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Post by Alan on Mar 18, 2006 11:17:41 GMT -5
Dear all,
I've been reading about pathogen/microbial issues related to chocolate production. It seems that cocoa bean shell is virtually always contaminated with a variety of different bacteria including salmonella and e. coli. This being the case, it seems that the last thing that we would want to do would be to get some of that bacteria in our liquor and then let it refine at a temperature right in the temperature danger-zone for an extended period of time.
Regarding this issue, I have some thoughts:
1) First, it seems that anytime we handle the raw beans, we should wash our hands/utensils with anti-bacterial soap before handling the roasted beans with those same objects.
2) It seems to me that taking into consideration some of the industry roasting techniques may be of interest. From what I have read, usually a fine water mist is applied to roasting beans during the last 20 seconds of roasting to make sure that bacteria are destroyed. It seems to be the same principle of an autoclave using wet heat. After the beans are sprayed, they are then cooled using filtered air. While we might not have such a setup, would it be worth the effort, when oven roasting, to upen the oven door and spray down the beans with wa mist of water a minute or so before the roasting is done? It seems to me that it couldn't hurt at the least, and probably would make some positive difference.
3) Considering the fact that we are unlikely to kill all of the bacteria, we don't want to create an environment in our chocolate where it becomes a nice cozy culture. So, regarding refining and conching, I think that temperature should be a concern of ours. Now, I know that usually people say that heating food up to 160 will kill salmonella, etc. However, I also know that temperature is only part of the equation. Time is the other part. It is actually possible to heat food to much lower than 160 for an extended period of time and have the same effect on bacteria. However, once one falls below a certain temperature the time becomes numbers of hours. My prooblem is that I can't find a chart that spells out the relationships. Does anyone know of an online version? Perhaps something authored by the FDA or USDA? Anyway, the idea though is that perhaps we should also be paying attention to temperature in relation to how long we refine/conch, and perhaps this can be discussed more fully with a chart available to us all.
These are just some things that I've been considering. After all, it seems that it would be to our benefit to do things as safely as possible if we are going to be feeding our loved ones with our chocolate, even if the risk of contamination is relatively small when compared to making products with meat.
One last thought, would milk chocolate be subject to greater possibility of bacterial contamination/growth than would milk-free chocolate? Could vanilla beans introduce pathogens as well, and if so, how should we treat them? Would it be possible to vacuum pack them and run them through an autoclave?
Any thoughts from those who know about these issues?
Alan
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Post by Sebastian on Mar 18, 2006 11:44:06 GMT -5
Remeber that dairy products can also carry pathogens. If microbiological concerns are important to you (and they should be), you can't neglect the dairy component.
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Post by Alan on Mar 18, 2006 13:04:43 GMT -5
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Post by Alan on Mar 20, 2006 20:00:31 GMT -5
Dear all,
I came across a study published in 1970 that found that though most microbes on cocoa beans are killed during roasting, even the one's that aren't, specifically the most resistant Salmonella bacterium, S. anatum, will be salmonella free after 24 hours at 160 F (71 C). Additionally, it was found that dark chocolate was far less susceptible to these bacteria than was milk chocolate. Therefore, with refining and conching for over 24 hours at 160 F, especially when milk is added, things should be fine. The good news is that if we bump the temperature up about 5 more degrees F then we can ensure the phase shift that John and others have mentioned that turns simple milk and sugar notes into maillard reaction formed caramel-flavor notes.
However, the current seal heat limit on the Santhas is around 165 F, so it is probably not a good idea to take the heat up this high, as John has also mentioned before.
But the good news is...
Though given an industrial manufacturing situation, we would want that 165 F temperature, given small-batch home production, we might be able to get away with being particularly careful with cleanliness and taking the temperature up to 141 F, the temperature at which most bacteria are killed in most situations (given enough time), for 24 hours or more.
This information also coincides with what I have been reading in United States food-safety regulatory manuals recently.
I also think that considering spraying the cocoa beans with a fine mist of water when there is still 1 minute left of roasting couldn't hurt.
Alan
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Post by Alchemist on Mar 21, 2006 14:10:58 GMT -5
Alan,
I have by means done definative studies, but I have done roasting vs bacteria tests and in even the very lightest of roasts I have had 100% kill rates. Having spoke with a very knowledgeable microbiologist about this at my lab, and discribing the roasting curves we use most of the time, these fall right into the "kill zones" of virtually all pathogens.
As for washing your hands, it is very good practice, but I will note that again from tests, dry hand cross contamination in cocoa beans is VERY low. I tried to dry contaminate roasted beans from known e. coli ones and could not get a single positive hit on the roasted bean. That said, I would steer away from misting with water. The wet hand/contact cross contamination tests showed wet or damp beans cross contaminate very easily.
