Ask the Alchemist #27

If you are making chocolate at home how can you make sure (if at all) that any harmful bacteria is killed as you can’t heat the chocolate to 165 F/75 C or above as this would ruin the chocolate. I suppose I could always heat the milk with the cocoa butter to the required temp before adding the beans.

Well, it would seem you have a misconception about heating and bacteria. Let’s try and clear those up.

To make chocolate (we are not going to talk about raw chocolate, but this conversation is actually one of my major issues with raw chocolate) you need to roast the cocoa beans. This reaches temperatures well over 250 F/120 C, more than hot enough to ensure any bacteria is killed.

After that, chocolate can still be heated above 75 C. Some chocolates are taken to 80 C without being ruined. Regardless, roasting takes care of it. Further (since you mentioned it), milk powders are already ‘safe’ and do not need any further heating to take care of bacteria. They (and cocoa butter and sugar) are tested for Salmonella, E. coli, and have a general HPC (hertrotrophic plate count – general bacteria) for which they must pass.

Alright, I think that clears up some of the misconceptions. Let’s talk a little more about roasting and bacteria and making chocolate.

Some years ago I analyzed raw and roasted cocoa beans for both e coli and a general HPC of a variety of cocoa beans I had on hand. I also treated some with some ‘classic’ food safe cleaning agents such as bleach (no, I would not want to eat this either), peroxide, water (general washing) and an over the counter produce wash.

I’ll say right off that I no longer have the actual reports and analysis, but as you will see, the results were so clear, I stopped testing.

All the beans I tested were positive for E. coli (I had previous tested 10 different origins, and picked the 3 that were contaminated – note, these were test beans, and I rejected them, so they were never for sale) and gave a result of TNTC (too numerous to count) for 10 beans in 100 ml of sterile water.

I prepared three roasts of three different beans (yes, 9 roasts).

  • 185 F for 60 minutes.
  • 250 F for 40 minutes
  • 350 for 20 minutes.

I choose those times as they give me something resembling a proper roast flavor (my at-home indicator).I also soaked each of the three origins in the following solutions:

  • 0.5% bleach (1:10 of household bleach – ICK)
  • 3% peroxide (what you can get readily)
  • Produce wash (just following the directions…at twice the concentration)
  • Water (sterile).

I let all of them soak 30 minutes (yes, I know, they would not be edible (did you know wet cocoa beans are slimy?), but I was proving a point here…busting a myth here one might say, before mythbusting became cool.)The results you ask?

All the roasted beans were E. coli negative.

All the roasted beans were <10 colony/10 beans (note, this does not mean I saw some colonies, only that of the 100 ml of liquid, we only used 10 ml, so the detection limit goes up – I saw no colonies) All the cleaning agent washes were UNCHANGED. Positive E. coli and the HPC were all TNTC. Roasting – Confirmed Washing solutions – Busted So, when you hear someone tell you they washed their raw beans for their great raw chocolate, you remember this. (Note: again, I am NOT saying raw chocolate is contaminated – only that treatments do bumkis. The only chance of safe raw chocolate is starting with safe, clean beans). Moving on. Once you have your clean beans (which you feel pretty damn good about simply because they taste fine – handy isn’t that), the only other thing you need to concern yourself with is cross contamination. You need to keep your raw and roasted cocoa beans separate so you do not cross contaminate them. This means dedicated bowls, spoons, etc. One for the raw, one for the roasted. That kind of thing. And you washed your hands, right? Look at that – mom was right again. So, will this guarantee your chocolate is bacteria free and safe to eat? Nope. Not unless you actually have it tested. But it DOES give strong evidence that if you follow basic food handling procedures (start with clean product, cook adequately, wash your hands, don’t cross contaminate) you are probably going to be just fine. Relax. Don’t worry. Have some chocolate.

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