61A-19 |
Effects of glycerol and salt on the physio-chemical properties of corn tortillas |
E. A. CLUBBS, T. H. Shellhammer, and Y. Vodovotz. Dept. of Food Science & Technology, Ohio State Univ., 110 Parker FS&T Bldg., 2015 Fyffe Rd., Columbus, 43210-1007 Traditional corn tortillas are produced from dehydrated masa and water, and have a very short shelf-life of 1-3 days. Commercial corn tortillas us carboxymethylcellulose and antimicrobial agents (propionates and benzoates) to delay staling and inhibit microbial spoilage, respectively. These additives are not only expensive, but they impart off-flavors to the product. The objective of this study was to investigate the anti-staling properties of glycerol and salt in corn tortillas. Tortillas were prepared by mixing dry masa and water (2:3 w/w), with and without glycerol (4% db) and salt (1% db), and cooked briefly on a 325°C griddle. Prior to packaging, samples were allowed to cool and lose moisture for various times up to 6 hours under ambient conditions (25 °C, 50% RH). Molecular and macroscopic changes were measured using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and Instron mechanical analysis. Moisture loss of similar degrees was evident from both control and glycerol/salt containing samples. For all samples, DSC thermograms showed a major transition around 0°C attributable to ice melting, while the amount of “freezable” water decreased with storage. DMA results showed a similar transition at 0°C, but also minor transitions at -60°C and 50°C. Glycerol/salt containing samples exhibited more homogeneous phase transitions and less variability than control samples. Furthermore, these samples had lower moisture contents than the control but maintained similar stiffness to the control. Glycerol and salt can provide structural flexibility and homogeneity to corn tortillas and potentially extend shelf-life through the reduction in moisture without significantly altering corn tortilla mechanical properties. Glycerol and salt may also increase the preservative effect against spoilage bacteria.
Session 61A, Carbohydrate
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