Applications of Biotechnology in Traditional Fermented Foods (1992) / Chapter Skim
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III. MILK DERIVATIVES
III. MILK DERIVATIVES
Pages 59-86
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From page 61... ...
From a biological standpoint, fermented milks are characterized by the accumulation of microbial metabolic products. It was realized very early that such microbial metabolites as lactic acid, ethyl alcohol, and dozens of other chemicals collectively called flavor substances, were not altogether unpleasant and even contributed to overall preservative action.
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From page 62... ...
One chapter of the latter lists some 80 fermented milks, including both traditional and nontraditional products. A soon-to-be-published encyclopedia of fermented fresh milk products (6)
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From page 63... ...
Microbial Actions Homemade fermented milk products, especially in nomadic or village environments, are still occasionally made by spontaneous fermentation, but most likely they are made by the use of an empirical culture. In other words, the inoculum is obtained from a previous production and its microbial identity is unknown.
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From page 64... ...
The current names of microorganisms recognized in fermented milks are listed in Table 1. TABLE 1 Current Names of Microorganisms in Fermented Milks Current Name Number of Former Designations and Synonyms Genus Lactobacillus L
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From page 65... ...
In 1908 he shared the Nobel Prize in Physiology and Medicine. Metchnikoff developed a theory that lactic acid bacteria in the digestive tract could, by preventing putrefaction, prolong life.
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From page 66... ...
Then came World War II, and until about 1950 very little research and development was seen on fermented milks. Since then increasing attention has been paid to fermented milk products worldwide.
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From page 67... ...
1935. Lactobacillus Acidophilus and Its Therapeutic Application.
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From page 68... ...
For this purpose, demineralized lactose-hydrolyzed whey concentrate has been fermented with Lactobacillus GG. Whey and lactic acid bacteria have thus been combined to provide a wholesome and nutritious beverage.
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From page 69... ...
Isolauri and co-workers (3) published the first study on infant rotavirus diarrhea in which the duration of diarrhea was reduced by 50 percent through the use of either freeze-dried Lactobacillus GG or Lactobacillus GG fermented milk products.
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From page 70... ...
1991. A human Lactobacillus strain (Lactobacillus cased strain GG)
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From page 71... ...
The safety of cheese with respect to food-borne diseases is of great concern around the world. This is especially true in developing countries, where production of milk and various dairy products often takes place under unsanitary conditions.
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From page 72... ...
Standard microbiological procedures were followed to determine the counts of aerobic mesophilic microorganisms, psychrotrophs, yeasts and molds, coliforms, bacterial spores, enterococci, Bacillus cereus, Listeria monocytogenes, staphylococci, and lactic acid bacteria. The pH of the samples was also measured.
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From page 73... ...
TABLE 2 Frequency Distribution (Percent) of Lactic Acid Bacteria, Bacterial Spores, Molds, and Psychrotrophs in Ayib Samples acfu/g Microorganisms 103 104 105 1o6 Lactic acid bacteria 14 33 13 40 Bacterial spores 4 68 24 4 Molds 12 25 35 23 Psychrotrophs — 13 20 67 aColony forming units
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From page 74... ...
1990. Effect of curd-cooking temperatures on the microbiological quality of ayib, a traditional Ethiopian cottage cheese.
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From page 75... ...
Basically, all these traditional dairy products are prepared by simply allowing the raw milk to ferment spontaneously at room temperature (15° to 25°C) for 1 to 3 days depending on the season.
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From page 76... ...
OBJECTIVES The application of modern technology to Moroccan traditional dairy products aims to assure the following: ~ Large-scale production of these products year-round by replacing raw milk with dry milk and butter oil. This will solve the problem of seasonality in Moroccan milk production.
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From page 77... ...
that the improved product should have to be acceptable to consumers. Selection of Starters Microbiological analysis of the different traditional fermented dairy products showed that an important proportion of their microflora was represented by lactic acid bacteria.
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From page 78... ...
The final results regarding censorial quality, chemical composition, and microbiological quality of traditional dairy products made with the improved technology are not yet available. Nonetheless, preliminary data obtained for raib and jben are very encouraging: ~ Sensorial quality: Laboratory samples of improved raib and jben gave similar or even higher sensory scores than market samples.
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From page 79... ...
In addition, the manufacture of traditional dairy products at an industrial scale will increase the production of these products and assure better distribution and marketing. On the other hand, the use of dry milk, which is more economical than raw milk for preparing products such as raib and jben, has the advantage of being available any time of the year.
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From page 80... ...
Our studies have compared traditionally fermented milk with Lacto. We included traditionally fermented pasteurized milk, since substitution of unpasteurized with pasteurized milk might be an alternative for 80
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From page 81... ...
We have characterized 10 predominant lactic acid bacterial isolates from traditionally fermented milk and four isolates from Lacto (3~. We have also carried out studies to determine the fate of pathogenic and nonpathogenic Escherichia cold during fermentation of Lacto and traditionally fermented pasteurized and unpasteurized milk.
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From page 82... ...
, 10 predominant morphologically different lactic acid bacteria colony types from plates inoculated with traditionally fermented milk and four morphologically different types of colonies from Lacto plates were selected and isolated into pure culture. The isolates were identified using numerical taxonomic techniques and reference strains.
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From page 83... ...
cold during fermentation and storage of Lacto and traditionally fermented unpasteurized milk since more E cold survived in unpasteurized fermented milk despite similar final lactic acid and pH levels of both milk products.
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From page 84... ...
Supposing we were to develop a starter culture based mainly on members of the genus Lactobacillus, it is debatable whether we would have the same organoleptic properties in a traditionally fermented pasteurized milk as found in traditionally fermented unpasteurized milk. If we developed and sold this starter culture for home use in fermentation of boiled milk, it is also unlikely that poor rural people would adopt such a fermentation since it has an added cost when compared with traditional fermentation.
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From page 85... ...
1990. Identification of some lactic acid bacteria from two Zimbabwean fermented milk products.
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