Physicochemical and Functional Properties of Four New Genotypes of Guar (Cyamopsis tetragonoloba L.)

Abstract

The objective of this work was to study the physicochemical and functional properties of four new guar genotypes (GM5, GM6, GM9 and GM34) collected from the experimental farm of University of Khartoum- Shambat. Proximate composition, tannin content, thousand kernel weight, Hectoliter weight and hard seeds percentage were carried out for the guar seeds. Physical characteristics and chemical composition were investigated for the gum extracted from the guar seeds. Water Holding Capacity, Emulsifying Stability and Foaming properties were determined for the gum. Results obtained showed that genotypes GM5 and GM34 had significantly (P≤0.05) higher values of 1000-kernel weight compared to the genotypes GM6 and GM9.Genotype GM5 gave the significant (P≤0.05) lowest percentage for hard seeds (11.67%) fallowed by GM34 (17.67 %) and GM6 (20.67 %) while GM9 gave the highest value (24.33%). Proximate analysis of guar seeds showed that the GM6 had significant (P≤0.05) highest protein content (42.8%) while GM34 gave the lowest value, genotype GM34 gave significant (P≤0.05) highest value for ash content (5.54 %), for carbohydrates (gum content) GM5 gave significant (P≤0.05) highest value (38.58%) fallowed by GM9 and GM34 but the genotype GM6 gave significant (P≤0.05) lowest value of gum content (30.26%). Tannin content was significantly (P≤0.05) lower in GM5 (0.030%). The chemical composition of guar gum showed no significant (P≤0.05) variation in protein and carbohydrate contents V among all genotypes. Minerals content (macro-elements) data was: 0.0075–0.020%, 0.019 – 0.024%, 0.20–0.30%, 0.020–0.035% and 0.06- 0.09% for P, Na, K, Ca and Mg respectively. Minerals content (microelements) (mg\kg) were 17.74– 43.5, 3.7– 27.4 and 0.19-0.54 for Fe, Zn, and Pb respectively. The results of the physical and functional properties of guar gum tested revealed that GM34 has significantly (P≤0.05) lowest value of pH and optical density. While genotype GM6 gave significant (P≤0.05) lowest value of viscosity (0.11cps). Genotypes GM5 and GM6 gave significant (P≤0.05) highest value of solubility compared with the values given by genotypes GM34 and GM9. Investigation revealed Water Holding Capacity (WHC) as follows: GM34 88.97%, GM5 81.67%, GM9 79.02% and GM6 58.84%, also results revealed no significant (P≤0.05) variation in foaming properties values for all genotypes under study. Generally the genotype GM5 has the best physical and chemical properties of guar seeds, while genotype GM34 has the best functional properties of guar gum.