Reversed phase HPLC analysis of α- and β-carotene from selected raw and cooked vegetables

Traditional AOAC colorimetric procedures for carotenoid analysis are known to lack specificity and accuracy. Newer HPLC methods provide the investigator with a more precise tool for carotenoid quantification in foods and tissues. In the present studies, reverse phase HPLC was utilized to evaluate the - and -carotene content in raw and cooked leaves of lettuce, spinach and winged bean as well as in the carrot root. The vegetables were boiled or steamed and the true retention of - and -carotene in the cooked products was determined. Boiling for 30 minutes resulted in a 53 and 40% loss of -carotene from lettuce and carrots, respectively. Full retention or even an increase in -carotene content in boiled winged bean leaves and spinach was noted. Steaming resulted in very good retention of - and - carotene in all vegetables (83–139% retention). Thus, although cooking procedures (especially boiling) may result in oxidative loss of carotenoids in some vegetables, heat treatment increases the chemical extractability of - and -carotene in others. The presence of carotenoproteins in some vegetables may effect the heat stability of extractability of - and - carotene.     

Effect of traditional open sun-drying and solar cabinet drying on carotene content and vitamin A activity of green leafy vegetables

Dried green leafy vegetables constitute a major dietary source of provitamin A carotenoids for people living in semi-arid areas of Tanzania. In the present study, eight vegetable varieties commonly consumed in these areas were either traditionally sun-dried or solar-dried, and the amount of provitamin A carotenoids were determined by HPLC. In the fresh blanched leaves, the contents of -carotene, -carotene, 9-cis--carotene and 13-cis--carotene were in the range of 526–917, 12–39, 80–136 and 16–40 g/g dry matter/basis; dmb, respectively. The average amounts of all-trans--carotene in the leaves after blanching, solar drying and open sun-drying were 662, 502 and 353 g/g dmb, respectively, all significantly different from each other (p <0.001). The average amounts of all-trans--carotene were 21, 15 and 8 g/g dmb (p <0.05) and of 9-cis--carotene 101, 82 and 63 g/g dmb (p <0.05) in the blanched, solar-dried and open sun-dried samples, respectively. Estimation of the amount of retinol equivalents provided by the dried vegetables for preparation of an edible portion of 100 g relish showed that solar-dried vegetables contributed more (between 120–275%) than the recommended level of vitamin A, and on average 43% more retinol equivalents than relishes of open sun-dried vegetables.Thus, it is concluded that the amount of provitamin A-carotenes in traditionally treated vegetables were highly reduced by open sun-drying while solar drying resulted in significantly more retention of the carotenes. All-trans--carotene and 9-cis--carotene were similarly affected as all-trans--carotene by the two drying methods. Consumption of a 100 g portion of solar-dried vegetable relish could provide the recommended daily intake of vitamin A.     

Levels of β-carotene and effects of processing on selected fruits and vegetables of the arid zone of India

Some locally available fruits and vegetables of the arid zone of Rajasthanwere analyzed for their -carotene content; the selected fruits and vegetables were: Dansra (Rhus myserensis), Kachri (Cucumis collosus), fruit Kachri (Cucumis collosus), Kair (Capparisdecidua) and Sanghri (Prosopis cineriria). The -carotene contents of the samples were estimated in fresh and various processed states (blanched, dried and roasted). The results showed the heat lability of -carotene. Among the samples, kair was found to be the richest source of -carotene. Variety, too, had an impact on the content of this fat soluble vitamin.     

Spirulina as a source of vitamin A

Experiments were carried out to assess spirulina fusiformis — a blue green algae as a source of vitamin A in rats. In one experiment, the control rats were fed synthetic vitamin A and the experimental rats spirulina as the sole source of vitamin A. The liver vitamin A concentration of spirulina-fed rats of both sexes was found to be significantly higher than that of the control rats. In another experiment the absorption of carotenes from the solvent extract of spirulina and their availability (vitamin A value) as judged by the levels of vitamin A and carotene in plasma and liver were compared with those of synthetic -carotene or vitamin A in male rats. The absorption of -carotene from spirulina extract tended to be lower than that of crystalline -carotene at doses of 550 and 1100 g of -carotene. The difference became insignificant at lower -carotene dose of 275 g.Spirulina carotene-fed rats did not show a strict dose related increase in the liver or serum vitamin A concentration. The liver vitamin A storage and plasma levels of vitamin A of spirulina carotene-fed rats was much hither than expected. The results of the two studies reported suggest that the algae spirulina can be a valuable source of vitamin A.     

