Amino acid digestibility of extruded chickpea and yellow pea protein is high and comparable in moderately stunted South Indian children with use of a dual stable isotope tracer method

Authors: DEVI, SARITA - St John'S National Academy Of Health Sciences; VARKEY, ANEESIA - Uc Davis Medical Center; DHARMAR, MADAN - Uc Davis Medical Center; HOLT, ROBERTA - University Of California, Davis; Allen, Lindsay - A; SHESHSHAYEE, M - University Of Agricultural Sciences; PRESTON, THOMAS - Scottish Universities Environmental Research Centre; KEEN, KARL - University Of California, Davis; KURPAD, ANURA - St John'S National Academy Of Health Sciences

Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/7/2020
Publication Date: 1/31/2020
Citation: Devi, S.K., Varkey, A., Dharmar, M., Holt, R.R., Allen, L.H., Sheshshayee, M.S., Preston, T., Keen, K.L., Kurpad, A. 2020. Amino acid digestibility of extruded chickpea and yellow pea protein is high and comparable in moderately stunted South Indian children with use of a dual stable isotope tracer method. Journal of Nutrition. 150(5):1178-1185. https://doi.org/10.1093/jn/nxaa004.
DOI: https://doi.org/10.1093/jn/nxaa004

Interpretive Summary: Legumes are an excellent plant source of the limiting indispensable amino acid (IAA) lysine in vegetarian, cereal-based diets. However, digestibility of legumes is poor largely because of their antiprotease content. Extrusion can enhance digestibility by inactivating trypsin inhibitors and thus potentially improve the protein quality of legumes. The objective was to measure the digestibility of extruded chickpea and yellow pea protein with use of a dual stable isotope method in moderately stunted South Indian primary school children. Twenty-eight moderately stunted children (height-for-age z scores <-2.0 and >-3.0) aged 6–11 years from low to middle socioeconomic status were randomly assigned to receive a test protein (extruded intrinsically [2H]-labeled chickpea or yellow pea) along with a standard of U-[13C]-spirulina protein to measure amino acid (AA) digestibility with use of a dual stable isotope method. Individual AA digestibility in the test protein was calculated by the ratios of AA enrichments in the test protein to the standard protein in the food and their appearance in blood plasma collected at 6 and 6.5 h during the experiment, when plasma levels were stable. The mean AA digestibility of extruded chickpea and yellow pea protein in moderately stunted children (HAZ; -2.86 to -1.2) was high and similar in both extruded test proteins (89.0% and 88.0%, respectively, P = 0.83). However, lysine and proline digestibilities were higher in extruded chickpea than yellow pea (79.2% compared with 76.5% and 75.0% compared with 72.0%, respectively, P < 0.02). We conclude that extruded chickpea and yellow pea protein had good IAA digestibility in moderately stunted children, which was 20% higher than an earlier report of their digestibility when pressure-cooked, measured by the same method in adults. Higher digestibility of lysine and proline highlights better retention of these AA in chickpea during extrusion-based processing. Extrusion might be useful for developing high-quality protein foods from legumes.

Technical Abstract: Background Legumes are an excellent plant source of the limiting indispensable amino acid (IAA) lysine in vegetarian, cereal-based diets. However, their digestibility is poor largely because of their antiprotease content. Extrusion can enhance digestibility by inactivating trypsin inhibitors and thus potentially improve the protein quality of legumes. Objective We measured the digestibility of extruded chickpea and yellow pea protein with use of a dual stable isotope method in moderately stunted South Indian primary school children. Methods Twenty-eight moderately stunted children (height-for-age z scores <-2.0 SD and >-3.0 SD) aged 6–11 y from low to middle socioeconomic status were randomly assigned to receive a test protein (extruded intrinsically [2H]-labeled chickpea or yellow pea) along with a standard of U-[13C]-spirulina protein to measure amino acid (AA) digestibility with use of a dual stable isotope method. Individual AA digestibility in the test protein was calculated by the ratios of AA enrichments in the test protein to the standard protein in the food and their appearance in blood plasma collected at 6 and 6.5 h during the experiment, representing a plateau state. Results The mean AA digestibility of extruded chickpea and yellow pea protein in moderately stunted children (HAZ; -2.86 to -1.2) was high and similar in both extruded test proteins (89.0% and 88.0%, respectively, P = 0.83). However, lysine and proline digestibilities were higher in extruded chickpea than yellow pea (79.2% compared with 76.5% and 75.0% compared with 72.0%, respectively, P < 0.02). Conclusion Extruded chickpea and yellow pea protein had good IAA digestibility in moderately stunted children, which was 20% higher than an earlier report of their digestibility when pressure-cooked, measured by the same method in adults. Higher digestibility of lysine and proline highlights better retention of these AA in chickpea during extrusion-based processing. Extrusion might be useful for developing high-quality protein foods from legumes. This trial was registered at www.ctri.nic.in as CTRI/2018/03/012439.