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

Zscheile, F. P.; Henry, R.L.; White, Jonathan; Nash, Harold A.; Shrewsbury, C. L.; Hauge, S. M.

doi:10.1021/i560127a016

Cited by 11 publications

(3 citation statements)

References 13 publications

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“…A bioassay comparison with the proposed spectrophotometric procedure on the three samples which were available showed fair agreement (see Table III). Similar agreement was obtained by Zscheile et al (16) on samples of butterfat analyzed by spectrophotometric methods, using a somewhat similar arbitrary correction factor. The comparison with the bioassay is made assuming that the vitamin A has a potency of 4,300,000 U.S.P.…”

Section: Discussionsupporting

confidence: 87%

Determination of Vitamin A in Dehydrated Eggs

Schrenk¹,

Chapin²,

Consad³

1944

Ind. Eng. Chem. Anal. Ed.

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Section: Discussionsupporting

confidence: 87%

Determination of Vitamin A in Dehydrated Eggs

Schrenk¹,

Chapin²,

Consad³

1944

Ind. Eng. Chem. Anal. Ed.

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“…Studies on the spectrophotometric and colorimetric estimations of vitamin A and carotenoids in butterfat (141,394,395) indicate that accurate correction cannot be made for the interference of carotenoids at the absorption maximum corresponding to preformed vitamin A. Correction for the blue color resulting from carotene involves certain arbitrary assumptions and errors-for example, failure to take account of isomerization and differences in the biological activity among the carotenoid pigments.…”

Section: Vitaminsmentioning

confidence: 99%

Food

Oser¹

1949

Anal. Chem.

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THE ultimate objectives of the food analyst and the variety of techniques employed to achieve them make this branch of chemistry particularly fascinating. The analytical methods of the food chemist may be applied in the development and enforcement of standards of identity, purity, or value; in problems of decomposition or spoilage under either normal or abnormal storage conditions; in studies designed to improve or control the quality of natural or processed foods; or in the determination of the nutritive value of foods for scientific, dietary, or labeling purposes. Interest in many of these objectives stems directly or indirectly from our federal and state food laws which are probably '

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“…The linearity of the ' subtraction curve' (26,27) from a number of these solutions over the range 310-5-335-5 m/x indicated that Morton & Stubbs's equation might be employed to determine irrelevant absorption, and it was found that 8-12% (average 10-0%) of the absorption at 325 m^x after filtration was irrelevant. In view of the failure of Zscheile et al (14) in their endeavour to purify the extract from butterfat residues, no further attempts to eliminate the colourless interfering compounds were made other than by exposing the filtered solutions to ultra-violet light (see later).…”

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confidence: 99%

399. The estimation of vitamin A in butter: A critical study of methods

McDowell¹

1949

Journal of Dairy Research

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1. The Lovibond Tintometer has been found more reliable than either the Pulfrich Photometer or the Spekker Absorptiometer for the assessment of the blue colour from the Carr-Price test on butterfat unsaponifiable residues.2. Using a Beckman Spectrophotometer, vitamin A in butterfat unsaponifiable residues has been estimated also by the intensity of absorption at 325 mµ. From spectrophotometric readings at this wavelength and at 450 mµ, the irrelevant absorption, due both to carotenoid and non-carotenoid compounds, may be calculated as follows:Corrected density reading at 325 mµ = 9/10 (A – 12/100B),where A = density reading of the unsaponifiable residue in petrol ether at 325 mµ, B = density reading of the same solution at 450 mµ.3. The Morton & Stubbs equation for irrelevant absorption in fish-liver oils is not generally applicable to butterfat unsaponifiable residues.4. A comparison of the vitamin A content of butterfat samples by the Carr-Price test and by the direct spectrophotometric method has shown a reasonably good agreement between the two values.

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

Cited by 11 publications

References 13 publications

Determination of Vitamin A in Dehydrated Eggs

Determination of Vitamin A in Dehydrated Eggs

Food

399. The estimation of vitamin A in butter: A critical study of methods

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