fermentation

THOSAI ??

What Is

• Fermented crepe or pancake

• Made from rice and urad dhal

• Usually taken during breakfast

• Healthy food : no sugar or trans fat

• Prepared by fermentation process

• Served with chutney or dhal curry

• Contains carbohydrate, protein and vitamins

Rice, ural dhal and fenugreek is soaked

in water for about 6 hours

The soaked mixture will be grind with adequate water to produce a smooth and fluffy paste

Salt can be added to make it tastier

The batter is set aside for approximately 12 hours to ferment

• Thosai is a products of natural lactic acid fermentation

• Natural microflora of the ingredient act as the starter

• Bacteria & yeasts are contributed by rice & urad dhal

• Prevalence of bacteria & yeasts affected by seasonal variations

• Starch digesting enzyme > amylase contribute in initial stage of fermentation

• Fermentation improves flavor, texture & enhance bioavailability of nutrients

Predominant bacteria responsible for souring and leavening of Thosai batter

From Rice :

Leuconostoc mesenteroides

Streptococcus faecalis

Lactobacillus fermentum

Bacillus amyloliquefaciens

Bacteria always dominate the overall microbial load

• Yeasts if present, belonged to :

Saccharomyces cerevisiae Debaryomyces hansenii Trichosporon beigelli.

• It produce flavor, enzymes and help in saccharification of starch

• During soaking, Leuconostoc and Streptococcus develops and continue multiplying

• Each eventually reaches more than 1 × 109 cells per gram after 11 to 13 hours

• Heterofermentative Leuconostoc mesenteroides produces CO2 in addition to lactic acid

• Streptococcus faecalis responsible for acid production

• After 23 hours, if batter is further incubated : Lactobacilli and streptococci decrease in numbers but Pediococcus cerevisiae develops

Biochemical changes : After 15 - 20 hours , 1: 2 ratio of Black Gram : Rice

• Increase in microbial load after fermentation at 30°C

• Increase in batter volume about 113 %

• Increase in total acidity to 2.2 %

• Increase in total nitrogen and soluble proteins

• Increase in vitamin B1 & B2 content lead to improved nutritional quality

• Increased activity of amylases but gradually decline with the progress

• Decrease in pH to less than 4.5

• Glucose ( reducing sugar ), decrease steadily from 3.3 ml/g to 0.8 ml/g which reflects utilization for acid and gas production..

• Fermented batter of Thosai shows 80% destruction of aflatoxin

• This may be due to the microorganisms involved in fermenting the batter

• Lactic acid causes degradation of aflatoxin B1 to B2a

• Fermentation process breakdown the bonding between protein and aflatoxin B1 molecule.

• Further destruction may be due to critical moisture and temperature of heat processing

• Fermenting finger millet with horse gram increases soluble proteins concentration in Thosai.

• A 4:1 ratio of finger millet : horse gram increases essential amino acid concentration

• This formulation produces a high protein food that could overcome malnutrition problem

• Zinc & iron concentration can be increased by 50 % & 127 % respectively

• Do not use air tight lid when batter is fermenting

• The fermentation can be retarded by Yogurt, Baking yeast, Baking soda or Baking powder.

• The best ambient temperature for fermentation is 30°C to 32.2°C

• If the temperature is below 30°C, it will take longer to achieve acceptable level of fermentation.

• If the temperature is higher than 32.2°C, the batter may become sour

• Chlorinated tap water can inhibit fermentation.

• Thosai is fried on pan with little oil while Idli is steamed in mould with water

• Thosai batter is thinner and finely grinded than Idli batter

• Thosai is crusty and crisp while Idli are soft and fluffy

• There is less Amylopectin in Thosai than Idli