Wheat flour tortillas are widely consumed in Mexico and are increasing in popularity in the United States and Europe. In the US the hot-press method is becoming the most popular method for producing wheat flour tortillas mainly because of its high efficiency and consumer preferences.
In general flour tortilla formulations contain four major ingredients: flour, water, salt and shortening/oil. However, other ingredients such as leavening agents, yeast, sugar, emulsifiers, preservatives, acidulants and gums (hydrocolloids) are commonly used to further improve quality (especially keeping quality) of wheat flour tortillas. Although some tortilla formulations rely on yeast instead of chemical leaveners for leavening the dough, yeast is added primarily as a flavouring agent. A fermentation flavor is produced by using up to 1% of active dry yeast or up to 3% of regular compressed yeast. An overview of the various methods for producing wheat flour tortillas and ingredients used is given by Serna-Saldivar et al (Cereal Foods World 33 (1988) 855-864).
A major problem in the production of wheat flour tortillas (especially when using the hot-press method) is that a resting period is required to relax the dough pieces before pressing them into round shaped tortilla. If the resting period is kept too short, the tortilla dough is difficult to press and will give tortillas of inferior quality upon baking. Reducing agents are commonly used to shorten resting times by increasing extensibility and decreasing elasticity of gluten protein. This is achieved with compounds such as L-cysteine, bisulfites, sorbic or fumaric acid which break of block gluten disulfide bonds thereby improving machinability of the tortilla dough. However, the use of these chemical components should be limited because at high dosages they tend to reduce shelf life stability (rollability over time) of wheat flour tortillas.
Proteases have been described as an alternative for chemical dough relaxing compounds in some baking applications. However, the use of this type of enzyme which remains active after mixing will greatly affect process tolerance making proteases less suitable as a dough relaxing agent in tortilla production. In addition, materials such as soy flour, wheat germ, garlic and inactivated dry yeast have been described as a useful source of low molecular weight SH compounds such as L-cysteine and/or glutathion. These materials have been described as a dough relaxing agent and mix time reducer in the production of various products from wheat flour. U.S. Pat. No. 4,643,900 describes the use of garlic as a dough relaxing agent in the production of baked goods such as bread, crackers, pizza and sweet goods. Japanese patent application J 61-009263-A describes the use of inactive dry yeast as a dough relaxing agent which improves extensibility and softness of noodle dough and shortens the process time for making noodles. EP-A-141754 describes a bread mix for preparing bread containing whole wheat flour, gluten and 0.1-0.2% of inactive dry yeast functioning as a mix-time reducer. EP-A-0262669 describes fat compositions suitable for use in bakeries and confectioners which contain, in addition to the fat component, disrupted yeast cells.
Fats play a very important role in the way a tortilla dough behaves during processing and greatly affect the quality of tortilla made from wheat flour. Wheat flour tortilla formulations generally contain between 5 and 15% (percentages based on flour weight) of plastic shortenings or liquid oils. These high levels of fat are essential in improving dough machinability and keeping quality (rollability over time). The use of emulsifiers in wheat flour tortilla production can reduce the amount of shortening needed in the tortilla formula. Normally 0.2-0.5% (based on flour weight) of an emulsifier with a good dough stabilising action such as SSL is used in tortilla formulations.
Gums such as (modified) starches, carboxymethyl cellulose, xanthan and arabic gums or mixtures thereof have found limited use for improving dough machinability and keeping quality (rollability) of wheat flour tortillas. These watersoluble hydrocolloids function as stabilisers and thickeners which bind large quantities of water and allow some reduction of the amount of fat in the tortilla formula. Partly solubilised cell walls from yeast have been described as thickeners and stabilisers having fat-like properties in U.S. Pat. Nos. 9,122,196 and 4,992,540. Reducing the amount of fat in tortillas is of considerable interest both to the tortilla manufacturers and to the consumer who wants to reduce calorie intake from fats. Despite the use of expensive gums and emulsifiers it is not possible yet to produce a tortilla of acceptable shelf life stability (rollability) and overall quality if no or only low levels of fat are used in the recipe.