摘要：The aim of this study is to evaluate the influence of ohmic treatment on ascorbic acid content of red raspberry juice using an HPLC-UV method. The ascorbic acid was eluted using a KH 2 PO 4 0.02 M corrected with o-phosphoric acid to pH 3.5 mobile phase, with a flow rate of 0.6 mL/min. The wavelength of the diode array detector (DAD) was set at 254 nm; the elution time was observed at 7.003 minutes. The ohmic treatment consisted in using 3 voltages (60 V, 100 V and 140 V, respectively) during an exposure time (1 min, 2 min, 3 min, 4 min and 5 min respectively). The ascorbic acid content ranged between 973 mg/L (initial concentration) to 941 mg/L (the lowest concentration reached at 140 V for 5 minutes). The evolution of ascorbic acid with voltage and exposure time has been modelled using a quadratic model, based on two parameters: voltage (60 V, 100 V and 140 V, respectively) and exposure time (1 min, 2 min, 3 min, 4 min and 5 min respectively), ob taining a model with a good regression coefficient (R 2 = 0.922%). The optimization applied to the experimental data it seems that the suitable conditions for the ohmic treatment are 98 V for 5 min as the ascorbic acid not to be damaged noticeable (972.13 g/L).
