Page 62 - FoodFocusThailand No.187 October 2021

STRONG QC & QA

Saccharose is subject to sugar inversion which changes the based on the fresh (not inverted) concentrate, partial or full inversion
composition of the beverage. Since many soft drinks are produced using of the product will cause under-dosing of the concentrate. If the recipe
beet or cane sugar as a sweetener, this chemical reaction has to be asks for inverted concentrate and the concentrate is still fresh,
closely monitored as the beverage composition gradually changes with overdosing of the concentrate will be the consequence.
progressing sugar inversion. Measuring the degree of sugar inversion Hence, as Figure 2 illustrates, the progress of sugar inversion must
plays a very important role for the production and quality control before, be known before and during soft drink production. To do so, two options
during, and after the production process and is relevant for producers exist: the traditional method of forced inversion
and bottlers of soft drinks with sugar. Remark:
What is sugar inversion? °Brix fresh: °Brix value before inversion
°Brix inverted: °Brix value after full inversion
The inversion of beet or cane sugar is the chemical conversion of
saccharose in solution into glucose and fructose. This process is How to track the progress of sugar inversion?
enhanced by acids and high temperatures. The angle of rotation of Method: 1 The traditional method: forced inversion
polarized light sent through the solution changes during the process of Forced inversion is a wet chemical method and requires the
inversion. following steps:
What happens during sugar inversion? • Degas the sample (if carbonated)
• Add acid
The disaccharide sucrose is split up into a 1:1 mixture of the • Place the sample in a preheated water bath (90 °C, 1 hour)
monosaccharide fructose and glucose, one molecule of sucrose • Allow the sample to cool
consuming one molecule of water. Consequently, the density of the • Measure the density of the sample
solution increases with progressing degree of inversion, and the volume • Use an appropriate conversion procedure (e.g., a polynomial
decreases as shows the process of sugar inversion. (Figure 1) function) to calculate the °Brix fresh or °Brix inverted from the measured
Why is the reaction called “Sugar inversion”? density.
Saccharose solutions rotate the plane of polarized light. The angle at If the degree of inversion is also required, the density is measured
which the plane of polarized light is rotated is specific for each sugar and twice: once after degassing before inversion and once after inversion.
depends on its concentration. An aqueous solution of saccharose is The total time consumption per sample is 60 to 120 minutes.
dextrorotatory. It causes a specific rotation of +66.5°. The specific rotation Method: 2 The instrumental method
of glucose is +52.5°, but fructose is strongly levorotatory (-92°). While The instrumental method combines density and sound velocity
inverting, the specific rotation gradually undergoes a change in direction measurements since these two properties are affected differently by
of polarized light from +66.5° to -19.7°. The inverted solution is levorotatory the ongoing inversion process. These properties are used as an input
and displays a specific rotation of -19.7°. for an algorithm which will provide information about concentration
sugar fresh, concentration sugar inverted, and the degree of inversion.
_
52.2° 92° = 19.7° The instrumental method requires the following steps:
_
2 • Degas the sample (if carbonated)
• Inject the sample into the measuring cells of the analytical
Why worry about Sugar inversion? instrument
Generally, soft drinks are produced by mixing concentrate with water at • Press <Start>
a defined ratio. Sucrose in the concentrate inverts during storage: the The total time consumption including degassing is 5 to 10 minutes.
concentrate’s density increases, its volume decreases. The weight of However, in soft drink process, it must be measured by this instrument
glucose and fructose together after full inversion is 360.32 g/mol whereas at the beginning of the process and final product for detect the sign of
the weight of saccharose before inversion is 342.30 g/mol. sugar inversion appeared which affected the quality of soft drink. Thus,
the instrument must be placed in the production line for promptly
360.32 g/mol measure.
= 1.053
342.30 g/mol
The °Brix fresh value will increase by about 5% after full inversion.
Thus, Fresh Brix = Inverted Brix * 0.95 More Information Service Info C010
For a correct mixing ratio of the syrup with water, the sugar content
of the syrup must be known. If the recipe for soft drink production is
Sugar Inversion and

The Quality of Soft Drink

Sugar inversion is the chemical conversion of saccharose into
glucose and fructose. This process is enhanced by acids and
high temperatures.

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