The aim of this study was to improve the quality of protein extracts from Cucumeropsis mannii Naud. and Arachis hypogaea L. The evolution of protein content and microbiological quality of aqueous extracts of A. hypogaea, C. mannii and M. oleifera seed powders were monitored over time during protein extraction. The protein contents of the extracts subjected to decantation and those subjected to centrifugation were determined by the Kjeldahl method. The microbiological quality of the different aqueous extracts was evaluated according to the standards NF EN ISO 7932, NF V 08-059 and NF EN ISO 4833-1. The results obtained show protein contents of 40.6 % for A. hypogaea, 25.4 % for C. mannii and 36.5 % for M. oleifera, after 24 h of decantation. The protein contents of the centrifuged aqueous extracts were higher and 55.9%, 36.7% and 37.6% for A. hypogaea, C. mannii and M. oleifera extracts respectively. The results of the microbiological analysis showed that the aqueous extracts of M. oleifera contain little microbial load. Significant growth of aerobic flora and Bacillus cereus was observed in the decanted extracts of C. mannii and A. hypogaea from 4 h to 24 h of decantation. Extracts obtained by centrifugation have a lower microbial load, because the treatment time was shorter. The aqueous protein extracts of A. hypogaea and C. mannii seed powders obtained by centrifugation were of better quality than those obtained by decantation, because they have higher protein contents and lower microbial loads. The water solubility of A. hypogaea and C. mannii seed proteins was also studied on protein suspensions at 2% at pH 3, 4, 5, 6, 7 and 8. The results obtained showed that adjusting the pH to 7 and 8 could improve the degree of protein extraction for A. hypogaea and C. mannii seeds.

Comparative studies of the chemical composition and the coagulanting activity of the seeds of Cucumeropsis mannii Naud., Arachis hypogaea L. and Moringa oleifera Lam. in the clarification of surface waters.

The aim of this study was to characterize the amino acids in the seeds of Citrullus lanatus, Vigna unguiculata and Zea mays; and the proteins in the coagulating solutions of the seed powders of these 3 plants. Amino acids were separated by ion exchange chromatography and determined by ninhydrin reaction with photometric detection. Proteins were characterized by steric exclusion high-performance liquid chromatography (SE-HPLC) on a Superdex column in the range of 10 kDa to 500 kDa and on a Shodex column in the range of 204 Da to 35000 Da. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE) was also performed. The results obtained showed that the most abundant amino acid in the seeds of the 3 plant species is glutamic acid, a negatively charged side chain amino acid at neutral pH. The respective contents are 6150 mg/100 g in Citrullus lanatus seeds; 4030 mg/100 g in Vigna unguiculata seeds and 1820 mg/100 g in Zea mays seeds. The percentage of protein constituents with a molecular weight less than 10 kDa is 87.3%; 74.1% and 61.6%; for Citrullus lanatus, Zea mays and Vigna unguiculata coagulant solutions respectively. The percentage of protein constituents with a molecular weight between 1000 Da and 1500 Da is 24.9%;20.4% and 29.2%; respectively for the coagulant solutions of Vigna unguiculata, Zea mays and Citrullus lanatus. A percentage of 25.8%, between 800 and 1000 Da, is also noted for Citrullus lanatus. The study of the coagulant activity showed percentages of turbidity reduction higher than 80%.

No abstract