Applications of Biotechnology in Traditional Fermented Foods (1992) / Chapter Skim
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II. OVERVIEW
II. OVERVIEW
Pages 9-58
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From page 11... ...
In technologically developed regions, the crafts of baking, brewing, wine making, and dairying have evolved into the large-scale industrial production of fermented consumer goods, including cheeses, cultured milks, pickles, wines, beers, spirits, fermented meat products, and soy sauces. The introduction of such foreign "high-tech" fermented products to tropical countries by early travelers, clergymen, and colonists was followed by an accelerated demand during the early postindependence period.
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From page 12... ...
In addition, ungraded heterogenous products, inconvenient unpacked bulk foods, or unattractive presentation inhibit consumers to develop regular purchasing attitudes. The contrast outlined here serves as a general guideline to the major targets for upgrading the present status of traditional indigenous fermented foods.
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From page 13... ...
The main advantage of natural fermentation processes is that they are fitting to the rural situation, since they were in fact created by it. Also, the consumer safety of several African fermented foods is improved by lactic acid fermentation, which creates an environment that is unfavorable to pathogenic Enterobacteriaceae and Bacillaceae.
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From page 14... ...
Although the mechanism of the stable coexistence of sourdough populations is not yet fully understood, lack of competition for the same substrate might play an important role. Other factors besides substrate competition, such as antimicrobial substances produced by lactic acid bacteria, might play an important role in the stability of such stable populations, obtained by "back-slopping" (4~.
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From page 15... ...
Although development of such gradually evolved and stable fermentation starters will be an attractive proposition for use in small-scale fermentations under nonsterile conditions, they will not be the most appropriate in all cases. This is exemplified by the sauerkraut (lactic acid fermented cabbage)
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From page 16... ...
Other examples of durable home-prepared starter materials used in Asian food fermentations are Indonesian ragi and Vietnamese men tablets (81. Depending on their specific purpose, these dehydrated tablets, prepared from fermented rice flour, contain mixed populations of yeasts, molds, and bacteria.
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From page 17... ...
. Depending on the particular substrate to be degraded, selected strains of molds are used, often as mixed cultures.
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1981. Future of fermented foods.
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Pp. 1-88 in: Industrialization of Indigenous Fermented Foods.
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From page 20... ...
These include mutation and selection techniques; the use of natural gene transfer methods such as transduction, conjugation and transformation; and, more recently, genetic engineering. These techniques will be briefly reviewed with emphasis on the advantages and disadvantages of each method for genetic improvement of microorganisms used in food fermentations.
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From page 21... ...
Mutation and selection techniques have been used to improve the metabolic properties of microbial starter cultures used for food fermentations; however, there are severe limitations with this method. Mutagenic agents cause random mutations, thus specificity and precision are not possible.
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From page 22... ...
Protoplast transformation procedures have been developed for some of the lactic acid bacteria; however, the procedures are tedious and time-consuming, and frequently parameters must be optimized for each strain. Transformation efficiencies are often low and highly variable, limiting the application of the technique for strain improvement.
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From page 23... ...
Although much of the microbial genetic engineering research since the advent of recombinant DNA technology in the early 1970s has focused on the gram-negative bacterium Escherichia coli, significant progress has been made with the lactic acid bacteria and yeast. Appropriate hosts have been identified, multifunctional cloning vectors have been constructed, and reliable, high-efficiency gene transfer procedures have been developed.
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From page 24... ...
naturally present in the chromosome that can transpose chromosomal DNA to plasmids could be used as an alternative strategy for developing integrative vectors for some strains of lactic acid bacteria.
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Transfer of bacteriocin production to microbial starter cultures could improve the safety of fermented products. Acid production is one of the primary functions of lactobacilli during fermentation.
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From page 26... ...
consumers are not aware of the role of bacteria in fermented foods and do not have a fundamental understanding of recombinant DNA technology, and they may be unwilling to accept the technology. This may be less of a problem in developing countries where improved microbial starter cultures could provide significantly safer and more nutritious foods with longer shelf life and higher quality.
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From page 27... ...
FERMENTED FOODS The Sudanese seem to bring just about anything edible or barely edible to the forge of the microbe, to the extent that one could confidently say: food in Sudan is fermented. The raw materials to be fermented include the better-known products such as sorghum, millet, milk, fish, and meat.
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From page 28... ...
· A comparison of the procedures followed in the preparation of some sorghum food products in Sudan with procedures for making similar products in other African countries suggests that the art of making these products traveled from Sudan to West Africa and perhaps to East Africa, too. In some cases the product travelled carrying the same Arabic-Sudanese name.
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From page 29... ...
These products are strictly confined to urban communities, where the Egyptian influence is more strongly felt. Fish Products Southeast Asia takes all the fame in the literature concerning the production of fermented fish products.
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From page 30... ...
The fermented product can then be cut into strips or pieces and sun dried and stored. The gall bladder is removed full with its gall juice.
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Its protein is of high quality, rich in the sulfur amino acids. Furundu, a similar meat substitute, is prepared from the seeds of red sorrel Hibiscus sabdariffa.
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From page 32... ...
. FERMENTED FOODS AND SURVIVAL STRATEGIES A careful examination of fermented food products of Sudan would immediately suggest a close link between food fermentation and food shortage in this part of the world.
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From page 33... ...
BIOTECHNOLOGY AND FERMENTED FOODS This relationship has not been discussed widely in the literature. One can imagine, however, that biotechnology can be of help in the improvement of fermented foods at three levels: · Raw materials.
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From page 34... ...
1985. Biochemical and microbiological studies on kawal, a meat substitute derived by fermentation of Cassia obtusifolia leaves.
