Pulse Industry

Project Abstract: Assessing the anti-nutritional properties of Canadian pulses

This project involves quantifying the levels of antinutritional compounds within a wide range of Canadian pulses and soybean (as a control) found as-is within the marketplace and after soaking/cooking using colourimetric and chromatographic assays. Work is being done through a colloborative research partnership between the University of Saskatchewan, the University of Manitoba and AAFC-Saskatoon.

The effects of legume type and processing (soaking and cooking) on enzyme inhibitors (α-amylase, trypsin and chymotrypsin inhibitors), lectins, phytic acid, total and soluble oxalates, total phenolics and total tannins in a wide range of Canadian pulses (4 peas, 9 lentils, 3 chickpeas, 2 fava beans and 4 beans) are being investigated, using soybean as a control. Within the final year of the project, data was collected for phytic acid, oligosaccharides and, vicine and convicine level in raw and cooked (boiling in 95oC water, for 1 h) pulses.

The vicine and convicine contents of whole and split fava beans were found to be similar with levels of 7.3-7.4 mg/g and 3.1-3.3 mg/g, respectively, which then declined to 4.6-5.4 mg/g and 2.1-2.4 mg/g, respectively upon cooking implying heat sensitivity of the compounds. Phytic acid levels within the raw and cooked pulses ranged between 0-2.1% and 0.7-2.5%, respectively. The levels in the vast majority of pulses remained unchanged by cooking suggesting phytic acid is relatively insensitive to heat. However, depending on the sample, some pulse samples increased slightly, whereas others declined. Oligosaccharide concentrations were measured for all pulses, in terms of their content in sucrose, maltose, raffinose, circeritol, stachyose and verbascose levels. Overall the impact of cooking resulted in a decline in most oligosaccharides. However, in some instances levels remained the same or in some cases increased, depending on the pulse and the particular oligosaccharide being examined. Results suggest that cooking was an effective method at reducing the levels of some oligosaccharides.

To summarize, the level of anti-nutritional factors in Canadian pulses varied widely, but levels were generally lower that those found in soybean. Processing, specifically heat processing, significantly reduced these levels.



For more information, contact Dr. Michael Nickerson (306) 966-5030 
This project involves quantifying the levels of antinutritional compounds within a wide range of Canadian pulses and soybean (as a control) found as-is within the marketplace and after soaking/cooking using colourimetric and chromatographic assays. Work will be done through a colloborative research partnership between the University of Saskatchewan, University of Manitoba, and AAFC-Saskatoon. A variety of market classes including chickpea, lentil, pea, faba bean, and beans were received from Alliance Grain Traders (AGT) and the Crop Development Centre at the University of Saskatchewan. These samples are processed to separate seed coat as one of the processing options. Then another set will be processed by soaking followed by boiling. For quantitation of selected antinutrients liquid chromatographic and colorimetric methods will be used. Colorimetric methods employed for pulses by other researchers will be evaluated and used for phytic acid, trypsin inhibitors, total tannins, and total phenolics contents. For saponins, oligosaccharides, and phenolic acid composition liquid chromatographic methods using HPLC. To date, levels of total phenolics, α-amylase inhibitor, trypsin inhibitor, lectins, and phytic acids have been assessed for both raw and cooked pulses. Results found that pulse type had a significant effect on levels of α-amylase inhibitor, trypsin inhibitor, lectins and phytic acid. Soybean contained the highest contents of trypsin inhibitor (45.89 TIU/mg), lectins (692.82 HU/mg), and phytic acid (22.91 mg/g) among all seeds investigated. α-Amylase inhibitory activity was absent in peas, lentils, chickpeas and faba beans, but was present in beans, where values ranged from 786– 1370 AIU/g. Trypsin inhibitor levels of raw peas, lentils, chickpeas, faba beans, and beans ranged from 3.16 – 20.8 TIU/mg, with the lowest values for peas and the highest for beans. Beans contained relatively high lectin levels followed by lentils, peas, faba beans, and chickpeas with very low values (2.73 – 2.74 HU/mg). Phytic acid was detected in all samples with the lowest levels in peas (8.55 – 12.40 mg/g) and the highest in faba beans (19.7 – 22.8 mg/g). Total phenolics we found to range between 4.4 to 5.1 mg/g for raw peas, 12.5 to 14.2 mg/g for raw lentils, 4.6 to 5.8 mg/g for raw chickpeas, 6.7-8.0 mg/g for raw pinto beans, 4.2-4.7 for Navy beans, 32.7 to 39 mg/g for faba bean, and 27.7-28.7 mg/g raw soybeans. Cooking of presoaked seeds was more effective; all proteinaceous anti nutrients (α-amylase inhibitor, trypsin inhibitor, and lectins) were reduced by 80-100%. Significant reductions in phytic acid content (11-39%) and total phenolics were also observed for all pulses. To summarize, the level of anti-nutritional factors in Canadian pulses varied widely, but levels were generally lower that those found in soybean. Processing, specifically heat processing, significantly reduced these levels.
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