Survey of soybean oil and meal qualities produced by different processes

Soybean oil and meal produced by extruding-expelling (E-E) are believed to have unique characteristics compared with products produced by solvent extraction (SE). A survey was conducted to compare quality characteristics of the;oils and meals produced from different types of soybean processing methods. Soybean oil and meal samples were collected three different times within a l-yr period from 13 E-E mills, 8 SE plants, and 1 continuous screwpress (SP) plant. Properties of oil and meal varied considerably between different types of plants and among plants of the same type and sampling times. In general, settled crude E-E and SP oils had significantly greater peroxide values than those of SE oils. E-E oils contained less free fatty acid and phosphorus than did SE and SP oils. The oxidative stability (AOM) of E-E oil was less than that of SE oil, and that of SP oil was intermediate. E-E and SP meals had higher oil and lower protein and moisture contents than those of SE meals. Protein dispersibility indices were lower for E-E and SP meals. Protein solubilities in KOH were similar for E-E and SE meal, but higher than that of SP meal (62%). Rumen bypass protein values were higher for the SP meal.