Browsing by Author "Garti, Humphrey Kwesi"

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    Yield and functional properties of acid and salt extracted proteins from cowpea (Vigna Unguiculata, Ayiyi)
    (1999) Garti, Humphrey Kwesi
    Acid proteinate (AP) and calcium proteinate (CP) extracted from cowpea (Vigna unguiculata, Ayiyi) flour at different pH and temperature levels were evaluated using response surface methodology. The yield (g/100g of flour) of AP (Maximum 30.37%, T50°C, pH=10) and CP (Max. 26.25% T45°C, pH=8.5) were significantly affected by different extraction combinations of pH, temperature and coagulating agents. Nitrogen content of the proteinates were not significantly affected by coagulation treatments. Foaming capacity (FC) for both proteinates decreased significantly with increased pH and temperature of extraction, CP (Max 72%, T=45°C, pH 8.5), and AP (Max. 52%, T=45°C, pH=8.5). The trend of foam stability (FS) as a function of pH and temperature was the same as for FC for both proteinates, and was characterised by a decrease as temperature and pH were increased. The maximum water and oil absorption capacity of AP were 8.0 g/g and 5.70 g/g and occurred at temperature 45°C and pH 8.5 while that of CP were 8.5 gig and 5.25 g/g, respectively, for the same pH and temperature of protein extraction. Emulsion capacity decreased significantly (P>0.05) with increasing pH and temperature of extraction. Maximum emulsion capacity for AP and CP were 83.33% (T=45°C, pH 8.5) and 100% (T=45°C, pH 8.5), respectively. CP produced more stable emulsions than AP. Least gelation concentrations increased with increasing levels of temperature and pH. It varied from 2 - 4% for CP and 7 - 10% for AP.