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Specific heat capacity of chocolate
Do you know what the specific heat capacity of chocolate is?
This figure is so important for anyone wanting to make chocolate machinery and yet I havent been able to find it anywhere. So, If you can help, Much Appreciated T
Replies to This Discussion
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Permalink Reply by Sebastian on -
it gets complicated rather quickly - it's formulation dependent (ie how much cocoa butter you have will directly impact it). drilling down to cocoa butter, since cocoa butter's triglyceride profile is different all around the world, each butter's specific heat will be different. and then you overlay the impact of tempering and crystal form (each of the 6 different forms have their own specific heat...). So there's no quick and easy answer if you're looking for an accurate number 8-)
The easiest thing to do, in my opinion, is average cocoa butter - a good ballpark figure for liquid cocoa butter at 40C would be, oh, about 0.5 cal/g. If you need to estimate SH in solid form, i'd start with 0.52 cal/g (20C, assuming predominance of form V).
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Permalink Reply by Anthony Lange on -
Sabastian, Thank you very much. (especially for the average) I was half expecting an answer like you began without an answer ar the end) I see youre a practical man. Thanks Tony
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Permalink Reply by Anthony Lange on
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Well lets see
I want to heat a 10kg slab of chocolate from 20C to 40C, using a 500W element
Specific Heat Capacity of Chocolate = 0.5cal/g
10kg = 10,000g
Formula to find J (ouls) or Energy require as j
j = m x Cg x (T final - T initial)
Mass 10000g
Cg 0.5
Temp Final 45
Temp Initial 20
Temp Diff 25
= 125000j or 125kj
Factor: 1 Wh = 3.6 kJ
125/3.6 = 34.7222wh
34.722/500 = 4.16664h
4.16hr to melt 10kg of Chocolate with a 500W element.... does this sound right? Anyone
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Permalink Reply by Brad Churchill on -
Call me a luddite here, but wouldn't other variables come into play? I'm thinking variables such as:
1. Heat loss created by the space and air flow between the heating element and the medium containing the chocolate, OR in the case of water being the medium carrying the heat (which is the case in almost all commercial chocolate equipment), how much energy is required to bring the water up to the correct temperature, and keep it there, and what is the rate of loss/transfer from the water, through the holding vessel, and to the Chocolate?
2. What is the medium the chocolate is being held in?
3. Does the medium reflect heat, or absorb heat. (In this case, think of simple table top tempering units that utilize a steel bowl and lightbulbs as a heat source. There's a reason the back of the bowls are all painted flat black.
4. What form is the chocolate in? Is it in a big block, or is it in small chips?
5. How much of that surface is actually in direct contact with the heat. The larger the surface contact with the heat source, the quicker the melt.
I've melted enough chocolate in the last two years to say definitively that I can melt 10kg of chocolate in one hour with four 110 watt lightbulbs. My staff do that almost every morning.
In my experience, sometimes "let's try a number of variations and see what happens" works a lot better than a calculator.
...just my two bits, and maybe some food for thought.
Brad.
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Permalink Reply by Anthony Lange on
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Thanks for that.... 10kg or 22lbs in 1hr with 440W. Wow. My calcs must be out. 22lbs of chocolate in an hour is a lot. I get the drift re losses but for now I must assume negligible losses. Thanks Brad.
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Permalink Reply by Brad Churchill on
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I'm not sure about your calcs. However the white ACMC tempering machines hold about 10 lbs of chocolate, and use two clear 110 watt light bulbs for heat, and no fan to circulate the air while heating. They melt the chocolate and heat it to 123 degrees F from our ambient room temperature of 64 degrees F, in almost exactly one hour. It then takes almost exactly one hour to run the machine through the rest of it's tempering cycle.
Like I said, my staff do this every morning, and do it with several of these machines at a time.
Interestingly enough, it takes almost the same time to cycle through the dark chocolate as it does the milk chocolate with those machines. The milk does however take a few minutes longer for each cycle.
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Permalink Reply by Anthony Lange on
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Oh, 10lbs that I can digest (excuse the pun). Not 10kgs.... Yes, that sounds right. 4.5kg in an hour sounds right. Thanks
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Permalink Reply by Anthony Lange on
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0.52 cal/g is that calories/g? Is that the unit of measue I want I would of thought it would be expressed in J/g? T
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Permalink Reply by Sebastian on
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I ran a quick test today on some milk chocolate i had handy. I won't give any specifics on it's formulation, but at 19C - 1589 J/KgC (or 0.378 Btu/lbF). If I were you, I'd increase that a bit for your chocolate.
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Permalink Reply by Anthony Lange on
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8.2kj/kgC = seems to read?
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