Some physical properties of tamarind (Tamaraindus indica L.) juice concentrates
1991
Manohar, B. | Ramakrishna, P. | Udayasankar, K.
Flow properties of tamarind (Tamarindus indica L.) juice concentrate were studied over a concentration range of 7-62 Brix and a temperature range of 298-343 K using a coaxial cylindrical viscometer. The concentrates showed Newtonian flow behaviour up to a concentration of 19 Brix and pseudoplastic nature beyond 23 Brix obeying the power law relationship. Flow behaviour index for concentrate of 23 Brix is 0.747, whereas it is 0.625 for concentrates of 28-62 Brix. Tamarind juice concentrates were more viscous than sucrose solutions especially at higher concentrations. Whereas the activation energy of sucrose solutions varies with concentration, it does not vary with concentration in the case of tamarind concentrates. Some other engineering properties such as boiling point elevation, specific heat and specific gravity of tamarind juice and concentrates were determined. The effects of concentration and operating variables on these properties were studied and mathematical models were proposed to relate them to the properties. The boiling point elevation of tamarind juice is twice that of sucrose solutions at 50% solid content and 150 mm Hg absolute pressure. However, the difference is less at lower concentrations (below 20% solid content). The specific heat of tamarind juice is less than that of sucrose solutions at all concentrations. The specific gravity of tamarind juice is approximately equal to that of sucrose solutions of the same concentration.
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