Comparison of starches isolated from three different Trapa species

• The kernels of Trapa species had different morphology, weight and starch content.
• Starch granules were all oval in shape with smooth surface and central hilum.
• Starches all exhibited CA-type crystalline, similar thermal and pasting properties.
• T. pseudoinisa starch had larger granule size, higher amylose content than others.
• T. pseudoinisa starch showed lower hydrolysis degrees by HCl and AAG than others.

Trapa (Trapaceae) is one of the most common aquatic plants. In order to make full use of the resource of Trapa, we investigated two Trapa cultivated species (Trapa quadrispinosa Roxb. and Trapa bispinosa Roxb.) and one Trapa wild species (Trapa pseudoinisa Nakai) popularly found in South China. The morphology, size, weight, and contents of water, starch and soluble sugar of fruit and kernel were significantly different among the three species. Starches isolated from their kernels were all oval in shape with smooth surface and central hilum. The starch granule size was larger and amylose content was higher in the wild species than in the two cultivated species. Starches from the three Trapa species all exhibited CA-type crystalline. T. pseudoinisa starch showed the highest swelling power and solubility. Starches from the three Trapa species had similar thermal properties except that T. pseudoinisa starch had higher onset temperature and lower conclusion temperature. T. pseudoinisa starch showed similar breakdown viscosity and higher setback viscosity compared with starches from the other two species. Similar hydrolysis degree by porcine pancreatic α-amylase was observed in starches isolated from the three species. However, T. bispinosa starch showed the highest hydrolysis degree and T. pseudoinisa starch showed the lowest hydrolysis degree by HCl and Aspergillus niger amyloglucosidase.

Morphology of fruit, kernel and starch granule from three different Trapa species. (A) Trapa quadrispinosa, (B) Trapa bispinosa, (C) Trapa pseudoinisa, (1) fruit, (2) kernel, (3) light microscope, (4) polarized light microscope, (5) scanning electron microscope.Figure optionsDownload as PowerPoint slide