BIOACCESSIBILITY OF BIOACTIVE COMPOUNDS IN OLIVE MATRICES DEBITTERED WITH THE ASSISTANCE OF ULTRASOUND (US) AND/OR PULSED-ELECTRIC FIELDS (PEF)

Debittering is an essential step in table olive production to remove phenolic compounds responsible for bitterness. The most conventional method bases on the immersion of olives in NaOH solutions for long processing times, also leading to high use of water and chemicals besides wastewater generation. In this context, Pulsed-Electric-Fields(PEF) and/or Ultrasound(US) appear to enhance the conventional debittering of green olives. Understanding how their mechanical effects influence the bioaccessibility of the remaining phenolic compounds in the olive is also a must. For this, Manzanilla green olives were subjected to four treatments in 1% NaOH solutions at 25 ºC for 360 min: Control(static), PEF(2 kV/cm;25 Hz;100 pulses), US (115 kPa), and PEF+US. The degradation of total phenolic compounds (TPC) was monitored using the spectrophotometric Folin–Ciocalteu method, while bioaccessibility was assessed through simulated in vitro gastrointestinal digestion using samples with comparable TPC contents. Both US and PEF accelerated the removal of TPC compared to the conventional treatment, leading to lower residual phenolic contents at the end of processing: 15.01, 7.95, and 5.70 mg GAE/g for PEF, US, and PEF+US, respectively, compared to 18.07 mg GAE/g for the control. These reductions were of ca.17, 56, and 68% compared to the control with the combined PEF+US treatment showing the best performance. This result was justified by the synergistic effect of electroporation promoted by PEF and the mass transfer enhancement caused by US. The bioaccessibility of TPC was 165.4%, 205.1%, 188.7%, and 224.4% for the control, PEF, US, and PEF+US treatments, respectively – all treatments showing higher availability of phenolic compounds for intestinal absorption during simulated in vitro digestion compared to control. All of these results confirm that, regardless the initial TPC concentration of the samples, bioaccessibility was affected by the structural modifications induced by the treatments. The nonconventional treatments made debittering faster also favoring the release and stability of bioactive compounds during digestion. Therefore, combining PEF and US resulted in not only more efficient and sustainable debittering processes, but also improved the nutritional and functional quality of table olives.