The application of steam explosion and enzymatic hydrolysis pretreatments on lemon (Citrus limon L.)
citrus peel wastes was studied to obtain bioethanol, galacturonic acid and other co-products, such as
d-limonene and citrus pulp pellets. Steam explosion pretreatment and recovery of lemon citrus essential
oils was carried out at pilot plant scale. The effect of steam explosion on lignocellulosic composition
of lemon peel wastes was studied by thermogravimetric analysis. The antimicrobial activity of lemon
essential oil on Saccharomyces cerevisiae and its influence on ethanol production during fermentation
were also studied. The steam-exploded lemon peel wastes were processed by sequential and simultaneous
hydrolysis and fermentation. Concentrations of sugars, galacturonic acid and ethanol were analyzed
to measure the efficiency of these processes. Significant antimicrobial activity of lemon essential oils
has been observed on S. cerevisiae at concentrations above 0.025%. The steam explosion pretreatment
has shown an interesting effect on lemon peel wastes processing for obtaining ethanol and galacturonic
acid. This pretreatment reduces the residual content of essential oils below 0.025% and significantly
decreases the hydrolytic enzyme requirements. Ethanol production in excess of 60 L/1000 kg fresh lemon
peel biomass can be obtained.