ADHESION OF SUGAR AND OIL SOLUTIONS

Salt was applied to surfaces coated with sugars and oils to test their adhesion. There was no difference in adhesion between 70% solutions of sucrose, glucose and fructose. Below 70%, adhesion by glucose was greater than for sucrose. Adhesion increased from propylene glycol with two hydroxyl groups to glycerol with three, but there was no change in adhesion from glycerol to sorbitol, which has six hydroxyl groups. The adhesion of glycerol and sorbitol was not different from sucrose. In corn syrups, adhesion increased with increasing dextrose equivalent. Increasing oil content increased adhesion up to 0.2 mg/cm², then plateaued. Oils produced a similar adhesion to solutions of 70% sugar. Adhesion varied with the type of oil. Most likely, the differences in adhesion were due to the presence of natural surfactants. When lecithin was added, the adhesion increased significantly. The addition of other surfactants did not significantly increase the adhesion.

PRACTICAL APPLICATIONS

Sugar and oil are frequently used to adhere powders and small particulates, such as seasonings and spices, to a food surface. The desire for low calorie foods means minimizing the sugar and oil used for adhesion. Glucose was shown to have greater adhesion than sucrose, therefore less of it could be used to achieve the same adhesion. Addition of lecithin to oils increased its adhesion. Certain oils had higher adhesion than others, due to natural surfactants. Most of the fat replacers tested did not show significant adhesion. Using this information, current tack agents could be replaced with other sugars or oils to produce the same adhesion at a lower concentration.