invert sugar

Inverted or invert^[1] sugar syrup is a sucrose-based syrup, produced by splitting each sucrose disaccharide molecule into its component monomers, glucose and fructose. The splitting is achieved through the action of invertase (a glycoside hydrolase enzyme), or an acid. Comparing solutions with the same dissolved weight of sugar, inverted syrups are sweeter than sucrose solutions.^[2]

The glucose present in inverted sugar syrup is substantially more hygroscopic than sucrose. This means that the syrup tends to keep products made with it moist for longer than when sucrose is used alone. It is likewise less prone to crystallisation and therefore valued especially by bakers, who refer to inverted sugar syrup as 'trimoline' or 'invert syrup'.

The term 'inverted' is derived from the method of measuring the concentration of sugar syrup using a polarimeter. Plane-polarized light, when passed through a sample of pure sucrose solution, is rotated to the right (optical rotation). As the solution is converted to a mixture of sucrose, fructose and glucose, the amount of rotation is reduced until (in a fully converted solution) the direction of rotation has changed (inverted) from right to left.

Chemical reaction of the inversion

C₁₂H₂₂O₁₁ (sucrose) + H₂O (water) → C₆H₁₂O₆ (glucose) + C₆H₁₂O₆ (fructose)

Hydrolysis is a chemical reaction during which one or more water molecules are split into hydrogen and hydroxide ions which may go on to participate in further reactions. It is the type of reaction that is used to break down certain polymers, especially those made by step-growth polymerization. Hydrolysis of sucrose yields glucose and fructose about 85%, the reaction temperature can be maintained at 50-60^oC.

Inverting sugar

Inverted sugar syrup can be easily made by adding roughly one gram of citric acid or ascorbic acid, per kilogram of sugar. Cream of tartar (one gram per kilogram) or fresh lemon juice (10 millilitres per kilogram) may also be used.

The mixture is boiled for 20 minutes, and will convert enough of the sucrose to effectively prevent crystallization, without giving a noticeably sour taste. Invert sugar syrup may also be produced without the use of acids or enzymes by thermal means alone: two parts granulated sucrose and one part water simmered for five to seven minutes will convert a modest portion to invert sugar.

All inverted sugar syrups are created from hydrolysing sucrose to glucose (dextrose) and fructose by heating a sucrose solution, then relying on time alone, with the catalytic properties of an acid or enzymes used to speed the reaction. Commercially prepared acid catalysed solutions are neutralised when the desired level of inversion is reached.

All constituent sugars (sucrose, glucose and fructose) support fermentation, so invert sugar solutions may be fermented as readily as sucrose solutions.

Shelf life

Invert sugar has a lower water activity than that of sucrose, so it provides more powerful preserving qualities (a longer shelf life) to products that use it.

The shelf life of partial inverts is approximately six months, depending on storage and climatic conditions. Crystallised invert sugar solutions may be restored to their liquid state by gently heating.

Examples

• Toffee
• Honey is a mixture (principally) of glucose and fructose, giving it similar properties to invert syrup. This gives it the ability to remain liquid for long periods of time.
• Jam, when made, produces invert sugar during extensive heating under the action of the acid in the fruit.
• Golden syrup is a syrup of approximately 56% invert syrup, 44% sucrose.
• Fondant filling for chocolates is unique in that the conversion enzyme is added, but not activated before the filling is enrobed with chocolate. The very viscous (and thus formable) filling then becomes less viscous with time, giving the creamy consistency desired.
• York Peppermint Patties contain inverted sugar.
• Junior Mints contain inverted sugar.
• Jones Soda sweeten their soda with inverted cane sugar.
• Jujubes contain inverted sugar.
• Sour Patch Kids contain inverted sugar.
• Caramello candy bars contain inverted sugar.
• Swedish Fish contain inverted sugar.
• Sour Patch contain inverted sugar.
• Sugar Babies contain inverted sugar.
• Cadbury eggs contain inverted sugar.
• Cigarettes use inverted sugar as a 'casing' to add flavour.^[3]

References

Notes

General references

• "Carbohydrates". Carbohydrates. http://biology.clc.uc.edu/courses/bio104/carbohydrates.htm. Retrieved 2006-05-01. 
• "Making simple syrup is an exercise in chemical reactions". A Word from Carol Kroskey. http://web.archive.org/web/20070714004114/http://www.bakers-exchange.com/articles/2000/april.html. Retrieved 2006-05-01. 
• "Frequently Asked Questions - Cookies". AIB International. http://techserv.aibonline.org/faqs/cookies.html. Retrieved 2006-05-01. 

External links

• Invertase
• Making sugar sweeter, an educational experiment in chemistry.