GC×GC-TOF/MS Chromatographic Analysis, Antioxidant Capacity and Phenolic Content of Rosa Canina L. at Different Maturities

The relationship between food and health has become increasingly significant as consumers now demand healthy, tasty and natural foods which perform a useful function in the body. In Turkey, rose hip (Rosa canina L.) is in popular use in foodstuffs such as marmalade, pestil (a traditional Turkish sweet) and syrup or in traditional medicine, mainly as herbal tea. The composition, total antioxidant capacity (TAC) and total phenolic content (TPC) of volatiles of rose hip samples were compared in relation to their stage of maturity and collection location. Rose hip fruit and seed were analyzed using a direct thermal desorption technique coupled with comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GCxGC-TOF/MS). The major components found in the volatile fraction released on extraction were free fatty acids. The various stages of maturity of rose hips (green, light yellow, yellow, orange and red coloured) and the place of collection (Istanbul, Mersin, York) resulted in some changes in volatile compound speciation, in TAC and TPC levels. Various extraction methods were compared; methanol extraction, traditional hot water infusion and boiling in water. Boiling in water for ten minutes was the method which demonstrated the highest extraction efficiency. TAC and TPC were determined using different electron transfer−based assays; the Cerium (IV) ions reducing antioxidant capacity, Cupric Reducing Antioxidant Capacity and Folin-Ciocalteu methods. The highest TAC and TPC were found in the red coloured (fully ripe) rose hip fruit, suggesting that colour is a suitable indicator for optimal harvesting time.