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F. R. DEL VALLE, B. Ojiaku, and D. Clason. Department of Chemical Engineering, New Mexico State University, P.O. Box 30001, MSC 3805, Las Cruces, NM 88003-8001

Two important quality parameters encountered in the manufacture of tortillas from corn tortilla flour are yield (kg wet masa or dough obtained per kg of flour) and tortilla flexibility. Yield affects masa functionality in tortilla-making machines, while flexibility assures that tortillas remain soft and pliable upon storage. For the above reasons, means for improving both of these parameters would be highly desirable. The purpose of this research, therefore, was to investigate the effects of incorporation, into tortilla flour, of two additives that were expected to improve both masa yield and tortilla flexibility; these were hydrophilic gums and cross-linked starches. A two- factor 7 x 5 split block experimental design was employed. Three hydrophilic gums (CMC, guar gum and tragacanth), each at two levels (0.1% and 0.3%, based on dry flour weight); and two types of commercial cross-linked starches (moderately and highly cross-linked), each at two levels (25% and 50% based on dry flour weight)were investigated. Data were analyzed using conventional linear modeling techniques, utilizing the SAS/STAT software package. Incorporation of gums generally increased yields with respect to controls (p<0.05). Guar gum gave the highest and CMC the lowest yields at both levels (p<0.007 and p<0.001, respectively); however, increases of dose from 0.1% to 0.3% increased yield only in the case of gum tragacanth (p<0.05). Incorporation of cross-linked starches generally decreased yields with respect to controls (p<0.05), with the highly cross-linked starch giving the lowest yields at both levels (p<0.016); increasing starch dose from 25% to 50% also resulted in decreased yields for both starches (p<0.05). Flexibility was not significantly affected by any of the additives studied. This research is significant because it has shown that yield may be increased or decreased by incorporation of gums or cross-linked starches, respectively.