Soybean oil extraction techniques were studied in which solvent was recirculated or pumped once through a suspension of soybean tissue. Both refractive index and ultraviolet absorbance were used to monitor the extraction continuously. Slices of soybean tissue showed rapid extraction from damaged tissue, followed by slow extraction from intact tissue. When soybean flakes were extracted, a continuously decreasing rate was noted. When solvent was forced through flakes, extraction was more rapid than when solvent was allowed to diffuse in and out of flakes. Reextraction of partially defatted flakes showed that the last soybean oil to be extracted was not inherently resistant to extraction. The adsorption of soybean oil to defatted flakes may account for slow removal of small quantities of oil at the end of the extraction.
A new method of total oil analysis is proposed in which the solvent was equilibrated with dissolved oil inside and outside of soybean particles rather than exhaustively removing all oil. By filtering, evaporating, weighing and multiplying by a factor (based on total miscella volume/sample volume) a satisfactory analysis could be done. Particle size was found to have a profound effect on amounts of oil in soybeans extracted by a conventional procedure. Sieving ground, dehulled soybeans into three particle sizes gave 15.3, 21.9 and 24.8% oil for >40 mesh, 40-100 mesh and <100 mesh, respectively, and 23.1% oil for the unsieved sample. Evidence is presented to support the idea that the amount of oil found in the smallest particle size was the true oil content of the soybeans analyzed. Using the equilibrium method to analyze the <100 mesh particles led to a rapid and economical analysis procedure. A comparison of the equilibrium and exhaustive extraction methods showed the exhaustive extraction gave a consistently larger oil content but less than 1% larger. The difference could be attributed to phospholipid.
Malate and citrate acidified juices produced statistically similar results for pH and titratable acidity FA), but these acidified juices were significantly different from nonacidified juice when comparing pH and TA. During storage time, the pattern of the pH and TA curves, regardless of acidification, were similar. Salted juice exhibited a significantly higher ascorbic acid content and greater viscosity than did the unsalted juice during storage. The organic acids citric, lactic, malic, and pyrocarboxylic increased immediately after heat processing for commercial sterility, while the presence of salt in this juice lowered these same organic acids. There was minimal correlation of the organic acids or the summation of the acid equivalents of all the organic acids to the titratable acidity or pH of the juices. Juices acidified with malate or citrate did not consistently display an increased level of that specific acid after processing and storage.
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