University of Khartoum

Effect of processing on Chemical Composition and biological value of cowpeas

Effect of processing on Chemical Composition and biological value of cowpeas

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Title: Effect of processing on Chemical Composition and biological value of cowpeas
Author: Nugdallah, Gaafar Abdelatif
Abstract: Two cowpea cultivar (Vigna unguiculata) namely "Ain Elgazal" and "Buff" were obtained from Elobeid Research Station and were used in this study. The seeds were analyzed for their chemical composition, protein soluble fractions, in-vitro protein digestibility (IVPD), phytic acid, trypsin inhibitor activity and tannin content of raw, boiled, roasted, autoclaved, germinated for four days, and germinated cooked samples. The proximate composition showed that moisture content ranged from 4.4% to 5.9% for Ain Elgazal cultivar and ranged from 4.4% to 5.5% for Buff cultivar. Protein content ranged from 25.6% to 31.0% for Ain Elgazal cultivar and ranged from 24.6% to 28.9% for Buff cultivar. Ash content ranged from 3.2% to 4.3% for Ain Elgazal cultivar and ranged from 3.5% to 4.3% for Buff cultivar. Fibre content ranged from 2.5% to 3.2% for Ain Elgazal cultivar and ranged from 2.2% to 3.1% for Buff cultivar. Oil content ranged from 1.5% to 1.6% for Ain Elgazal cultivar and ranged from 1.6% to 1.7% for Buff cultivar. All the processing treatments had little effect on oil content and significantly (P X04; 0.05) increased protein content, ash content and fibre content for both cultivars. The raw and germinated samples were fractioned, the major protein fraction Globulin showed significant (P X04; 0.05) decrease, they were 87.5%, 80.6%, 76.4%, 71.4% and 70.2% for Ain Elgazal raw seeds, the first, second, third and fourth days respectively. Similarly for buff raw and germinated seeds, they were 89.8, 81.3, 78.3, 75.6 and 72.7% respectively. The Albumin fraction significantly (P < 0.05) decreased they were 4.0%, 3.8%, 2.3%, 1.9% and 2.5% for Ain Elgazal raw seeds, the first, second, third and fourth days respectively. Similarly for Buff raw and germinated seeds, 3.6%, 1.5%, 2.2%, 2.2% and 1.2% respectively. The prolamin fraction for Ain Elgazal raw and germinated seeds were 4.0%, 3.3%, 4.0%, 1.6% and 4.6% respectively. Similarly for buff raw and germinated seeds were 4.5%, 2.7%, 2.8%, 3.9% and 1.4% respectively. The G1-glutelin fraction for Ain Elgazal raw and germinated seeds showed significant (P X04; 0.05) decrease, they were 2.4%, 2.1%, 1.3%, 0.8% and 1.7% respectively. Similarly for Buff raw and germinated seeds were 2.3%, 1.2%, 1.3%, 2.1% and 1.3% respectively. The G2-glutelin fraction for Ain Elgazal raw and germinated seeds were 2.4%, 2.1%, 1.9%, 1.4% and 1.7% respectively. For Buff raw and germinated seeds were 2.5%, 6.4%, 5.1%, 3.9% and 4.5% respectively. The G3-glutelin fraction showed significantly (P X04; 0.05) increase, they were 4.8%, 9.8%, 12.0%, 13.5% and 10.4% for Ain Elgazal raw seeds, the first, second, third and fourth days respectively. Similarly for Buff, they were 4.5%, 10.0%, 12.5%, 11.1% and 11.7% respectively. The insoluble protein fraction showed significant (P X04; 0.05) increase, they were 1.2%, 2.5%, 2.1%, 9.2% and 6.0% for Ain Elgazal raw seeds, the first, second, third and fourth days respectively. Similarly for Buff raw and germinated seeds were 1.2%, 1.7%, 1.9%, 3.6% and 6.1% respectively. Cooking significantly (P X04; 0.05) reduced globulin, they