The occurrence of sterigmatocystin (STC) in paddy and processed rice samples produced in Italy was surveyed. After extraction and purification, STC was analysed using HPLC-MS/MS. STC was detected in all paddy rice samples (n = 49), in the range 0.29-15.85 μg·kg-1. As regards processed rice, a widespread contamination was found in brown and parboiled rice. All the brown rice samples were contaminated between 0.12 and 1.32 μg·kg-1; for parboiled rice, the incidence was 90.9% and the maximum level was 1.09 μg·kg-1. The contamination in white rice was significantly lower (p < 0.01). The STC distribution in different rice fractions, obtained by the de-hulling and polishing processes, was evaluated. After de-hulling, the STC percentage remaining in brown rice was in the range 21.2%-30.8%. The polishing process, from brown to white rice, caused another remarkable decrease of contamination; the STC remaining in white rice was 2.2%-8.3% of the amount found in paddy rice.
Keywords: paddy rice; processed rice; sterigmatocystin.