R. S. McKinney

Preparation and some properties of tung oil monoglycerides

SummarySeveral methods for the preparation of tung oil monoglycerides were investigated. Products richest in both monoglyceride (78%) and triene conjugation (63% as eleostearic acid) were obtained by glycerolysis with sodium methoxide in pyridine solution. Attempts to increase the content of monoglyceride and triene conjugation by selective solvents were unsuccessful. The monoglycerides were effective in lowering the surface tension of water as well as the interfacial tension of several oils, including tung oil, against water. The tung oil monoglycerides behaved as fugitive emulsifiers and, after drying, retarded the removal of spray residue (lead arsenate) by washing with a water spray more than did other emulsifiers, such as cottonseed oil monoglycerides. The ammonium soap of tung oil fatty acids also acted as a fugitive emulsifier.

The analysis of tung fruit

Methods applicable to the routine analysis of tung fruits were developed by taking into account such factors as variation in moisture content of individual fruit, high oil content of the tung kernels and the high reactivity of the extracted oil. It was found that in a closed container the moisture distributes itself evenly between individual fruits, that the oil can be extracted completely from tung kernels if they are reground with sand, and that the moisture can be removed from ground tung kernels and the solvent completely removed from the extracted tung oil without deterioration in a vacuum oven at 100° C. with 28–29 inches vacuum.

Phosphatides in American soy beans and oil

SummaryIt has been found that the precipitate separating from clarified expressed crude oil from soy beans grown in North Carolina and Virginia is composed chiefly of phosphatides. Methods have been described for the determination of phosphatide phosphorus in soy beans which is applicable to seeds in general and in the oil. Soy beans of the more important varieties used by the oil mills both in the Eastern and Middle West States have been examined for their respective phosphatide content. With but few exceptions it was found that the beans grown in the East contained less phosphatides than those from the West, which indicated that the quantity of these substances present is not a factor in causing a partial separation of them in some oils but not in others. Regardless of whether or not a separation of phosphatides takes place, all the crude soy bean oils which have been examined so far have contained notable quantities of them.

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.

A further study on the composition of American tung oil with special reference to the linoleic acid content

The complete separation of elaeostearic acid from linoleic acid by the irradiation and crystallization of tung oil fatty acids was found difficult if not impossible. The application of several cold alkaline permanganate oxidation procedures to samples of tung oil fatty acids indicated the presence of less than one per cent of linoleic acid in tung oil. A study of the reaction of maleic anhydride with alpha elaeostearic, beta elaeostearic acid, and with the alpha elaeostearic acid glyceride present in tung oil showed that this reagent does not react with them quantitatively but only to 86.6 per cent of the theoretical amount. It was found that the elaeostearic acid content of a tung oil can be calculated by dividing its diene value by 78.4, the determined diene value of pure alpha elaeostearic acid. In this way it was calculated that two samples of American tung oil contained 85.5 and 89.4 per cent of elaeostearic acid. It was found that alpha elaeostearic acid and the mixed fatty acids from tung oil when exposed to the air quickly underwent a change to form an extremely sticky material whose use as an adhesive for insecticides will probably soon be determined.

A new procedure for the analysis of tung fruit

SummaryA new procedure for the analysis of tung fruit for oil and moisture content has been developed wherein it is possible to largely eliminate the sampling errors which occur in component procedure used in the past because of the relatively small samples used. Collaborative studies have indicated that to obtain results similar to those obtained in analysis by the component procedure a correction of 0.37% must be subtracted from the oil content obtained with the Wiley-Bauer ground fruit, but no correction appears to be necessary in the case of the Wiley-Raymond ground material.

California apricot oil

SummaryThe characteristics and the percentages of the fatty acids present in apricot kernel oil as glycerides have been determined. The oil studied was found to contain about 90.6 per cent of unsaturated acids consisting of a mixture of oleic and linoleic acids. The saturated acids amounted to about 3.6 per cent and were composed almost entirely of palmitic and stearic acids.Mention is made of the utilization of the press cake for the recovery of volatile oil, for fertilizer, and as a feed for livestock. An analysis of the press cake is given. A table of the smoking points for various fats and oils by the J. M. McCoy procedure is given for comparison with that of apricot kernel oil.In addition to the established use of the oil by cosmetic manufacturers, other possible outlets include its use as a salad and cooking oil, for the roasting of shelled nuts, and for the manufacture of soap.

Materials balance in a tung oil mill

SummaryWeights were determined and analyses made of tung fruit milled and of all products leaving the mill for two runs of about 90 tons each in a commercial mill under normal operating conditions. Dry matter, oil, and nitrogen in the fruit were satisfactorily accounted for in products leaving the mill, 101% of the oil being accounted for in each run. This showed that the methods of analysis and sampling were accurate.Losses occurred principally in particles of kernels occluded with the hulls and in the screw-press cake. Seventy-eight and 82% of the oil in the fruit was recovered as filtered oil.Repressing the filter-press cake by adding it back to the stream of ground nuts just before they entered the screw-presses was not proven to be economical as at the end of the run just as much cake was on hand, and it had as high an oil content as if no filter cake had been fed back through the screw presses. Only about half as much oil could be filtered per filtration cycle, resulting in an increase in cost of labor and a decrease in filtering capacity.The apparent oil content of the screw-press cake decreases by about 2% after four to eight days as compared to its apparent oil content at the time of pressing because of polymerization. Thus, screw-press cake samples should be analyzed for oil as soon as possible after extrusion.

Loss of oil in hulling tung fruit in the field and at the mill

SummaryMethods for analyzing commercial tung hulls for oil have been developed. Samples of tung hulls from mill and field hulling operations have been collected and analyzed. The loss of oil when the fruit are hulled was found to vary from 0.6% to 7.3% with an average loss of 2.7% based on the total amount of oil in the fruit. The difference in the loss of oil between grove and mill hulling was not significant. With a loss of 2.7% of the oil in hulling, a recovery of 87.9% oil on the hulled nuts would be equivalent to a recovery of 85.5% oil on the whole fruit.

Studies in the expression of oil from tung fruit

Summary1. Tests indicated that best results in yield of crude and filtered oil by an expression procedure are obtained with a tung meal containing 4.2% moisture and 20% shell.2. The drying of tung meal using an initial air temperature of 320° F. appeared to adversely affect the yield of filtered oil from the expeller process.3. A filtration test was developed for determining the amount of foots in a crude tung oil.4. It was found difficult to obtain efficient oil expression from tung meals containing filter cake; in one test with this material the resulting press cake was high in oil content, while in another test the crude tung oil contained about twice as much foots material as was present in crude tung oil from tung meal containing no filter cake.5. The expression of tung oil from a tung meal consisting of ground old tung kernels and tung shell was found difficult if not impossible. This difficulty appeared to be due, at least partly, to the fact that the meal from old kernels will not plasticize when subjected to heat and pressure. When these kernels were mixed with new kernels no difficulty was experienced in expressing the tung oil from the meal.6. Tests indicated that hulling the moist tung fruit in the grove does not interfere with the expression of the oil if the moist dehulled tung fruits are properly dried before pressing.7. A process was developed for producing a clear tung oil by treating the crude oil with a chemical agent to precipitate certain non-oil constituents in the crude tung oil followed by either pressure filtration or centrifugation.8. When tung oil filter cake was mixed with an equal amount of tung press cake, over 98 percent of the oil could be solvent-extracted by petroleum solvents.