Propionic swiss cheese

Bacteria from the genera Lactobacillus and Streptococcus are involved in the first steps of dairy production (3). The raw materials produced by their effects usually only acquire their final properties after additional fermentation processes. For example, the characteristic taste of Swiss cheese develops during a subsequent propionic acid fermentation. In this process, bacteria from the genus Propionibacterium convert pyruvate to propionate in a complex series of reactions (2). 

S. thermophilus metabolizes lactose to l( +) lactic acid but utilizes only the glucose moiety of lactose, leaving the galactose moiety in the cheese (Tinson et al. 1982). In Swiss cheese manufacture, S. thermophilus metabolizes the lactose and L. helveticus metabolizes the galactose to d( —) and l( + ) lactic acid (Turner et al. 1983). The l( + ) lactate isomer is preferentially utilized by propionibacteria to form acetic and propionic acids, which are essential for the development of the characteristic flavor in Swiss cheese (Langsrud and Reinbold 1973). 

Laboratory-scale experiments which used L. casei symbiotically with Propionibacterium freudenreichii in the fermentation of whey gave an average yield of 2.2 mg of vitamin per liter the maximum was 4.3 mg/liter. Production of vitamin Bi2 is not species-specific. All species of Propionibacterium, when cultivated under the same conditions, produce active substances, but in different quantities. P freudenreichii and P zeae synthesized sufficient quantities to warrant their consideration for commercial exploitation. Because propionic acid bacteria are active during Swiss cheese ripening, it was anticipated, and actually demonstrated, that production of vitamin Bi2 in Swiss cheese is influenced by the same factors that influence its production in pure culture, particularly by the cobalt content of milk (Hargrove and Leviton 1955). 

The potent odorants of Swiss cheese have been evaluated by the methods reported in 6.2.4.2 [51-53]. Table 6.32 shows the identified neutral odorants. Furanones nos. 7 and 8 are of special interest as there are indications that - in addition to sweet tasting calcium and magnesium propionate ]54] - they contribute to the sweet and caramellike note which has been perceived in the flavour profile of emmental ]55], Further experiments revealed that lactic acid bacteria cause the production of furanone no. 7 in Swiss cheese ]56],... 

Propionic acid (Figure 2.12) was first described in 1844. Propionic acid occurs in foods by natural processing. It has been found in Swiss cheese at concentrations of up to 1% and is produced by the bacterium Propionibacterium shermanii. Antimicrobial activity of propionic acid is reported to be primarily against molds and bacteria (Barbosa-Canovas et al., 2003). Commercial products containing propionic acid include... 

Swiss cheeses are distinguished from other varieties by different starter cultures used and the subsequent growth of propionibacteria with gruyere cheeses, yeasts and coryneforms. Fermentation of lactic acid and residual sugars by propionic bacteria to propionic acid is vital in flavor development, and follows initial lactic acid fermentation by the starters. The propionibacteria also apparently contain peptidases which release the sweet-tasting amino acid proline, according to some investigators(13), an important Swiss cheese tastant. 

Propionic acid (propanoic acid) CH3CH2COOH Swiss cheese Gk protos, first pkm, fat... 

Calcium and sodium propanoate are used commercially as preservatives in bread, cakes, and cheese to prevent the growth of bacteria and molds (see Figure 5.6). The parent acid, CH3CH2COOH, occurs naturally in Swiss cheese. The labels for these bakery products often contain the common name propionate, rather than the lUPAC-acceptable name propanoate. 

CH3CH2COH Swiss cheese Propionic acid Propanoic acid 141... 

There is evidence that among the fatty acids only butyric and caproic acids 42), at sub-threshold concentrations, interact to contribute to the desirable butter flavor 367). A whole set of fatty acids provide a background flavor in the case of Cheddar cheese. Propionic acid is an essential flavor component in Swiss cheese 330). The characteristic flavor of blue cheese, however, is due to the presence of aliphatic methyl-ketones 161, 308). 

Carbohydrates are also precursors of carboxylic adds. Bacteria of the genera Clostridium, Butyribacterium and Butyrmbrio ferment sugars primarily to acetic and butyric acids. Bacteria of the genus Propionibacterium (P. freudenreichii subsp. shermanii) ferment lactose to lactic acid, which is reduced to propionic acid, an important add of the most famous Swiss cheese, Emmental (Figure 8.39). The first step of this biosynthesis is the reaction of... 

Lactic acid-producing bacteria associated with fermented dairy products have been found to produce antibiotic-like compounds caUed bacteriocins. Concentrations of these natural antibiotics can be added to refrigerated foods in the form of an extract of the fermentation process to help prevent microbial spoilage. Other natural antibiotics are produced by Penicillium wqueforti the mold associated with Roquefort and blue cheese, and by Propionibacterium sp., which produce propionic acid and are associated with Swiss-type cheeses (3). 

Fermentation of lactic acid to yield propionic acid, carbon dioxide, acetic acid, and succinic acid is important for proper eye formation and flavor development in Emmental, Gruyere, and Swiss-type cheese varieties. This fermentation is associated with Propionibacterium spp. subspecies of Propionibacterium freudenreichii are of greatest significance. These organisms can also be used for industrial production of vitamin Bi2 and propionic acid. 

Lactate serves as substrate for the production of propionic acid, acetic acid, and CO2 during the ripening of Swiss-type cheeses. 

Propionic acid is an active microbicide in the undissociated form only in consequence it exhibits optimum efficacy at pH values below 5. Propionic acid is primarily effective against moulds. The activity against yeasts is minimal and the activity against bacteria is poor. Microbes belonging to the genus Propionibac-terium produce propionic acid during fermentation of Swiss Gruy re cheese. However, Bacterium mesentericus is an exception as it is very sensitive to the effect of propionic acid. 

Propionic acid is produced by Propionibacterium from lactic acid. Ripe Swiss and Jarlsberg cheese may contain up to 1% of propionic acid (Blom and Mprtvedt, 1991). 

Bi2 in Russia, Great Britain, Hungary. Hard rennet cheeses (Swiss, Emmental, Soviet and others), in which propionic acid bacteria are involved, are produced almost everywhere. 

The classical manufacturing process of the Swiss-type cheese did not rely on special introduction of propionibacteria (as the starter), but sufficient numbers of propionic acid bacteria were present naturally in raw milk and rennet extract. At present, pasteurized milk is used in cheese making, and during heating at 71 C for 15 s most of the propionibacteria are killed (Alekseeva et al, 1983). A standard requirement for the content of propionibacteria is 2T0 -4T0 per g Soviet cheese, that is why it is necessary to add propionic acid bacteria with high acid-, gas- and lipolytic... 

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