Main Article Content
corn ﬂuor, Ca(OH)2, thermo-alkaline treatment, gelatinization.
A design of a controlled cooking system (CCS) for corn ﬂours production is presented. The system allows reproducibility in the samples preparation with
control of the time and the temperature. The treatment of corn was performed with a cooking time of 120 minutes at 92.5◦C, by adding calcium hydroxide (Ca(OH)2) in concentration between 0 and 0.5% compared to the corn weight.
The cooking process was monitored via measures of moisture absorbed by the corn kernels and pH of the solution. The samples were manufactured by operation steps like wet milling, dehydration, dry milling and sieving. The samples were analyzed using modulated diﬀerential scanning calorimetry (MDSC)
and thermogravimetric analysis (TGA) techniques, which were focused in the thermal stability of the ﬂours and their physical variables: gelatinization range (∆T), enthalpy (∆H), change in heat capacity (∆Cp), temperature decomposition of maximum decomposition rate (Tmd) and residue after decomposition (Rs). The adding of Ca(OH)2 moves the peak gelatinization and the maximum peak of decomposition towards higher temperature. The TGA analysis showed that the addition of calcium hydroxide improves the thermal stability of the ﬂour, since the degradation temperature shifts to higher temperatures as the amount of calcium hydroxide increases. The results were compared with the same analysis performed on raw corn. This study proposes an experimental method, including a controlled cooking system for the production of ﬂour enriched with calcium, which could have a major impact in the ﬁeld of nutrition.
PACS: 64.60.-i, 61.25.hk, 61.25.hp, 83.10.Tv
 M.E. Rodríguez, J.M.Yáñes-Limón, J.J. Alvarado-Gil, O. Zelaya-´Ángel, F. Sanchez-Sinencio, H. Vargas, F. Figueroa, F. Martínez-Bustos, M.D. Silva, J. González-Hernández and L. Miranda. nfluence of the Structural Changes during Alkaline Cooking on the Thermal, Rheological and Dielectric Properties of Maize Tortillas, Cereal Chemistry, ISSN 0009–0352, 73(5), 593–600 (1996).
 W.S. Ratnayake and D.S. Jackson. A New Insight Into the Gelatinization Process of the Native Starches, Carbohydrate Polymers, ISSN 0144–8617, 67, 511–529 (2007).
 D. Fessas and A. Schiraldi. Water Properties in Wheat Flour Dough II: Classical and Knudsen Thermogravimetry Approach, Food Chemistry, ISSN 0308–8146, 90, 61–68 (2005).
 K.A. Rosentrater. A Review of Corn Masa Processing Residues: Generation, Properties and Potential Utilization, Waste Management, ISSN 0956–053X, 26, 284–292 (2006).
 M. Borda-Cardoso, J.L Putaux, D. Samios and N. Pesce da Silveira. nfluence of alkali concentration on the deproteinization and/or gelatinization of rice starch, Carbohydrate Polymers, ISSN 0144–8617, 70, 160–165 (2007).
 G. Mendez-Montealvo, M.M. Sanchez-Rivera, O. Paredes-López and L.A. Bello- Pérez. Thermal and rheological properties of nixtamalized maize starch, Biological Macromolecules, ISSN 0141–8130, 40(1), 59–63 (2006).
 ASTM International. Standard Test Method for Compositional Analysis by Ther- mogravimetry, E 1131–03, (2003).
 Association of Oficial Analytical Chemists. Oficial Methods of Analysis, 16th ed. Oficial Method 968.08: Association of Oficial Analytical Chemists, Maryland, USA, 1998.
 G. Ramos, M. Pezet-Valdez, A. O’Connor-S´anchez, C. Placencia and R.C. Pless. Hydration Rates for Various Types of Mexican Maize Based on Single-Kernel Measurements, Cereal Chemistry, ISSN 0009–0352, 81(3), 308–313 (2004).
 A. Gowen, N. Abu-Ghannam, J. Frias and J. Oliveira. Modeling the water absorption process in chickpeas (Cicer arietinum L.)-The effect of blanching pre- treatment on water intake and texture kinetics, Journal of Food Engineering, ISSN 0260–8774, 78, 810–819 (2007).
