Studies on the Carotenoids

Determination of Vitamin A and Carotenoids in Butterfat. Spectroscopic Characteristics of Butterfat Fractions and Problems Involved in Biological Interpretations

“…They may be used with most spectrophotometers with a minimum possibility of error due to inexact wave-length calibration or to wide spectral regions isolated because the maximum of 8carotene occurs at 4525 Á. and the minimum of 8-carotene at 4675 Á. [also near the flat region of the neo-8-carotene curve (2) ].…”

Long-term preservation of carotene in alfalfa meal

“…One sample, after storage in darkness at 90°for 27 weeks, contained 365 ppm, indicating 98% retention of carotene. The characteristic curve (Beadle and Zscheile, 1942; Zscheile and Whitmore, 1947) of this sample was superposable on that of the original material at wavelengths of 400-500 nm, indicating negligible additional isomerization of the all-trons form of /3-carotene. Similar results were obtained on two other samples stored 35 and 55 weeks at 90°; characteristic curves of the carotene fraction were similar but had higher absorption at the shorter wavelengths.…”

“…After drying in a circulating hot air oven 2.5-4 hr, they were ground (to 40-mesh) and the meal was mixed. Analysis showed 374 ppm of carotene, primarily a mixture of all-irons-/3-carotene (81%) and neo-¡3-carotene (co. 19%) (Beadle and Zscheile, 1942).…”

Determination of Vitamin A and Carotenoids in Butterfat. Comparison of Direct Spectrophotometry with Filter Photometry and Use of the Antimony Trichloride Reaction

“…[This neo-beta-carotene probably consists largely of the isomer designated by Polgár and Zechmeister (11) as neo-beta-carotene B.] Significant quantitative differences in both wave length and intensity of absorption were found between these absorption curves and those presented for the same pigments in hexane solution (4). The curves for the two pigments in ether solution are coincident at 4370 Á.…”