Evaluation and Analysis of Nutritional Components in Mature Seeds of 30 Flax Germplasm Resources

To clarify nutritional characteristic differences in mature seeds among flax germplasm resources, 30 accessions (YY01-YY30) were used as materials. Crude protein, 17 hydrolyzed amino acids, 37 fatty acids, crude fat, and mineral elements (Fe, Zn, Ca, Mg) were determined via the Kjeldahl method, amino acid analyzer, gas chromatograph, Soxhlet extraction, and inductively coupled plasma optical emission spectrometer, followed by statistical analysis. Results showed crude protein ranged 12.07-23.97 g/100 g (coefficient of variation, CV = 10.41%), with YY-30, YY-02, and YY-05 as high-protein germplasm (>23 g/100 g); lysine had the highest CV (28.57%) among essential amino acids, EAA, and YY-26's EAA/total amino acid, TAA, (41.59%) met Food and Agriculture Organization/World Health Organization, FAO/WHO standards. α-Linolenic acid (average 33.6%, max 40.3% in YY-15) was the main functional fatty acid, strongly positively correlated with linoleic acid (R² = 0.9983, p < 0.0001). Crude fat ranged 28.49-40.22% (CV = 7.26%), with YY-26, YY-22, and YY-27 as high-oil germplasm. Fe had the largest CV (16.68%) among the four mineral elements, with YY-30 having the highest Fe content (58.94 mg/kg); in addition, Ca was weakly positively correlated with Mg (p = 0.02). The screened high-quality germplasm and the clarified nutritional differences among flax germplasm resources provide a scientific basis for flax breeding and the development of flax-based functional foods.