Review—A Portable Voltammetric Sensor for Determining Titratable Acidity in Foods and Beverages

Abstract

When 3,5-di-t-butyl-1,2-benzoquinone (DBBQ) is electrochemically reduced in an unbuffered solution, the addition of small amounts of acid to the solution is found to give rise to a new peak (termed the prepeak) at a more positive potential than the original reduction potential of DBBQ. In addition, the prepeak current heights of DBBQ are proportional to the added acid concentration. From these findings, we utilized the voltammetric behaviors of DBBQ to develop an analytical method for the determination of titratable acidity in food and beverage samples. Moreover, a portable voltammetric sensor (weight, 100 g; power, two AAA batteries), that implements this analytical method, was developed in order to provide an on-site analytical device. To show the applicability of this portable sensor, the determination of titratable acidity in fruit juice, wine, Japanese sake, and shochu was performed. The results obtained by the portable sensor showed a good correlation with those from official potentiometric titration using 0.1 mol/L NaOH. In conclusion, the present sensor required a reduced sample volume and measurement time for an assay compared with conventional potentiometric titration, consequently showing potential for quality assessment in a wide range of food and beverage analyses.

Potential Use of Cross-flow Microfiltration System in Separation of Functional Compound from Fermented Beetroot (Beta vulgaris L.) as Natural Oxidation Prevention

“…bacteria [26]. Acetic acid is analyzed according to the titration method [27]. The MF process indicated succeeded separation in both TMP 6 and 2 bar, as shown by more particles retained on the membrane surface (retentate) in comparison to permeate, as shown in Fig.…”

p<i>K</i>_a Determination of Strongly Acidic C-H Acids Bearing a (Perfluoroalkyl)sulfonyl Group in Acetonitrile by Means of Voltammetric Reduction of Quinone

“…12,20 In our voltammetric study of quinones in an unbuffered aqueous media, a small amount of acid was found to cause a new peak, called a prepeak, at a more positive potential than that of the original reduction peak of quinone. 21 The potential of the prepeak was shifted to a more positive side accompanied by an increase in the acidity of the compounds, i.e. the appearance of a prepeak potential is dependent on the acidity of compounds.…”

Electrochemical Determination of Titratable Acidity for the Discrimination of Schisandrae Chinensis Fructus and Schisandrae Sphenantherae Fructus

“…16 Moreover, using linear sweep voltammetry, we developed an electroanalytical method for determining total acid content, called titratable acidity, and the present voltammetry was applied to the development of a portable sensor for determining titratable acidity in beverages such as fruit juices and Japanese sake. 17,18 Our electrochemical method is based on the voltammetric reduction of quinone such as 3,5-di-tert-butyl-1,2-benzoquinone (DBBQ) in the presence of acid compounds, where quantitative acid analysis can be performed by the observation that the specific reduction peak current (called prepeak) caused by acid compounds is proportional to acid concentration in an unbuffered electrolyte solution. 19,20 Explanation regarding the observation of prepeak of quinone in the presence of acid has been provided in the supporting information.…”