Michal Mienik

Jess Dee wrote:
Commercial processing plants have the ability to use heat and pressure to get things to a much higher temperature than you do on the stove, which means they can safely can things that you can't.  

The one thing I don't know is whether a flash heating process is used like with UHT milk.  Otherwise all chocolate spread and peanut butter jars sold here lack a safety button in the cap to indicate whether the product was opened.  They just have a sheet of aluminium foil that could be easily compromised without the consumer noticing.

Jess Dee wrote:
They also have access to a ton of chemical preservatives that I assume you won't be using.  I haven't read a Nutella label lately, but I bet it has some preservatives in it.  

The good news is no chocolate spread contains preservatives.  Not even salt.

Jess Dee wrote:
I also don't think a youtube video is really sufficient to base a choice like that on, particularly when the available science currently indicates this is not safe for home canning.  Botulism is very rare, but also very serious.  If you do insist on trying to can this recipe, please don't give any of it away as gifts - it's one thing to take a risk with yourself, but another thing entirely to put others at risk without their knowing.

The video was a possible indication of what the process is rather than definitive evidence.

I've been doing a lot of reading over the past day, and it appears that C. Botulinum requires a water activity of 0.91 or higher to grow.  It's not just about pH, which mislead me as preserving/canning web sites almost only talk about pH when it comes to safety.  Granted, almost all food that's generally associated with canning would be above 0.91.

Chocolate spreads have a water activity of around 0.5, indicating nothing at all will grow in them, not even the hardiest mold or yeast.
http://palmoilis.mpob.gov.my/publications/POD/pod45-salmi.pdf
https://courses.ecolechocolat.com/lobjects/pdf/water_activity_confectionery.pdf

It looks like I need to eliminate or at least greatly reduce water content and find a lab to measure water activity for me.  In the meantime I'll use my pressure canner for conventional uses such as vegetables.

Thank you for your response.

I guess my post may have been a little misleading as the product is about 15% dairy based, with the majority being sugar and fat.  I've done a lot of reading about canning in the meantime and the general advice is 'don't do it' for low acid, high density foods.  However that would also suggest a product like Nutella or green tea spread shouldn't exist as it clearly falls into the low acid category.

I've watched a few videos on how Nutella is made and it appears to go straight from bottling to label printing without a cooking process in between: https://www.youtube.com/watch?v=CgtoG08CYro  

The maker of Nutella suggests Nutella has a 12 month shelf life even after opening: https://www.ferrerofoodservice.com/ca/en/faq  No botulism concerns there even after the product is opened, exposed to airborne pathogens, and closed again and left on the shelf.

My recipe probably has too much water in it, but if I reduce it to basically zero like Nutella then surely the water activity will be so low as to prevent C. Botulinum growth regardless of pH?

I have just purchased a Presto 21L pressure canner and want to preserve my dairy spread in 250ml (1/2 pint) jars.  It's basically like Nutella but with different flavour.

I tried out my canner for the first time by putting four jars I made earlier (stored in fridge) into the canner, 10 minutes steaming time, 40 minutes pressure canning at 10psi, and then releasing the steam.  The final product was very disappointing.  The outside of the product has caramelized to a dulce de leche kind of colour and taste.  I'll try another batch made fresh and hot.

The product I'm canning is basically just like Nutella:  sugar, oil, water, milk powder, skim milk powder, whey powder, soy lecithin, flavour.  There is water added in the mix, about as much water as oil.  All up the recipe is 30% sugar by weight.  

- Do I need to pressure can this at all?  It's not acidic, but may content enough sugar to prevent botulism.  I haven't however been able to find how much sugar is required.  It's 23% water by weight (some inevitably boils off).  Too much water?  Not enough sugar?  I don't know.

- I cook the mixture to the right consistency at 90C (194F) and place into 250ml (1/2 pint) jars with commercial style (not Mason) closures.  How long should I pressure can it to make it safe, but not caramelize the product?

- How does the number of jars affect canning time?  I tried with just 4 jars and it was apparently far too long.  If I fill the canner with 15 or so jars is 40 mins too long?  How do I tell what the internal temperature of the jars is?

The Presto instructions do not have any suggestions for preserving a sugar/oil/dairy based spread.  That's why I tried 40 minutes.  If I pressure can for 10 things may be better, but I run the risk of not heating the 250ml jars all the way through.