Amino Acid Composition and Nitrogen-to-Protein Factors for Grain Legumes

Abstract

Eleven grain legumes were analyzed for amino acids (AA), AA scores and essential AA indexes (EAAI). Nitrogen-to-protein (N:P) factors were determined from these data. Concentrations of AA per gram of nitrogen were relatively constant among species with the exception of the AA arginine, methionine, tryptophan and cystine which had coefficients of variation of 23–30%. On average, arginine, leucine, lysine, aspartic acid and glutamic acid accounted for 50% of the total of all AA. These grain legumes met adult human requirements for essential AA except for methionine and cystine which were deficient in all species. This resulted in an average AA score and EAAI of 56 and 89, respectively. The N:P factor was 5.6 for the 11 species but this value was 5.0 if corrected for nonprotein nitrogen.

Effect of Nitrogen Fertilizer on the Agronomic Performance and Seed Quality of Annual Canarygrass

“…Except as noted below, the profile observed in this study was similar to those reported for a range of cultivars by Robinson and The average N-to-protein factor over samples and years was 5.5 (Table 4). This value was similar to the average of 5.6 for seven cereals (Tkachuk 1969) or 11 grain legumes (Sosulski and Holt 1980) and to the 5.7 commonly used for converting Kjeldahl N to crude protein in cereals (Tkachuk 1969 The amino acid profrle of the caryopsis was similar to that of other cereals and the N-toprotein factor was 5.5.…”

Genetic diversity of physical, nutritional and functional properties of cowpea grain and relationships among the traits

“…On this basis, the range of crude protein contents in our previous study using 1541 genotypes, 17.5 to 32.5% (Boukar et al, 2011), is equivalent to 15.3 to 28.3%, within which our results from the 240 genotypes comfortably fit. A factor of 5.45 for cowpea (or 5.6 for grain legumes in general; Sosulski and Holt, 1980) will provide good estimates of crude protein content in cowpea. The AA compositions among the 20 genotypes show that the composition ratio of each AA was stable, although contents varied among genotypes depending on their total protein contents.…”

“…A factor of 6.25 is typically used to calculate the crude protein content from the N content of legumes, although much lower factors, ranging from 5.32 to 6.03, have been suggested (Sosulski and Holt, 1980;Fujihara et al, 2010). From the AA composition of the grain of the 20 genotypes, we calculated an average factor of 5.45.…”

Quantitative determination of the composition of individual pea seeds by fourier transform infrared photoacoustic spectroscopy

“…The total protein content was calculated following analysis of total nitrogen using a Perkin Elmer Nitrogen Analyzer model 2410 (ADAC method 7.016). For the peas, nitrogen content was converted to protein per unit weight using a factor of 5.4 (Sosulski and Holt 1980), whereas the more usual 6.25 factor remained in use for the pumpkin globulin.…”