Inverted sugar syrup

Inverted sugar syrup, also calledinvert syrup,invert sugar,simple syrup,sugar syrup,sugar water,bar syrup, syrupUSP, orsucrose inversion, is asyrupmixtureof themonosaccharidesglucoseandfructose, that is made byhydrolyticsaccharificationof thedisaccharidesucrose. This mixture'soptical rotationis opposite to that of the original sugar, which is why it is called aninvertsugar.
It is 1.3xsweeterthantable sugar,and foods that contain invert sugar retain moisture better and crystallize less easily than those that use table sugar instead.Bakers, who call itinvert syrup, may use it more than othersweeteners.
Commercially preparedenzyme-catalyzed solutions are inverted at 60 °C (140 °F). The optimum pH for inversion is 5.0.Invertaseis added at a rate of about 0.15% of the syrup's weight, and inversion time will be about 8 hours. When completed the syrup temperature is raised to inactivate the invertase, but the syrup is concentrated in a vacuum evaporator to preserve color.
Though inverted sugar syrup can be made by heating table sugar in water alone, thereactioncan be sped up by addinglemon juice,cream of tartar, or othercatalysts, often without changing the flavor noticeably.Common sugar can be inverted quickly by mixing sugar andcitric acidorcream of tartarat a ratio of about 1000:1 by weight and adding water. Iflemon juice, which is about five percent citric acid by weight, is used instead then the ratio becomes 50:1. Such a mixture, heated to 114 °C (237 °F)and added to another food, prevents crystallization without tasting sour.
Commercially preparedhydrochloric-acidcatalyzed solutions may be inverted at the relatively low temperature of 50 °C (122 °F). The optimum pH for acid-catalyzed inversion is 2.15. As the inversion temperature is increased, the inversion time decreases.They are then given a pH neutralization when the desired level of inversion is reached.
In confectionery andcandy making,cream of tartaris commonly used as the acidulant, with typical amounts in the range of 0.15–0.25% of the sugar's weight.The use of cream of tartar imparts a honey-like flavor to the syrup.After the inversion is completed, it may be neutralized withbaking sodausing a weight of 45% of the cream of tartar's weight.
All constituent sugars (sucrose, glucose, and fructose) supportfermentation, so invert sugar solutions of any composition can be fermented.
Syrup is used to feed microbiological life, which requires oxygen found in the water. For example,kombuchais produced by fermenting inverted sugar syrup withteausing asymbioticculture of bacteria and yeast(SCOBY), andyeast in winemakingis used forethanol fermentation. Cold water can hold more dissolved oxygen than warm water, but granulated sugar does not dissolve easily in cold water.
Water in a container with wide bottomsurface areaallows for faster dissolving of the sucrose, which only has to be mixed a few times periodically to form a homogeneous solution. Also, amixerorblendermay be used to rotate the sugar, in turns, if necessary.
Inverted sugar syrup is the basis insweetened beverages.
Table sugar (sucrose) is converted to invert sugar byhydrolysis. Heating a mixture orsolutionof table sugar and water breaks thechemical bondthat links together the two simple-sugar components.
Thebalanced chemical equationfor the hydrolysis of sucrose into glucose and fructose is:
Once a sucrose solution has had some of its sucrose turned into glucose and fructose the solution is no longer said to be pure. The gradual decrease in purity of a sucrose solution as it is hydrolyzed affects achemical propertyof the solution calledoptical rotationthat can be used to figure out how much of the sucrose has been hydrolyzed and therefore whether the solution has been inverted or not.
Plane polarized lightcan be shone through a sucrose solution as it is heated up for hydrolysis. Such light has an 'angle' that can be measured using a tool called apolarimeter. When such light is shone through a solution of pure sucrose it comes out the other side with a different angle than when it entered, which is proportional to both the concentration of the sugar and the length of the path of light through the solution; its angle is therefore said to be 'rotated' and how many degrees the angle has changed (the degree of its rotation or its 'optical rotation') is given a letter name,α{\displaystyle \alpha }(alpha). When the rotation between the angle the light has when it enters and when it exits is in the clockwise direction, the light is said to be 'rotated right' andα{\displaystyle \alpha }is given to have apositiveangle such as 64°. When the rotation between the angle the light has when it enters and when it exits is in the counterclockwise direction, the light is said to be 'rotated left' andα{\displaystyle \alpha }is given anegativeangle such as −39°.
