Establishment and Single Laboratory Validation for Quantitative Determination of Tamarind Seed Polysaccharide by Iodine Staining

Tamarind seed polysaccharide (TSP) belongs to the galactoxyloglucan family and is used as a thickener or stabilizer in the food industry. To establish a quantitative method for TSP, the iodine-staining method was implemented and validated using various marketed TSP products in terms of selectivity, linearity, range, trueness, precision, and uncertainty. Good linearity was confirmed for the TSP reference standard (RS) over the concentration range of 5 – 449 µg/g. The tested method yielded good recovery from the spiked test (99 – 107%) and precision using RS and various marketed TSP products (repeatability precision (RSDr): 1.0 – 1.9%, intermediate precision (RSDi): 1.5 – 3.5%), suggesting the validity of the quantitative method. The quantitative method was applicable to currently marketed TSP products. We conclude that this method is a simple and practical method with high trueness and precision for the determination of TSP concentration to certify marketed TSP products as food additives.