Abstract:
Idli is one of the flour-based foods fermented by lactic acid bacteria. This
study was designed to characterize the lactic acid bacteria isolated from
Idli batter and to determine their antibacterial activity. Physicochemical
changes of batter during fermentation and sensory qualities of the final
product (Idli) also were determined. Lactic acid bacteria were isolated
from Idli batter and characterized up to genus level. Agar well diffusion
assay was used to determine the antibacterial activity of isolates
against foodborne pathogens (Salmonella enterica, Escherichia coli and
Staphylococcus aureus). Changes of pH, lactic acid bacterial count, titratable
acidity of batter during fermentation and sensory properties of the final
product were measured. Ten isolates (I-1 to I-10) were isolated from Idli batter, of which, six were rod and other four were cocci shaped. All ten
isolates were Gram positive, non-motile, non-spore formers and catalase
activity negative. It was confirmed that all isolates belong to lactic acid
bacteria up to genus level. Based on diameter of the inhibition zone, among
ten isolates, I-6 was considered as the highest potential bacteriocinogenic
isolate. Inhibition zone diameter of isolates ranged from 7.3±1.53 to
16.3±0.58 mm. The pH dropped steadily from 6.28 to 3.72, while titratable
acidity increased from 0.24 to 0.92% throughout the fermentation period
(0-32 h). With fermentation, the lactic acid bacterial count was increased,
and highest lactic acid bacterial count of 9.88 log10cfu/g was observed
after 12 h of fermentation. Idli prepared from Idli batter after 8-12 h of
fermentation scored maximum for the sensory quality. From this study
it is concluded that all lactic acid bacteria isolates possess antimicrobial
activity and physicochemical and sensory qualities of Idli batter changed
with duration of fermentation.
