Extraction, modification, and characterization of tamarind seed (Tamarindus indica) starch

Abstract

Tamarind ( Tamarindus indica L.) seeds are often discarded despite their potential as a valuable source of starch. This study investigated the valorization of tamarind seeds through starch extraction and sodium hypochlorite treatment to produce modified tamarind seed starch (MTSS). Native tamarind seed starch (NTSS) was extracted using 0.16% sodium metabisulphite, followed by treatment with 5% (w/v) sodium hypochlorite and drying. MTSS exhibited significantly higher swelling power, peak viscosity, trough viscosity, thermal transition temperatures, and light transmittance, along with lower breakdown viscosity than NTSS and NCS ( p < 0.05), indicating altered functional, pasting, and thermal properties following sodium hypochlorite treatment. Differential scanning calorimetry (DSC) revealed changes in thermal transition behavior, while Fourier transform infrared (FTIR) spectra showed characteristic starch absorption bands, Scanning Electron Microscopy (SEM) revealed slight changes in granule morphology, and XRD analysis demonstrated retention of the A-type crystalline structure. Overall, sodium hypochlorite treatment was associated with changes in the functional, pasting, thermal, FTIR, SEM, and XRD characteristics of tamarind seed starch. However, because carbonyl and carboxyl contents were not directly quantified, the degree of oxidation could not be determined. These findings support further studies to quantify the degree of oxidation and evaluate MTSS for specific food and industrial applications.