Study of the Egyptian outer pigmented onion skins composition
showed that these skins were carbohydrate polymers
(holocellulose and pectin) – rich with low moisture and ash
contents (Table 1). Six fungal species were tested in shaken cultures
containing pigmented onion skins as the sole carbon
source, at different culture ages for their pectinase productivity
(Table 2). The results showed T. viride potency in four days
shaken cultures at 30 C for pectinase production, consequently,
it was selected for effective pectinase production.
Some preliminary effective pretreatments of the pigmented
onion skins included physical, chemical and physico-chemical
treatments revealed that the physico-chemical pretreatment
by skins milling, then sodium chlorite and GAA treatment was the most appropriate for maximal pectinase productivity
(Table 3).