Impact of cryomilling on phenolic compounds of rapeseed cake

Cilj ovog rada bio je odrediti utjecaj vremena i tipa mljevenja (uz/bez kriohlađenja) na sastav i koncentraciju fenolnih spojeva u pogači uljane repice. Nakon proizvodnje ulja, dobivena pogača usitnjena je na kriomlinu bez i s hlađenjem pomoću tekućeg dušika kroz 2, 4, 8 i 12 minuta. U samljevenim pogačama određeni su slobodni i vezani polifenolni spojevi te tanini pomoću kromatografskih i spektrofotometrijskih metoda, nakon čega im je određena antioksidacijska aktivnost. Rezultati su pokazali da način mljevenja ima značajan utjecaj na koncentraciju polifenolnih spojeva. Mljevenjem uz hlađenje koncentracija slobodnih polifenola se smanjila, a koncentracija vezanih povećala. Nasuprot tome, koncentracija tanina nije ovisila o načinu mljevenja već o duljini mljevenja. HPLC metodom detektiran je sinapin kao dominantni polifenolni spoj pogače uljane repice u udjelu većem od 70 %. Rezultati antioksidacijske aktivnosti znatno su oscilirali te nije utvrđen značajan utjecaj tretmana ni duljine mljevenja na koncentraciju polifenola.The aim of this study was to determine the impact of time and milling type (with/without cryocooling) on composition and concentration of rapeseed cake phenolics. After the oil production, expeller extracted rapeseed cake was grounded on cryomill with or without liquid nitrogen cooling for 2, 4, 8 and 12 minutes. Free and bound phenolic compounds, as well as tannins, were determined in milled cake samples using chromatographic and spectrophotometric methods. In addition, antioxidant activity of produced cakes was also investigated. Results showed significant impact of milling type on phenolic concentration. Cryocooling decreased concentration of free phenolic compounds, increasing the bound phenolics at the same time. However, milling type had no significant impact on the tannin concentration unlike milling time that increased tannin concentration during longer process. Sinapin, the dominant phenol derivate in rapeseed cake, was detected using HPLC contributing to more than 70 % of phenolic content. Results of antioxidant activities oscillated significantly, having no statistical impact of the time and type of milling on the polyphenols