were 16.4%, 19.0%, 18.1%, 18.0% and 17.8% for Ain Elgazal raw first, second, third and fourth days respectively. Similarly for Buff raw and germinated seeds were 15.7%, 19.9%, 22.0%, 22.6% and 23.0% respectively. Cooking significantly (P X04; 0.05) reduced Albumin, they were 1.9%, 2.8%, 3.1%, 1.8% and 1.4% for Ain Elgazal raw, first, second, third and fourth days respectively. Similarly for Buff raw and germinated seeds were 2.2%, 1.6%, 1.6%, 2.1% and 1.3% respectively. Cooking significantly (P X04; 0.05) increased prolamin fraction, they were 4.2%, 6.3%, 4.8%, 5.1%, and 5.0% for Ain Elgazal raw, first, second, third and fourth days respectively. Similarly for Buff raw and first and then decreased second, third and fourth days they were 4.6%, 5.1%, 2.7%, 2.7% and 1.8% respectively. Cooking significantly (P X04; 0.05) decreased G1-glutelin fraction they were 2.0%, 1.4%, 1.3%, and 1.3% for Ain Elgazal raw, first, second, and third days respectively, but it increased to 2.6% in the fourth day. Similarly for Buff raw and germinated seeds were 2.7%, 1.2%, 1.1%, 1.6% and 1.0% respectively. Cooking significantly (P X04; 0.05) increased G2-glutelin fraction, they were 3.4%, 4.4%, 4.4%, 4.0% and 5.7% for Ain Elgazal raw, first, second, third and fourth days respectively. Similarly for Buff raw and germinated seeds were 5.1%, 7.5%, 7.5%, 7.9% and 8.8% respectively. Cooking significantly (P X04; 0.05) increased G3-glutelin fraction, they were 63.8%, 61.0%, 62.0%, 61.6% and 57.0% for Ain Elgazal raw first, second, third and fourth days respectively. Similarly for Buff raw and germinated seeds were 69.3%, 59.0%, 62.3%, 60.1% and 62.1% respectively. Cooking significantly (P X04; 0.05) increased the insoluble protein fraction, they were 5.5%, 8.0%, 8.8%, 9.6% and 10.2% for Ain Elgazal raw, first, second, third and fourth days respectively. Similarly for Buff raw and germinated seeds were 5.5%, 6.6%, 6.5%, 6.1% and 6.5% respectively. Autoclaving at 120؛C under 15 psi for 30 min for Ain Elgazal raw seeds significantly (P X04; 0.05) reduce globulin fraction from 87.5% to 29.2% and albumin from 4.0% to 1.2% but increased prolamin from 4.3% to 4.5%, reduced G1-glutelin from 2.3% to 1.2% and G2-glutelin from 2.4% to 1.2% and increased G3-glutelin from 4.8% to 59.5% and insoluble protein fraction from 1.2% to 8.0%. Autoclaving at 150؛C under 20 psi for 30 min for Ain Elgazal raw seeds significantly (P X04; 0.05) reduce globulin fraction from 87.5% to 27.6%, albumin fraction from 4.0% to 1.2% but increased prolamin from 4.3% to 4.8%, decreased G1-glutelin from 2.3% to 2.0%, increased G2-glutelin from 2.4% to 4.0%, increased G3-glutelin from 4.8% to 60.2% and increased insoluble protein fraction from 1.2% to 6.0%. Roasting Ain Elgazal raw seeds at 90؛C for 60 min significantly (P X04; 0.05) reduce globulin fraction from 87.5% to 85.0%, albumin showed changeless, prolamin fraction reduced from 4.3% to 3.6%, G1-glutelin fraction reduced from 2.3% to 2.0%, G2-glutelin fraction reduced from 2.4% to 1.2%, G3-glutelin fraction increased from 4.8% to 6.0% and insoluble protein fraction increased from 1.2% to 3.0%. Roasting Ain Elgazal raw seeds at 120؛C for 60 min significantly (P X04; 0.05) reduced globulin fraction from 87.5% to 41.0%, albumin fraction reduced from 4.0% to 1.2%, prolamin fraction reduced from 4.3% to 4.2%, G1-glutelin fraction reduced from 2.3% to 1.2%, G2-glutelin fraction increased from 2.4% to 3.2%, G3-glutelin fraction