The effect of popping, soaking, boiling and roasting processes on antinutritional factors in chickpeas and red kidney beans

This study was conducted to determine the effect that a popping head (like a rice cake machine), a low-shear and low-water processing technology, has on the concentration of antinutritional factors in chickpea and red kidney beans. Seeds were popped under several parameters (popping time, sample format and equipment type) and analysed against soaking (1: 5 w/v in reverse osmosis water for 24 h), roasting (100 g at 180 degrees C for 20 min) and boiling (1:5 w/v in reverse osmosis water at 100 +/- 1 degrees C for 1 h) processes. Popping and roasting significantly reduced phytic acid content in chickpeas (6%-22%) and red kidney beans (16%-39%). In contrast, phytic acid content after soaking and boiling was not significantly different to raw seeds. Condensed tannins were significantly reduced in red kidney beans after soaking (74%), boiling (100%) and 4 s popping (28%-42%) treatments and increased in both pulses after roasting (137%) and 8 s popping (21%-47%). Further analysis showed that the soluble phenolic content increased with popping, but total and bound phenolic content was reduced. These results demonstrate that the high temperatures and pressures applied during the popping process effectively reduce antinutritional factors in pulses, compared to conventional processing methods.