Micrococcaceae Cultures

Most meat starter cultures available in the United States contain species belonging to two genera of lactic acid bacteria, Lactobacillus and Pediococcus. In Europe, a quite different type of starter culture has been used. Most of the cultures used for European or European-style fermented sausages contain not only lactic acid bacteria, but also totally unrelated organisms belonging to the family Micrococcaceae.These include species of coagulase-negative Staphylo-coccus, Micrococcus, and Kocuria. In fact, when lactic acid bacteria starter cultures were first introduced in the United States nearly fifty years ago for sausage manufacture, the first European cultures contained only Micrococcus. These mi-crococci cultures are still available.

Whereas the main function of the lactic starter culture—to produce lactic acid and lower the pH—is generally considered to be essential, the inclusion of Micrococcaceae in meat starter cultures, while important, is strictly optional.These bacteria are not fermentative and they produce no acid end products. Moreover, although they are metabolically active, they hardly even grow in the sausage. Rather, these bacteria are included in starter cultures to convert nitrate to nitrite via expression of the enzyme nitrate reductase.Along the way, they help form flavor and enhance color (Box 6-1). Is it important to note that because they are mesophilic, the fermentation temperature must fall within the range of 18°C to 25°C. Thus, the lactic acid bacteria present in the culture must also be capable of growth within this range. If fermentation were to occur at higher temperatures (e.g., 32°C to 40°C), the rapid acid development would inhibit growth of the micrococci and the benefits they provide would not be achieved.

In summary, then, there are at least five functions performed by meat starter cultures (Table 6-4).The culture must: (1) produce lactic acid and lower the pH; (2) produce desirable flavors; (3) out-compete spoilage and pathogenic microorganisms for substrates and nutrients; (4) lower the Eh, since Salmonella, S. aureus, and other pathogens grow better aerobically; and (5) in the case of the Micro-coccaceae cultures, enhance flavor and color development via reduction of nitrate.Although a number of factors account for the excellent safety record of fermented meat products (Box 6-3), the role of the culture in producing safe, high-quality products cannot be overemphasized (see below).

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