Indian idli is a small, white, acidic, leavened, steam-cooked cake made by lactic fermentation of a thick batter made from polished rice and dehulled black gram dhal, a pulse (Phaseolus mungo). The cakes are soft, moist, and spongy and have a pleasant sour flavor. Dosa, a closely related product, is made from the same ingredients, both finely ground. The batter is generally thinner, and dosa is fried like a pancake.

Idli fermentation is a process by which leavened bread-like products can be made from cereals other than wheat or rye and without yeast. The initial step in the fermentation is to wash both rice and black gram dhal. They are then soaked for 5 to 10 hours and drained. The coarsely ground rice and black gram are then combined with water and 1 percent salt to make a thick batter. The batter is fermented in a warm place (30 to 32°C) overnight, during which time acidification and leavening occur. The batter is then placed in small cups and steamed or fried as a pancake. The proportions of rice to black gram vary from 4:1 to 1:4, depending on the relative cost on the market.

Idli and dosa are both products of natural lactic acid fermentation. L. mesenteroides and S. faecalis develop during soaking, then continue to multiply following grinding. Each eventually reaches more than 1 × 109 cells per gram, 11 to 13 hours after formation of the batter. These two species predominate until 23 hours following batter formation. Practically all batters would be steamed by then. If a batter is further incubated, the lactobacilli and streptococci decrease in numbers and P. cerevisiae develops. L. mesenteroides is the microorganism essential for leavening of the batter and, along with S. faecalis,is also responsible for acid production. Both functions are essential for producing a satisfactory idli.

In idli made with a 1:1 ratio of black gram to rice, batter volume increased about 47 percent 12 to 15 hours after incubation at 30°C. The pH fell to 4.5 and total cidity rose to 2.8 percent (as lactic acid). Using a 1:2 ratio of black gram to rice, batter volume increased 113 percent and acidity rose to 2.2 percent in 20 hours at 29°C. Reducing sugars (as glucose) showed a steady decrease from 3.3 milligrams per gram of dry ingredients to 0.8 milligrams per gram in 20 hours, reflecting their utilization for acid and gas production. Soluble solids increased,
whereas soluble nitrogen decreased. Flatulence-causing oligosaccharides, such as
stachyose and raffinose, are completely hydrolyzed.

A 60 percent increase in methionine has been reported during fermentation. The increase would be of considerable nutritional importance if true, but the results conflict with earlier findings. Thiamine and riboflavin increases during fermentation and phytate phosphorous decreases have also been reported.

3 komentar

  1. mouhajmal  

    7 April 2011 pukul 16.57

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    Mouhamad Ajmal. A

  2. Unknown  

    4 Januari 2016 pukul 20.07

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    2 Januari 2019 pukul 02.55

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