Frank C. Pack

A halogenation method for the determination of the total unsaturation of tung oils and of eleostearic acids

SummaryA new modification of the Rosenmund-Kuhnhenn method has been developed for determining the total ethylenic unsaturation of tung oil and of eleostearic acids. With tung oils this method results in iodine values which are in agreement with those obtained by quantitative catalytic hydrogenetation and, in the case of α- and β-eleostearic acids, with the theoretical value. Good agreement was found with hydrogen-iodine values of various partially hydrogenetal tung oils. An essential feature of the method is the addition of mercuric acetate to the oil prior to the addition of the Rosenmund-Kuhnhenn reagent in contrast to the Benhan-Klee modification in which the Rosenmund-Kuhnhenn reagent is added first. The latter method gives iodine values for tung oil and for eleostearic acid approximately 8% higher than those obtained by quantitative catalytic hydrogenation. Light was found to affect the results obtained by both methods so greatly that use of low-actinic flasks, addition of the Rosenmund-Kuhnhenn reagent in a partially darkened room, and storage of the reactants in complete darkness during the reaction period (1 hour) is recommended.

A method for the determination of linoleic acid and conjugated dienoic acids in materials containing eleostearic acids

SummaryA procedure has been described which extends the scope of the spectrophotometric method for polyun-saturated acids to the determination of linoleic and conjugated acids in the presence of large quantities of conjugated trienoic acids.Basis for the proposed method rests on equations which are offered to correct the “end” or “back-ground” absorption of the highly absorbing triene conjugated acids at 233 mμ, the position of maximum absorption of conjugated dienoic acids and alkali isomerized linoleic acids. The method is limited to samples which do not contain nonconjugated trienoic acids (linolenic acids).The method has been tested by the analysis of several mixtures of cottonseed and dehydrated castor oils of known composition, to which varying amounts of alpha, beta, and mixtures of alpha- and beta-eleostearic acids have been added. These samples have been used to demonstrate the application of the proposed method for the determination of dienoic conjugated acids, alpha-eleostearic acid, beta-eleostearic acid linoleic acid, oleic acid, and total saturated fatty acids.Comparisons of the results obtained with similar values, calculated from the known composition of the mixtures, prove that the proposed method gives reasonable results. Standard deviations between determined and calculated results vary from 0.36 for diene conjugated acids to 1.40 for oleic acid.The method has been applied to the analysis of foreign and domestic tung oils.

The characteristics of domestic tung oils

ConclusionDomestic tung oil is a very uniform product as shown by the determination of the chemical and physical properties of 74 samples taken over three successive milling seasons.The refractive index, refractive dispersion, and heat test are correlated with the total eleostearic acid content, the correlation coefficients being 0.69, 0.73, and −0.62 respectively, which indicates that any one of these values can be taken as a rough measure of the elostearic acid content. The correlation of the eleostearic acid content with the Wijs and hydrogen iodine values was lower, 0.48 and 0.53, respectively. A correlation of −0.81 was found between refractive index and heat test.

Determination of the fatty acid composition of partially hydrogenated tung oils

SummaryRecently developed spectrophotometric methods for the determination of linoleic and conjugated dienoic acids in the presence of large amounts of eleostearic acid have been applied to the determination of the fatty acid composition of a series of progressively hydrogenated tung oils. Utilizing hydrogen-iodine values and independently obtained values for saturated fatty acids, it has become possible to calculate concentrations of isolinoleic and of monoethenoic acids. Use of these methods gives a more complete and accurate knowledge of the fatty acid composition of a partially hydrogenated tung oil, or mixture of other oils containing the same types of components, than has been obtainable by previously published spectrophotometric methods. They are also much less time-consuming than solvent fractionation methods.Data are presented which show the changes in fatty acid composition occurring during the hydrogenation (170°, 5 p.s.i.g. H2, 0.1% Ni) of a domestic tung oil from an iodine value of 231 to 78.

Dilatometric investigations of fats. VII. Melting dilation and polymorphism of an alpha and beta tung oil

SummaryThree polymorphic forms of beta tung oil have been recognized and differentiated on the bases of their melting points and x-ray diffraction spacings. These modifications, which melt at 52.8°, 44.4°, and 28.0°C., have been designated as Forms I, II, and III, respectively. Polymorphism was not observed in alpha tung oil.The expansibilities of alpha tung oil and the three original polymorphic modifications of beta tung oil have been determined in both the solid and liquid states, and the melting dilation of each substance was calculated. The absolute densities of the alpha and beta oils were determined, and the absolute specific volumes over the ranges of melting of all these substances were calculated and reduced to graphic form.Forms II and III of the beta oil irreversibly transformed to Form I with contraction in volume during dilatometric examination.The contents of solid and liquid phases of alpha and beta tung oils were calculated over the ranges of melting of these oils. The amount of glycerides in the liquid state was found to increase substantially during the final 10 degrees of the melting range.The isomerization of alpha to beta tung oil under ordinary laboratory illumination was found to be accompanied by a decrease in volume of about 4% and an increase in density. Isomerization in the absence of light reached approximate equilibrium with a decrease in volume of only about 60% of that occurring in the presence of light.

