The heat and hold method?

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"...Most broad spectrum preservatives prevent additional bacteria from growing, but do not kill what is already present...."

I question the accuracy of this statement. The existing microbial load will drop in a product shortly after an effective preservative is added and the count will remain low, at least for as long as the preservative is effective.

For example, Liquid Germall Plus is a formaldehyde producer. It produces only tiny traces of formaldehyde, but it's enough to control microbial growth. Do you really think a live bacterium can survive exposure to formaldehyde?

A preservative will get used up quickly if the starting microbial load in the product is high, however. It's important to reduce the microbial load (bacteria and fungi) in a product by using sanitary manufacturing practices. AND it's also important to not encourage any microbes that do survive to reproduce by not adding sources of protein, sugars, and starches. These steps will help the preservative stay as effective as possible in the product for the longest time.

I agree with the others who are explaining the heat and hold is primarily a method of ensuring the most stable emulsion when using certain types of emulsifiers (it's not strictly required for all -- just some). It is not a surefire way of ensuring a product is sanitary. It might help, yes, and certainly can't hurt, but it cannot guarantee.

Also bear in mind we aren't able to STERILIZE our products. We can only SANITIZE.
 
"...Most broad spectrum preservatives prevent additional bacteria from growing, but do not kill what is already present...."

I question the accuracy of this statement. The existing microbial load will drop in a product shortly after an effective preservative is added and the count will remain low, at least for as long as the preservative is effective.

For example, Liquid Germall Plus is a formaldehyde producer. It produces only tiny traces of formaldehyde, but it's enough to control microbial growth. Do you really think a live bacterium can survive exposure to formaldehyde?

I agree and it's also why I use Liquid Germall Plus. However, there are a number of "natural preservatives" being touted to DIYers as "Broad Spectrum" that are not truly broad spectrum. For example: Leucidal
My statement could have been clearer to be sure.

A preservative will get used up quickly if the starting microbial load in the product is high, however. It's important to reduce the microbial load (bacteria and fungi) in a product by using sanitary manufacturing practices. AND it's also important to not encourage any microbes that do survive to reproduce by not adding sources of protein, sugars, and starches. These steps will help the preservative stay as effective as possible in the product for the longest time.

I agree 100%

I agree with the others who are explaining the heat and hold is primarily a method of ensuring the most stable emulsion when using certain types of emulsifiers (it's not strictly required for all -- just some). It is not a surefire way of ensuring a product is sanitary. It might help, yes, and certainly can't hurt, but it cannot guarantee.

True, it is not a way to sterilize your ingredients, but if by chance it kills "something" that could cause problems with my products I have a hard time letting go of the procedure. I would rather do what I can to minimize potential contaminants especially if it does nothing more then waste a bit of my time. 20 minutes is a small price to pay for potential added safety.

Also bear in mind we aren't able to STERILIZE our products. We can only SANITIZE.
Agreed

As always @DeeAnna, I value your expertise and love to hear your comments around the science of making soaps and other products. Thank you for chiming in on the discussion. :)

For others watching the thread, here are a couple of articles that may help with determining which preservatives to use with which products you're making and the importance of using preservatives.

Preservative Reviews (makingskincare.com)
A Guide to Cosmetic Product Preservatives — The Eco Well
 
Specifically, I want to see if I can find challenge testing on and both sides.
I had both tested - the heat and hold recipe and the non - well, kind of... the testing I had done was plate counts. I sent two samples of each in, 4 samples total (Sample A, Sample B, Sample C and Sample D).
Sample A was the heat & hold product put directly into a pump bottle and allowed to cool before capping.
Sample B was the heat & hold but tampered with. I placed it in a glass bowl with no lid, mixed it around with dirty fingers, left it in the well trafficked bathroom for 3 days, spilled some on the vanity and put it back in the bowl ... basically gave it a good exposure to what the lotion may experience in a customer's care. I then bottled it in the same pump bottle.
Sample C was the non-heat & hold, same process as Sample A.
Sample D was the non-heat & hold, same process as Sample B.