When plane polarized light enters and exits a solution ofpuresucrose its angle is rotated 66.5° (clockwise or to the right). As the sucrose is heated up and hydrolyzed the amount of glucose and fructose in the mixture increases and the optical rotation decreases. Afterα{\displaystyle \alpha }passes zero and becomes a negative optical rotation, meaning that the rotation between the angle the light has when it enters and when it exits is in the counter clockwise direction, it is said that the optical rotation has 'inverted' its direction. This leads to the definition of an 'inversion point' as the per cent amount sucrose that has to be hydrolyzed beforeα{\displaystyle \alpha }equals zero. Any solution which has passed the inversion point (and therefore has a negative value ofα{\displaystyle \alpha }) is said to be 'inverted'.
As theshapes of the molecules('chemical structures') of sucrose, glucose, and fructose are allasymmetricalthe three sugars come in several different forms, calledstereoisomers. The existence of these forms is what gives rise to these chemicals' optical properties. When plane polarized light passes through a pure solution of one of theseformsof one of the sugars it is thought to hit and 'glance off' certain asymmetricalchemical bondswithin the molecule of that form of that sugar. Because those particular bonds (which incyclic sugarslike sucrose, glucose, and fructose include ananomeric bond) are different in each form of the sugar, each form rotates the light to a different degree.
When any one form of a sugar is purified and put in water, it rapidly takes other forms of the same sugar. This means that a solution of a pure sugar normally has all of its stereoisomers present in the solution in different amounts which usually do not change much. This has an'averaging' effecton all of the optical rotation angles (α{\displaystyle \alpha }values) of the different forms of the sugar and leads to the pure sugar solution having its own 'total' optical rotation, which is called its 'specific rotation' or 'observed specific rotation' and which is written as[α]{\displaystyle [\alpha ]}.
In the circumstance of 20 °C, the specific optical rotation of sucrose is known to be 66.6°, glucose is 52.2°, and fructose is −92.4°.
Water molecules do not havechirality, therefore they do not have any effect on the measurement of optical rotation. When plane polarized light enters a body of pure water its angle is no different from when it exits. Thus, for water,[α]{\displaystyle [\alpha ]}= 0°. Chemicals that, like water, have specific rotations that equal zero degrees are called 'optically inactive' chemicals and like water, they do not need to be considered when calculating optical rotation, outside of the concentration and path length.
The overall optical rotation of a mixture of chemicals can be calculated if the proportion of the amount of each chemical in the solution is known. If there areN{\displaystyle N}-many optically active different chemicals ('chemical species') in a solution and themolar concentration(the number ofmolesof each chemical perliterof liquid solution) of each chemical in the solution is known and written asCi{\displaystyle C_{i}}(wherei{\displaystyle i}is a number used to identify the chemical species); and if each species has a specific rotation (the optical rotation of that chemical were it made as a pure solution) written as[α]i{\displaystyle [\alpha ]_{i}}, then the mixture has the overall optical rotationα=∑i=1NCi[α]i∑i=1NCi=∑i=1N(Ci∑i=1NCi)[α]i=∑i=1Nχi[α]i{\displaystyle \displaystyle \alpha ={\frac {\sum _{i=1}^{N}C_{i}[\alpha ]_{i}}{\sum _{i=1}^{N}C_{i}}}=\sum _{i=1}^{N}\left({\frac {C_{i}}{\sum _{i=1}^{N}C_{i}}}\right)[\alpha ]_{i}=\sum _{i=1}^{N}\chi _{i}[\alpha ]_{i}}Whereχi{\displaystyle \chi _{i}}is themole fractionof theith{\displaystyle i\mathrm {^{th}} }species.
