Summary Sensory evaluation was used to determine the effect of lysine and tryptophan fortification on certain properties of corn tortillas. Lysine and tryptophan were added to nixtamalized corn flour to give concentrations which were either 83, 100 or 150% of suggested FAO concentrations. The analysis of sensory panelists results as well as colour parameter changes of enriched tortilla have shown that nixtamalized corn flour would be capable of supplying up to 83% of lysine and tryptophan needed in the diet of an average consumer. It would be logical to offer enriched tortillas mainly to the low income groups of Latin Americans, who normally consume tortillas as a main source of protein in their diet.

This study was conducted to determine sensory changes of fortified nixtamalized corn flour with lysine and tryptophan up to 83, 100, and 150% of suggested FAO pattern after 2 months storage at room temperature (30 degrees C). Totally, 16 trained panelists participated in sensory study of tortilla made of enriched and normal corn flours where six attributes and a total of 19 descriptors were taken into consideration. A reflectance colorimeter was also used in determination of changes in tortilla color parameters. No significant differences were found in the analysis of 19 descriptors of tortilla made of enriched and normal nixtamalized corn flour after 2 months storage. Also, no color parameter changes were found between normal and enriched tortillas.

Summary It has been shown, by sensory panels and tests on colour changes, that tortillas, enriched by nixtamalized cornflour, are acceptable for consumption and could supply up to 83% of Food and Agricultural Organization (FAO) recommended levels of lysine and tryptophan. We studied recovery of lysine and tryptophan which had been used to fortify nixtamalized cornflour and tortillas, which had been stored for 2 months at an ambient temperature of 30 °C. Three different levels of fortification of lysine and tryptophan, 83, 100 and 150% of the FAO recommended amounts, were used. Cornflour enriched with lysine and tryptophan did not lose important amounts of these amino acids after storage for up to 2 months at room temperature. Perhaps this was caused by the process of nixtamalization, which removed many reactive low molecular compounds normally present in corn and which could react with the free amino acids added for enrichment.