Protein and antioxidant composition of quinoa (Chenopodium quinoa Willd.) sprout from seeds submitted to water stress, salinity and light conditions

Abstract

The demand for healthy foods with high functional value has encouraged the search for alternatives to enhance food beneficial characteristics. Special attention has been given in recent years to quinoa (Chenopodium quinoa Willd.) due to its high nutritional value like. high quality protein content. Quinoa seeds also contain various bioactive substances such as polyphenols, carotenoids, dietary fiber, and oleic acid, all of importance on human health. Recent studies have shown that edible sprouts have higher nutritional value than mature plants. The objectives of this study were i) to determine the effect of controlled water regimes during grain filling on the protein content, and electrophoretic pattern (albumins, globulins) of washed and unwashed quinoa seeds and ii) to evaluate changes in quinoa sprouts total polyphenol content. Seeds were produced under controlled irrigation conditions during grain filling. Seeds of quinoa cultivar AG2010 were grown under three water regimes (95%, 40%, and 20% soil available water). Experiments were conducted in a randomized complete block design with a split-plot arrangement. Albumin content of washed and unwashed seeds of AG2010 varied between 11.7 and 27.0mgmL−1 and globulin content ranged between 15.3 and 31.9mgmL−1, respectively, but differences among water regimes were not significant. However, seed protein fractions decreased significantly when seeds were washed before the analysis. The number of albumins/globulins bands extracted from washed seeds was higher compared with the number of bands extracted from unwashed seeds; some of them probably correspond to dehydrins. Sodium chloride solution increased germination percentage (GP), vigor index (VI), and sprout fresh weight (FW) of B080 seeds compared with sucrose solution. No effects were observed in total polyphenol content (TP) of sprouts between sodium chloride or sucrose solutions. Similarly, light quality had no effect on GP, VI, FW, and TP content. In conclusion, quinoa seeds produced under different water regimes had different globulin content. Washing the seeds prior to sprouting to remove saponins changed the concentration and electrophoretic pattern of albumins and globulins. Stress caused by sodium chloride, sucrose, or light quality did not affect TP content in quinoa sprouts; however, sodium chloride decreased sprout growth.