Kenneth L. Simpson

Use of reversed-phase high-performance liquid chromatographic analysis for the determination of provitamin A carotenes in tomatoes.

The usual methods for provitamin A evaluation of foods convert the total pigment amount, determined spectrophotometrically, into vitamin A units. Since the totally inactive lycopene is the major carotenoid in the tomato, such readings result in erroneously high provitamin A values. In view of the recent development of chemically bonded, reversed-phase, microparticulate packings and their use in high-performance liquid chromatography which combines highly accurate and reproducible resolution with the speed and ease of operation, a new method using such a system was developed to isolate carotenoid pigments from tomato samples. A 15-min column separation was thus achieved, dramatically decreasing the analysis time of the classical open column chromatographic procedures, which often result in unresolved and altered fractions due to long-term exposure to oxygen, light, solvents and sometimes adsorbent. beta-Carotene and lycopene were determined and quantitated in six tomato samples. beta-Carotene, 100% vitamin A-active, was expressed in International Units of vitamin A. The newly developed method gives a more reliable evaluation of the fruit potency in vitamin A than the methods of the Association of Official Analytical Chemists currently used for food composition tables.

Growth response of Tilapia zillii fingerlings fed isocaloric diets with variable protein levels

Abstract Six purified casein diets within a range of 21–53% crude protein were fed for 3 weeks to young tilapia (Tilapia zillii) to determine the optimum protein requirement and protein: energy ratio for growth. Growth rate increased proportionally to protein level of the diet to an incorporation rate of about 35%. Beyond this a gradual retardation in growth rate was observed. The diet containing about 30% crude protein with a protein: energy ( P E ) ratio of 81, however, appeared to be more efficiently utilized by the fish in terms of protein deposition and energy retention than diets with higher levels of crude protein. These results indicate that Tilapia zillii requires about 35% protein in the diet for optimum growth while 30% for the maximum bodily protein deposition when casein is used as the sole source of protein. All six diets, however, showed an excellent feed conversion. Protein efficiency ratio (PER) decreased with the increase in protein in the diet.

Metabolism of astaxanthin in the rainbow trout (Salmo gairdneri)

Abstract 1. 1. Astaxanthin, lutein, 3′-epilutein and zeaxanthin were isolated from rainbow trout fed racemic astaxanthin. 2. 2. The results showed that astaxanthin was converted to zeaxanthin but that it was not converted to vitamin A1 or A2 in vitamin A-sufficient trout. 3. 3. Fish fed a vitamin A and carotenoid-devoid diet in 35 days and then force-fed astaxanthin showed an increase in vitamin A. 4. 4. Strips of duodenum or everted sacks of trout intestines converted H3 astaxanthin to retinol (12.3% in the duodenum—3% in the ileum).

Chemical Changes in Natural Food Pigments

This symposium is structured around the chemical changes in food processing. While some of these changes are beneficial, most result in lowered quality. Nowhere is a change more apparent than one involving a change in pigmentation. This may result in a change in intensity as in bleaching of a food or a hue change resulting in off-color. Even if the color change is the only change, that difference could be sufficient for consumer rejection. Color also plays a role in product identification. Fabricated products, soda, candies, etc., and natural products such as trout and salmon are identified on the basis of color even though color affects only the visual appearance and is only related to diet as in the case of the salmonids.

Effects of various diets on the nutritional value of Artemia sp. as food for the prawn Penaeus monodon

The nutritional value of Artemia sp. as food for marine fish and crustacean larvae has been linked to the level of its polyunsaturated fatty acid (PUFA) content. Experiments in August 1984 were conducted to determine the effects of various artificial diets and algae on fatty acid composition of PUFA-deficient Artemia sp. (Utah GSL strain) and their resulting value as food for postlarvae of the prawn Penaeus monodon (Fabricius). Nauplii of the brine shrimp were grown on extracts of corn, copra, soybean and rice bran containing precursors (C18) to long-chain PUFA and also on algal species containing different levels of long-chain PUFA (C20). The nauplii were then used as food for P. monodon postlarvae. The results revealed that absence of C20 polyunsaturates from the feeds and their presence in the algae were reflected in the polyunsaturated fatty acid content of the tissues of Artemia sp. When fed with brine shrimp fed on algae, P. monodon displayed better postlarval survival and significantly higher growth; related to the content of polyunsaturated fatty acids in Artemia sp. A practical feeding approach in prawn hatcheries would be to grow Artemia sp. on a cheap diet such as rice bran, and then to enhance its nutritional value with a diet high in PUFA prior to harvesting, in order to improve hatchery production.

