Help! How does it work?

[Ubarrow Peter]

I'm dry curing some bacon and I'm a little bit at sea!

How does a cure actually work? I know that the saltpetre (or equivalent) somehow resists spoilage but what does the main ingredient i.e. the salt actually do? Does it just draw out the moisture or does it actualy also inhibit bacteria?

Next question: How does the cure penetrate the bacon? Is it some kind of osmotic process, or what?

And now the quantities: I've got about a dozen different sets of directions which give very different quantitities. Sometimes it simply does not seem enough to cover the meat. The quantities all relate to a given weight but does it make a difference if (as I have at the moment) you are curing six small flitches of just over 5 kg each, therefore there is a lot more surface area than , say, 2 large ones?
Some recipes tell you to put the meat on a bed of salt and then to cover it. This takes a lot of salt! depending on the container, obviously.

However some of the smaller quantities seem to make it impossible to cover the surface of the meat, especially on the skin side. I'k rubbing it in well, does this actually penetrate the skin and do the trick.

Some books tell me that the amount of salt has no effect on the saltiness of the bacon and that this is purely a consequence of the time left in the cure. Any thoughts on this?

And finally (!) I'm told that the salt content of bacon makes it inadvisable to freeze for more than a month. Is this true?

My basic cure is Salt, brown sugar and saltpetre 4lb, 1lb, 1oz are the ratios.

If anyone can help with these queries then I'l be most grateful

[Oddley]

I'll do my best to answer your questions.

How does a cure actually work? I know that the saltpetre (or equivalent) somehow resists spoilage but what does the main ingredient i.e. the salt actually do? Does it just draw out the moisture or does it actually also inhibit bacteria?

Next question: How does the cure penetrate the bacon? Is it some kind of osmotic process, or what?

Let me explain how a brine works first. If you put meat in a strong solution of salt. Because there is an imbalance of salt, the salt draws the water from the meat, replacing it with salt. This is called osmosis. This action dehydrates the meat, causing another imbalance. Therefore water and other dissolved chemicals re-enter the meat. This is called reverse osmosis.

The same applies to dry cure where the salt cure is rubbed on the meat. This take a little longer, because the salt has to first mix with the water drawn from the surface.

Some bacteria are susceptible to elevated salt levels some are not. Some bacteria's are resistant to salt levels of 30%. Most bacteria are effected by the drying of the meat. Not all though. Most bacteria are inhibited by low temperatures below 4.6C. Again not all.

And now the quantities: I've got about a dozen different sets of directions which give very different quantities. Sometimes it simply does not seem enough to cover the meat. The quantities all relate to a given weight but does it make a difference if (as I have at the moment) you are curing six small flitches of just over 5 kg each, therefore there is a lot more surface area than , say, 2 large ones?
Some recipes tell you to put the meat on a bed of salt and then to cover it. This takes a lot of salt! depending on the container, obviously.

The reason some recipes require you to lay the meat on, and cover the meat in salt, is to completely cure the meat, by drying it. All the water will be drawn out, with no chance of reverse osmosis. This makes the meat very salty, if the process is completed. Less salty, if taken out before the completion of the process. Time will then equalise the salt, throughout the meat so time is therefore a factor.

On some cures a percentage weight of salt is calculated, ensuring only a certain amount of salt can be absorbed. If not air dried, this will cause the meat to react similar to fresh meat, and spoil in a shorter length of time.

Meat fat is mainly impermeable and has little water content, therefore inhibiting osmosis. So it is a waste putting more than 10% of cure, on the fat side.

Some books tell me that the amount of salt has no effect on the saltiness of the bacon and that this is purely a consequence of the time left in the cure. Any thoughts on this?

As you can see by the above text, the applied salt and time in cure, directly effect's the saltiness of the meat.

And finally (!) I'm told that the salt content of bacon makes it inadvisable to freeze for more than a month. Is this true?

I have read that the salt will have an effect on the fat, if frozen. I have frozen bacon for a couple of months, with no ill effect. But on occasion, if left too long, the bacon will spoil.

I hope this makes sense. I have tried to explain this complex subject, as simply as I can.

[Ubarrow Peter]

Thanks Oddley

That's very clear. I'll go away and think a little more (!) and probably come back with another question.

Meanwhile I've got to keep an eye on some bacon flitches.

Peter