Buckwheat Starch Isolated From Varieties Grown in Washington State: A Qualitative Characterization

Buckwheat, a gluten-free pseudocereal with high starch content, has great potential for use in numerous food product applications. Variability in the technofunctional properties across varieties is not well understood. Starch was isolated from two varieties of common buckwheat, Koto (KB) and Tinker (TB), cultivated in Washington State. Analysis was conducted on the chemical, functional, thermal, pasting, and morphological attributes of the isolated buckwheat starch. The findings exhibited great purity of starch (85.21%-89.31%) with high amylose content (23.06%-25.04%), minor ash (0.17%-0.42%), and protein fractions (1.36%-1.55%) exhibiting statistically significant differences among the varieties. Buckwheat starch micrographs showed the presence of polygonal, spherical, and round granules with smooth surfaces. Buckwheat starch granules displayed a smaller size (1.84-14.60 µm) with an average size of 6.35-6.68 µm. The solubility as well as swelling power of starch showed an increasing trend with rising temperatures from 30 to 90°C for both varieties. Both buckwheat varieties showed similar peak positions on their thermographs, ranging from 70.31 to 71.11°C. The greater starch peak viscosity of Koto buckwheat starch (743.55 ± 0.91 BU) was associated with starch granule sizes. Pearson correlation analysis exhibited a strong positive correlation among starch content and peak viscosity, breakdown viscosity, setback viscosity, end-of-cooling period viscosity, and amylose content. Nonetheless, there was an inverse association between starch content as well as water solubility, swelling power, and water absorption capacity. The findings revealed favorable functional and pasting attributes of buckwheat starches, indicating potential usage across a range of food products, such as bakery products, ready-to-eat meals, and frozen foods.