increased from 4.8% to 48.0% and insoluble protein fraction increased from 1.2% to 6.0%. Autoclaving at 120؛C under 15 psi for 30 min for Buff raw seeds significantly (P X04; 0.05) reduced globulin fraction from 89.8% to 32.0%, albumin fraction from 3.6% to 1.0%, prolamin from 4.5% to 3.0%, decreased G1-glutelin from 2.3% to 2.0%, G2-glutelin fraction increased from 2.5% to 3.0%, G3-glutelin increased from 4.5% to 55.0% and insoluble protein fraction increased from 1.2% to 6.0%. Autoclaving at 150؛C under 20 psi for 30 min for Buff raw seeds significantly (P X04; 0.05) reduce globulin fraction from 89.5% to 36.0%, albumin fraction from 3.6% to 1.0% prolamin fraction from 4.5% to 4.0%, G1-glutelin from 2.3% to 1.2%, G2-glutelin increased from 2.5% to 3.2%, G3-glutelin increased from 4.5% to 50.8% and increased insoluble protein fraction from 1.2% to 7.0%. Roasting Buff raw seeds at 90؛C for 60 min significantly (P X04; 0.05) decreased globulin fraction from 89.5% to 88.0%, albumin showed changeless, prolamin fraction decreased from 4.5% to 4.0%, G1-glutelin from 2.3% to 2.2%, G2-glutelin fraction increased from 2.5% to 2.8%, G3-glutelin fraction showed changeless, insoluble protein fraction increased from 1.2% to 1.4%. Roasting Buff raw seeds at 120؛C for 60 min significantly (P X04; 0.05) decreased globulin fraction from 89.8% to 45.5%, albumin fraction from 3.6% to 1.0%, prolamin fraction increased from 4.5% to 6.0%, G1-glutelin decreased from 2.3% to 2.0%, G2-glutelin fraction increased from 2.5% to 3.0%, G3-glutelin fraction increased from 4.5% to 42.0% and insoluble protein fraction increased from 1.2% to 6.0%. Samples were analyzed for phytic acid, tannin and trypsin inhibitor activity. Germination reduced phytic acid from 310.3 (mg/100g dry weight) of raw seeds to 286.1 mg/100g, 248.9 mg/100g, 201.7 and 139.8mg/100g for Ain Elgazal germinated seeds in the first, second, third and fourth days respectively. Similarly for Buff raw seeds phytic acid was 376.3 which reduced by germinated to 346.2, 301.0, 225.7 and 180.7mg/100g for the first, second, third and fourth days respectively. Cooking showed significant (P X04; 0.05) decreased of phytic acid for Ain Elgazal raw and germinated seeds, they were 290.3mg/100g, 268.9mg/100g, 229.0mg/100g, 181.5mg/100g and 128.6mg/100g for raw, first, second, third and fourth days respectively. Similarly for Buff they were 353.7mg/100g, 311.6mg/100g, 270.9mg/100g, 205.4mg/100g and 162.6mg/100g for raw, first, second, third and fourth days respectively. Autoclaving at 150؛C under 20 psi for 30 min reduced phytic acid for Ain Elgazal raw seeds from 310.3 to 300.0mg/100g. Similarly for Buff raw seeds autoclaving reduced phytic acid from 376.3 to 350.0mg/100g. Roasting at 120؛C for 60 min reduced phytic acid for Ain Elgazal raw seeds from 310.3 to 301.0mg/100g. Similarly for Buff roasting reduced phytic acid from 376.3 to 352.0mg/100g. Germination significantly (P X04; 0.05) decreased tannins from 0.48g/100g of Ain Elgazal raw seeds to 0.36g/100g, 0.30g/100g, 0.24g/100 and 0.20g/100g in the first, second, third and fourth days respectively. Similarly for Buff raw seeds tannins was 0.50g/100g it reduced by germination to 0.42g/100g, 0.36g/100g, 0.30g/100g and 0.22g/100g in the first, second, third and fourth days respectively. Autoclaving at 150؛C under 20 psi for 30 min reduce tannins for Ain Elgazal raw seeds from 0.48g/100g to 0.38g/100g. Similarly for Buff autoclaving reduce tannins from 