Acidfermented Leavened Bread And Pancakes

These are highly accepted as food. The acid fermentation makes the food resistant to spoilage and development of food toxins and less likely to transfer pathogens.

(a) Indian Idli: Idli is the Indian equivalent of the Western sourdough bread. It differs from sourdough bread as first leavening is achieved by bacterial instead of yeast activity and secondly wheat or rye is not used as source of protein to retain carbon dioxide during leavening. Idli is prepared by bacterial fermentation of batters produced from washed, soaked rice, and dehulled black gram. After fermentation overnight at around 30°C, the batter is poured into cups of an idli steamer, placed in a covered pan and steamed for about 15 min until the idli cakes are soft and spongy. The texture and flavor can be achieved by replacing rice by other cereal grains, and a variety of legumes can be used instead of black gram. The lactic acid bacterium Leuconostoc mesenteroides is important for batter leavening. Yeasts are not essential, although when added they will contribute to leavening, flavor, and increasing levels of the vitamins thiamine and riboflavin. The yeasts used in fermentation for production of idli include Saccharomyces cerevisiae, Debaromyces hansenii, Hansenula anomala, Trichosporon beigelii, Oidium lactis, Torulopsis holmii, Torulopsis candida, and Trichosporon pullulans (Soni and Sandhu 1999); (b) Philippine Puto: Puto is similar to Indian Idli except that there are no legumes in Puto, so the flavoring is excluded. It is produced by grinding soaked rice grains in water, adding sugar and a starter culture containing L. mesenteroides, Streptococcus faecalis, and S. cerevisiae, so allowing the mixture to ferment. This fermentation lasts for about 15 h, before adding sodium hydroxide (lye) and more sugar. A second fermentation continues for about 5 h before steaming for 30 min. S. cerevisiae is a minor component until the final stage of the fermentation in which it can reach as much as 18% of the total population, resulting in a small amount of ethanol. The yeast together with L. mesenteroides may play an important role in leavening the batter (Rosario 1987); (c) Sri Lankan Hopper: Rice and wheat flour, either alone or mixed, are added to sugar, coconut water, coconut toddy, and inoculum (a collection of yeast and acid-producing bacteria) or baker's yeast (S. cerevisiae). After the mixture has formed into a stiff batter, it is covered with a piece of wet cloth and allowed to stand at room temperature for about 12 h to allow carbon dioxide to be produced by the yeast. Following this fermentation, coconut milk and salt are added. Sodium bicarbonate may also be introduced to raise the batter during cooking. The mixture is then poured into an oiled hot pan and baked for about 4 min. A longer fermentation period produces a better flavor. Nutritionally, the yeast provides proteins and B vitamins, and the coconut supplies some proteins, long-chain fatty acids, and flavor (Ekmon and Nagodawthana 1977); (d) Ethiopian Enjera: Enjera, also known as injera, wanjera, manjeriya, and kissra habashiya, is made from teff (grain of a type of grass related to love-grass), wheat, barley, sorghum, corn or a mixture of them. It is a fermented sour leavened pancake-like bread. The teff flour is mixed with water and starter culture before being incubated for 1-3 days to produce a paste. The fermented paste is then mixed with water, boiled, and cooled down before baking for several minutes to give enjera. A number of fungi including Aspergillus, Candida, Hormodendrum, Penicillium, Pullaria, Rhodotorula, and Torulopsis species have been identified as being used in this process. It has been suggested that Candida guilliermondii is the primary fermenting organism although evidence has been presented that gram-negative rod-shaped bacteria may be responsible for the initial fermentation (Stewart and Getachew 1962); (e) Ghanian Kenkey: Kenkey appears in the form of sour maize dough balls or cylinders enclosed by maize husks or plantain leaves. To prepare kenkey, maize kernels are washed and soaked in water before being ground into fine particles. The powder is moistened with water, packed, and covered tightly to ensure anaerobic conditions before leaving to ferment for 1 -3 days. A portion of the dough is then precooked, while salt is added to the rest of the mixture. The precooked dough is mixed with the remaining dough, made into balls and wrapped with maize husks or plantain leaves prior to thorough cooking. This fermentation process is uncontrolled and initially involves Aspergillus, Penicillium, and Rhizopus species. Saccharo-myces sp. have also been detected and as yeasts esterify organic acids and alcohols, they give a distinctive aroma to kenkey. Bacteria are also involved in this process. Gramnegative, catalase-positive bacteria appear in the beginning but soon disappear, to be replaced by gram-positive, catalase-negative bacteria. This microbial activity contributes to its nutritive value by increasing the content of thiamine, riboflavin, and protein in kenkey (Christian 1970); (f) Nigerian Gari: Gari is a fermented cassava product. Peeled cassava roots are washed, grated, and packed into a bag that is weighted to squeeze the juice out. Natural fermentation is allowed to proceed for several days resulting in a lower cyanide content and softer mushy extreme of the cassava. The yeasts including Candida sp. together with bacteria (L. mesenteroides) are responsible for the flavor and changes in acidity during fermentation (Oneyekwere et al. 1989); (vii) Nigerian Kamu: Kamu is a starch-cake food produced from fermented millet. The yeasts, S. cerevisiae and Candida krusei and the lactic acid bacteria are used in fermentation. The mixture of soaked millet grains, pepper, ginger, and fruit is wetmilled with water and sieved. Kamu is the sediment obtained after the filtered liquor is allowed to settle for several hours and can be used to make porridge (Oyeyiola 1991); (h) Nigerian Ogi: Ogi is made by fermenting cereals including maize, sorghum, and millet that not only give them different flavors, but also result in different colors. Fungi and bacteria are included in the fermentation. Aspergillus, Cephalo-sporium, Cerecospora, Fusarium, Oospora, Penicillium, Rhizopus, Rhodotorula, and Saccharomyces are fungi associated with fermenting maize. The yeasts contribute to the flavor of Ogi. The bacteria involved are Lactobacillus plantarum, Lactobacillus brevis, Acetobacter sp., Coryne-bacterium sp., and Lactobacillus plantarium, which is the predominant organism producing lactic acid (Akinrele 1970); (i) Sudanese Kisra: Kisra is bread or stiff porridge prepared by fermenting sorghum flour. To prepare Kisra, sorghum grains are subjected to dry milling and sieving before fortification with wheat or millet grains. The mixture is then milled, and mixed with water before a starter culture is added to start fermentation. After half a day at around 37°C, water is then added before baking. Many microbes are involved in this process, Yeasts, Candida intermedia, D. hansenii, and S. cerevisiae multiply throughout the fermentation. The molds of the fungal genera Aspergillus, Penicillium, Fusarium, and Rhizopus are also found. The bacteria involved include Erwinia ananas, Klebsiella pneumonia, and Acetobacter sp. Dough leavening is caused by Acetobacter converting alcohol to acetic acid and yeasts produce CO2 (Mohammed et al. 1991).

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  • Obo
    What are the microorganism responsible for the spoilage of enjera?
    3 years ago

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