2. Methods
2.1. Raw materials
Whole orange (Citrus sinensis L. cv. Valencia) and
lemon (Citrus limon L. cv. Meyer) peels were collected from
a process plant and air-dried. Both varieties are commonly
used for juice production in Greece (Manganari, 1996).
Freshwater algal biomass (slime) was collected from two
sedimentation tanks of a municipal wastewater treatment
plant, at Keratea, a small town, 50 km SE from the city
of Athens. The biomass was collected in sterile bottles
and was air-dried for five days. Representative samples
were examined under a compound microscope for eukaryotic
organism identification to the genus level.