On the other hand, mass transport limitations hinder chemical
reactions and consequently the initial reaction rate was lower
for immobilized than for free yeasts. After the first fermentation
cycle, the free yeasts were extracted from the reaction medium,
centrifuged and incorporated into a fresh reaction medium to
start a second reaction cycle. The immobilized yeast was simply
removed mechanically from the reactor, gently washed and incorporated
into a fresh reaction medium. The results are shown in
Fig. 5c and d for free and immobilized yeast respectively (also
see Table 5).