Hi Guys,
At this point in our project, a small increase in temperature is not as critical as the rate of
diffusion and
evaporation. Without a starter culture it would be. A bit of temperature raise will not harm the lactobacilli. However, the
staphylococcus aureus and
micrococcaceae spp., begin to grow at temps above 60°;F. These are the guys responsible for flavor (and color) and right now they must have Aw > 0.96. This is the reason we must not drop the available water down too quickly. They need a little water to work, but after another day, they should be just finishing up. As we continue to lower the moisture gradually, we are drying the sausage
from the inside out. This is called
diffusion - the water moving from inside the sausage to the outer casing. When the water leaves the outside of the casing and is expelled into the atmosphere, it is called
evaporation. Our goal is to balance the two, in a state of
equilibrium.
If the
diffusion rate exceeds the
evaporation rate, moisture will collect on the exterior and create a slimy surface that will host unwanted yeasts and ...yuck, colored, fuzzy, molds! On the other hand, if the rate of
evaporation exceeds the rate of
diffusion, the casing will dry out and harden. This "case hardening" will promote the growth of both pathogenic and spoilage bacteria, as moisture will have become trapped inside. Rytek Kutas used to say that it was just like welding the ends shut on a length of pipe. Could this case hardening become dangerous? Yes, possibly. The growth of pathogenic bacteria always presents a danger to our health. Remember, bacteria need water, and meat is 75% water. At the beginning of the "fermentation" stage, we want about 90% humidity and an airflow of < 0.7 m. per second to avoid case hardening.
Balancing diffusion and evaporation in this early stage of fermentation, has been known to drive sausage makers to the point of neuro-psychosis, where the use of foul and colorfully descriptive adjectives begin to affect their language, much to the consternation and dismay of their spouses. Soon, showing the first signs of "
noevapodiffusem", a victim will begin exhibiting bizarre behavior, including throwing rocks at the mailman and making obscene gestures toward politicians and newscasters!
Moreover, if this occurs during a full moon, one stands no chance at all!
Have you ever cut open a salami and found a gray ring around the outer edges of the sausage? Years ago, I had to buy a salami because I was away to school. Not only did it have an ugly gray ring, it was sour as a dill pickle. It was beyond tangy and just a bite of it would put a frown on a lottery winner`s face! This is case hardening.
Once the lactic acid bacteria have done their job (creating enough acidity that bacteria cannot survive), more moisture can be removed at a little faster pace, but remember... a large diameter salami should dry at a slower rate than a skinny little pepperoni.
Wanna hear something crazy? As the pH becomes more acidic, the drying becomes less difficult. Why? Because the myofibrillar proteins (remember
mosin and
actin?)are losing some of their binding quality at this point. During the last week, the air speed should have been gradually slowed to only about one and a half miles per hour. However cowboys, that is over another horizon yet. Right now, we`re concentrating on
equilibrium. Do what you can to balance the
diffusion and the
evaporation. Good luck buckaroos!
Best Wishes,
Chuckwagon