By knowing the refractive index of a substance, users can understand such properties as the sugar content of must or juice and many other products throughout wine and food industry.
Refractometry is the method of measuring a substances refractive index (one of their fundamental physical properties) in order to assess their composition or purity. Refractive Index is defined as the ratio of the speed of light in empty space to the speed of light in the substance. A result of this property is that light will “bend”, or change direction, when it travels through a substance of different refractive index. This is called refraction.
The critical angle can be used to easily calculate the refractive index according to the equation:
sin (θ critical) = n2 / n1
The refractive index of a substance is strongly influenced by temperature and the wavelength of light used to measure it, therefore, care must be taken to control or compensate for temperature differences and wavelength. Digital refractometers are an ideal solution for those looking to measure the composition of their products. Characterizing a substance is quick and easy with any one of our refractometers, and analysis only requires a sample size as small as 2 metric drops.
Sugar in food and wine
Sugar is an essential component in the production of wine. During alcoholic fermentation, yeast consume sugars found in the grape juice, or must, and converts it to ethyl alcohol and carbon dioxide. In the case of certain styles of wine such as semi-sweet or dessert wines, some sugar is allowed to remain post-fermentation. This residual sugar can serve to provide a sweeter character to the final blend or play a role in microbial stability.
The primary fermentable sugars found in grapes are glucose and fructose. These two simple sugars are also known as reducing sugars because they contain functional groups capable of being oxidized under certain conditions. After reaction with excess alkaline cupric tartrate (Fehling reagents), the content of reducing sugars can be determined calorimetrically. The Fehling method is not an exact determination but an index of the reducing sugar concentration, because the reaction depends upon the amount and type of reducing sugars present. When the reducing sugar content is known at the beginning of fermentation, the potential alcohol degree can be estimated by multiplying the sugar concentration (in g/L) by 0.06.
Hanna offers five wine refractometers to meet the various requirements throughout the wine industry. The HI96811, HI96812, HI96813, HI96814 and HI96816 Digital Wine Refractometers are rugged, lightweight and waterproof for measurements in the lab or field.
Hanna also offers five sugar refractometers to meet the requirements of the food industry. The HI96800 Refractive Index/Brix, HI96801 % Brix (sucrose), HI96802 Fructose, HI96803 Glucose and HI96804 Invert Sugar digital refractometers are rugged, portable and water-resistant for measurements in the lab or field.
These optical instruments employ the measurement of the refractive index to determine parameters pertinent to sugar concentration analysis.
5 Digital Refractometers for Sugar Analysis to Choose from
- Measures the refractive index in aqueous solutions. Readings can also be displayed with sucrose temperature compensation (nD₂₀) or % Brix.
- 3300 to 1.5080 Refractive Index range with ±0.0005 accuracy
- 0 to 85% Brix range with ±0.2% accuracy
- Measures the refractive index to determine the % Brix of sugar in aqueous solutions. The refractive index of the sample is converted to % Brix concentration units.
- Temperature Compensation algorithms based on sucrose solution
- 0 to 85% Brix range with an accuracy of ± 0.2%
- Measures the refractive index to determine the % fructose in aqueous solutions. The refractive index of the sample is converted to % mass (% w/w) concentration units.
- Temperature Compensation algorithms based on fructose solution
- 0 to 85% fructose by weight range with an accuracy of ± 0.2%
- Measures the refractive index to determine the % glucose in aqueous solutions. The refractive index of the sample is converted to % mass (% w/w) concentration units.
- Temperature Compensation algorithms based on glucose solution
- 0 to 85% glucose by weight range with an accuracy of ± 0.2%
- Measures the refractive index to determine the % invert sugar in aqueous solutions.The refractive index of the sample is converted to % mass (% w/w) concentration units.
- Temperature Compensation algorithms based on invert sugar solution
- 0 to 85% invert sugar by weight range with an accuracy of ± 0.2%