Dairy products fermented

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). 

Inhibit mold in natural cheeses and other fermented dairy products. 

Antibiotics in milk can affect dramatically the production of fermented dairy products such as cheese, yogurt, buttermilk and sour cream. Routine application of antibiotic test kits such as the Delvo kit are required to avoid major losses on the line. 

P. J. Groenen and E. Busink, Alkylating activity in food products - especially sauerkraut and sour fermented dairy products - after incubation with nitrite under quasi-gastric conditions. Eood and Chemical Toxicology An International Journal Published for the British Industrial Biological Research Association, 26(3), 215-225. 1988. 

Apart from public health impacts, residual antimicrobials in animal products can bring about technoeconomic losses in the food processing industry. It has long been known that the presence of some antimicrobial compounds in milk can dramatically affect the production of fermented dairy products such as yogurt, cheese, buttermilk and sour cream (72, 73). As shown in Table 10.2, even minute concentrations of antibiotics in milk can cause inhibition of the growth of commonly used dairy starter cultures (74). 

Law, B. A. 1979. Reviews of the progress of dairy science Enzymes of psychrotrophic bacteria and their effects on milk and milk products. J. Dairy Res. 46, 573-588. Law, B. A. 1981. The formation of aroma and flavor compounds in fermented dairy products. Dairy Sci. Abstr. 43, 143-154. 

Law, B. A. 1981. The formation of aroma and flavor compounds in fermented dairy products. Dairy Sci. Abstr. 43, 143. 

On the other hand, fermented dairy products such as yoghurt have been hypothesized to reduce LDL-cholesterol due to their effects on encouraging a gut microbial environment to facilitate the production of short chain fatty acids and thus reduce the synthesis of cholesterol (Nestel, 2008). Fermented dairy has in fact been proposed as a nutraceuti-cal with cholesterol-lowering potential (Chen et al., 2008). 

Enzymatic and microbial processes which liberate low molecular weight volatile chemicals. Biological reactions are particularly Important 1n the aromas of fruits and vegetables, berries, fermented dairy products, and alcoholic beverages. A recent ACS Symposium reviewed these processes (1). 

In recent years, a few fermented dairy products with naturally occurring antihypertensive peptides have been launched in both the Japanese and Finnish market. The Japanese sour milk product Calpis is made by inoculating skim milk with a starter containing L. helveticus and S. cerevisiae. The fermented drink is rich in the peptides Val-Pro-Pro and Ile-Pro-Pro, which have proven to lower blood pressure both in animal model studies and in clinical trials with hypertensive humans (Takano 2002). 

Takano, T. 2002. Anti-hypertensive activity of fermented dairy products containing biogenic peptides. Antonie van Leeuwenhoek 82, 333-340. 

Imhof, R., Bosset, J.O. 1994. Relationship between microorganisms and formation of aroma compounds in fermented dairy products (review). Z. Lebensm. Unters. Forsch. 198,267-276. 

Oxidized flavor is of minor importance in fermented dairy products such as cheese or yogurt (Wong et al., 1973 Czulak et al., 1974 Korycka-Dahl et al., 1983). Several factors may be involved, including depletion of oxygen by the growth of starter bacteria, the acidic pH of the products, peptides produced by proteolysis, and the formation of antioxidants by microorganisms (Eriksson, 1982). 

Ranch dressings containing fermented dairy products, such as buttermilk, are often a source of wild culmres. These cultures, often heterofermentative Lactobacillus, can cause gassiness and product spoilage. Processing often includes pasteurization of the dairy component. 

Milk of UF-standardized protein and total solids content enables the production of fermented dairy products of improved quality and characteristics compared with those produced from milk fortified with milk powder or evaporated milk [11]. Due to the similarity of the protein fractions in HMPP and those of skim milk and the virtual absence of lactose, Mistry and Hassan [134] suggested its utilization for the development of new dairy products and the improvement of existing ones. When these authors used HMPP to produce nonfat yogurt, they found that fortification level up to 5.6% protein can produce acceptable yogurt with smooth texture and firm body that did not exhibit whey separation even without the addition of stabilizers. They noted, however, that >5.6% protein concentration, the yogurt becomes excessively firm and has a grainy texture and flat flavor. 

Yogurt and fermented dairy products Probiotics Improve gastrointestinal health... 

Recently, phospholipids, e.g., lecithin, were classified as nutraceutical foods (Colbert, 1998). The off-flavor associated with lecithin produced in fermented dairy products includes 2,4-nonadienal, 2,4-decadienal, and hydrogen peroxide (Suriyaphan etal., 2001). 

Although the safety of traditional lactic starter bacteria has never been in question, the more recent use of intestinal isolates of bacteria (bifidobacteria, intestinal lac-tobacilli, and enterococci), to be delivered as probiotics in high numbers to consumers with potentially compromised health, has raised the question of safety. These intestinal isolates do not share the centuries-old tradition of being consumed as components of fermented dairy products. However, their presence in commercial products over the past few decades has not given any indication of a safety concern. 

Fonden, R. et al., Effect of fermented dairy products on intestinal microflora, human nutrition and health current knowledge and future perspectives, Bull. IDF, 352, 1, 2000. 

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. 

Examples of products whose aroma are primarily biologically derived are vegetables, fruits, berries, essential oils, fermented dairy products and alcoholic beverages. 

One important class of foods possessing natural flavors that arise via enzymatic and microbial action are "fermented" dairy products. This important food group, consisting of cheeses, yoghurt, buttermilk, sour cream and similar products is very interesting and illustrates the importance of taste and odor in food selection. 

There is no doubt that this group of fermented dairy products significantly contributes to our caloric intake and our over-all nutrition. As consumers we use these products in a multitude of ways. 

We consume them directly, combine them with other foods directly or through cooking, convert them into sauces, etc. There seems to be no end to the creative way we utilize and consume fermented dairy products. The lesson is clear, we use these products because we enjoy their odor and taste. In the selection process, their nutritional value is secondary when compared to their flavor. Since food consumption is a necessary part of life, and in most societies food selection is primarily based on hedonics, then a priori, the biological origin of aromas is an important subject. 

Certain lactic acid producing bacteria have the ability to grow on dairy milk to produce various types of fermented dairy products, including acidophilus milk (sour milk), cultured buttermilk, yogurt, cheese, and other cultured milk products. The microbial action not only increases the shelf-life and nutritional value of these products, but also makes them mote pleasant to eat or drink. 

Bullennan, L. B. (1981). Public health significance of molds and mycotoxins in fermented dairy products. J. Dairy Sci. 64, 2439-2452. 

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