Browsing by Author "Adu-Kwarteng, Evelyn"

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    Glycemic index of different varieties of yam as influenced by boiling, frying and roasting
    (Food Science & Nutrition, 2021) Ampofo, Deborah; Agbenorhevi, Jacob K.; Firempong, Caleb K.; Adu-Kwarteng, Evelyn; 0000-0002-8516-7656; 0000-0002-1358-125X
    Yam is one of the commonly consumed carbohydrate staples. The objective of this work was to investigate the effect of boiling, roasting, and frying on the glycemic index (GI) of white yam (Dioscorea rotundata), yellow yam (Dioscorea cayenesis), and water yam (Dioscorea alata). Yam tubers were obtained (peeled, sliced, washed) deep fried in vegetable oil for 35–40 min and boiled in water for about 35–45 min. Sliced unpeeled tubers were also roasted at about 120°C for 40–45 min. The cooked yam samples were fed to 10 healthy subjects aged between 20–50 years. A glucometer was used to measure the blood glucose concentrations of the test individuals before consuming the yam diets and after the 15th, 30th, 45th, 60th, 90th, and 120th min of consumption. The average incremental area under the curves (IAUC) obtained from the recorded blood glucose concentrations were used to calculate the GI of various yam diets. The GI of the yam diets were found to be in the following increasing order: White-yam-boiled (44.26%) < Water-yam-boiled (50.12%) < White-yam-roasted (50.62%) < Water-yam-roasted (54.04%) < White-yam-fried (59.13%) < Yellow-yam fried (65.08%) < Water-yam-fried (69.16%) < Yellow-yam-roasted (70.62%) < Yellowyam-boiled (75.18%). White yam diets relatively had lower GI compared to yellow yam and water yam. Boiling was found to give generally lower GI in the white and water yams and could therefore be applied in the preparation of lower GI diets for diabetics.
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    Grain quality evaluation of rice from breeding lines and local collections in Ghana
    (1999-02-15) Adu-Kwarteng, Evelyn
    Rice is gaining increasing popularity in Ghana among both rural and urban dwellers. However more than 60 % of the nation’s annual requirements is still imported to meet demand levels while many local varieties are considered to be of inferior quality. Local research on the crop has generally lacked grain quality components, both for our local varieties and the breeding lines used in Crop Improvement Programmes. Twenty (20) rice varieties made up often breeding lines (B.L.) and ten local varieties (L.V.) were studied. The samples were analysed for grain size, shape and appearance, milling quality, total ash, potassium, calcium, phosphorus, protein content, amylose content, cooking quality and pasting characteristics (rheological properties). Mean values for grain length, length-to-width ratio, total milling recovery, broken grain fraction and degree of whiteness were higher for the B.L. (7.04 mm, 3.12. 67.2 %. 38.08 % and 76.90 respectively) than the LV. (6.61 mm, 2.66. 63.50 %, 30.24 % and 73.96 respectively). Among the LV., grain chalkiness score and 1000 grain weight had higher mean values (2.4 and 28.7 g respectively) than the B.L. (1.1 and 26.14 respectively). Mean protein, albumin, total ash, potassium and calcium contents were higher among the L.V. (8.14 %. 0.33 %. 0.56 %. 87.05 mg!100 g and 24.11 mg/100 g respectively) than the B.L. (7.54 %. 0.28 %. 0.52 %, 85.44mg/100 g and 21.74 mg/100 g respectively) while phosphorus. Amylase, water uptake and volume expansion (during cooking) ratios were lower in the L.V. (131.74 mg/100 g, 22.11 %. 2.89 and 3.49 respectively) than in the B.L. (167.98 mg/100 g, 27.20%, 2.94 and 3.65 respectively). Cooking time was shorter among the B.L. (mean: 19.20 minutes) than in the L.V. (mean: 19.95 minutes). Amylograph peak viscosity and iscosit breakdown were higher among the LV (mean 710 B U and 301 B U respectively than the B.L. (mean: 615 B.U. and 175 B.U. respectively) while hot paste. cold paste and setback viscosities were higher among the B.L. (mean: 440. 944.5 and 329.5 B.U. respectively) than the L.V. (mean: 409. 817.5 and 107.5 B.U. respectively). Significant differences existed between varieties for most of the parameters studied. Among the L.V. significant correlations existed between amvlose and the following parameters: cooking time (r = 0.64), breakdown and setback viscosities (r = -0.74 and 0.67 respectively). However for the B.L. correlation with amylose existed only for cold paste viscosity (r = 0.62). For the formulated rice-based snack from selected varieties, there was a high acceptability rating for the product although varietal differences existed.