Electrochemical Determination of Antioxidant Capacity of Traditional Homemade Fruit Vinegars Produced with Double Spontaneous Fermentation

Abstract

In the current study, the antioxidant activity of traditional homemade fruit vinegars (HMV) was estimated by measuring the rate of homogeneous redox reaction with 2,2’-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid radical cation (ABTS•+) using cyclic voltammetry. The antioxidant capacity of six HMV produced using traditional methods and the physicochemical characterization were measured in different vinegar production steps throughout a double spontaneous fermentation process, i.e., without any addition of yeasts or acetic acid bacteria. Their antioxidant capacity was compared with seven fruit commercial vinegars (ComV). Furthermore, the antioxidant capacity was independently measured with the TEAC (Trolox equivalent antioxidant capacity) assay, aiming at correlating with the electrochemical experimental data. Obtained results from both methods, the electrochemical and TEAC assays, interestingly indicated that all HMV have at least 10 times higher antioxidant activity than ComV. Furthermore, the large range of values for antioxidant capacity in samples of commercial vinegars from apples attested the importance of the raw material quality and technological procedures. The positive correlation between total phenolic content and antioxidant capacity measured by the two type of assays indicated that rose hip homemade vinegar (HMV5) has the highest antioxidant capacity. In contrast, the lowest levels of phenolic compounds and antioxidant capacity were found in apple and persimmon homemade vinegars (HMV1 and HMV6, respectively) which indicated that the type of fruit is crucial towards the production of high-quality vinegars. In this way, the use of traditional processes for the production of fruit vinegars proved to be very promising in terms of producing differentiated vinegars and, concomitantly, reaching high levels of health-promoting antioxidant capacities.

Comparison of Chemical Properties between Traditional and Commercial Vinegar

“…Sung et al [30] mention a value of 12% for apple cider vinegar, and Beceanu and Anghel [36] mention a total titratable acidity of 5.39 g/100 mL acetic acid for apple vinegar. Chochevska et al [33] identified a total acid content of 17.4 g/L in homemade rosehip vinegar, a higher value compared with the one obtained in this study. It is found that there is a difference for this parameter, depending on the method of production and the raw material used.…”

“…Pashazadeh et al [31] mention a pH of rosehip vinegar of 3.70, a value close to that obtained in the present study for R. canina vinegar (3.42), while Kalemba-Dro żd ż et al [32] obtained a pH of 2.85 for the same species. Chochevska et al [33] confirms a similar pH value of 3.4 at homemade rosehip vinegar. Özdemir et al [25] identified a pH of hawthorn vinegar (C. tanacetifolia) of 3.63, similar to the value obtained for C. monogyna (3.67) and higher than C. pentagyna vinegar (3.25).…”

Bioactive Phenolic Compounds from Lingonberry (Vaccinium vitis-idaea L.): Extraction, Chemical Characterization, Fractionation and Cellular Antioxidant Activity

“…Cyclic and square wave voltammetry were used for the determination of the antioxidant capacity of the three lingonberry samples. All electrochemical measurements were performed using potentiostat/galvanostat Palm Sens Instrumentation (PalmSens 3, Houten, The Netherlands), controlled by PCT race version 3.0.6 software (Houten, The Netherlands) [30]. Briefly, the antioxidant capacity of the lingonberry XAD-7 extract and its fractions were determined by measuring of 1 mg/mL samples diluted in phosphate buffer using a glassy carbon working electrode (3 mm-φ).…”

Nanozymes with reductase-like activities: antioxidant properties and electrochemical behavior

“…The obtained EC 50 data of food products are in good correlation with the data described in literature. 50 …”