Ultrasound Treatment Influence on Antioxidant Properties of Blueberry Vinegar

Abstract

As one of the most widely used acidic condiments in the world, vinegars have demonstrated physiological functions. Due to their polyphenol content, blueberries (Vaccinium myrtillus L.) are a valuable source of natural flavours and antioxidants for vinegar production. Ultrasound treatment is recognized as an effective technique for improving the extraction yield of bioactive compounds from various plant materials. The aim of this research was to investigate the antioxidant properties of experimental vinegar variants obtained by an innovative manufacturing recipe using an alcoholic substrate containing blueberry juice for a rapid initiation of acetic fermentation. The substrate was subjected to ultrasound treatment at a frequency of 20 kHz and an amplitude (A) of 40%, 60%, and 80% for 3, 4, and 5 min. Under these conditions, total polyphenol content (TPC), total anthocyanins content (TAC), antioxidant activity based on ABTS and DPPH assays, as well as the sensory attributes in blueberry-vinegar formulations, were evaluated. The level of TPC and TAC and the antioxidant activity of the developed vinegar variants were optimized using response surface methodology (RSM). The obtained results revealed that ultrasound treatment resulted in increased TPC and TAC and improved antioxidant properties and sensory characteristics of blueberry vinegar. Our data revealed that the optimum values of the ultrasound treatment parameters were amplitude A: 78.50% and time t: 3.96 min. The following predicted values were determined for the main parameters: TPC: 628.01 mg GAE/L, TAC: 22.79 mg C3G/L, ABTS: 391.7 μmol/100 mL, and DPPH: 229.17 μmol/100 mL. The results of this study recommend the integration of both the use of an alcoholic substrate containing blueberry juice and the application of ultrasound treatment in vinegar production as innovative technological interventions with practical applicability for a rapid initiation of acetic fermentation and for improving the antioxidant properties of blueberry vinegar. In addition, RSM can be considered a valuable tool to optimize the ultrasound treatment’s effect on the antioxidant properties of the vinegar formulations.