James C. Kuck

Bleaching of off-colored cottonseed oils

The adsorption of fixed red pigments from refined off-colored cottonseed oil by several adsorbents is described by the empirical Freundlich adsorption isotherm. Numerical values for the coefficient and the exponent in the Freundlich equation were determined for several oils and several adsorbeuts. Activated alumina was found to be a superior adsorbent for removing the red color bodies. It was observed that the variations from oil to oil in the numerical values of the coefficient and the exponent of the Freundlich equation were smaller for the several aluminas than they were for the other adsorbents studied. The particle size and moisture contents of the alumina, and the temperature of activated adsorption were of importance in determining the effectiveness with which the red color bodies were removed from the oils. The conditions required for optimum bleaching with alumina had no detectably adverse effect on oil quality.

Effects of cyanide on peanut lipoxygenase

Acidic and alkaline lipoxygenase isozymes were separated and assayed for activity while incubated in the presence of various concentrations of cyanide. Inhibition due to cyanide per se was not found. Instead, cyanide caused an increase in pH, which decreased the activity of the acidic isozyme to a rate corresponding to the same pH on the activity curve for the cyanide-free reaction.

Reactivation of alumina used in bleaching of off-colored cottonseed oils

Spent alumina recovered from bleaching cottonseed oil with activated alumina can be reactivated by simple incineration at 400–700°C. and remoistening to at least 10% moisture content. The cycle of bleaching and regeneration may be repeated indefinitely with only nominal mechanical losses of alumina. Losses of refined oil by entrainment in activated alumine need be only 0.5%.

Lysine, gossypol, and nitrogen solubility in chemically treated cottonseed meals

The effects of treatment of commercial prepress-solvent extracted and direct-solvent extracted cottonseed mares with several chemical agents and solvents were studied. The analytical results for “free” and “total” gossypol of the finished meals show that treatment with aliphatic amines, followed by extraction with a suitable solvent, removed large proportions of the “free” as well as “bound” gossypol. This reduction of “free” and “bound” gossypol was accompanied, in some experiments, by an increase in the nitrogen solubility and available lysine, as compared with the results obtained with the untreated air-dried marcs. The available lysine contents of the treated mares was significnatly correlated with the nitrogen solubility in 0.02N aqueous NaOH.

Bleaching of refined cottonseed oil with modified alumina adsorbents

Activated aluminas, modified by treatment with inorganic and organic acids were tested for their efficiency as bleaching agents and for their ability to eliminate the response of refined cottonseed oil to the Halphen test. The best of these adsorbents, an alumina containing catalytic amounts of adsorbed sulfurous acid, is a bleaching agent that is effective in removing problem pigments from offcolored cottonseed oils, and is superior to activated aluminas in removing green chlorophyll-like pigments. Oils bleached with the catalytic adsorbent are negative to the Halphen test, and are free of sulfur.Study of the rate of reduction in the Halphen test response as a function of bleaching time and temp indicated that sulfurous acid treated alumina has a pronounced catalytic effect. The Halphen test response is eliminated during a 30 min bleaching period at 225C. Deodorization conditions employed had little effect on Halphen test reduction.

Determination of amine or amide nitrogen in vegetable oils

A procedure is described for the determination of small amounts of amine or amide nitrogen in vegetable oils. Amines are extracted quantitatively from the oil after it is treated with aqueous HCl and steam. Nitrogen then is determined in the aqueous extract by the Kjeldahl method.

Physical and chemical properties of alumina bleached cottonseed oil

No detectable amount of polymerization or triene conjugation occurred on bleaching refined cottonseed oil with either activated alumina or with sulfurous acid-treated alumina, although insignificant amounts of diene conjugation andtrans- isomerization occurred. AOM stability, tocopherol content, and fatty acid composition, as determined by gas-liquid chromatography (GLC), were comparable with values obtained with oil bleached with natural earth. Hydrogenation of the oils proceeded normally. Taste panel evaluations of the deodorized oils revealed their flavor stability to be equal to that of the same oil bleached with AOCS official earth.