Effect of shell content and storage on expelling of tung nuts

Summary and ConclusionsExpeller tests were made on ground tung nuts containing all of the shell (33%) at the time of hulling and after the nuts had been in storage for one and two months. Comparative tests were also made on material containing about 24% shell which had passed through the disc huller in regular mill operation. One test was made on hand-shelled kernels which were entirely free of shell.It was found that meal containing all of the shell not only processed satisfactorily, but the recovery of oil from such material was somewhat higher than from material containing about two-thirds of the shell. The amount of oil expelled per hour was about the same in both cases. The kernels completely cleaned of shell expelled very inefficiently. In general, therefore, it seems that, with the particular type of expeller used, a considerable amount of shell in the meal is essential for efficient expelling.Bags of nuts with hulls removed but with the shells intact showed no deterioration after two months’ storage in a well-ventilated shed.

The effect of extended storage on the properties of tung oil

SummaryTung oil has been stored in clean, well-filled gallon containers for more than three years and at the end of that time still met A.S.T.M. specifications.Storage locale (indoor, outdoor, sheltered, or unsheltered containers) and the exterior coating on the containers in exposed locations were found to be of less importance than protection of the stored oil from atmospheric oxygen.The most pronounced effect of prolonged storage on tung oil is a shortening of the heat test (gel time at 282°C.).Uncontaminated tung oil does not spontaneously isomerize during storage.

Studies on the refractive index and dispersion of American tung oil

Conclusions1.Tung oil has a refractive index and a dispersion so far above those of any other common oil that both are valuable criteria for identification purposes. With proper equipment the dispersion, in addition to the refractive index, can be determined with little extra effort and would confirm the conclusions drawn from the refractive index.2.Mixtures of tung oil with another vegetable oil (except oiticica and other rare conjugated oils) can be analyzed to within 0.5% from the refractive index for either the sodium or the mercury line if the refractive indices of the separate oils are known. The mixtures can be analyzed from the dispersion to within about 1% of the correct composition if the dispersions of the separate oils are known. If the adulterating oil is not known the adulteration can be more closely estimated from the depression of the dispersion than from the depression of the refractive index.3.When tung oil is bodied by heat the refractive indices for the sodium and mercury lines and the dispersion fall rapidly and continuously to the point of gelation, but the changes are so similar that no worth-while additional information is obtained by determining more than one refractive index. The fact that refractive index decreases as viscosity increases suggests the use of the refractive index in controlling the bodying of tung oil.4.Other things being equal, the refractive index for the mercury line should give more accurate information on tung oil than that for the sodium line because of the greater changes in the refractive index for the mercury line upon adulteration or heating.5.A correlation coefficient of 0.83 was found for refractive index with the diene number of tung oil. A lower correlation coefficient was found for refractive index with the iodine number, but the latter would probably be higher if a more accurate method for the determination of the iodine number of tung oil were available.

The destruction of gossypol in cottonseed oil soapstock by a heat treatment

Summary and ConclusionsSuccessful operation of the apparatus, as described in this paper, was conducted at rates of feed that ranged from 1.89 to 5.51 Ibs. per hour. The data show that cottonseed oil soapstock can be heat-treated continuously on a pilot-plant scale so that both the free and total gossypol content, as measured by thep-anisidine method (2,3), are reduced to values as low as 0.003%. In the work reported, the heat transfer medium was oil, heated electrically. Commercially a direct, gas-fired, heat exchanger would be more practical. These experiments indicate that additional work on a larger or plant scale is justified, provided, of course, that the marketing economics involved are favorable.

Comparison of the whole fruit and component methods of analysis of tung fruit

SummaryThe effect of moisture content and fineness of grinding on the percentages of oil extracted by the whole fruit method were investigated and the results compared with those obtained by the component method.The spacing of the plates on the Bauer laboratory mill used for grinding whole tung fruit for oil analysis was found not to be critical within certain narrow limits. No differences were found in the oil content when samples of fruit were ground with plate spacings from 0.004 inch to 0.012 inch, but the results were lower with plate spacings of 0.020 inch.No difference was found in the percentages of oil obtained by the component and the whole fruit methods when the results were calculated on the basis of the original moist sample and no correction had to be applied in the calculation of the results by the whole fruit method.The average percentage of moisture obtained by the two methods differ, consequently care must be used in comparing oil contents calculated to a moisture-free basis since the differences in moisture content will be reflected in the values for the apparent oil content.Careful analyses of tung fruit by either the whole fruit or the component method yield reliable results over a wide range of moisture content although in the case of the component method unusually wet kernels (above 10% moisture) must be partially dried before regrinding in a mortar and pestle during the extraction operation.