In my still learning opinion, beware of the potential from cross contamination, keep you equipement clean, transfer only from clean to clean (don't restore your roasted beans in the bag they came in for instance) and in all likelyhood you will be alright.
And I don't adverse this fact, but I spot test all my stock for coliforms and do not carry any that I have found e coli on, or are grossly (TNTC) contaminated from general coliforms.
Finally, this is the primary reason I don't advocate the current practice of some people in eating raw cocoa beans. I find it rather risky.
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Post by Sebastian on Mar 21, 2006 15:03:24 GMT -5
I can guarantee you that using dry oven roasting procedures that you're currently using, you will not get regular, effective micro kills, especially as you are whole bean roasting. Not to be argumentative, but i do think the misting with water is a step in the right direction (autoclaves are much more effective than ovens). The risks associated with contamination are so significant that industrial roasting operations are done under a positive pressure environment to keep as many of them out as possible. I'm not going to comment on specifically what you need to do to ensure kills (that puts me in a potentially precarious legal position..), but note that industrial roasters are built specifically with micro kill in mind, and their design and subsequent downstream pathogen testing should make you consider if that much attention is given to the issue industrially, perhaps a 15 minute warm up in the amana range at home may not be sufficient to ensure regular pathogen kills.
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Post by Alchemist on Mar 21, 2006 15:15:49 GMT -5
Sabastian,
I am sort of in the same position. I can't and won't say for a fact that the roasting anyone does kills everything. Like you said, I don't want to be arguemenative either. I just want people to be safe. I know from the kill curve charts I have seen, in theory it is possible for something to survive my standard roast, and I too have seen what they do in the industry to be sure they have 100 % kill rates. I just have yet to see postitives come through in any of the bacteria and mold tests I have performed.
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Post by Alan on Mar 21, 2006 16:07:28 GMT -5
Yes, and just to clarify, I am also not at all claiming that by doing any of the things that I have suggested that there will never be any problems. I am simply trying to think through some of these issues so that we can all be as safe as possible.
Alan
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Post by Alchemist on Mar 22, 2006 15:42:42 GMT -5
I can guarantee you that using dry oven roasting procedures that you're currently using, you will not get regular, effective micro kills, especially as you are whole bean roasting. Not to be argumentative, but i do think the misting with water is a step in the right direction (autoclaves are much more effective than ovens). **Anti-Argumentative disclaimer** ;D Speaking with the same long time microbiologist, it is his "professional" opinion that anything that kills e.coli (which is only a pathogen indicator bacteria in most cases btw) is going to kill Salmonella and a host of other pathogens. His opinion that the 300-325 F for 15-20 minutes IS going to be effective. The whole bean may not be at this temperature, but the surface where the potential contamination resides is going to see this killing temperature. (BTW, note, this is a good reason to stir your beans if you oven roast). OTOH, his and my take is that misting with water is going to do nothing to improve kill rates, and may actually reduce kill rates as you are cooling the beans (less hot time for the bacteria). That is all it is for in the industry anyway - cooling. It is not going to act in any way like the autoclave. The water is going to vaporize and not as a "wet heat". Autoclaves are not more effective just because they are a wet heat (I think the beans are actually sealed and kept dry) but because the increased temperature and pressure kill better. Finally, I don't want to give the impression I don't take pathogen contamination seriously. I take it so seriously that I considered completely shutting Chocolate Alchemy down because I did not want to be the direct cause of someone getting sick. It took me a lot of research, tests and experiments to convince myself that we as a community could safely make chocolate at home. As it is, expect to see warning or caution labels on raw beans at some point.
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Post by Sebastian on Mar 22, 2006 18:29:27 GMT -5
Ditto the same disclaimer I've got an entire lab of microbiologists working for me, and a few decades of data to support the exact opposite. It's not a safe assumption to assume that only the surface of the shell is contaminated - the drying process will introduce all sorts of fissures and cracks. Industrial roasters are designed with the capability of wetting the beans during roast - and all industrial processors I'm aware of do this, by the way - for micro reduction purposes. I don't want to scare anyone away from this, that's not my intention. It is important to make fact based decisions and understand the risks, however.
