Browsing by Author "Noetzold Horst"

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    Digestibility and Antinutrient Properties of Acidified and Extruded Maize–Finger Millet Blend in the Production of Uji
    (ScienceDirect, 2004) Onyango Calvin; Noetzold Horst; Ziems Annette; Hofmann Thea; Bley Thomas; Henle Thomas
    Lactic and citric acids were used as alternatives to backslop fermentation in the manufacture of extruded uji (a thin porridge from eastern Africa). Acidity of the blends was reduced by fermentation or progressively lowered with 0.1, 0.5 and 1.0 mol/l lactic or citric acids before extrusion. The absence of ethanol soluble starch in the extrudates indicated that extrusion solubilizes starch without formation of maltodextrins. In vitro starch digestibility increased from 20 mg maltose/g starch in the raw blend to about 200 mg/g after extrusion. Extrusion reduced total dietary fibre by 39–68%, redistributed soluble to insoluble fibre ratios and had a negligible effect on the formation of resistant starch (less than 1 g/100 g). In vitro protein digestibility increased after fermentation or acid treatment followed by extrusion. Nitrogen solubility index decreased by 40–50% when the unfermented, lactic or citric acid treated blends were extruded, but increased by 20% when the blend was fermented before extrusion. Amino acid analysis showed that histidine, lysine and arginine contents were lowest in the fermented-extruded blends. Tannin content decreased from 1677 mg/100 g in the raw blend to between 551 and 1093 mg/100 g in the extrudates whereas phytate content remained unaffected by extrusion (248–286 )
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    Proximate Composition and Digestibility of Fermented and Extruded Uji From Maize– Finger Millet Blend
    (LWT - Food Science and Technology, 2004) Onyango Calvin; Noetzold Horst; Bley Thomas; Henle Thomas
    The proximate composition, amino acid profile and in vitro starch and protein digestibilities of raw; fermented; fermented and cooked; unfermented and extruded; and fermented and extruded maize–finger millet blend was studied. Aspartic acid, glycine,cystine, methionine, tyrosine and lysine increased after fermentation, while contents of all other amino acids showed no significant changes. Greater losses of amino acids occurred when the fermented blend was extruded than when cooked. Fermentation improved protein and starch digestibilities, whereas cooking or extruding the fermented blend reduced the digestibilities. Extruding the unfermented blend increased protein and starch digestibilities and reduced nitrogen solubility index by 50%. Raw flour had 0.41 g/100 g water-soluble starch which declined to 0.05 g/100 g on fermentation but increased to 20–34 g/100 g after extrusion