Ethanol production from mahula flowers using free and immo-bilized cells S. cerevisiae (CTCRI strain) started in the log phase of
the growth and maximum ethanol production was achieved during
the stationary phase (96 h) (Fig. 2). In the present study, there was
a marginal fall of 21% and 11.5% in total sugar concentration over
initial content with simultaneous production of 31 and 23.6 g eth-anol/kg flowers up to 24 h of fermentation for the free and immo-bilized yeast cells, respectively. The decrease in sugar reserve
might be also due to its utilization in part, for initial growth andethanol/kg flowers), respectively. The decrease might be due to
marginal leakage of cells from luffa matrix during each batch of
fermentation. Similar results were obtained on ethanol production
from cane molasses using alginate-luffa as the carrier matrix for
the immobilization of yeast cells [12] . In their study, the ethanol
production was same during the 1st and 2nd cycle of operation
(91.7 g/l cane molasses), with a marginal decrease (0.5%) in the
3rd cycle (90.6 g/l cane molasses).The growth and fermentation kinetics of free and immobilized
cells were also studied (Table 1). The ethanol concentration ( P) ob-tained with luffa immobilized cells (37.2 g/l) was 9.2% more than
that of free cells (33.8 g/l). The volumetric substrate uptake (Qs)
was also found to be more in case of immobilized cells (0.850 g/
l/h) than that of free cells (0.831 g/l/h). Likewise, the ethanol yield
(0.455 g/g) and volumetric productivity (0.387 g/l/h) by immobi-lized cells were more than that of free cells (0.424 g/g and
0.352 g/l/h).