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Thermal treatments to partially pre-cook and improve the shelf-life of whole pearl millet flour



BACKGROUND: Pearl millet flour is highly susceptible to rancidity during storage. Urbanization has created a demand for pearl millet flour with longer shelf-life and short cooking time. To try to prevent rancidity and pre-cook the flour, pearl millet grain was subjected to the thermal treatments of toasting, boiling, and toasting then boiling.

RESULTS: Fat acidity of flour from the untreated grain increased from 0.11 to 3.73 g KOH kg−1 during three months' storage, whereas the wet thermally treated samples showed no significant increase (P > 0.05). Peroxide and conjugated diene values of wet thermally treated samples increased substantially, whereas those of flour from untreated grain did not, indicating less formation of rancid final oxidation products in the wet thermally treated samples. Starch degree of cook of the wet thermally treated samples was two times higher than the other treatments. Descriptive sensory evaluation revealed that porridges of flour from untreated grain were associated with hydrolytic rancidity, whereas those of flours from thermally treated grains were not. Consumers showed a preference for the porridges prepared from flour of boiled as well as toasted grain.

CONCLUSION: Thermal treatments can be applied to extend whole pearl millet flour shelf-life, and the treatment of boiling can be used to produce pearl millet flour that cooks more quickly. Copyright © 2008 Society of Chemical Industry