Assuming no extra chemical products are formed by accident (that is, there are noside reactions) a completely hydrolyzed sucrose solution no longer has any sucrose and is a half-and-half mixture of glucose and fructose. This solution has the optical rotationα=12[α]glucose+12[α]fructose=12(52.7∘−92.0∘)=−19.7∘{\displaystyle \displaystyle \alpha ={\frac {1}{2}}[\alpha ]_{\text{glucose}}+{\frac {1}{2}}[\alpha ]_{\text{fructose}}={\frac {1}{2}}(52.7^{\circ }-92.0^{\circ })=-19.7^{\circ }}
If a sucrose solution has been partly hydrolyzed, then it contains sucrose, glucose and fructose and its optical rotation angle depends on the relative amounts of each for the solution;α=χs[α]s+χg[α]g+χf[α]f{\displaystyle \displaystyle \alpha =\chi _{s}[\alpha ]_{s}+\chi _{g}[\alpha ]_{g}+\chi _{f}[\alpha ]_{f}}Wheres{\displaystyle s},g{\displaystyle g}, andf{\displaystyle f}stand for sucrose, glucose, and fructose.
The particular values ofχ{\displaystyle \chi }do not need to be known to make use of this equation as the inversion point (per cent amount of sucrose that must be hydrolyzed before the solution is inverted) can be calculated from the specific rotation angles of the pure sugars. The reactionstoichiometry(the fact that hydrolyzing one sucrose molecule makes one glucose molecule and one fructose molecule) shows that when a solution begins withx0{\displaystyle x_{0}}molesof sucrose and no glucose nor fructose andx{\displaystyle x}molesof sucrose are then hydrolyzed the resulting solution hasx0−x{\displaystyle x_{0}-x}moles of sucrose,x{\displaystyle x}moles of glucose andx{\displaystyle x}moles of fructose. The total number of moles of sugars in the solution is thereforex+x0{\displaystyle x+x_{0}}and thereaction progress(per cent completion of the hydrolysis reaction) equalsxx0×100%{\displaystyle {\frac {x}{x_{0}}}\times 100\%}. It can be shown that the solution's optical rotation angle is afunctionof (explicitly depends on) this per cent reaction progress. When the quantityxx0{\displaystyle {\frac {x}{x_{0}}}}is written asr{\displaystyle r}and the reaction isr×100%{\displaystyle r\times 100\%}done, the optical rotation angle isαr=(x0−x)[α]s+x[α]g+x[α]fx0+x=11+r([α]s+([α]g+[α]f−[α]s)r){\displaystyle \displaystyle \alpha _{r}={\frac {(x_{0}-x)[\alpha ]_{s}+x[\alpha ]_{g}+x[\alpha ]_{f}}{x_{0}+x}}={\frac {1}{1+r}}\left([\alpha ]_{s}+([\alpha ]_{g}+[\alpha ]_{f}-[\alpha ]_{s})r\right)}
By definition,α{\displaystyle \alpha }equals zero degrees at the 'inversion point'; to find the inversion point, therefore, alpha is set equal to zero and the equation is manipulated to findr{\displaystyle r}. This givesrinversion=[α]s[α]s−[α]g−[α]f=0.629{\displaystyle \displaystyle r_{\text{inversion}}={\frac {[\alpha ]_{s}}{[\alpha ]_{s}-[\alpha ]_{g}-[\alpha ]_{f}}}=0.629}Thus it is found that a sucrose solution is inverted once at least62.9%{\displaystyle 62.9\%}of the sucrose has been hydrolyzed into glucose and fructose.
Holding a sucrose solution at temperatures of 50–60 °C (122–140 °F) hydrolyzes no more than about 85% of its sucrose. Findingα{\displaystyle \alpha }when r = 0.85 shows that the optical rotation of the solution after hydrolysis is done is −12.7° this reaction is said to invert the sugar because its final optical rotation is less than zero. A polarimeter can be used to figure out when the inversion is done by detecting whether the optical rotation of the solution at an earlier time in its hydrolysis reaction equals −12.7°.