EFFECT OF ULTRAFILTRATION AND CONCENTRATION PROCESSES ON THE PHYSICAL AND CHEMICAL COMPOSITION OF BLOOD ORANGE JUICE

The effects of ultrafiltration with different molecular weight cut-off (MWCO) membranes and concentration level on the L-ascorbic acid (AA) and total anthocyanin contents (TAC) of Moro blood orange juice were investigated. Ultrafiltration was carried out with three different MWCO polyethersulfone membranes, i.e., 30, 50 and 100 kDa. The clear blood orange juice was concentrated to three different soluble solid values (approximately 45, 55 and 65°Bx) and the reaction kinetics (k value) and half-life times (t1/2) were calculated using changes in the TAC and AA content, depending on the degree of concentration. According to the results, the most suitable membrane was found to be 100-kDa MWCO membrane; TAC, AA and total phenolic contents of the permeate were found to be 150.63 mg cyn-3-glu/L, 39.97 mg/100 mL and 1,135.17 mg gallic acid equivalent/L, respectively. TAC and AA content of the samples were decreased with the increasing concentration level. Practical Applications Ultrafiltration process is commonly used in clear fruit juice production, e.g., apple, grape and sour cherry juice, whereas it is a new process in blood orange juice production. In this study, different molecular weight cut-off (MWCO) membranes were used. These membranes have not been used in the ultrafiltration of blood orange juice. In addition, the effects of ultrafiltration and concentration on the L-ascorbic acid and total anthocyanin contents were investigated. The results of this study can gain useful contributions to the literature and fruit juice industry. Thus, optimum MWCO in the ultrafiltration can be used for the production of clear blood orange juice, including maximum functionality in the technology.