Metabolic alterations of lutein, β-carotene and chlorophyll a during germination of two soybean sprout varieties

The metabolic changes of lutein, β-carotene and chlorophyll a during germination of the soybean (Glycine max (L.) Merr.) sprout varieties, ‘Pungsannamulkong’ and ‘Bosug’, have been studied. Seeds were germinated at 20 °C with 80% humidity in the darkness and sampled at 2 day intervals for 10 days. Partial least squares (PLS) scores plot showed that the responses of three metabolites during germination were linearly linked with each other except for day 2 in both varieties. PLS loading plots indicated that lutein content in whole sprout and cotyledon was closely associated with germination in ‘Pungsannamulkong’ while the chlorophyll a content in whole sprouts was highly linked with germination in ‘Bosug’. Heatmap analyses revealed that lutein and β-carotene levels, but not those of chlorophyll a, accumulated in whole soybean sprouts and cotyledon. While hypocotyls did not accumulate lipophilic pigments during germination, the accumulation of lutein and β-carotene in the cotyledons was greater in ‘Pungsannamulkong’ than in ‘Bosug’ sprouts. In addition, the contents of lutein, β-carotene and chlorophyll a increased from those in the seeds. Overall, the metabolic changes of lutein, β-carotene and chlorophyll a during germination are affected not only by variety but also by organ type.