0.50g/100g to 0.40g/100g. Roasting at 120؛C for 60 min reduced tannins for Ain Elgazal raw seeds from 0.48g/100g to 0.36g/100g. Similarly for Buff roasting reduced tannins from 0.50g/100g to 0.42g/100g. Cooking showed significant (P X04; 0.05) further reduction of tannins for Ain Elgazal raw and germinated seeds, they were 0.26g/100g, 0.18g/100g, 0.15g/100g, 0.12g/100g and 0.10g/100g for raw, first, second, third and fourth days respectively. Similarly for Buff they were 0.30g/100g, 0.22g/100g, 0.20g/100g, 0.18g/100g and 0.11g/100g for raw, first, second, third and fourth days respectively. Germination significantly (P X04; 0.05) reduced trypsin inhibitor activity for Ain Elgazal raw seeds from 22.0 TUI/mg protein of raw to 11.8 TUI/mg protein, 10.6 TUI/mg protein, 8.0 TUI/mg and 8.0 TUI/mg protein for first, second, third and fourth days respectively. Similarly for Buff they were 25.0 TUI/mg protein, 12.5 TUI/mg protein, 10.0 TUI/mg protein, 9.6 TUI/mg and 9.0 TUI/mg protein for raw, first, second, third and fourth days respectively. Cooking autoclaving at 150؛C under 20 psi for 30 min and roasting at 120؛C for 60min eliminates trypsin inhibitor activity. Germination improved in-vitro protein digestibility (IVPD), it were 73.4%, 75.3%, 77.9%, 80.4% and 84.4% for Ain Elgazal raw seeds, first, second, third and fourth days, respectively. Similarly for Buff they were 74.2%, 75.7%, 79.3%, 82.4% and 83.6% respectively. Cookin germinating seeds showed significant (P < 0.05) further increase of in-vitro protein digestibility, they were 86.2%, 87.2%, 87.5%, 88.8%, and 88.5% for Ain Elgazal raw, first, second, third and fourth days respectively. Similarly for Buff were 85.4%, 86.3%, 86.6%, 87.9% and 88.3% for raw, first, second, third and fourth days respectively. Autoclaving at 150؛C under 20 psi for 30min increased IVPD for Ain Elgazal raw seeds from 73.4% to 86.0% and increased by roasting at 120؛C for 60min to 84.0% Similarly Buff increased by autoclaving from 74.2% to 87.0% and by roasting to 84.0%. Effect of substrate on in-vitro protein digestibility was carried out using mixed samples. Increasing the proportion of heat treated material in comparison to raw material significantly (P X04; 0.05) increased in-vitro protein digestibility. For Ain Elgazal the proportion were 0.192g raw materials plus 0.192 heat treated material, 0.096g plus 0.282g, 0.048g plus 0.336g, 0.0 plus 0.384g, 0.288g plus 0.096g, 0.336g plus 0.048g and 0.384g plus 0.0g. The heat treated material were roasted at 90؛C and 120؛C for 30min, 45min and 60min. The material were autoclaved at 115.5؛C under 10psi and at 120؛Cunder 15 psi for 15 min, 30 min and 45min. The IVPD ranged from 73.4% to 84.0% and 73.4% to 84.2 for raw plus roasted mixed samples respectively. The IVPD ranged from 73.4% to 82.0%, 73.4% to 83.0%, 73.4% to 84.0%, 73.4% to 85.0%, 73.4 to 85.5% and 73.4% to 86.2 for raw plus autoclaved (mixed samples) for Ain Elgazal respectively. Similarly for Buff IVPD were ranged from 74.2% to 79.7%, 74.2% to 79.9%, 74.2% to 79.8%, 74.2% to 83.8%, 74.2 to 84.0% and 74.2% to 84.6 for raw plus roasted (mixed samples) respectively. The IVPD ranged from 74.2% to 80.2%, 74.2% to 84.8%, 74.2% to 84.8%, 74.2% to 85.0%, 74.2 to 85.0% and 74.2% to 85.4 for raw plus autoclaved (mixed samples) respectively.
Description: October – 2003
URI: http://khartoumspace.uofk.edu/handle/123456789/10525
Date: 2015-05-11


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