Advances in Food Mycology

Mycobiota and Citrinin in Black Olives 205
Moulds may also shorten the shelf life and produce mycotoxins. P. citrinum
and P. crustosum have been isolated from the surface of olives
during fermentation (Oral and Heperkan, 1999).
This study provides information on the mycoflora and citrinin production
in black table olives obtained from a survey conducted in
Turkey.
2. MATERIALS AND METHODS
2.1. Samples
Whole black table olives were surveyed. A total of 69 samples were
randomly collected from markets in the Marmara and Aegean
Regions, Turkey in 2000-2001. Each sample comprised approximately
2 kg and was maintained at 4˚C until analyzed.
2.2. Mycobiota
Dilution plate techniques were used to determine the mycobiota.
For the enumeration and isolation of moulds Malt Extract Agar with
chloramphenicol was used. Plates were incubated at 25˚C for 7 days.
Moulds were identified according to Pitt and Hocking (1997) and
Samson et al. (1996).
2.3. Citrinin Analysis
Citrinin standards were purchased from Sigma Chemical, St
Louis, MO. Pre-coated silica gel TLC plates (Merck) were used for
citrinin analyses. The citrinin standard was dissolved in chloroform
and the UV absorption was read at 322 nm. The concentration of
the solution was calculated using the formula for aflatoxins
(Trucksess, 2000). The extraction and separation method of
Comerio et al. (1998) was modified. Olive samples (25 g) were
blended with acetonitrile (180 ml), 4% KCl (20 ml) and 20% H 2 SO 4
(2 ml) for two min at high speed and filtered through Whatman No
4 filter paper. After filtration, hexane (50 ml) was added and the mixture
was shaken for 15 min in a separating funnel. The oil from the
olives was extracted into the hexane (upper) phase preventing it from
interfering with the assay. Citrinin partitioned into the lower phase.
The first 100 ml of the lower phase was transferred to a second