A selection of common lactic acid fermentations is shown in Table 7.1. The sequence of lactic acid bacteria in a fermentation is determined mainly by their acid tolerance. For example in milk, Streptococcus liquifaciens, Lactococcus (formerly Streptococcus) lactis or the closely related Streptococcus cremoris are inhibited when the lactic acid content reaches 0.7–1.0%. They are then outgrown by more acid-tolerant species including Lactobacillus casei (1.5–
2.0% acid) and Lactobacillus bulgaricus (2.5–3.0% acid). Similarly, in vegetable fermentations, Lactobacilli spp. are stronger acid producers than Streptococci spp. Of the four main groups of lactic acid bacteria, Streptococcus spp. and Pediococcus spp. are homolactic, Leuconostoc spp. are heterolactic and Lactobacillus spp. vary according to the strain.
In some fermentations, particularly those that involve low-acid substrates (for example
milk and meat), a starter culture is added to rapidly generate large numbers of the desired
A selection of common lactic acid fermentations is shown in Table 7.1. The sequence of lactic acid bacteria in a fermentation is determined mainly by their acid tolerance. For example in milk, Streptococcus liquifaciens, Lactococcus (formerly Streptococcus) lactis or the closely related Streptococcus cremoris are inhibited when the lactic acid content reaches 0.7–1.0%. They are then outgrown by more acid-tolerant species including Lactobacillus casei (1.5–2.0% acid) and Lactobacillus bulgaricus (2.5–3.0% acid). Similarly, in vegetable fermentations, Lactobacilli spp. are stronger acid producers than Streptococci spp. Of the four main groups of lactic acid bacteria, Streptococcus spp. and Pediococcus spp. are homolactic, Leuconostoc spp. are heterolactic and Lactobacillus spp. vary according to the strain.In some fermentations, particularly those that involve low-acid substrates (for examplemilk and meat), a starter culture is added to rapidly generate large numbers of the desired
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