The excessive intake of fluoride causes several diseases as dental and skeletal fluorosis. The fluoride intake is from the diet, vinegar is liquid widely used as condiment and food preservative. To determine the concentration of fluorides in different types of vinegars and to compare the content with the concentrations found in wines. A total of 31 samples of vinegars were analyzed by potentiometric determination using a fluoride selective ion electrode. The fluoride concentrations found in all samples were less than 1mg/L, which is the recommended limit for fluoride in wines, with an average concentration of 0.39±0.17mg/L. The fluoride content is not very high. The consumption of vinegar is low because it is a condiment; however, it is widely used as a preservative so it would of interest to study the transferability of fluoride from vinegar to the food preserved with it.
Vinegar, whose name comes from the Latin acrid vinum meaning sour wine, is a sour-tasting liquid widely used as a condiment and food preservative. The chemical composition of vinegar depends on the type in question, for example, the content of acetic acid (ethanoic acid) in water may range from 5-20%, and may contain small amounts of tartaric acid (2,3-Dihydroxybutanedioic acid) and citric acid (2-hydroxypropane-1,2,3-tricarboxylic acid) .
There are different types of vinegars, with vinegars made from wine being the most consumed type in Europe. Vinegar was traditionally obtained from wines that went sour and was produced by two fermentation processes. Alcoholic fermentation (conversion of sugar into alcohol) takes place in the first step and this fermentation is carried out by bacteria such as Saccharomyces cerevisae , and the second step consists of the acetic fermentation of the alcohol performed by the bacteria Mycoderma aceti [1,3]. At present, the process of obtaining vinegar is by adding a culture of bacteria to the wine from which you want to obtain the vinegar; this process takes place over a period of 24 - 36 hours. The reactions to obtain the vinegar are as follows:
1. C6H12O6 → 2CH3CH2OH + 2CO2
2. CH3CH2OH + O2 → CH3COOH + H2O
However, there is another method of obtaining vinegar, in which the bacteria are not added to the wine, but are kept in direct contact with the surface of the wine. This process is slower . This process produces higher quality vinegars with better organoleptic characteristics.
As for apple cider vinegar (cider), this type of vinegar is obtained following the same process as wine vinegar [4,5]. Apple cider vinegar may also have beneficial effects on diseases such as arthritis, obesity and asthma , which may increase the consumption of this vinegar.
Vinegar may contain fluorides because it is produced from wine. Fluoride in wines comes mainly from irrigated water, volcanic soils, as a result of its storage in cement tanks or the use of antiseptics and anti ferments containing fluoride. In the same way, apple cider vinegar contains the fluoride in the apples originating in the soil and irrigated water.
Fluoride is necessary as it plays an important role in the mineralization of teeth and bones, activation of enzymes, prevention of caries, etc. However, at high concentrations,
fluoride is toxic and produces numerous detrimental effects
on human health such as dental and bone fluorosis [7,8,9].
Numerous institutions have set recommended values for
fluoride intake, e.g., the European Food Safety Authority (EFSA)
set a Recommended Daily Intake (RDI) of 4 and 3mg/day for
adult men and women, respectively . On the other hand, the
Institute of Medicine, Food and Nutrition Board has established
a maximum allowable daily intake (ADI) of 10mg/day for adults
Although vinegar is not consumed in large quantities, it is
widely used as a food preservative, which is why; consequently,
the concentration of fluoride in these foods can increase. For this
reason, a total of 31 samples of vinegars of different types and
origins have been analyzed in order to know the fluoride content
and compare this with the fluoride concentrations obtained in
The following solutions were prepared for the fluoride
1. 10-1 M fluoride solution: prepared by dissolving 2.210g
of NaF, previously dried in an oven at 120 °C for 2 hours,
flushing in a 1L plastic volumetric flask in distilled water
2. Buffer solution of TISAB-CDTA (Total Ionic Strength
acid): 58g of NaCl p.a. (Sigma Aldrich, Germany) and 57ml
of glacial acetic acid p.a. (Honeybell Fluka, Germany) were
added to 500ml of distilled water in a 1-liter beaker add.
