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Fats ABSTRACTA method and instrumentation for measuring the solid fat content is reported that is both accurate and precise. It involves using transient nuclear magnetic resonance (NMR) measurements for determining the percentage of solids in commercial shortenings and hydrogenated oils at selected temperatures. The incorporation of a tempering step at 26.7 C for all samples before measurement has improved the precision of the solids content actually measured (+-0.2% solids) which approximates that of dilatometry. Duplicate measurements are not required to obtain this precision. The instrument is equipped with six 10-mm sample holders in combination with a precise variable temperature accessory system which eliminates the temperature difference between the sample and sample holder. This improved and exact temperature conditioning of samples provides better sample stability and easier handling for routine conditions of analysis. A single temperature result can be made in less than 1 hr and typical 5 temperature results obtained in 2.5 hr. Our work also indicates that temp e r i n g does influence results, the net effect being to decrease the amount of solids at temperatures less than the tempering temperature. In comparing the pulsed NMR measured solids with these measured by dilatometry, differences between methods of measurement are minimized when samples have had the s a m e tempering and temperature history. This method provides flexibility, speed, and increased sample throughput of up to 60 samples/day. The selfcontained equipment requires only 9 sq ft of space and is ready for measurements within 45 rain after start-up.

A procedure is described for the accurate analysis of thetrans content of fats and oils in the range of 0.5–36%trans. This procedure is shown to be more accurate than other current infrared spectrophotomeny methods. This increased accuracy is obtained by using a 2‐component calibration standard mixture and measuring the samples as methyl esters. Good agreement between this method and the measurement oftrans content by a gas chromatography procedure is demonstrated.

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A new method is described for the determination of caffeine in coffee, based on high-pressure liquid chromatography. The caffeine is extracted from the sample with water and/or methylene chloride, and then separated from interfering materials by passing an aliquot of the extract through a high-pressure column containing sulfonated cation exchange resin, using 0.01M nitric acid as the mobile phase. An ultraviolet detector measures the absorption of the solution directly. The method is rapid and eliminates the lengthy separations common to other methods. The procedure was applied successfully to decaffeinated and non-decaffeinated green, roasted, and instant coffees. This method gives a more accurate measure of the caffeine content in decaffeinated coffee samples than the micro Bailey-Andrew and modified Levine methods, with equal or better precision. This method gives results equal to those obtained by the official methods for non-decaffeinated samples.