One of the charms of wheat tortillas is their convenience. Wrapped around a filling, they quickly transform into a tasty meal to be eaten at leisure or on the go. Or that’s the theory. For many busy consumers and caterers, the charm can quickly fade when tortillas stick together in the packaging, only to tear when pulled apart.
Although tortilla adhesiveness is a recognized problem, only a few scientific studies have been made on the subject. These attribute responsibility to a complex combination of technical aspects, among them water activity, polar surface energy and starch crystallinity.
Our own experience at DuPont is that various ingredients have the ability to reduce the issue. But they do not work alone. Storage conditions also play a role, particularly temperature, both immediately prior to packing and during storage, and the degree of pressure placed on tortillas when stacked in warehouses.
We decided to test our hypothesis that storage factors actually have greater influence on the adhesiveness of tortillas than the ingredients in the recipe.
Using our test recipes, we tested a series of parameters over a 30-day storage period, taking measurements on days 7 and 30. This is what we looked at:
- The degree of adhesiveness when using alternative types of oil and shortening in the test recipes, each recipe containing 8% fat based on the flour ◦The change in adhesiveness observed when taking out emulsifier from the recipe.
- The level of adhesiveness in tortillas stored at 20°C, 40°C, or at 20°C while subject to 6kg of pressure.
Some of our key findings are illustrated in the two graphs below.