Fermented milk products

All sour milk products have undergone fermentation, which can involve not only lacticacid bacteria, but also other microorganisms, e. g., yeasts. To the lactic acid bacteria count the genera Lactobacillus, Lactococcus, Leuconostoc, and Pedio-coccus. The most important species are presented in Table 10.25. 

Depending on the microorganisms involved, fermentation proceeds via the glycolysis path- 

Apart from the type of fermentation, the configuration of the lactic acid formed also depends on 

cellobiosus L. brevii L. hilgardii L vermiformis L. reuteri D,L-Lactic acid 

Pediococcus acidilactici thermophilic, homofermentative, D,L-Lactic acid 

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Yogurt. Yogurt is a fermented milk product that is rapidly increasing in consumption in the United States. Milk is fermented with Uactobacillus bulgaricus and Streptococcus thermophilous organisms that produce lactic acid. Usually some cream or nonfat dried milk is added to the milk in order to obtain a heavy-bodied product. 

Fermented morama milk products such as morama yoghurt have been reported by Phuthego et al. (2009). Morama milk yoghurt like soymilk yoghurt, provide economic and nutritional benefits, because they are likely to have higher protein levels at comparable or lower cost than regular fermented milk products (Karleskind et al., 1991). This is because... 

Whey powders, demineralized whey powders, whey protein concentrates, whey protein isolates, individual whey proteins, whey protein hydrolysates, neutraceuticals Lactose and lactose derivatives Fresh cheeses and cheese-based products Functional applications, e.g. coffee creamers, meat extenders nutritional applications Whey powders, demineralized whey powders, whey protein concentrates, whey protein isolates, individual whey proteins, whey protein hydrolysates, neutraceuticals Various fermented milk products, e.g. yoghurt, buttermilk, acidophilus milk, bioyoghurt... 

Gels prepared from heated milk synerese poorly (assuming that the milk does coagulate). Such reduced syneresis properties are desirable for fermented milk products, e.g. yoghurt (milk for which is severly heated, e.g. 90°C x 10 min) but are undesirable for cheese. 

Fermented milk products exhibit thixotropic rheological properties, i.e. the viscosity (resistance to flow) decreases as the rate of shear increases a typical relationship is shown in Figure 10.33. The rheological properties are major parameters of quality and are controlled by varying the total solids content of the milk, the heat treatment and homogenization of the milk and the use of hydrocolloids, e.g. gelatin or carageenan. 

Fermentation of lactose during the growth of micro-organisms in milk has a major effect on its redox potential. The decrease in the h of milk caused by the growth of lactic acid bacteria is shown in Figure 11.3. A rapid decrease in h occurs after the available 02 has been consumed by the bacteria. Therefore, the redox potential of cheese and fermented milk products is negative. Reduction of redox indicators (e.g. resazurin or... 

Rykshina, Z. P. 1961. Biological means to enrich fermented milk products with vitamin B12 (abstract). Milchwissenschaft 16, 434. (German)... 

It is presumed that dietary consumption of fermented milk products facilitates the interaction of immunoregulatory LAB with cells of the GALT system and there is plenty of evidence for the direct interaction of LAB with intra-intestinal lymphoid foci (De Simone et al. 1987, Yasui and Ohwaki 1991). Recent studies have shown that LAB can potentiate the expression of cytokine receptors on IFN-activated human intestinal cells and can regulate immune phenotype and cytokine expression at intestinal sites following oral delivery in mice (Herias et al. 1999, Maassen et al. 2000). 

Rodriguez-Otero, J.L., Hermida, M. 1996. Analysis of fermented milk products by near infrared reflectance spectroscopy. J. Assoc. Off. Anal. Chem. Ini. 79, 817-821. 

Collado, C.M., Hernandez, M. (2007). Identification and differentiation of Lactobacillus, Streptococcus and Bifidobacterium species in fermented milk products with bifidobacteria. Microbiol. Res., 162, 86-92. 

As the free sugar only in small amount in wine and fermented milk products (cheese and yogurt). Constituent of oligosaccharides and polysaccharides... 

Lactic acid bacteria are used to produce fermented milk products, and the exopolysaccharides produced by the bacteria influence the texture of the resulting products. More importantly, these exopolysaccharides are thought to have several health benefits. There is evidence they lower cholesterol, modulate the immune system, help prevent colon cancer, and fight ulcers [342,343]. There is thus interest in establishing stmcture-function relationships for these stmctures, as well as in metabolic engineering of lactic acid bacteria to produce capsular polysaccharides with the desired properties [342,343]. 

Hsin-Yu, C. and Chou, C.-C. 2001. Acid adaptation and temperature effect on the survival of E. coli 0157 H7 in acidic fruit juice and lactic fermented milk product. International Journal of Food Microbiology 70 189-195. 

Long term tradition, as well as scientific knowledge, shows that consumption of fermented milk products is beneficial for human health. For instance, longevity in some Mediterranean areas is attributed to an increased consumption of sheep cheese and fermented milk. More than 100 years ago Russian biologist Ilya Mechnikov already mentioned health effects of fermented milk. 

Agerbaek M, Gerdes LU, Richelsen B (1995) Hypocholesterolaemic effect of a new fermented milk product in healthy middle-aged men. Eur J Clin Nutr 49 346-352 Agerholm-Larsen L, Raben A, Haulrik N, Haulrik N, Hansen AS, Manders M, Astrup A (2000) Effect of 8 week intake of probiotic milk products on risk factors for cardiovascular diseases. Eur J cun Nutr 54 288-297... 

Fermentation whey protein concentrates, whey protein isolates, individual whey proteins, whey protein hydrolysates, neutraceuticals Various fermented milk products, e.g. 

Most polysaccharides used today are of plant origin. However, also bacteria produce polysaccharides. Especially extracellular polysaccharides (eps s) produced by lactic acid bacteria may find application in foods. Lactic acid bacteria are food-grade organisms and the eps s produced offer a wide variety of structures. The presence of eps is considered to contribute greatly to texture and structure of fermented milk products. An exopolysaccharide produced by Lactococcus lactis ssp. cremoris B40 was chosen as a subject of study. The eps was a gift from the Dutch Institute of Dairy Research (NIZO), Ede, the Netherlands. The eps had no gelling properties, could not be precipitated in plates by ethanol or cetylpyridinium chloride and did not show interaction with Congo red. 

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