Phenols content and composition before and after ultrasound treatment in marasca sour cherry juice

Cilj ovoga rada bio je utvrditi sastav i udjel fenolnih spojeva u soku višnje prije i nakon ultrazvučne obrade. Sokovi su obrađeni ultrazvukom visokog intenziteta pri 100% amplitudi, frekvenciji od 20 kHZ pri dvije temperature (20 i 50 °C), sa sondama različitih promjera (12,7 i 19,1 mm) u različitim vremenskim periodima (3 min, 6 min, 9 min). Rezultati HPLC analize pokazuju da je iz skupine derivata hidroksicimetne kiseline najzastupljenija kloregenska kiselina. Najzastupljeniji antocijani su cijanidin-3- glukozilrutinozid, cijanidin-3-glukozid, cijanidin-3-rutinozid i cijanidin-3-soforozid. Na udjel i sastav fenolnih spojeva utječu temperatura obrade > promjer sondi > vrijeme obrade. Antioksidacijska aktivnost je određena pomoću DPPH metode. Najveću antioksidacijsku aktivnost imao je uzorak obrađen sondom promjera 19,1 mm pri temeperaturi od 20 oC i vremenu od 3 minute. Uzorci obrađeni pri 50˚C su imali najvišu a vrijednost što je u skladu s udjelom antocijana koji su odgovorni za crvenu boju višanja.The aim of this work was to determine the content and composition of phenolic compounds before and after ultrasound treatment in Marasca sour cherry juice. Sour cherry juice was sonicated with processing variables of 100% amplitude at constant frequency of 20kHZ, sonication temperature (20 and 50 °C), ultrasound probe diameter (12,7 and 19,1 mm) and sonication times (3 min, 6 min, 9 min). Chlorogenic acid was the main hydroxycinnamic acid derivative. HPLC results showed that cyanidin-3-glucosylrutinoside, cyanidin-3-glucoside, cyanidin-3-rutinoside and cyanidin-3-sophoriside were the major anthocyanins. The greatest effect on the amount and composition of phenolic compounds had the sonication temperature > probe diameter > sonication time. DPPH assay was used to evaluate the antioxidative activity of treated juices. The highest antioxidant activity had a sample processed with probe of 19.1 mm diameter at temperature of 20oC and time of 3 minutes. With regard to amount of anthocyanins which are responsible for the red colour of sour cherries, samples treated at 50˚C had the highest value