The contents were stirred until complete dissolution and
4g of CDTA p.a. (Sigma Aldrich, Germany) (1,2-diaminocyclohexanetetraacetic
acid) were then added. Stirring was
continued until the solids completely dissolved and the
solution was finally adjusted to pH 5.5-5.5 with 50% NaOH
Potentiometer with fluoride selective ion electrode (brand
CRISON 96 55) and reference electrode Ag/AgCl (CRISON 52-
41) and a pH meter (CRISON GLP 22) with pH electrode of high
alkalinity (CRISON 5204) and magnetic stirrer (SELECTA) with
stirring magnet (Figure 1). The measures were recorded using
Figure 2 shows the response given in the fluoride ion
determination at pH = 5.0 by using the fluoride ion selective
electrode. The theoretical Nerstian slope for monovalent cations
was followed in order to assure the accuracy of the method. The
correlation coefficient was 0.999.
The method is based on the measurement of the potential
before and after addition of a known amount of fluoride to a
mixture of sample/and conditioning solution. The following
formula has been used for the fluoride concentration:
Before measuring the sample potential, the apparatus was
calibrated using two commercial solutions (CRISON) of pH 7 and pH 4, and a pH meter. It is necessary to use a conditioning solution
or buffer to prevent interferences in the potential measurement.
The buffer solution used in this study was the solution of TISABCDTA,
which was chosen according to the studies conducted by
García et al.  where this solution was reported to be the one
with the best response.
Because of the acidity of the vinegar, it is necessary to
adjust the pH before the potential measurements. In order to
do this, 50ml of vinegar and 10ml of 4M NaOH are placed in a
polyethylene cup to adjust the pH. Afterwards, 50ml of pHadjusted
vinegar was taken and 5ml of TISAB-CDTA buffer
solution were added. The fluoride electrode and the reference
electrode were then introduced into the solution and the
potential difference was measured, with constant stirring
throughout. Once the measurement is stabilized, an aliquot of
F-10-3M standard solution was added, and the potential was
(Table 1) shows the concentrations of fluoride (mg/l)
obtained for each sample analyzed, as well as the data
concerning trademark, acidity, type of vinegar, origin and
packaging. The lowest concentration of fluoride was found in
a white wine vinegar from Logroño, whose concentration was
0.12 mg/l. Whereas, the highest concentration was in a red wine
sherry vinegar from Seville, with a concentration of 0.97mg/l.
The mean concentration of all vinegars, without distinguishing
their origin, was 0.39 ± 0.17mg/l.
(Figure 3) shows the average concentrations of fluoride
(mg/l) depending on the origin of the vinegar. The vinegars from
Seville and Córdoba had the highest average concentrations
of fluoride. The vinegars from Logroño and Catalonia had the
lowest concentrations of fluoride.
As for the type of vinegar, the same mean concentration of
fluoride was found for each type, and this figure was 0.39mg/l.
(Table 2) shows the fluoride concentrations (mg/l) obtained
by the other consulted authors for vinegar samples. Lapa et al.
 reported higher fluoride concentrations than those found in
the present study. Whereas the mean concentration obtained by
García et al.  is greater than those obtained here.
(Table 3) shows the mean concentrations of fluoride
(mg/l) reported by other authors in wine samples. The mean
concentration obtained here for wine and cider vinegar (0.39
mg/l) was higher than the mean concentrations reported in wine
samples by Bernal et al. , De Baenst et al. , Deschreider et
al. , Hardisson , Hidalgo et al. , Martínez Rincón et al.
, Pérez-Olmos et al. , Pérez-Olmos et al. , Rodríguez
Gómez et al.  and Paz et al. .
The concentration obtained in wine samples by Martín et al.
, Moreno et al.  and USDA , was greater than that
obtained in the present study for both types of vinegars.
Although vinegar is not a product that is consumed in large
quantities, it is widely used as a food preservative. Therefore,
it would be of interest to study the transfer of fluoride from
vinegar used as a preserving liquid for food, as this could be a
source of fluoride.
In addition, apple cider vinegar is consumed because of its
possible beneficial properties. The Recommended Daily Intake
(RDI) of apple cider vinegar is 30ml, and therefore the fluoride
intake from this type of vinegar would be 0.29 and 0.39% of
the Recommended Daily Intake (RDI) for men and women,
The fluoride concentrations found in the vinegar samples
analyzed are not very high, and therefore, taking into account
the low consumption of vinegar, fluoride in vinegar does not
pose any health risk. However, in cases where the vinegar is used
as a preservative of other foods, it would be interesting to study
the fluoride contribution in food preserved in vinegar.