Characterizing traditional rice varieties grown in temperate regions of Italy: free and bound phenolic and lipid compounds and in vitro antioxidant properties

Objectives: A comparative study regarding the fatty acid profiles and antioxidant properties of the two most common varieties of rice (Carnaroli and Karnak) cultivated in Sybaris (Southern Italy) was conducted. Carnaroli variety from Pavia district (Northern Italy) was also investigated. Methods: Free and bound lipids were separately extracted. Fatty acid composition was determined by high resolution gas chromatography (HRGC). Free and bound phenolic acids were determined using high performance liquid chromatography (HPLC). The antioxidant properties were assessed using 2,2’-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. Results: The total lipid content was found to be higher in both Sybaris species with respect to the Pavia variety. The lipid distribution was also significantly different. In particular, the amount of bound lipids (14.2–16.3 mg g−1) was higher than the free lipids (7.2–7.5 mg g−1), and unsaturated fatty acids (USFA) were significantly higher in the free-FA fraction than in bound-FA in both Sybaris varieties. By contrast, Carnaroli variety from Northern Italy displayed a higher content of free (5.3 mg g−1) than bound lipids (2.5 mg g−1) and a higher content of USFA in the bound-FA. The antioxidant activity of Pavia rice extract was higher than that of both Sybaris varieties. Conclusions: The two Sybaris varieties are richer in lipids than the Pavia rice, while exhibiting the same qualitative fatty acid profile with some differences in the content of individual fatty acids. The distribution of lipids (free or bound) was found to be significantly different in the Carnaroli varieties, highlighting the effects of different climatic and pedological areas.