for darker pans so you don't have to flip them out.  Red, dark blue, black, dark brown, glass, etc.  


kolobezka's picture
kolobezka

Thanks Mini. Ok, next time I will check the temperature withour removing from pans.

I just don't understand - does glass have the same browning properties as dark pans? I have 2 dark (Kaiser pans, non stick ceramics) and one glass.

Do you think that baking all three pans side by side (I have a standard 62l oven) may contribute to slower baking?

zdenka

Mini Oven's picture
Mini Oven

No, glass browns faster.  Glass pan instructions suggest reducing the oven temp by 25°F and follow recipe baking time.

3 loaves at a time?   Yes.   One loaf in the oven will bake faster than 3 loaves in the oven.   There is a different space ratio from empty space to heat absorbing space.   I would keep plenty of room between the staggered pans and rotate them as well half way through the bake.  

Mini

Grenage's picture
Grenage

Am I the only person who has never checked a loaf's internal temperature? Perhaps this is something I should also be checking.

Do the pans perhaps contribute to heat build-up (heat loss from opening aside).

MangoChutney's picture
MangoChutney

I used to check the internal temperature of my loaves when I was trying to work out my bread recipe.  It prevented me from ending up with loaves that were either doughy inside or totally dried out, in addition to whatever else was wrong with them in that incarnation of the recipe.  Once I had my recipe worked out, I no longer needed to check it. 

So, I would say if your loaves seem fine, you don't need to check the temperature of them.

gerhard's picture
gerhard

I have never measured the internal temp of bread, I just knock the bottom of the loaf to hear that hollow sound and for cake type baking a tooth pick seems to do the trick.  I have actually never heard of anyone getting sick from undercooked bread, most people I imagine would not eat bread that isn't thoroughly baked as it would be unappetizing.

 

Gerhard