Sample A & C (the untampered samples) came back with ND (non detected) for plate count.
Sample B & D (the tampered samples) came back less than 100 for plate count - from memory the heat and hold was in the 50's, and the non h&h was in the 90's.
For plate counts, anything less than 1000 is safe to use, so these tested well.
I used Germall Plus as my preservative following supplier recommended usage rates and temperatures.
 
I had both tested - the heat and hold recipe and the non - well, kind of... the testing I had done was plate counts. I sent two samples of each in, 4 samples total (Sample A, Sample B, Sample C and Sample D).
Sample A was the heat & hold product put directly into a pump bottle and allowed to cool before capping.
Sample B was the heat & hold but tampered with. I placed it in a glass bowl with no lid, mixed it around with dirty fingers, left it in the well trafficked bathroom for 3 days, spilled some on the vanity and put it back in the bowl ... basically gave it a good exposure to what the lotion may experience in a customer's care. I then bottled it in the same pump bottle.
Sample C was the non-heat & hold, same process as Sample A.
Sample D was the non-heat & hold, same process as Sample B.

Sample A & C (the untampered samples) came back with ND (non detected) for plate count.
Sample B & D (the tampered samples) came back less than 100 for plate count - from memory the heat and hold was in the 50's, and the non h&h was in the 90's.
For plate counts, anything less than 1000 is safe to use, so these tested well.
I used Germall Plus as my preservative following supplier recommended usage rates and temperatures.

Wow @amd I am sooo happy to see this! I am sooo stats driven that my brain seems to need the details before it can fully believe some things. Thank you so much for sharing! :nodding::dance::nodding::dance:

I don't care what anyone says, I will continue using Germall Plus!
 
I’m finding this thread fascinating. I’ve been making my own moisturiser for 10 years and have only bought both phases up to 70oC and then mixed them to emulsify. I don’t use water, but rose hydrosol.

amd, what a great experiment. In the early days I used citrus seed extract. I am now more educated about preservatives but it’s nice to know good hygiene practices certainly help.

Jubilee8269, is sounds like you’ve really thought things out. Maybe you could use silicone measuring cups, certainly lighter, but not sure how they go when heated up. Good luck with everything.
 
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Thanks so much for all of this information! And about the Ice emulsifiers @justjacqui I had no idea those existed. This is exactly why I came and asked the question. I've seen so many beauty DIYers say some mismatching things on YouTube that I wanted to be sure. I even saw one the other day insisting that essential oils were preservatives and I swear my brain melted a bit when I saw her doing that after reading on this forum and watching Brambleberry videos. Some places give out such misleading information.
 
I bought this kettle a few months ago and love it. It has six preset temperatures and will heat and hold for you. I bought it for coffee and tea but am now thinking I may buy another for heating and holding. The top is about 4 1/4” in diameter and the lid blocks part of that so making anything in big batches or with a significant amount of liquid that needs to be heated and held might not be ideal.
HadinEEon Variable Temperature Electric Kettle, 1200W Electric Tea Kettle, 8 Big Cups 2.0L Glass Electric Kettle with 4Hrs Keep Warm Function & Boil-D https://www.amazon.com/dp/B07HT3FXCY/ref=cm_sw_r_cp_apip_WEYWsrXZY35nr
 
I bought this kettle a few months ago and love it. It has six preset temperatures and will heat and hold for you. I bought it for coffee and tea but am now thinking I may buy another for heating and holding. The top is about 4 1/4” in diameter and the lid blocks part of that so making anything in big batches or with a significant amount of liquid that needs to be heated and held might not be ideal.
HadinEEon Variable Temperature Electric Kettle, 1200W Electric Tea Kettle, 8 Big Cups 2.0L Glass Electric Kettle with 4Hrs Keep Warm Function & Boil-D https://www.amazon.com/dp/B07HT3FXCY/ref=cm_sw_r_cp_apip_WEYWsrXZY35nr

I really like that this is clear so you can make sure there is no algae, mold, or hard water stains and the 4hr keep warm function is ideal. Thank you for sharing this, now to find out how to hide the incoming package or request it for an anniversary gift...
 
