After stuffing, semidry sausages are typically hung on sticks, placed on racks, and moved to fermentation chambers. The conditions for fermentation should provide optimum temperature, humidity, and time for the chosen lactic acid-producing bacteria. These conditions may range from about 27°C to 43°C with 95-99% relative humidity, depending on the culture used. Appropriate conditions will allow rapid culture growth to overwhelm undesirable organisms, rapid production of acid to control pathogens, and sufficient produc tion of other metabolic products to result in expected product characteristics. Semidry sausages are typically fermented at relatively high temperature (over 35°C) to shorten fermentation time and allow greater production capacity. Fermentation in 12 hr or less is not unusual for the high temperature processes.
Although relatively high fermentation temperatures are characteristic of semidry sausages, it is important that product temperature be raised relatively slowly when the product is first being heated. Initially, cold product surfaces are likely to develop surface condensation when exposed to warm, humid air and blotchy colors may develop if the surface condensation is not well controlled. Uneven heating is another potential problem that can result from condensation because water will increase in temperature more slowly than fat. If fat is overheated, it is likely to separate, resulting in a greasy product surface or fat pockets in the product.
For semidry sausages, smoke is often applied during product heating. Because smoke is a microbial inhibitor, it is best to apply smoke after the fermentation is complete and after cured color development has also been completed. An important point to note relative to the cured color development is that cured pigment formation is maximized in products fermented below pH 5.0 (22). Acid conditions greatly facilitate the development of cured color.
The final step of the heating process for semidry sausages is cooking/finishing to reach an internal product temperature that will assure product safety. In the past, many products received relatively mild heat treatments, often finishing at 60 °C internal temperature. Many of these processes are no longer considered sufficient for pathogens such as E. coli O157:H7. Many processors now finish semidry sausages with internal temperatures of 68.3 °C or more to ensure safety. An added benefit to higher finishing temperatures may be realized in longer shelf life as well.
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