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The lipid component of orange juice has received considerable attention because of its possible influence on flavor changes which develop in the canned juice during storage. Several investigators (2,4,5, 7,8,9,10,11) have presented analytical data, both qualitative and quantitative, on this fraction. Huskins, Swift, and Veldhuis ( 4 ) analyzed the lipids from canned pasteurized orange juice stored for 2 years under normal climatic conditions at Winter Haven, Florida (annual mean temperature about 22°C.). They found that the phosphorus had decreased to one-tenth of its original value and the nitrogen to one-fifth, choline having entirely disappeared. Also, the amount of lipid which could be extracted from the stored juice had decreased. They concluded that the phosphatides had hydrolyzed and that the choline and ethanolamine, as well as part of the phosphorus, had been lost to the aqueous phase of the juice. These investigators also noted changes in the fatty acid constituents, which could have been the result of oxidation. I n this previous work, no attempt was made to establish whether these changes occurred rapidly o r slowly. The present analyses of the lipid from pasteurized, stored Valencia orange juice were carried out to study this question. Attention was given only to the changes in the phosphorus, nitrogen, and fatty acid constituents. EXPERIMENTAL Extraction of lipids. Fresh Valencia orange juice was obtained from a local cannery in 1950. I n the laboratory i t was mixed, pasteurized at 88"C., canned, and quickly cooled.About one-third of the cans were held at 0-5°C. for 2 days until the lipid could be extracted. The extraction was carried out by passing the juice through an Oliver Precoat filter and then extracting the lipid from the filter-aid with acetone as described by Huskins, Swift, and Veldhuis (4,5). The solvent was evaporated and the lipid taken up in petroleum ether. This step eliminated the water which the acetone also extracts from the damp filter-aid. The petroleum ether solution of the lipids was then stored under refrigeration (0-5°C.) until the analysis could be made.After storage periods of 6 and 13 months, portions of the stored juice were processed f o r lipids as outlined above.Prior to analysis, the petroleum ether solutions of the lipids were treated as follows: each solution, in a 3-necked flask equipped with a mechanical stirrer, condenser, and vacuum gauge, was warmed over a steam bath to evaporate most of the solvent at atmospheric pressure. Then the flask was immersed in cold water, the stirrer was started,The remaining two-thirds of the cans were stored in the laboratory loft.

Earlier investigations at this laboratory (3,5) demonstrated that changes occur in the lipid fraction of pasteurized orange juice during storage, but did not show whether any of these vere due to pasteurization. Since pasteurization is a time-temperature treatment like storage, although employing a higher temperature for a shorter time, it might conceivably produce similar effects. One of the possible explanations of differences in the flavor of pasteurized as compared to the flavor of fresh orange juice might be compositional changes in the juice lipids-probably in combination with loss o r change in the volatile flavoring constituents during heating; caramelizatioii of the sugars ; reactions involving sugars, acids, amino acids, ascorbic acid, and proteins.The purpose of this paper is to compare analytical data on the compo-&ion of the lipids from fresh orange juice and from the same juice almost immediately after pasteurization. EXPERIMENTAL Preparation of lipids. The fresh Valencia orange juice was obtained from a local processing plant during the 1950 season. In the laboratory, it was mixed and divided into 2 equal batches. One batch was pasteurized at 90.4"C., canned, cooled quickly, and placed in storage at 2-5°C. for 2 days until the lipid could be extracted. The fresh juice was processed promptly.Lipids were extracted from the batch of fresh juice and later from the pasteurized juice using the procedure described by Huskins, Swift, and Veldhuis (3). The juice was passed through an Oliverb filter and the lipids were extracted from the material retained in the filter cake with acetone. This solvent was then removed by evaporation and the lipid taken up in petroleum ether. This step eliminated the water that had been extracted from the damp filter cake. The petroleum ether solution of the lipids was placed in a 3-necked flask equipped with a stirrer and condenser. After most of t h e petroleum ether had been distilled at atmospheric pressure, the flask was immersed in cold water, the stirrer was started, and vacuum connected. The water bath was heated slowly (45 minutes) to boiling and f o r 15 minutes thereafter. During this time t h e lipid was stirred continuously and the vacuum was maintained at 10 mm. of mercury. Ice water was circulated through the condenser and a dry ice t r a p was placed in t h e line between the vacuum pump and the condenser. During this vacuum process of drying the lipid, a small amount of fragrant volatile liquid was retained in the dry ice trap. This substance was only slightly soluble in water and had a spectral absorption maximum of 244 mp. It was not identified.Analytical methods. Samples of the lipids were saponified and the unsaponifiable matter was determined according to the Eerr-Sorber method. The f a t t y acids were extracted from the acidified aqueous residue with petroleum ether. Aliquots of the aqueous solution remaining were used for the determination of the resin acids, referred t o b y "One of the laboratories of the Bureau of Agricultural and Industrial Chemist...