Study on the Extraction and Utilization of Natural Dye from Tamarind Seed Testa

The present research work is emphasized on the preparation of natural dye (concentrated solution) from tamarind seed testa. Tamarind seed contains nearly 30 percent of testa and 70 percent of kernel. The testa was removed from the seeds by roasting and subsequent pounding. The testa contains a dyestuff which was used for dyeing of cotton fabrics. The physico-chemical properties such as pH, acidity, moisture content, ash content and total solids content of tamarind seed testa were determined by Association of Official Analytical Chemists (AOAC) method. The chemical compounds present in tamarind seed testa were investigated by phytochemical tests. An attempt was made on the dyeing of cotton fabrics using of natural dye (concentrated solution) from tamarind seed testa with different mordants such as zinc sulphate, potassium dichromate, ferrous sulphate and three different dyeing methods such as pre-mordanting, post-mordanting and simultaneous mordanting and dyeing method. Moreover, fastness for rubbing and washing of dyed cotton fabrics was determined. Staining and colour change of dyed cotton fabrics were assessed by using standard Grey scale. The dye extraction was carried out at testa to water ratio of 1:40 and the resulting natural dye (concentrated solution) was employed for dyeing of cotton fabrics. Dyeing at 90ºC for 45 min followed by postmordanting with potassium dichromate enhanced the highest amount of dye adsorbed on cotton fabrics and good fastness properties.