Interlaboratory comparison of soybean protein and oil determinations

Abstract

Iowa State University coordinated an interlaboratory comparison study of Kjeldahl protein and ether oil extraction methods. Blind duplicates of 10 clean, single‐variety soybean samples were sent to 30 laboratories grouped in 3 categories of 10 each in public (government and university), commercial and processor facilities. Five of the commercial laboratories were AOCS‐certified. Standard deviations among laboratory means across all samples were 3.87 and 1.82 percentage points (dry basis) for protein and oil, respectively (0.48 and 0.27, respectively, for the AOCS‐certified laboratories). The average differences between blind duplicates of a sample were 0.71 percentage points for protein and 0.87 percentage points for oil (0.28 and 0.45, respectively, for the certified laboratories). Average standard deviations across laboratories on an individual sample were 2.37 and 1.71 percentage points for protein and oil, respectively (1.87 and 0.99, respectively, for the certified laboratories.

Soybean Seed Quality Characteristics in Response to IndigenousBradyrhizobiumInoculation and N Fertilization in Kashmir–Pakistan

“…N at the rate of 25, 50 and 100 kg N ha −1 designated as N 25 , N 50 and N 100 , seven indigenous Bradyrhizobium strains isolated from the native soil, i.e. NR 4 , NR 13 , NR 18 , NR 20 , NR 22 , NR 25 and NR 35 , an exotic Bradyrhizobium japonicum strain TAL102 and an un-inoculated control. Altogether a total of 12 treatments were used in the experiment.…”

“…This analysis was carried out at Oil-grain Quality Lab, Crop Breeding Division, Nuclear Institute of Food and Agriculture, (NIFA), Peshawar, Pakistan. Seed oil content was determined according to standard method [21] and method described earlier [22]. Ground seed was placed into an extraction thimble, and the oil was extracted using Soxhlet extraction apparatus with n-hexane for 6 h. The solvent was then evaporated using rotary vacuum evaporator, and the remaining oil was weighed.…”

“…Bradyrhizobium inoculation and N fertilization significantly increased oil content compared to the un-inoculated control. The seed oil content varied between 16.2 and 21.5 %, highest in the seeds treated with indigenous Bradyrhizobium strains NR 22 , NR 25 and NR 35 , and mainly composed of linoleic acid (47 %), and oleic acid (24 %). Inoculation and N fertilization both decreased the saturated fatty acids (palmitic and stearic) and increased unsaturated fatty acids (linoleic acid and oleic acid).…”

“…The mineral nutrient content of N, P, and K and their accumulation in seed increased by 2-3-fold compared to the corresponding control. Indigenous Bradyrhizobium strains were able to generate the highest values for seed oil content (NR 22 , NR 25 , and NR 35 ), unsaturated fatty acids, i.e. linoleic acid and oleic acid (NR 25 , and NR 35 ) and N, P and K uptake (NR 20 , and Soybean cultivation in Pakistan remained limited to a very small area and therefore has not been able to attain a respectable position among the oilseed crops of the country.…”

Determination of oil content in oilseeds by analytical supercritical fluid extraction

“…The analytical determination of oil content in oilseeds has been traditionally accomplished through the use of a Soxhlet-based extraction method with organic solvents as the extraction medium (1)(2)(3). An excellent review of the methodology that has evolved is provided by Lumley and ColweU (4), including the plethora of solvent systems that have been utilized in oil/fat determinations.…”