Consider alternatives to carboxymethylcellulose to maintain pliability of tortillas.

Traditional corn tortillas are produced from dehydrated masa and water. They have a very short shelf life of up to three days because of their firmness. Commercial corn tortillas contain carboxymethylcellulose (CMC), a semisynthetic water-soluble polymer used to delay staling. However, this gum is not only expensive, it also imparts off-flavors to the product. Alternative additives, such as glycerol and salt, may prove to be a viable option.

Scientists at The Ohio State University wanted to investigate the physicochemical changes caused by adding glycerol, salt and CMC to corn tortillas during their storage. They found that to maintain the pliability of the product, glycerol and salt may prove to be a viable alternative to CMC if they are used in combination with other antistaling agents.

Investigators prepared tortillas using a 60-to-40 water-to-masa ratio, both with and without 4% glycerol, 1% salt or 0.5% CMC. The tortillas were vacuum-packaged individually in high-barrier flexible pouches.

The scientists measured molecular and macroscopic changes using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA) and mechanical analysis during the time that the product was stored at 25 C over a two-week period. During storage, all samples exhibited an increase in amylopectin crystallization. The tortillas containing glycerol and salt had the greatest increase. The freezable water content of all tortillas decreased over the first three to five days of storage. There were no further changes. Moisture content remained constant.

The glycerol and salt tortillas exhibited a more homogenous composition throughout the storage period. However, CMC tortillas were significantly less stiff initially than the control. Glycerol and salt tortillas became stiffer at a greater rate during the second week of storage.

Further information. Yael Vodovotz, Department of Food Science and Technology, The Ohio State University, 2015 Fyffe Court, 110 Parker Food Science Building, Columbus, OH 43210; phone: [phone]; fax: [phone]; email: [e-mail].