Keeping tortillas soft, moist and mould-free has been a top-of-mind issue since the first day they went into factory production. While the traditional, handmade wrap is made for day-to-day consumption, shelf-life expectations for its industrial counterpart stretch from one or two months all the way up to nine.
To fulfil these expectations, two key functionalities must be integrated in tortilla formulations: the ability to resist the onset of mould, and a fresh-keeping property that maintains flexibility and an appealing texture and mouthfeel.
In flatbreads stored at room temperature, a pH level around 7 and high water activity create the ideal conditions for mould. Measures for controlling water activity include partial replacement with glycerol and the use of modified atmosphere packaging. But, when it comes to mould inhibition through a lower pH, the task is a little trickier.
The pH challenge
At DuPont, we have run many trials to determine the best methods for reducing tortilla pH. Only when pH is low are preservatives able to exert a mould inhibiting effect. Challenges arise, however, when pH reduction of the dough has negative consequences for processing and the quality of the final baked tortilla.
Acids are an obvious choice for achieving a lower pH – our preference is to use the organic acids, citric and malic acid. But problems arise when they are released too quickly in the dough and react prematurely with the sodium bicarbonate. CO2 is then produced too early in the process, causing unappealing translucent patches and excessive puffing in the final baked tortilla. At the same time, the dough becomes stiff, inelastic and hard to press out to the desired diameter.
To overcome such issues, we work with encapsulation technology. The acid is then locked inside a fat-based coating to delay its release. This ensures the optimum conditions for dough processing and development before the acid acts upon pH, reducing it to around 5.2 for effective mould inhibition.
At the moment, our bakery specialists are looking at new opportunities for optimising mould inhibition. These include acid coating materials based on certified sustainable mass balance palm oil and a palm-free emulsifier based on rapeseed oil.
Preserving the fresh-keeping quality of tortillas requires another approach. Here, we have been able to draw on the know-how obtained from our work with fresh-keeping in bread. This has contributed to a series of optimised solutions that combine hydrocolloids, emulsifiers, enzymes and encapsulated acids.
One of the primary functionalities is the ability to delay the retrogradation of wheat starch, which is a major contributory factor in staling.
The result is tortillas with a stay-fresh feel, lasting flexibility and no dry edges – ready to be wrapped around a filling without cracking even after nine months on the shelf.