Preparation of idli batter, its properties and nutritional improvement during fermentation

Abstract

Idli is a traditional fermented rice and black gram based food. Idli batter is prepared by soaking polished parboiled rice and decorticated black gram for 4 h at 30 ± 1 °C in water. The soaked mass was ground using a grinder with adequate amount of water. The blend ratios of 2:1, 3:1 and 4:1 (w/w) batter were allowed for fermentation for different periods with the addition of 2% (w/w) of salt. The rheology of the product was assessed using a Brookfield Viscometer having disc spindles. Shear stress values were in the range of 0.22 and 4 Pa and reached a maximum value at 7 h of fermentation. The density, pH, and percentage total acidity of batter during fermentation for different blend ratios ranged between 0.93 and 0.59 gm cm⁻³, 4.21 and 5.9 and 0.44 and 0.91% respectively. During fermentation, maximum production of riboflavin and thiamine were found to be 0.76 mg/100 gm and 0.73 mg/100 gm in 3:1 blend ratio of idli batter; and the folic acid content was found to be at a maximum of 0.75 mg/100 gm of idli batter after 10 h of fermentation. Digestibility in terms of amino N₂ content was analysed by formol titration.