Definition: Liquid sugar is generally term for saturated aqueous solutions of sugar (sucrose), invent sugar, glucose, fructose, etc Slightly or in blended of different proportions.
There two basic types of liquid sugar derived from the sucrose.
- Liquid Sucrose (It is almost all sucrose generally at 67% solids)
- Liquid Invert (It has 76% solids out of that 55% invert sugar remaining percent having sucrose.)
They are two basic types of liquid sucrose.
One is made from melted granulated sugar, usually filtered with a small quantity of powered carbon to improving the colour and clarity. The other type is made from high grade refinery process liquors that have been carbon treated without prior crystallization. Some refiners purify these high grade liquors by a mixed bed ion exchange process to further reduce the soluble ash and colour content.
It has lower in reducing sugars and low ash and high quality liquid sugars. Its has not more than 0.4% reducing sugars. This is storage at slightly above 8.0pH has been found to minimized the bacteriological problems. It is essential that all 67 brix syrups be produced, stored and distributed with careful attention to the best sanitary practices.
The most popular liquid invert is that of 52 to 58% reducing sugars at 76 Brix. It is produced from two different methods One is produced by acid inversion of melted granulated sugar is usually filtered with a small quantity of carbon to improving the color and clarity, The second type is produced from high grade liquor treated with carbon char. Which further processed by the a two bed ( Cation — Anion ) ion exchange process. The strong acid cation resins, operated at proper temperature and contact time, produced the required level of inversion.
Inverting sucrose can be accomplished by
- Batch acid inversion,
- Continuous acid/ heat inversion,
- Ion exchange and enzyme.
- Continuous methods feature a low-acid and or high temperature with short retention time.
Batch Inversion Process:
Batch methods can invert from the 50 to 92% level in reasonable time periods. Control is accomplished by polarimetric readings, To stop the inversion, a base is added to neutralize the acid sugar solution. Different invert percentages can be produced by blending with sucrose solutions.
Optimum conditions for producing liquid invert , by acid inversion of 68 Brix sucrose solution are 2.5 to 3.0 ml/lt solution at 680C for 15 min. The acid employed are always the mineral acids allowed by food regulations (EUI 995), such as sulfuric and hydrochloric acid. However organic acids such as citric; malic or acetic acids, can also be used. The inverted sugar solution is neutralized with sodium or potassium hydroxide.
Continuous acid/ heat inversion:
In this process continuously by pumping a sugar solution, to which acid is added, through the heated plug flow reactor or cascade of vessels with stirrers In this process, the degree of inversion can be controlled by varying the temperature, The solution is subsequently neutralized and, if necessary, concentrated by evaporation and cooled.
Inversion by enzymes:
The hydrolysis of sucrose using suitable enzymes like invertases, sucrases, a-glucosidases, ß-fructosidase, ß-fructofuranosidse, or ß- fructofuranoside-fructohydrolase. Sucrose solutions are in some cases still inverted in batches using free invertase. This is done by warming the solution in heated vessels under agitation to 550C, adjust the pH value to 5.5, generally with the citric acid, and adding invertage. Once the desired inversion level reached, the invertage is denatured by heating to at least 650C.
The liquid invert sugar is commercially termed medium invert or 50% invert to differentiate it from total invert or 100% invert shipped at 70 to 72% Brix, Which is limited to specially uses.
Specifications of liquid sugars:
|#1 sucrose||#2 sucrose||Medium Invert||Total Invert|
|Solid %||67.3 to 67.7||67.3 to 67.7||73.3 to 76.7||71.0 to 74|
|Invert %||35 to 42||93|
|pH||7.9 to 8.5||7.9 to 8.5||4.7 to 5.3||3.5 to 4.5|
Storage of liquid sugar:
- Liquid sugars are protected from microbiological contamination by a variety of methods:
Tight filtration & heat, Pasteurizing, Elevated density,
- Sterilization of equipment and tanks. (Sterilization of equipment can be accomplished with chlorine, tamed iodine, hot water, and steam.)
- Storage tanks are constructed of stainless steel, aluminum, mild steel coated with interior protection, or fiberglass-reinforced plastics and are self-draining.
- The head space above the syrup storage in the tanks is kept dry by blowing in heated, filtered, and ultraviolet (UV)-treated air to prevent condensation from forming on the top of the interior of the storage tank and dripping onto the surface of the liquid sugar. In addition, UV lamps are mounted in the ceiling of the storage tanks to control microbial activity in the airspace above the syrup and on the surface of the syrup.
Liquid syrup must be stored and handled very carefully. Contamination by colour, sediment, or microbiological content will result in recycling of entire storage system. The main source of contamination is from yeast fermentation. Once contamination occurs, it is a matter of time until the numbers of organisms will exceed the product specification and a complete cleanout will be required. This involves complete evacuation of the entire sugar system washing all pipes and tanks before sanitizing with sanitizing agent such as chlorine or tamed iodine.
A well-designed and well-controlled sugar system should maintain quality for 6 months to 1 year.
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