The sunflower (Helianthus annuus L.) seed and sprout is a ubiquitous crop with abundant nutrients and biological activities. This review summarizes the nutritional and medical importance currently recognized but under-researched concerning both seed and sprout highlighting the potential benefits of their phytochemical constituents including phenolic acids, flavonoids and tocopherols. Furthermore, the dynamic metabolite changes which occur during germination and biological activities are evaluated. The aim is to provide scientific evidence for improving the dietary and pharmaceutical applications of this common but popular crop as a functional food.

The metabolite and flavor characteristics of roasted germinated sunflower seeds (RGSF) were evaluated and compared with those of roasted ungerminated sunflower seeds (RUSF) by gas chromatograph-flame ionization detector (GC-FID) and headspace solid phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS). During roasting, α-tocopherol, β-sitosterol, fructose, and glucose content were higher at 125 °C compared to those at 135 and 145 °C in RGSF, and lower reductions of alanine, glycine, phenylalanine, serine, asparagine, and γ-aminobutyric acid (GABA) content at 125 °C in RGSF. Considering their nutritional value, it is suggested that sunflower seeds are roasted at 125 °C. The dominant volatile compounds in RGSF were α-pinene, furfural, pyrazines, 1-octen-3-ol, and 2-methylbutanal. High-temperature heating for long term led to a large accumulation of unpleasant odors like pyridine, hexanal and nonanal, especially in RUSF. To examine the distribution of the individual metabolites and flavor compounds among different roasting conditions. A heatmap diagram combined with agglomerative hierarchical clustering (AHC) analysis and principal component analysis (PCA) showed that most Maillard reaction substitutes (amino acids and reducing sugars), products (2-methylpyrazine 2-ethyl-3,5-dimethyl-pyrazine, and 3-ethyl-2,5-dimethylpyrazine), and Strecker degradation products (3-methylbutanal, 2-methylbutanal, and isobutanal) contributed to separate RGSF from RUSF.