The biosynthesis of astaxanthin- XVI. The carotenoids in Crustacea.

Abstract 1. 1. The carotenoids were isolated from seven species of Crustacea. 2. 2. Astaxanthin was the most prominent pigments in both carapaces and internal organs. 3. 3. Other pigments isolated include β-carotene, echinenone, canthaxanthin, lutein, zeaxanthin, 3-hydroxy-canthaxanthin and 3,3′-dihydroxy-ϵ-carotene.

Effect of dimethyl sulfoxide (DMSO) on the biosynthesis of carotenoids in detached tomatoes

Abstract β-Zeacarotene was isolated from the tomato fruit. Treatment with DMSO resulted in reduction of the total carotenoid content of the ripening fruit. The synthesis of phytoene, phytofluene, ζ-carotene, and lycopene was inhibited. The levels of β-zeacarotene, γ-carotene, and β-carotene remained essentially unchanged. Two possible modes of action of DMSO are discussed.

The isolation of a poly-cis ζ-carotene from the Tangerine tomato☆

Abstract A contaminant of the β-carotene fraction of Tangerine tomato fruit extract was isolated and identified as a poly-cis isomer of ζ-carotene. The ripening fruit contains 0·8 μg/g dry weight of the pigment. The possible role of poly-cis ζ-carotene in the biosynthesis of poly-cis carotenes is discussed.

Effect of CPTA and cycocel on the biosynthesis of carotenoids by Phycomyces blakesleeanus mutants

CPTA and cycocel cause accumulation of lycopene and γ-carotene, simultaneously inhibiting the formation of β-carotene and β-zeacarotene in Phycomyces blakesleeanus mutant strain C115. Phytoene synthesis is enhanced. CPTA is more effective than cycocel. Kinetic studies show that with increasing concentrations of CPTA, lycopene and γ-carotene increase with the concomitant decrease in β-carotene, the total of these three carotenes being almost equal to β-carotene present in the control. When CPTA-treated mycelium is washed free of the chemical and resuspended in phosphate buffer solution containing 2·5% glucose (pH 5·6), β-carotene is formed at the expense of both γ-carotene and lycopene. β-Zeacarotene, which is not present in the mycelium, reappears upon resuspension. These results indicate that CPTA is inhibiting the enzymes causing cyclization both at neurosporene and lycopene levels. Studies on the effect of CPTA on the high lycopene mutant strain C9 reveal that with increasing concentrations of the compound, lycopene increases slightly and both β-carotene and γ-carotene decrease. Phytoene synthesis is stimulated up to a certain level of CPTA and then becomes steady. In the albino mutant strain C5, there is a slight increase in phytoene formation on the addition of CPTA to the medium. No other carotenoid is formed, suggesting that CPTA cannot remove the block caused by genetic mutation and exerts its influence in an already existing biosynthetic pathway.

Isolation and identification of 2-hydroxyplectaniaxanthin from Rhodotorula aurantiaca

Abstract A new trihydroxyl carotenoid has been isolated from the yeast Rhodotorula aurantiaca (Saito) Lodder C.B.S. 317 and identified as 2-hydroxyplectaniaxanthin (3′,4′-didehydro,1′,2′-dihydro-β, ψ-caroten-2,1′,2′-triol). Its m.p., partition coefficient, Rf, extinction coefficient, ms and NMR spectra are reported. Since the hydroxyl group at C-2 of the β-ionone ring is unusual, a possible mechanism for the biosynthesis of this carotenoid has been proposed.