Charcutebrew, you wrote:
If the difference between salami & jerky is the water activity & pH... what makes the difference?
Jerky dehydrated quickly, is safe to eat because the salt used to "cure" the product isolates and "binds" the water that is available to bacteria. The meat does not have a chance to spoil. On the other hand, in a slowly dehydrated salami, the initial salt content is the meat`s only protection from pathogenic bacteria because it "binds" and restricts the available water, while the lactobacilli go to work producing lactic acid from the nutrients (sugar).
Lactobacilli are much less sensitive to water activity and perform very well until the Aw (water activity) drops down to Aw 0.92.
No, there is not necessarily more salt in one than the other. With jerky, we are concerned with
dehydration - the loss of moisture until a point is reached where bacteria are no longer a threat and meat becomes "microbiologically stable". In jerky, the pH level is of little concern. We are considering the Aw level.
On the other hand, in making salami we are concerned with
fermentation AND
slow dehydration. In order to have safe and controlled fermentation we must initially control the water "available" to pathogenic bacteria. Therefore we incorporate salt which "binds" the available water to bacteria while lactobacilli go to work increasing the acidity of the product.
Whether or not comminuted meat is inside a casing, makes little difference other than in salami, the sausage dries from the inside out. That`s why it is so important not to dry the outside too quickly, trapping moisture inside where it will eventually spoil the meat. In a fermented sausage, we encourage the spoilage process (fermentation) by actually slowing down the drying process by keeping it in a chamber of controlled higher humidity. This allows
lactobacilli and
pediococci the opportunity and time to produce lactic acid without competing for nutrient by disparate pathogenic bacteria. The fermentation continues until a point is reached where no more sugar is available to the bacteria.
Stan Marianski wrote, "Removing water content by drying a sausage is a slow process which is not practical when we want to make a product safe to consume within a few days". He continued, "Slow, controlled drying is the method applied to traditionally made slow-fermented sausages which require three months or more to produce. As the process proceeds, water starts to evaporate making meat stronger against spoilage and pathogenic bacteria." -
(Home Production Of Quality Meats And Sausages - p.337)
You asked if it was the salt that slows down the dehydration. No. Please understand that the addition of salt to meat does not compel water to evaporate. Again, let me share Stan Marianski's wisdom. I don't think he'll mind a bit if I quote him a few times here. Salt merely immobilizes "free water" and prevents it from reacting with anything else... including bacteria. Water activity (Aw) indicates how tightly water is "bound" inside a sausage. It does not indicate how much water is actually there, but it does indicate how much water is "available" to support the growth of the three microorganisms - yeasts, molds, and bacteria. Eventually, a point is reached where bacteria are no longer a threat and meat becomes "microbiologically stable". As long as it is kept in low humidity at low temperature, it is safe. However, if these two factors are increased, new bacteria on the outside of the product will migrate toward the center of the sausage, spoiling it eventually.
You wrote:
Really, really interesting to me that the difference between 3% and 3.5% salt can make the difference between fermentation & just dehydration. MAN that makes me want a more accurate scale to make sure I weigh the salt exactly right for my recipes!!!!
You`d better believe it dude! Always weigh it and for goodness sakes, don`t reduce the amount in a recipe thinking you are doing yourself a favor. The stuff modifies proteins and binds meat among other purposes. How about checking out this link:
http://wedlinydomowe.pl/en/viewtopic.php?t=4824 Fresh sausages normally contain about one and a half to two percent salt. An amount exceeding 3.5% is pushing the limit. At 5% the product is generally not palatable. The best rule to follow is "two grams of salt for a hundred grams of meat". In other words, in fresh sausages, use two percent. Fermented sausages require just a bit more - about 2.5% - 3%. If you`re not using a starter culture, it`s best to add 3% - 3.5% salt.
In meat containing only 1% salt, lactobacilli will grow slower and only a barely noticeable decrease takes place in the growth of spoilage bacteria. At 3% salt, lactobacilli will still grow but spoilage and pathogenic bacteria become subdued. At 4% salt, lactobacilli are repressed but amazingly still growing slowly. However, pathogenic and spoilage bacteria have become inhibited at this point.
Best Wishes,
Chuckwagon
And I generally do my reading when I get into something. Must be the doggone grad degree in English, I'm stuck on some language things. Sorry! Not tryin' to be a snot in any way!
And then... if salt slows down dehydration, why doesn't it have the same effect on jerky? Massively different quantities of salt or something?