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. Cereal grains account for more than 60 percent of food materials used in the preparation of indigenous fermented foods in Africa.
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From page 36... ...
Of the total world production of over 58 million metric tons in 1990, developing countries produced 62 percent, together with 54 percent of world nut production (121. Fermented products from legumes are not as popular in Africa or Latin America as in the Far East and South and Southeast Asia, where soybean, for instance, is used extensively in the production of fermented products such as soy sauce, miso, and tempe, and black gram dhal for the production of idli and dosa.
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From page 37... ...
There are hundreds of fermented products from cereal grains in the tropical regions of the world that require extensive studies on methods of preparation and biochemical, microbial, and nutritional changes. These include the West African fura or fula, jamin-bang of the Kaingang Indians of Brazil, and the Maori's kaanja-kopawai, a process of fermenting maize in water prior to eating.
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From page 38... ...
Gari, a popular West African staple food that is also eaten in other tropical African countries, is prepared by fermenting cassava; details of improved methods of production are given by Steinkraus et al.
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From page 39... ...
PRODUCTS FROM LEGUMES, PULSES, AND OTHER SEEDS In Savannah Africa, fermented products from legumes and other seeds are important food condiments and are generally strong smelling. Quite often seeds that are used for fermentation are inedible in their raw unfermented state.
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From page 40... ...
COMMERCIALIZATION To industrialize some of these fermented plant foods from traditional processes, extensive studies must be made to determine the essential microorganisms, optimum fermentation conditions, biochemical changes, nutritional profile, and possible toxicological problems associated with certain plant materials or the fermented product itself. Commercial or large-scale processes for indigenous fermented foods need to be adapted to specific local circumstances.
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From page 41... ...
1983. Indigenous fermented foods.
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From page 42... ...
1986. Lesser-known fermented plant foods.
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From page 43... ...
The lactic acid fermentations are generally inexpensive, and often little or no heat is required in their preparation, making them fuel efficient as well. Foods fermented with lactic acid play an important role in feeding the world's population on every continent.
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From page 44... ...
Depending on the salt concentration, salting directs the subsequent course of the fermentation, limiting the amount of pectinolytic and proteolytic hydrolysis that occurs, thereby controlling softening and preventing putrefaction. Lactic acid fermentations have other distinct advantages in that the foods become resistant to microbial spoilage and toxin development.
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From page 45... ...
Lactobacilli and pediococci cannot grow well at this temperature, and the fermentation may not be completed for 6 months. At 18°C a total acidity (as lactic acid)
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From page 46... ...
Idli and dosa are both products of natural lactic acid fermentation.
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From page 47... ...
SOURDOUGH BREADS AND RELATED FERMENTATIONS There is a close relationship between yeasts and lactic acid bacteria in sourdough breads, soy sauce, miso, and kefir. Sourdough leaven contains both yeasts and lactobacilli.
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From page 48... ...
It is made by lactic acid fermentation of corn, sorghum, or millet. Soybeans may be added to improve nutritive value.
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From page 49... ...
PHILIPPINE BALAO BALAO Balao balao is a lactic acid fermented rice-shrimp mixture, generally prepared by blending cooked rice, whole raw shrimp, and solar salt and then allowing the mixture to ferment for several days or weeks, depending on the salt content. The chitinous shell becomes soft, and when the fermented product is cooked, the whole shrimp can be eaten.
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From page 50... ...
Tomato, tomato paste, or onion are sometimes added. In all cases the milk or buttermilk undergoes a typical lactic acid fermentation in which the pH ranges from 3.5 to 3.8 and titratable acidity is 1.3 to 1.8 percent (as lactic acid)
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From page 51... ...
In Chinese soy sauce (Japanese shoyuJ and Japanese miso and related meat-flavored, amino acid peptide sauces and pastes, the essential microorganism for amylolytic, proteolytic hydrolysis of the soybean-wheat or soybean-rice or barley substrates is Aspergillus oryzae. Following overgrowth of the substrate by the mold, the koji is subsequently allowed to ferment in approximately 19 percent salt brine for the sauces and 6 to 13 percent salt for the pastes.
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From page 52... ...
All of these combinations are encountered in Oriental food fermentations. The earliest studies of microorganisms were those made on mixed cultures by van Leeuwenhoek in 1684.
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From page 53... ...
In the miso and shoyu fermentations, these compounds are then acted on by lactic acid bacteria and yeast to produce flavor compounds and alcohol. · In some mixed cultures a remarkably stable association of microorganisms may occur.
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From page 54... ...
· Mixed cultures can provide necessary nutrients for optimal performance. Many microorganisms, such as the cheese bacteria, which might be suitable for production of a fermentation product, require growth factors to achieve optimum growth rates.
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From page 55... ...
However, there are a large number of food fermentations based on plant substrates such as rice, wheat, corn, soybeans, and peanuts in which mixed cultures of microorganisms are used and will continue to be used One example of the complex sequential interaction of two fermentations, and which employs fungi, yeast, and bacteria, is the manufacture of miso. This Oriental food fermentation product is based on the fermentation of soybeans, rice, and salt to make a paste-like fermented food.
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From page 56... ...
The inoculum consists of osmophilic yeasts Saccharomyces rouxii and Candida versatilis and one or more strains of lactic acid bacteria, typically Pediococcus pentosaceus and P halophilus (4~.
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From page 57... ...
Harrison (3) , in his summary of the future prospects of mixed-culture fermentations, very succinctly concluded as follows: No claim'for novelty can be made for mixed cultures: They form the basis of the most ancient fermentation processes.
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