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| Viscometric study on the Hydrocolloids of Brachystegia eurycoma and Detarium microcarpum at varying temperature for use as stabilizers, binders and thickeners |
Monday Justice Ayibakeditonmuni
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Abstract:
Brachystegia eurycoma (achi) and Detarium microcarpum (ofor) are leguminous plants and their seed powder forms hydrocolloids with water and these hydrocolloids are widely used in Nigeria as soup thickeners, paint emulsifiers, material and tablet binders. They also have medicinal uses when ingested such as the reduction of blood cholesterol, diabetes, treatment of tuberculosis, meningitis, diarrhea etc. These applications of Brachystegia eurycoma and Detarium microcarpum hydrocolloids are related to their respective viscosity at different temperatures. Despite the numerous application of these hydrocolloids from the seed powder of these leguminous plant, little is known on how the viscosities of the hydrocolloids changes with varying temperature and how it affects the thickening, binding and emulsifying properties of the seed powders when used. This research work varied the viscosities of the hydrocolloids of these powders at temperature range (40 oC, 50 oC, 60 oC, 70 oC, 80 oC, 90 oC & 100 oC) and also determined their gelatinization temperature, swelling index and bulk density which indicated what powder functions better as thickener, binder and emulsifier. From the experiment carried out, the viscosities of the hydrocolloids increases with increasing temperature and Detarium microcarpum had higher viscosities compared to Brachystegia eurycoma at the temperature ranges. Detarium microcarpum also had higher peak gelatinization temperature of 65 oC and swelling index of 5.32 compared to Brachystegia eurycoma. The high gelatinization temperature shows that starch in Detarium microcarpum seed powder resist gelatinization compared to Brachystegia eurycoma and the high swelling index accounts for the high viscosity recorded in Detarium microcarpum compared to Brachystegia eurycoma at the same temperature range. At temperature above 100 oC gel is formed on both hydrocolloids. The formation of gel is faster in Detarium microcarpum compared to Brachystegia eurycoma which shows that there is high degree of dissociation of the double helices in the crystalline regions of Detarium microcarpum powder hydrocolloid and expansion of its granules compared to Brachystegia eurycoma as their polymer hydrates. The formation of gel is also influenced by air, quantity of powder and water used. Thus the seed powder of Detarium microcarpum is a better choice for use as thickener, binder and as an emulsifier varying temperature range.
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