Why don’t dry aged/hung sausages go bad

Here is a quote from the company that makes the registered trademark Baileys Irish Cream:

Baileys® is the only cream liqueur that guarantees its taste for 2 years from the day it was made, opened or unopened, stored in the in the fridge or not when stored away from direct sunlight at a temperature range of 0-25 degrees centigrade.

One of the keys to achieving this 2 year shelf-life is in our patented process of blending of fresh Irish cream with the spirits and the whiskey without the use of preservatives. The alcohol acts as a natural preservative for the product.

Under normal conditions of storage Baileys has a shelf-life of 30 months.

If you are concerned about a bottle of Baileys® please check the best consumed before date on the bottle - all bottles now carry a best before date. This number is located on the bottom left hand side of the back label. Example : Code 11 20XY would mean that we guarantee the product would taste perfect until that date (XY is the year 2 years from the date of manufacture)

(source).

The alcohol content is the sole preservative listed.

I'm assuming you're wanting to make classic dried sausage such as the salamis and saucisson of Italy and France.

Common salt is certainly the key to the drying process and a quarter pound per 10 pounds of meat is a pretty commonly used ratio, but you must also use a curing salt which helps protect against some of the truly nasty food poisoning bugs such as Clostridium botulinum. This just loves the warm, oxygen-free centre of a curing sausage and produces the botulinum toxin which kills around 5% of people who contract the illness.

Sodium nitrite (often called pink salt) or sodium nitrate (Insta Cure #2 - which converts to nitrite over time in the sausage and the nitrite then does the actual curing) are two commonly available salts.

One-half ounce per 10 pounds of meat in addition to the regular salt is a commonly-used ratio. Don't use more and be sure to keep it away from kids and your regular salt - in quantity it is very dangerous.

Something else I always use in dried sausage (but not hams or bacon) is a live starter culture such as LS-25 or one of the various stains sold as Bactoferm. Added to your mix at two ounces per 10 pounds of meat with say three ounces of dextrose sugar and they will feed on the sugar and excrete lactic acid (just like the bacteria that you add to milk to make yogurt). This lowers the pH of the sausage which makes it even harder for dangerous bacteria to grow. It also produces that delicious acid tang to fermented sausage. If you use this, you hang the sausage in a really moist warm place for the first 24 hours to give the bacteria you added a head start (I have a tall old box with a lightbulb in the bottom).

As far as temperature and humidity goes, 60F and 70 percent humidity are ideal. Humidity below 60 percent can dry out the casing and meat surface too fast which can then harden and prevent the centre from drying (which will then just rot). You could try hanging the sausage above a bowl of water to increase the general humidity in the room.

Your sausage is ready when it has lost at least 30 percent of its original weight. Dry white mould on the casing is good, fuzzy black and green is bad. If you see a little you can rub it off with a cloth dipped in strong brine. Any sign that it is more than just on the surface and you'll have to bin the sausage and start again.

So to recap. Chill your 10 pounds of meat and mince it to your taste. (at least 20% fat gives good texture and flavour). Dissolve the LS25 in a little water and then add it, a quarter pound of salt, a half ounce of Insta Cure #2, up to a couple of ounces of spice of your choice (ground chilli and paprika for chorizo or fennel for something more Italian) a half ounce of finally chopped garlic, a glass of red wine and mix it really well. Then stuff into soaked casings, pricking out any air bubbles with a pin. Hang in a warm place for a day to get the good bacteria you added going, and then hang them in a cool, dampish place until the sausages have lost at least 30% of their weight.

I hope I haven't put you off - it's really as simple as baking a cake and homemade dried sausage is a tremendous thing of joy and beauty - but you really must get the ratios of salt and curing salt right.

If you want to be safe and make fabulous cured sausage I can absolutely recommend Cooking by Hand by Paul Bertolli and Charcuterie by Michael Ruhlman & Brian Polcyn which are both available in the US and Europe from Amazon.

But please don't eat your current batch. Throwing it away won't hurt like paralysis that starts with the face and slowly descends to the rest of the body, bringing death by respiratory failure...