Flavor compounds lactic acid bacteria

The only substrate always metabolized by the same pathway by all species of wine bacteria is L-malic acid. Cellular activity is modulated by the presence of other compounds acting on the transport level or on the enzyme activity. The growth of lactic acid bacteria in wine is sought after because of this activity indeed, it is the only activity truly desired. It permits the softening of wine provoked by deacidification and by the replacement of malic acid with lactic acid, a compound with a less aggressive flavor. 

Production of Flavor Compounds by Lactic Acid Bacteria in Fermented Foods... 

Figure 19.1. Numbers of papers published in relation to the formation of flavor compounds by lactic acid bacteria in different fermented foods. Interrogation of the ISI Web of Science database in June 2014, over the period 1994-2014,...

Organic acids may exhibit other sensory properties. For example, citric acid possesses sweet-and-sour sensory notes, and succinic acid has a salty-bitter taste. On the other hand, the typical taste and flavor of Emmental cheese can be ascribed to the propionic acid and a few other compounds, such as proline. In fact, taste and flavor result from the combination of different food constituents in definite proportions. Raw meat smells much like lactic acid, which arises from postmortem anaerobic glucolysis and determines the pH of meat, its final properties, and microbial stability. This same organic acid has been related to the inhibition of certain pathogenic bacteria in yogurt (3). Table 1 lists the reported threshold concentrations for various organic acids in different media (4-6). 

The so-called starter distillates used by the dairy industry are now produced on a commercial scale from lactic acid cultures. These distillates in which 70% of the substrate is converted to diacetyl have been patented(67) and are used to impart a buttery taste to edible oils. They are manufactured by the steam distillation of cultures of bacteria grown on a medium of skim milk fortified with 0.1% citric acid. Organisms used are Streptococcus lactis. S. cremoris. S. lactis subsp. diacetvlactis. Leuconostoc citrovorum and L dextranicum. Diacetyl comprises 80-90% of the flavor compounds in the aqueous distillate but is present at only 10-100 ppm. 

Industrial Fermentation. The primary and largest industry revolves around food products. Milk from cows, sheep, goats, and horses have traditionally been used for the production of fermented dairy products. These products include cheese, sour cream, kefir, and yogurt. More recently so-called probiotics appeared and have been marketed as health-food drinks. Dairy products are produced via fermentation using lactic bacteria such as Lactobacillus acidophilus and Bifidobacterium. Fungi are also involved in making some cheeses. Fermentation produces lactic acid and other flavors and aroma compounds that make dairy products taste good. 

Perhaps the most important bacteria in terms of flavor and odor production are the lactic streptococci discussed earlier. In addition to acetaldehyde, these organisms produce a wide variety of neutral and acidic carbonyl compounds which result in the sharp, buttery, fresh taste of dairy products. Some bacteria including... 

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