Winemaking: An Art and Science with Cutting-Edge Technology from Auxilab S.L.

Winemaking is a complex and delicate process that requires a series of controls to supervise the proper development and maturation of wines. At Auxilab S.L., we understand the importance of each stage in the winemaking process and offer a wide range of instruments designed to measure various key parameters throughout this process. Below, we will explore some of these instruments and their relevance in winemaking.

Refractometers

Refractometry is based on the change in speed that a light ray experiences when it passes through a surface that separates two different media, such as air and the liquid to be analyzed. This change in speed results in a variation in the direction of propagation, the relative measure of which is the refractive index (n).

Probable Alcohol Content in Must

Must, or grape juice, contains variable amounts of sugars, mainly glucose and fructose, which during the alcoholic fermentation process are transformed by yeast into ethanol and carbon dioxide, thus producing wine. The sugar content in the grape will therefore determine the alcohol content of the wine (each 17.5 g/l of sugar equals 1 degree of alcohol, which is 1% by volume). The higher the concentration of sugars in a must, the greater its density and the slower the light passes through it. Refractometers measure the refractive index of musts, translating it directly into a measure of the sugar concentration or the probable alcohol content.

To achieve good quality in wines, it is crucial to harvest the grapes at the optimal time, as the sugar composition varies during the ripening process. To determine the appropriate time for harvesting, it is necessary to periodically monitor the ripeness of the grape using refractometry. Additionally, it is advisable to compare the values of probable alcohol content with those obtained in the best harvests of previous years.

pH Meters

A pH meter is an instrument that measures the potential difference between a reference electrode and a pH reading electrode, both submerged in a liquid. pH is a measure of the concentration of hydrogen ions in solution.

Total Acidity

Grapes are an acidic fruit, and therefore, wine is also an acidic beverage. The most common acids in wine are tartaric, malic, and lactic acids, all of which play an important role in its organoleptic characteristics. Additionally, the determination of the total acidity of the must, along with the sugar content, allows for the calculation of the grape's ripeness index (sugar/total acidity), necessary to determine the appropriate time for harvesting.

The determination of the total acidity of a wine or must is practically performed based on an acid-base titration, using a strong base such as NaOH as the titrating reagent, and using a pH of 7.0 as the equivalence point.

Densimeters

Densimetry is based on Archimedes' principle for determining the volumetric mass of liquids based on the buoyancy presented by a body of constant weight in them. The instruments used are called densimeters and are introduced into the liquid whose density or mass is to be measured.

Volumetric Mass and Relative Density at 20°C

Volumetric mass is the weight of a given wine or must measured using a densimeter called an aerometer (graduated in volumetric units); and relative density is the ratio between the volumetric mass of the wine or must and that of water.

Acquired Volumetric Alcohol Content

This parameter indicates the alcohol content of the wine at a given moment and is expressed by the number of volumes of ethanol contained in 100 volumes of wine, both measured at 20°C. Alcohol content partially determines the density of a wine (the higher the proportion of alcohol, the lower the density); however, this also depends on the amount of other substances such as sugars, acids, or pigments. Therefore, before determining the acquired alcohol content, the wine must be distilled, leaving acids, sugars, and pigments as residues, with only alcohol and water passing into the distillate. The densimeter used in this case is an alcoholometer (a densimeter calibrated in alcohol degrees).

Dry Extract

This concept expresses the amount of dissolved substances that do not evaporate, such as acids, pigments, sugars, glycerin, or grape minerals. A lack of these substances makes wines seem weak and light on the palate, while an excess makes them seem ordinary. By knowing the total density of a wine and its alcohol content, the value of the dry extract can be determined.

pH

Determining the pH in wine is a complementary measure of total acidity because it allows us to measure the strength of the acids it contains. The stability of a wine, its acidic taste, or color are closely related to its pH.

García Tena Equipment

Volatile Acidity

One of the negative acids that can be found in wine is acetic acid, responsible for the unpleasant smell of "spoilage." Therefore, good winemaking should minimize the presence of this acid. This acid is also volatile, so its determination is called volatile acidity and is performed using García Tena kit. This method is based on the separation of volatile acids from the wine through fractional distillation and a subsequent acid-base titration of the second portion of the distillate.

VIS Spectrophotometers

Spectrophotometry is based on emitting a monochromatic light beam (opposite the color to be studied) over the sample to be analyzed and subsequently measuring the amount of light that passes through it. The more color the sample has, the lower the proportion of light that will pass through.

Total Polyphenols

Polyphenols consist of one or more phenol molecules and significantly contribute to the organoleptic characteristics of the wine (color, astringency, etc.). White wines contain fewer polyphenols than red wines because their production process does not include maceration of the must with the grape skins and solid parts, the main source of polyphenols. The total polyphenolic compounds in the wine oxidize with the Folin-Ciocalteu reagent, giving a blue coloration directly proportional to the polyphenol content and measurable at 750 nm.

Chromatic Characteristics

Chromatic characteristics are mainly defined by color intensity (amount of color) and hue (color quality). These routine control measures are performed at three wavelengths: 420 nm (yellow color of white wines), 520 nm (red color of red wines), and 620 nm (blue-violet color of red wines). Color intensity is determined by the sum of absorbances, measured in cuvettes of 10 mm (white wines) or 1 mm (red wines) optical path length, at the three wavelengths mentioned above. On the other hand, hue (important in rosé and red wines) is expressed by the ratio between the absorbance at 420 nm and the absorbance at 520 nm. If the wine is young, this ratio will be less than one, while if it is old, it will be greater than one.

Conclusion

Wine analysis is a fundamental branch of enology and is part of the winemaking process. Therefore, all enology laboratories must have instruments that allow them to analyze the parameters mentioned above to standardize wine production and ensure quality for the consumer. At Auxilab S.L., we are committed to excellence in winemaking, providing the best instruments and solutions for each phase of the process.

Are you interested in improving the quality of your winemaking? Contact us for more information about our specialized products and services.