Natural milk cultures

Studies on the use of natural milk culture (developed following a standardized manufacture protocol) from ewe s milk to make semi-hard cheeses are in hand in Argentina. Preliminary results demonstrate that natural milk cultures would be a source of interesting Strep, thermophilus strains. Cheeses from diverse manufactures made with these natural milk cultures showed adequate microbiological quality and sensorial properties (Meinardi, Personal Communication). 

Reinheimer, J.A., Binetti, A., Quiberoni, A., et al. (1997) Natural milk cultures for the production of Argentinian... 

Cheese is a concentrated dairy food produced from milk curds that are separated from whey. The curds may be partially degraded by natural milk or microbial enzymes during ripening, as in cured cheeses, or they may be consumed fresh, as in uncured cheeses like cottage cheese. Most commonly, a bacterial culture with the aid of a coagulating enzyme like rennin is responsible for producing the initial curd. The... 

Biochemical tests are usually performed after pure cultures have been obtained. The standard indole, methyl red, Voges-Proskauer, citrate, and litmus milk tests may be used to show important physiological characteristics. To study the functional diversity of bacteria, the utilization of carbohydrates, amines, amides, carboxylic acids, amino acids, polymers, and other carbon and nitrogen sources can be tested.28 Dilution-based most-probable number (MPN) techniques with phospholipid fatty acids as biomarkers have been employed for studying different bacterial species in lakes.40 The patterns of antibiotic resistance in bacteria isolated from natural waters have been useful for identifying sources of water pollution.34... 

The flavor of the cream may be enhanced by culturing, adding food-grade lactic acid bacteria, or adding natural flavors obtained by distilling a fermented milk cream may also be added to the finished butter. In addition, color, derived from an FDA-approved source, may be used (61). 

Low Molecular Weight Carbonyl Compounds. In the dairy field, a major product made this way is starter distillate. The main component is diaceyl which is a very important aroma compound responsible for the characteristic buttery flavor of fermented dairy products such as sour cream or buttermilk. The dairy industry relies upon fermentation by lactic streptococci for the production of diacetyl in cultured products. Starter distillate is a natural product rich in diacetyl which is produced by distilling such lactic cultures. The key intermediate in the biosynthesis of diacetyl is aL-acetolactic acid which is decarboxylated to form diacetyl (Figure 3). The starting material of the biosynthetic pathway is citrate which is a natural component of milk. 

Lb.helveticus is used as a bacterial starter in Emmental cheese. Lb.casei occurs normally in cheese milk and cheesemaking equipment and is a part of the natural flora. It seems, however, to have a benefical role in cheese ripening. We compared how these two bacteria differ when growing in milk, investigating two different strains of each bacterium. Lb.casei strains were isolated from cheese and Lb.helveticus strains from pure cultures intended for Emmental cheesemaking. 

Although the transformation of C20 5 and C22 6 by ruminal microorganisms to other fatty acids is evident, the nature of the intermediates and endproducts is less clear. When fish oil was fed to dairy cows, no increase in the flow of any cis, trans CLA to the omasum was observed, including the cis-9, trans-W Cl8 2 isomer (23). However, increased omasal flows of trans-9, transA 1 CLA and several nonconjugated dienes were seen. Several studies reported the accumulation of transAl Cl8 1 in ruminal cultures (53) and omasal contents of cows (23), indicating the potential of the fish oil fatty acids to promote cis-9, trans-W production in body tissues and milk from desaturase activity. 

The natural souring of milk prior to manufacture of cheese and fermented milk has proved to be unreliable, vulnerable to failure and the quality of the end product can vary tremendously. Only through the use of composed cultures is it possible to achieve the specific results wanted. A major problem in this context is the interaction between strains in a culture. Great care must be taken to avoid strain dominance during subculturing of multi-strain cultures. 

Isoflavones (2) have usually been found as small amount phytochemicals from the legumes, grains and vegetables, and their processed foods such as traditional tofu and Indonesian tempeh which is a traditional soy product originally from Indonesia [Indonesian tempeh is made by a natural culturing and controlled fermentation process that binds soybeans into a cake form of similar to a very firm vegetarian burger patty], miso, natto, soya milk, bean curds and bean sprouts. 

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