Abstract: The water distribution in hydrogel systems prepared from six different starches at different concentrations was analyzed by low-field nuclear magnetic resonance (LF-NMR) spectroscopy. The results showed that legume (corn and wheat) and legume (pea and mung bean) starch gels exhibited three water forms, while tuber (sweet potato and potato) starch gels exhibited only two water forms. Immobilized water (T23) was the major water form in the six starch gels. With increasing starch concentration (5%–14%), the transverse relaxation time decreased, and the ability of starch gels to bind immobilized water increased. At the same starch concentration, the ability of pea starch gels to bind water was the strongest, while that of potato starch gels was the weakest, and that of cereal starch gels was in the middle. With increasing starch concentration, the relative content of immobilized water in starch gels decreased, and the differences among legume, tuber and cereal starch gels became more obvious. This study provides a theoretical reference for the improvement of sensory texture in starch-based food processing.

Key words: starch gel; nuclear magnetic resonance; water content; immobilized water