Yes... But..... The primary test for fermented sausage is lowering the pH to a safe level to inhibit bacterial growth, salt content and smoke in some cases... and water activity... Water activity and % weight loss can be correlated if you know the Aw of the original hunk of meat, (each cut of meat and meat type has a different initial Aw and will affect the final weight for a safe product) did not add any liquid during the process as the weight of the added liquid influences the total loss of water and give meaningless numbers... UNLESS....
Weight of the original meat + added stuff + added water.... Subtract the ADDED water and use that number as the ZERO starting weight and calculate weight loss from there....
Fermenting IS Rocket Science....
Drying When the sausage is stuffed its Aw should not be lower than Aw 0.96 as bacteria need some moisture to grow. Color and flavor forming bacteria (Staphylococcus, Kocuria) are aerobic (need oxygen to survive) and are concentrated close to the surface of the sausage (area with most oxygen). They are sensitive to changing water activity levels and fast drying at low humidity levels will rapidly remove moisture from the surface area of the sausage. This will inhibit the action of color and flavor forming bacteria and will affect the development of proper color and flavor. A gray surface ring is a typical example. Lactic acid bacteria are less sensitive to water activity and perform well until water activity drops down to 0.92. Drying is normally performed at 66 → 54º F, 18 → 12º C with decreasing humidity, from about 85% to 65-70%. Higher temperatures and humidity over 75% will promote the development of mold on the surface of the sausage. When making slow fermented sausages without starter cultures, drying temperatures should fall in 54-59º F, 12-15º C range as Staph.aureus starts growing faster at 15.6º C (60º F) and obviously it is best to avoid this and higher temperatures. Sausages dry from inside out and and to have a correct drying process, there must be a balance between moisture diffusion towards the surface and moisture evaporation from the surface. If diffusion is faster than evaporation, moisture will accumulate on the surface of the sausage, causing it to be slimy and yeasts and molds will follow. If evaporation is faster than diffusion, the outside surface area of the sausage will dry out and harden creating a barrier to subsequent moisture removal. As a result moisture will be trapped inside of the sausage, creating favorable conditions for the growth of spoilage and pathogenic bacteria. Water activity can be lowered faster in a sausage which contains more fat than a leaner sausage. Meat contains about 75% of water but the water content of fat is only about 10 - 15%. A fatter sausage containing less meat also contains less water and will dry out faster. Drying basically starts already in the fermentation stage and the humidity is kept at a high level of about 90-95%. Air flow is quite fast (0.8 m/sec) to permit fast moisture removal but the high humidity level moisturizes the surface of the casing preventing it from hardening. Drying is a very important process especially in the initial stages of production. One may say why not to dry a sausage very quickly which will remove moisture and be done with all this pH stuff and bacteria. Well, there are basically two reasons:
1. The outside layer of the sausage must not be hardened as it may prevent the removal of the remaining moisture. It may affect the curing of the outside layer which will develop a gray ring that will be visible when slicing the sausage. 2. Bacteria naturally found in meat and/or introduced starter cultures need moisture to grow. They have to go through the so called ”lag phase” first. Only then, can they metabolize sugar and produce lactic acid. Once, when a sufficient pH drop is obtained, lactic acid bacteria are not needed anymore and more moisture can be removed. Drying is affected by the following factors: Humidity - higher humidity, slower drying. Temperature - higher temperature, faster drying. For the perfect drying the humidity of the drying room should be 5% lower than the water activity (Aw) within the sausage. This requires water activity measurements and computer operated drying chambers where parameters such as temperature, humidity and air speed are continuously monitored and readjusted. This relationship remains constant and every time the water level drops, the humidity is lowered accordingly. At home we have to improvise, and do our best under circumstances which are present during production. And it can be done as the best proof lies in the fact, that we have been making those products without sophisticated equipment in the past. Increasing the acidity of the meat (lower pH) facilitates drying and the movement of moisture towards the surface is much smoother. As the pH drops, it approaches the isoelectric point of the myofibrillar proteins (actin and myosin) where their ability to bind water reaches a minimum. This happens around pH of 4.8-5.3. In simple words, lowering pH aids in the removal of moisture. Depending on the method of manufacture, diameter of a casing and the content of fat in a sausage mass, fermented sausages lose from 5 - 40% of their original weight. Drying continues after the fermentation stage and more moisture is removed from the sausage. This becomes easier as the acidity increases as the forces binding water inside, lose some ot their holding power. As the Aw (water activity) keeps dropping lower, the humidity level is decreased to about 0.85-90%. Maintaining previous fast air flow may harden the surface of the casing so the air speed is decreased to about 0.5 m/sec (1.8 miles/per hour-slow walk). And the process continues until the desired amount of dryness is obtained. There is less available water to bacteria and the sausage becomes more stable.
The length of the sausage has no influence on drying time. Sausages should be dried at a rate not higher than the moisture losing ability of the sausage. Traditionally made sausages have pH of about 5.3 and Aw about 0.88 at the end of the drying process. The drying chamber should not be overloaded as a uniform air draft is needed for proper drying and mold prevention. Air speed - higher air speed, faster drying. Casing type (pore size) - bigger pores, faster drying. Amount of fat - more fat in sausage, faster drying. Meat particle size - bigger size, faster drying. Sausage diameter - bigger diameter, slower drying. Sausage length does not affect drying. A medium diameter sausage should lose about 0.5-0.7% of its weight per day when in a drying chamber. Load capacity of the drying room-fully loaded chamber will dry slower as air movement is restricted. Molds will develop more quickly if there is no air draft at all. Excessive drying hardens the surface and closes the casing pores. If the outside of the sausage becomes greasy, it should be wiped off with a warm cloth otherwise it may inhibit drying.
I highly recommend the book by Marianski listed below ....
Marianski, Stanley. Home Production of Quality Meats and Sausages (Kindle Locations 9322-9337). Bookmagic LLC. Kindle Edition.