Amino Acid and Elemental Composition of Sunflower and Pumpkin Seeds1

Abstract

AbstractThe research was undertaken because knowledge of the amino acid and elemental composition of sunflower (Helianthus annuus L.) and pumpkin (Cucurbita pepo L) seeds is meager and incomplete. Yet, in contrast to their present use as snacks, both species are widely‐adapted crops of potential use for staple human food. Seeds of the two species were evaluated as foods, to meet major protein and mineral requirements of adult humans. Sunflower cultivars used for birdfeed, human food, and oil were analyzed to discover differences and similarities. Nitrogen percentage to protein percentage conversion factors for various products are commonly based on the N percentages of their major isolated proteins. A single factor (6.25 or 5.30) is used for sunflowers and pumpkin. Using amino acid analyses from this research, a different N to protein conversion factor was calculated for each species.Sunflower seeds for analyses were harvested from cultivar trial plots grown at four locations for 1 to 4 years. Soils were Typic Hapludoll, Aeric Calciaquolls, and Typic Eutroboralf. ‘Lady Godiva’ pumpkin seeds were harvested for 2 years at Rosemount, Minn. Concentrations of oil were determined by the Soxhlet method, of N by the Kjeldahl method, of other elements by an emission spectrograph, and of amino acids by an automatic amino acid analyzer.Analyses for 18 amino acids and for 15 elements indicate that < 400 g of either sunflower or pumpkin seeds will supply the total daily protein and mineral requirements, other than Ca and Na, for adult humans. Good nutritive value and simple storage and processing requirements make sunflower seeds a potentially important human food. Sunflower seeds of nonoilseed cultivars were significantly higher than ‘Peredovik’ oilseed cultivar in total protein and in concentrations of 16 amino acids and nine elements. Sunflower pericarps had lower concentrations of oil, protein, ash, and 8 of 15 elements than those of the seeds. Factors to convert N percentage to protein percentage were calculated by dividing 100 by the percentage N in the total amino acids of the seed. The factors for all seed‐lots within each species were nearly identical (6.10 for sunflower and 5.65 for pumpkin). These are better estimates of N conversion values than the single factor presently used for both species.