|WU, GEYANG - WASHINGTON STATE UNIVERSITY|
|MURPHY, KEVIN - WASHINGTON STATE UNIVERSITY|
Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/23/2017
Publication Date: 10/13/2017
Publication URL: http://handle.nal.usda.gov/10113/5833790
Citation: Wu, G., Morris, C.F., Murphy, K. 2017. Quinoa starch characteristics and their correlations with texture of cooked quinoa. Journal of Food Science. 82:2387-2395.
Interpretive Summary: Quinoa (Chenopodium Quinoa Willd.) is a pseudocereal which has high protein content, but also provides high quality protein. The essential amino acids are balanced; protein efficiency ratio and true protein digestibility are comparable to those of casein, which considered as a good protein resource. In addition, quinoa is a halophytic crop species which has the capacity to grow and produce seed in highly saline soil. This research studied the effect of NaCl and Na2SO4 concentration on quinoa seed quality parameters across diverse quinoa varieties and different fertility treatments. The seed was prepared in green house using Split-Split design. The concentrations of 8, 16, and 32 dS m-1 of NaCl and Na2SO4 were applied respectively in the soil. Four quinoa varieties (Baer, UDEC-1, QQ065, and CO407D) and two levels of fertilization (3 g N, 0.86 g P, 0.86 g K per pot for high level; 1 g N, 0.29 g P, and 0.29 g K per pot for low level) were included. Protein content, hardness, and density of the seeds were determined. Seed protein content was different across soil salinity level, variety, and fertilization level. Protein content of quinoa growing under salinized soil ranged from 13.0% to 16.7%, comparable to those from normal conditions. NaCl and Na2SO4 exhibited different impacts on protein content. The different concentrations of NaCl did not show different influence on protein content, while seed from 32 dS m-1 Na2SO4 contained the highest protein. Seed hardness was significantly different among varieties, but not influenced by fertilization. Saline soil exhibited a moderate impact on seed hardness (P = 0.0925). The different concentrations of NaCl and Na2SO4 did not influence hardness. Seed density was affected significantly by variety and salinity, but not the fertilization. NaCl and Na2SO4 exhibited different influence on density. Density did not change according to the increased concentration of NaCl, ranging from 0.68 to 0.71 g/cm3. The samples from 8 dS m-1 Na2SO4 soil had lower density (0.66 g/cm3) than those from 16 dS m-1 and 32 dS m-1 Na2SO4, 0.74 and 0.72g/cm3, respectively. In sum, quinoa from saline soil did not show huge decrease in seed quality of protein content, hardness, and density. Protein content and seed density were comparable to those from normal soil. The influences of NaCl and Na2SO4 were different. Higher concentration of Na2SO4 tended to increase protein content and seed density, while concentration of NaCl did not exhibit significant difference on those quality indexes.
Technical Abstract: Starch characteristics exhibited significant influence on the functionality and end-use quality and cereal product. The composition and properties of quinoa starch were studied in this paper. The correlations between starch characteristics and the texture of cooked quinoa were investigated. The correlations between starch characteristics and other seed qualities were discussed. Eleven varieties and two commercial samples were included. Result showed that total starch content ranged from 53.2 to 75.1 g/ 100 g. Aparent amylose content ranged from 2.7 – 16.9 %. Degree of amylose-lipid complex ranged from 3.4 – 43.3 %. Amylose leaching properties, starch water solubility and swelling power were different among samples. Starch gel texture, starch thermal properties and pasting properties were as well different among samples. Texture of cooked quinoa were strongly correlated with amylose content, degree of amylose-lipid complex, amylose leaching, starch enthalpy, and pasting parameters such as trough, final viscosity, and peak time. Decline of seed yellow color during cooking was negatively correlated with all the texture parameters. In sum, starch plays a significant role on the texture of cooked quinoa. Varieties with different starch properties should be utilized in different end-products.