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Post by Alan on Mar 22, 2006 18:57:41 GMT -5
Dear all, I don't think that there is any risk of any heated arguments getting started here. We can obviously all discuss these various issues, even if there are points of contention, without any problems. So... I think that one thing I have been coming away from reading with is this ( Disclaimer: listen to my thoughts at your own risk. I don't claim that anything I say will work for sure ): Milk chocolate has a higher risk of microbe growth than does dark chocolate. The reason is simple: milk. I think that while discussing what the safest roasting techniques are is important, what seems equally, if not more important to me is to discuss the refining and conching periods, and this seems particularly important with milk chocolate. After all, even if a particular roasting method doesn't kill all the microbes, it seems that a large number, indeed, will be killed. This said, the key is to not put the liquor, from those roasted beans, in an environment where it becomes perfect for microbe growth. When milk powder is added, this becomes more important because not only will the milk powder contain very low levels of bacteria already, but milk is a better medium for the spread of things like salmonella than is cocoa liquor itself. There is also the issue of vanilla, which apparently can carry quite nasty bacteria itself, albeit usually at low levels. But, give those same bacteria a nice, warm, long-term (over 4 hours) place to grow and there is increased risk. That said, regardless of all these potential risks, it does seem, based on what I've read, that chocolate, as far as most foodstuff goes, is not as prone to microbe problems as many other things. However, if there are things that we can do to minimize live bacteria numbers and prefered growth environments, then it is probably better for us. Will most of us have any problems with bacteria? Likely no, based on the fact that plenty of people are making chocolate now and were doing so before the bacteria issue was well understood. Will some people have problems? Who knows? It seems only likely that somewhere down the line if we don't think seriously about all of this, that someone may run into a problem. Again, I am absolutely no expert at all. I am just going by the various books I'm currently reading about the subject. Based on these books, my thoughts are these. Sorry if I keep repeating them: 1) Proper roasting. It seems that we still need some discussion on this issue. I have, indeed, read that brief water misting (it was 20 seconds in the industry roaster I read about) does greatly reduce bacteria numbers. However, John is hearing otherwise from a microbiologist. We need to work out why we are hearing varying stories I think. 2) Proper temperature for refining and conching, especially when making milk chocolate. To me, based on the study and books I've read, this means attaining a temperature of 160 F if possible, and certainly trying to attain a temperature of over 140 F, the temperature past which bacteria start dying, and therefore, stop growing. Thus, even if we don't kill them all, the number would remain relatively low and gradually fall away. This is why I'm using that 75 watt lamp ($6 US) for my current batch. It will raise the heat in the chocolate and since usually things stabilize at 120 F, I am hoping that it can push the mass up to 140 F at the least. I don't know if it will. I'll keep everyone posted. These are my thoughts, but I am certainly willing to be corrected and only want to learn. Alan
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Post by Alchemist on Mar 23, 2006 12:22:22 GMT -5
Ditto the same disclaimer I don't want to scare anyone away from this, that's not my intention. It is important to make fact based decisions and understand the risks, however. I think that absolutely sums it up the best and I ditto that. I DON'T know it all. The day I stop learning I expect to be dead (no relation to the above conversation ) I also know we can't all test like the big boys, but I can do some of it. Toward that avenue, giving everyone as much information as possible is great. And that includes that I am attempting to offer beans that have a minimum of detectable bacteria present, are whole high quality beans and thus hopefully putting us all ahead of the curve.
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Post by seneca on Oct 30, 2007 14:24:11 GMT -5
For what it's worth, we've concocted a decent temperature regulation system for the Santha using a PID controller, a heater and an infrared thermocouple. This allows us to set a conche temperature and maintain it precisely.
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Post by delsalto on Nov 29, 2007 21:58:42 GMT -5
Wow, excellent, and I wanted to roast by the sun. No, I guess I am going to have to do some serious studies...
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Post by ripvanwinkle on Dec 22, 2007 1:13:19 GMT -5
Seneca - interesting about the temperature controller. Would you like to share the design? We all are concerned about the bad bacteria like e-coli but I suspect the many other pathogens also. Question - where can I find a tester for those bad bugs? I'm interested for sure since my next expedition is into milk chocolate. Balancing our concerns about bad bugs - a friend who has traveled the world on scientific expeditions all his long life tells me that when he lands he consumes a container of locally made yogurt. He states that he has never gotten diarrhea from the local food after the "dose" - and that most of his fellow travelers have - consistently - fallen. The cause of the 'runs' is probably not the deadly bugs so we are talking a different game but his advise to eat the yogurt seems practical. Now I note some doctors telling parents that Junior doesn't - and shouldn't - be shielded from all bugs. (How can he be expected to develop resistance if he has never had to resist?) Back to focus: Where can we find a practical e-coli testing kit? Does anyone have suggestions? Note: Just searched and found test kit for E-coli SALMONELLA KIT $70. for 25 tests. metrofasf.com/index.php?main_page=product_info&cPath=370&products_id=1813&zenid=41d0e41ea992dca206cd0b6226d7782eNot too shabby - *if* the results are accurate. So - what company makes a dependable test system?
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