PHENOLIC COMPOUNDS IN AÇAÍ JUICE ARE INCREASED AFTER HIGH PRESSURE PROCESSING

Due to health claims attributed to açaí, there is an increasing demand for açaí juice worldwide. Phenolic compounds have mostly been related to these health-promoting effects, but their bioactivities could be impaired by high temperatures utilized in thermal pasteurization (TP), which is currently the main preservation technique applied in this product. In this context, high pressure processing (HPP) is a non-thermal preservation technology that may provide food products with microbiological safety equivalent to that of TP, with minimal effects on thermal-label compounds. Thus, this study investigated the effect of HPP on phenolic compounds in açaí juice. The processing settings for HPP were 400 MPa, 450 MPa, 500 MPa, or 600 MPa for 5 minutes at 20ºC. For TP, samples were pasteurized for 1 min at 85 ºC. Control corresponded to samples that did not undergo any treatment. Anthocyanins (cyanidin 3-glucoside, cyanidin 3-rutinoside) and non-anthocyanin phenolic compounds (NA) (3,4-dihydroxybenzoic, 4-hydroxybenzoic, vanillic, caffeic, syringic, p-coumaric, ferulic acids, isoorientin, orientin) were analyzed by reverse phase high performance liquid chromatography coupled to a diode array detector. Both HPP and TP caused a decrease in the content of cyanidin 3-glucoside and cyanidin 3-rutinoside compared to the control, however, TP resulted in 40% decrease whereas HPP averaged 20%. This could be due to the thermal degradation of these compounds (TP) or to residual enzymatic activity in HPP samples. Globally, NA has not been adversely affected by TP compared to control. On the other hand, samples processed at 500 MPa had a higher amount of all the studied NA in comparison to control and TP. This could be attributed to the higher extractability of these compounds promoted by high pressure. In conclusion, açaí juice processed at 500 MPa for 5 min at 20ºC was the best processing condition, providing açaí juice with increased bioactive compounds contents.