University of Khartoum

Effect Of Processing On Anti-Nutritional Factors And Mineral Bioavailability Of Sorghum

Effect Of Processing On Anti-Nutritional Factors And Mineral Bioavailability Of Sorghum

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Title: Effect Of Processing On Anti-Nutritional Factors And Mineral Bioavailability Of Sorghum
Author: Badi, Wisal Hassan Idris
Abstract: Two sorghum cultivars, Wad Ahmed (high tannin) and Tabat (low tannin) were used in this study. Investigation showed that the two cultivars contained 90.2, 95.0 dry matter, 3.5, 3.4%, fat, 1.8, 1.2% ash, 2.7, 2.3.% crude fibre, 10.8, 7.5% crude protein, 71.4, 80.7% carbohydrates, 6.3, 7.0 mg/100g Na, 450, 441.7 mg/100g K, 10.8,12.5 mg/100g Ca, 59.3, 63.0 mg/100 Mg, 3.8, 4.5 mg/100g Fe, 303.0, 283 mg/100g P, 3.21, 3.53 mg/100g Zn, 3.9, 3.5 mg/100g, Mn and 0.21, 0.18 mg/100g Co, 265, 233 mg/100g phytate, 0.96 and 0.35 (catechin equivalent) tannin for Ahmed and Tabat, respectively. Control uncooked sorghum flour of Wad Ahmed and Tabat showed a availability % of 66.7, 64.3% for Na, 46.3, 51% for K, 33.3, 35.7% for Ca 46.3, 55.6% for Mg, 4.2, 6.0% for Fe, 43.4, 44.9% for P, 47.7, 53.8% for Zn, 40.8, 46.2% for Mn, and 66.7, 72.2% for Co, for Wad Ahmed and Tabat, respectively. Cooking of sorghum dough (control) of the two cultivars was significantly (P< 0.05) reduced in tannin content by 55.2 and 48.6% for Wad Ahmed and Tabat, respectively. No significant reduction occurred for phytate and no significant improvement in mineral extractability was observed. However, cooking of 14 h fermented dough reduced tannin content by 75.7 and 78.1%, for Wad Ahmed and Tabat, respectively, and reduced phytate content of the two cultivars Wad Ahmed and Tabat by 37.6 and 36% when compared with control uncooked. The phytate content increased with cooking of fermented dough from 85.9 to 165.5 mg/100g for Wad Ahmed, and from 91.1 to 151.8 mg/100g for Tabat compared with uncooked 14 h fermented dough. Cooking of fermented dough resulted in highly significant (P<0.05) improvement in extractability for all minerals compared to control uncooked sorghum, but less than that of fermented uncooked. Cooking of 14 h fermented dough caused a highly significant (P< 0.05) increase in the concentration of total iron of the two cultivars Wad Ahmed and Tabat (3.8 to 6.5, 4.5 to 9.4 mg/100g), respectively. Cooking of malted - fermented sorghum (5% two days old-malt incubated and fermented for 14 h) caused a very high significant reduction in tannin by 81.2 and 100% for Wad Ahmed and Tabat, respectively and a reduction of phytate by 59.3 and 62.2% compared to control uncooked samples with is less than 90.5, 87.4% reported for malted fermented uncooked. Cooking of malted 14 h fermented dough resulted in highly significant (P< 0.05) increase in the concentration of total iron for the two cultivars Wad Ahmed and Tabat from 3.8 to 6.3 and from 4.5 to 11.1 mg/100g for Wad Ahmed and Tabat, respectively, and highly significant (P< 0.05) improvement in availability % of all minerals specially for that of iron (30.7, 49.5%) for Wad Ahmed and Tabat, respectively.. Germination of Wad Ahmed and Tabat for 24, 48, 96 h resulted in a highly significant improvement in availability % of minerals (Ca, P, Mn and Co). Germination of the two cultivars for 24, 48 and 96 h resulted in a significant reduction of both tannin and phytate. except for cultivar Tabat where was no further tannin reduction after 48 h germination. Germination of Wad Ahmed and Tabat for 96 h resulted in tannin reduction amounting to 73.6 and 34.3, respectively and the reduction of phytate was 90.9 and 88.3%, respectivel. Sorghum malt was added in concentrations of 1, 5 and 10% to sorghum flour. The mixtures were incubated for 30, 60, 90 and 120 min. The results revealed that the rate of reduction in phytate and tannin was higher with increasing age of malt, period of incubation and concentration of the malt. Availability % of minerals also improved significantly (P< 0.05) as a result of malt pretreatment; the rate of improvement depends upon the age, concentration of malt and period of incubation with malt. 10% four days old-malt incubated for 120 min. resulted in 92.0, 93.3% phytate reduction and 97.9, 95.7% tannin reduction for Wad Ahmed and Tabat, respectively. A highly significant (P< 0.05) improvement in availability % of mineral was observed specially for Ca, K, Zn, Mn and Co.
Description: August, 2004
URI: http://khartoumspace.uofk.edu/handle/123456789/10661
Date: 2015-05-12


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