Here's a roaster that would work. It's out of stock right now, but I'm sure they'll be back before the next big holiday. :)

Oster 18 Quart Red Roaster with High Dome & Self-Basting Lid - Walmart.com - Walmart.com
I’m hunting for a roaster… I had one very similar to this, but after a year of use the coating inside the pan was definitely being worn away and I had to stop using it. Have you got any experience with this? Are there certain materials I should look for? Mine was a Nesco 18 quart w “enamel coating” on the pan, so now I don’t trust any of these to last.
 
Ohh ... gotcha. So you mean heating in separate devices? I guess I wasn't looking at it that way. It would work both ways, as long as they are both help to temp and combined while still at that temp.

I've seen the debate on heat and hold and in a more sterile environment, I might agree that it isn't necessary. However, in my house I have 2 dogs, a cat and DH. I prefer to continue heat and hold just to be on the safe side. ;)
I don't heat and hold. I'm sure I only did it once or twice in the beginning. I sanitize my equipment very well and I've never had an issue.

I also make cold processed creams, lotions and shampoo. I think she or he will be ok with a kettle. I use my kettle for batches under a gallon. Love it!
 
I’m hunting for a roaster… I had one very similar to this, but after a year of use the coating inside the pan was definitely being worn away and I had to stop using it. Have you got any experience with this? Are there certain materials I should look for? Mine was a Nesco 18 quart w “enamel coating” on the pan, so now I don’t trust any of these to last.
Are you using this for making bath & body products? Perhaps the tools you use in the process is contributing to the damage to the coating. Or perhaps the heat was too high.

Enamel coating is not necessarily impervious to damage. And enamel coatings are not all created equal. Also how you care for the enamel coated cookware matters. So perhaps what you need to do is to search for a better quality product with better quality enamel as well as look at the types of things you may be doing to decrease the longevity of the the enamel coating.

https://www.hunker.com/13420328/are-there-dangers-of-enamel-cookware
 
As I understand "heat and hold" it wants a consistent temperature over a specific amount of time. I do heat and hold for a few of my products - a toner and cbd oil - and realized that whether I used an oven, a crock pot, a kettle, or the stove, the temperature would fluctuate because once the temperature is reached, the oven or crock pot turn off, the temp goes down a bit, then they turn back on to again reach the desired temperature. So I bought a sous vide, which is the only thing that I have found to keep a constant temperature over the time period. Plus, you can actually use it to cook food, which is what it was designed for. Here is an example of one that is mid-priced. There are more expensive and less expensive ones. https://smile.amazon.com/Anova-Culinary-Precision-Bluetooth-Included/dp/B07C7PW3PC/ref=sr_1_2?crid=2AH13QPFPUOMN&keywords=sous+vide+anova+nano&qid=1661092979&sprefix=sous+vide+anova,aps,496&sr=8-2
 
I agree and it's also why I use Liquid Germall Plus. However, there are a number of "natural preservatives" being touted to DIYers as "Broad Spectrum" that are not truly broad spectrum. For example: Leucidal
My statement could have been clearer to be sure.



I agree 100%



True, it is not a way to sterilize your ingredients, but if by chance it kills "something" that could cause problems with my products I have a hard time letting go of the procedure. I would rather do what I can to minimize potential contaminants especially if it does nothing more then waste a bit of my time. 20 minutes is a small price to pay for potential added safety.


Agreed

As always @DeeAnna, I value your expertise and love to hear your comments around the science of making soaps and other products. Thank you for chiming in on the discussion. :)

For others watching the thread, here are a couple of articles that may help with determining which preservatives to use with which products you're making and the importance of using preservatives.

Preservative Reviews (makingskincare.com)
A Guide to Cosmetic Product Preservatives — The Eco Well
Great article! I mostly produce for fun, friends, and family but I am a nurse and I rely on the WSP website for information about each preservative they suggest and I use them! I get the creepy crawlies thinking of using “preservative-free” products. Especially if I buy from Etsy.
 

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