Resumo

PINEDA-GOMEZ, P; CORAL, D.F; RAMOS-RIVERA, D  e  ROSALES-RIVERA, A. Study of the thermal properties of corn flours produced by thermal-alkaline treatment. ing.cienc. [online]. 2011, vol.7, n.14, pp.119-142. ISSN 1794-9165.

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 (ΔT), enthalpy (ΔH), change in heat capacity (ΔC_p), temperature decomposition of maximum decomposition rate (T_md) and residue after decomposition (R_s). 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.

Palavras-chave : corn fluor; Ca(OH)₂; thermo-alkaline treatment; gelatinization.

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