 J.L. Fernández-Muñoz, A.A. Acosta-Osorio, M.A. Gruintal-Santos and O. Zelaya- Ángel. Kinetics of water diffusion in corn grain during the alkaline cooking at different temperatures and calcium hydroxide concentration. Journal of Food Engineering, ISSN 0260–8774, 106, 60–64 (2011).
 A. Quintanar-Guzmán, M.E. Jaramillo-Flores, R. Mora-Escobedo, L. Chel-Guerrero, and J. Solorza-Feria. Changes on the structure, consistency, physic-ochemical and viscoelastic properties of corn (Zea mays sp.) under different nixtamalization conditions, Carbohydrate Polymers, ISSN 0144–8617, 78, 908–916(2009).
 A. Santoveña, M.J. Piñero and M. Llabrés. Comparison between DSC and TMD-SC in the investigation into frozen aqueous cryoprotectants solutions, Drug Development and Industrial Pharmacy, ISSN 0363–9045, 36(12), 1413–1421 (2010).
 E. Gutiérrez-Cortez, I. Rojas-Molina, A. Rojas, J. L.,Arjona, M. A. Cornejo-Villegas, Y. Zepeda-Benítez, R. Velázquez-Hernández, C. Ibarra-Alvarado and M. E. Rodríguez-García. Microstructural changes in the maize kernel pericarp during cooking stage in nixtamalization process, Journal of Cereal Science, ISSN 0733–5210, 51, 81-88 (2010).
 J.M. Yeomans. Statistical Mechanics of Phase Transitions, Primera Edición, ISBN-10 0198517300. Oxford University Press, New York, 1992.
 W.S. , A.B. Wassinger and D.S. Jackson. Extraction and characterization of Starch from alkaline cooked corn masa, Cereal Chemistry, ISSN 0009–0352, 84(4), 415–422 (2007).
 L.A. Bello-Pérez, P. Osorio-Díaz, E. Agama-Acevedo, J. Solorza-Feria, J.F. Toro-Vázquez and O. Paredes-López. Chemical and physicochemical properties of dried wet masa and dry masa flour, Journal of the Science of Food and Agriculture, ISSN: 1097–0010, 83(5), 408–412, (2003).
 I. Tan, C.C., Wee, P.A., Sopade and P.J. Halley. Investigation of the starch gelatinisation phenomena in water-glycerol systems: application of modulated temperature differential scanning calorimetry, Carbohydrate Polymers, ISSN 0144–8617,58, 191–204 (2004).
 P. Pineda-Gómez, D.F. Coral, M.L. Arciniegas, A.Rosales-Rivera and M.E. Rodriguez-García. Papel del Agua en la Gelatinización del Almidón de Maíz: Estudio por Calorimetría Diferencial de Barrido, Revista Ingeniería y Ciencia, ISSN 1794–9165, 6(11), 129–141 (2010).
 K.D. Nishita and M.M. Bean. Grinding methods: Their impact on rice flour properties, Cereal Chemistry, ISSN 0009–0352, 59, 46-49 (1982).
 X. Jin, T.S Ellis and F.E. Karasz. The effect of the crystallinity and crosslinking on the depression of the glass transition temperatura in nylon 6 by water, Journal Polymer Science, ISSN 1099–0518, 22, 1701–1717 (1984).
 B. M. Gough and J. N. Pybus. Effect of metal cations on the swelling and gelatinization behaviour of large wheat starch granules, Starch/Staerke, 25, 123– 130 (1973).
 B. J. Oosten. Explanation for the phenomena arising from starch electrolytes interactions, Starch/Staerke, ISSN 0038–9056, 35, 166–169 (1983).
 J. Jane. Mechanism of starch gelatinization in neutral salt solutions, Starch/Staerke, ISSN 0038–9056, 45, 161–166 (1993).
 C.M., Bryant and B.R. Hamaker. Effect of Lime on Gelatinization of Corn Flour and Starch. Cereal Chemitry, Cereal Chemitry, ISSN 0009–0352, 74(2), 171–175 (1997).
 L. C. Thomas. Characterization of melting phenomena in linear low density polyethylene by modulated DSCTM, T. A. Instruments. 2007.
 P. Aggarwal and D. Dollimore. The Effect of Chemical Modifiacation on Starch Studied Using Thermal Analysis, Thermochimica Acta, ISSN 0040–6031, 324, 1-8 (1998).