What are the important Methods of Preparation of Syrup?

Preparation of syrup depends on the physical and chemical characteristics of the substance employed for its preparation. Four methods are commonly used for preparation of syrups.

1. Agitation without Heat:

This method is used for the preparation of syrups containing volatile substances. In this process active substance is added in solution and agitated in a glass-stoppered bottle. Closing of bottle is necessary to protect the syrup from contamination and loss of solution during the process.

For preparation of large quantities, glass lined tank with mechanical agitators is employed. This method is used for the preparation of wide variety of syrups. Cough syrups are commonly prepared by this process, (e.g., codeine syrup, ephedrine sulfate syrup etc.)

2. Solution with heat:

This process is generally preferred as it is simple and less time consuming method, particularly if the constituents are not effected by heat and are non volatile in nature. In this process sucrose is added in the aqueous solution and heated till the sucrose is dissolved completely. Adding remaining amount of distilled water makes up volume of the solution. If the syrups containing any substances which are coagulated, it can be separated subsequently by straining.

The concentration of the syrup is measured using saccharometer if the specific gravity of the solution is known. Excessive heating of syrup is not suitable because more inversion of sucrose occurs with the increase in temperature. Syrups cannot be sterilized in autoclave without caramelization. This solution is converted in yellowish to brown color due to formation of caramel by the effect of heat on sucrose.

3. Addition of a medicated liquid:

This method is put to use in those cases in which tinctures, fluid extracts or other medicated substances in liquid form are added to syrup to medicate it. In this process some time precipitation takes place due to the presence of resinous and oily substances. It is necessary to take care that medicated substance should not get precipitated in this process.

4. Percolation:

In this process, purified water or an aqueous solution is allowed to pass through a bed of crystalline sucrose. A pledget of cotton is put in the neck of the percolator and purified water or aqueous solution is added in the percolator containing sucrose. The flow rate is controlled by the stopcock and maintained such that drops appear in rapid succession. If required, a small portion of liquid is re-passed through the percolator to dissolve the sugar completely in the liquid or aqueous solvent.

Preservatives

Syrup should be kept at low temperature, about 25°C is suitable for preservation. Following preservatives are used to prevent bacterial and mould growth viz. methy1paraben, sodium benzoate, benzoic acid, glycerin etc.

Label and storage:

Syrup should be kept in well-closed containers and stored at temperature below 30 °C. Bottle should be completely filled, carefully stoppered and stored in cool dark place.

Example 01: Prepare and Dispense simple syrup

Sucrose

Purified water, sufficient to produce

or

Sucrose

Purified water, sufficient to produce

Example 02: Prepare and Dispense Invert syrup

Sucrose

Purified water, sufficient to produce

Hydrochloric acid

Sodium carbonate solution as neutralizing agent

Method of Dispensing:

Prepare syrup of sucrose 66.7% w/w in purified water and add hydrochloric acid slowly with continuous stirring. Neutralize the solution using sodium carbonate solution. Identify inversion of simple syrup to invert syrup by measuring optical activity of syrup.

Example 03: Prepare and Dispense Lemon Syrup (100 ml)

Lemon spirit

Citric acid monohydrate

Invert syrup

Syrup, sufficient to produce

Formula for Lemon spirit (A)

Lemon oil 100.0 ml

Ethyl alcohol (96%) sufficient to produce 100.0 ml

Formula for Invert syrup (B)

Sucrose 66.7 g

Purified water, sufficient to produce 100.0 g

Hydrochloric acid qs

Sodium carbonate solution as neutralizing agent

Method of Dispensing:

Cut thin slices of lemon and prepare lemon spirit by maceration process using 60 percent alcohol. Dissolve the citric acid monohydrate in simple syrup. Add freshly prepared invert syrup and lemon spirit, prepared using formula A and B, mix and add sufficient amount of syrup to produce 1000 ml. Lemon syrup has a weight per ml of about 1.33 g

Example 04: Prepare and dispense Tolu Syrup (100 ml)

Tolu balsam 1.25 g

Sucrose 66.0 g

Purified water, sufficient to produce 100.0 g

Method of Dispensing:

Boil 400 ml of purified water in dish or tared vessel. Add weighed amount of tolu balsam in boiled water. Cover the vessel partially and boil the contents for 30 min. with frequently stirring. Add purified water to make the contents of the vessel about to 360 g. Cool it and filter the solution. Add sucrose in the solution and
warm it on a water bath to dissolve sucrose completely. Add sufficient purified water to make 1000 g of the solution.