Uses and functions of sugars and syrups

Uses in biscuit doughs

Sugars are important for the taste and structure of most biscuits. Relatively large quantities of sucrose and syrups are used in all short doughs, smaller quantities in semisweet doughs and to a much lesser extent in cracker doughs and wafer batters. In short doughs there is not normally enough water in the formulation to allow all the sugar to dissolve so the crystal size of the sucrose used affects the baking and eating characteristics of the biscuit or cookie.

As mentioned above, lower sugars affect the sweetness and the colouration of biscuits during baking.

Uses in biscuit filling creams

In filling creams there is a need to have a smooth mouth feel and rapid dissolution of the sugar in the mouth. Very fine particle sized sucrose, icing sugar, is used. Sometimes some dextrose is used to reduce the overall sweetness. Dextrose (usually used as the monohydrate) has a negative heat of solution so gives an attractive cool mouth feel as it dissolves.

Uses in jams and jellies

Mixtures of sucrose and invert sugars are important in jams and jellies. The concentration of the sugars must be at least as high as 67% to prevent microbial spoilage and in jams used for biscuits the concentration may be as high as 78%. Combining lower sugars with sucrose reduces the tendency of sucrose to crystal from solution.

Use in marshmallow

Marshmallow is a foamed mixture of sugar syrups and a gelling agent such as gelatine or agar agar.

Uses in chocolate

Sugar is a major ingredient in chocolate. In the course of manufacture the chocolate is ground very finely so it is not possible to detect the sugar crystals when the chocolate is eaten. The sugar in chocolate is in a fat suspension, any moisture in the chocolate will result in solution of the sugar and a viscous syrup will impair the consistency of the molten chocolate during enrobing or moulding processes.

Function of sugars in biscuits

  • For sweetness and flavour. The brown sugars and sucrose syrups are very valuable sources of flavour in biscuits.
  • For structure and hardness, particularly in short doughs. High levels of sucrose give hard glassy textures. This is because molten, concentrated sugar solutions, which are formed when the dough pieces are heated in the oven, set on cooling. If some glucose syrup is added to the formulation the hardness may be reduced at a given level of sucrose.
  • As a bulking agent in creams and chocolate. The sucrose is used not only for its sweetness but as a filler that dissolves readily when eaten.
  • As a flavour enhancer and to make flavours seem correct. Small quantities of sucrose allow a much greater appreciation of certain flavours. Salt is another common flavour enhancer. Some flavours do not seem correct unless they are in a sweet context. Good examples are fruit flavours which are associated with sweetness and often acidity.
  • As a fermentation food. In doughs that are fermented, such as Cream Crackers, additions of small quantities of sugar encourage the yeast to grow more vigorously and hence speed the fermentation process.
  • To aid surface colouration during baking. Only the reducing sugars do this. During baking the reducing sugars combine with amino acids from proteins (found in flour, milk products and eggs) in a complex reaction known as the Maillard reaction. This reaction gives attractive foxy brown colours on the surface of baked goods. The higher the concentration of the reducing sugars present the darker the colours produced. The Maillard reaction is also more prevalent in alkaline than acid conditions and this is one of the reasons why sodium bicarbonate is used in biscuit recipes to increase the alkalinity.
  • As a decoration on the surface of biscuits. Sucrose crystals dusted on to the surface of dough pieces before baking adhere strongly and add to the attractive appearance of the biscuits. The size of the crystals is critical to obtain the desired effect. In some cases where hot oven conditions are used and the expansion of the dough piece is great during baking it is possible to melt the sucrose on the biscuit surface to obtain a sugar glaze.