Utilization of β-carotene fromSpirulina platensis by rats

The availability of -carotene from Spirulina as compared to standard all trans -carotene was studied by the liver and kidney vitamin A storage method. After 21 days of vitamin A depletion, the rats were repleted with -carotene from Spirulina and a standard source at two dietary levels (60 and 120 µg/day) for a 10 day period. At lower levels, the liver storage levels of vitamin A and the percent of -carotene absorption were comparable to those of the standard. At higher levels both these parameters of the Spirulina fed group were significantly (P<0.01) inferior to the standard source fed group. However, the Spirulina fed group showed better (P<0.05) growth than the standard fed group did at both low and high levels of feeding.     

Effect of home processing on ascorbic acid and β-carotene content of spinach (Spinacia oleracia) and amaranth (Amaranthus tricolor) leaves

The present investigation was conducted to study the concentration of ascorbic acid and -carotene in spinach and amaranth leaves as affected by various domestic processing and cooking methods which included storage of leaves in polythene bags or without packing for 24 and 48 hours in refrigerator at 5 °C; at 30 °C in polythene bags; drying (sun and oven); blanching (5, 10, 15 min); open pan and pressure cooking. Ascorbic acid content of fresh leaves was 624.1 to 629.0 mg and -carotene content was 35.3 to 53.1 mg/100 g dry weight. The percent loss of ascorbic acid ranged from 1.1 to 6.3 and 55.3 to 65.9 while lower losses (0.0 to 1.3 and 1.5 to 2.1) of -carotene were observed in leaves stored in refrigerator and at 30 °C, respectively. A markedly greater reduction in ascorbic acid and -carotene was observed in dried, blanched and cooked leaves. The study recommended the storage of leaves in refrigerator, drying in oven, blanching for shorter time and cooking in pressure cooker for better retention of these two vitamins.     

The biochemical oxidation of β -carotene

Summary -carotene has been oxidized with a lipoxidase-linoleate system. Chromatography of the products shows that several of the bands have spectra corresponding to epoxide of -carotene. Three of the other fractions have been examined more closely by spectrophotometric methods and it is suggested that they are conjugated polyene ketones.Oxidation of -carotene by a ferrous phthalocyanine — linoleate system shows that the products vary depending upon the physical state of the oxidizing system.

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Zusammenfassung -Karotin wurde durch ein Lipoxydase-Linoleat-System oxydiert. Die Chromatographie der Oxydationsprodukte zeigt, dass mehrere Banden typische Spektren zeigen, die auf das Epoxyd von -Karotin hinweisen. Drei andere Fraktionen wurden mittels der spektrophotometrischen Methode genau untersucht; es wäre möglich, dass diese Substanzen konjugierte Polyen-Ketone wären. Die Oxydation von -Karotin durch ein System Eisen-2-Phthalocyanin-Linoleat zeigt, dass die Produkte variieren mit dem physikalischen Zustand des Oxydations-Systems.

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Résumé Le carotène- a été oxydé par le système lipoxidase-linoléate. La chromatographie des produits d'oxydation montre plusieurs bandes dont les spectres correspondent aux époxydes du -carotène. Trois autres fractions ont été examinées de près par les méthodes spectrophotométriques, et il est possible de suggérer que ce sont des polyénes conjugués à fonctions cétones à qui nous ne pouvons pas encore donner de formules. L'oxydation du -carotène par le système phthalocyanine ferreux-linoléate, montre que les produits d'oxydation varient en fonction de l'état physique du système oxydant.

     

Changes in β-carotene and ascorbic acid content of fresh amaranth and fenugreek leaves during storage by low cost technique

Leafy vegetables are highly perishable and their shelf life depends on duration and conditions of storage. A low cost storage structure was used to extend the shelf life of amaranth and fenugreek and their quality was evaluated on the basis of retention of -carotene, ascorbic acid and chlorophyll during storage. Losses of -carotene ranged from 46.5 to 85.0% for amaranth and 24.0 to 73.0% for fenugreek depending on duration and conditions of storage. Similarly ascorbic acid retention varied from 9–32% for amaranth and 23–80% for fenugreek. Results showed that the degradation of quality parameters was faster at ambient conditions and packaging of leaves in low density polyethylene bags was beneficial in improving shelf life and nutritive value. Low cost storage structure was similar to low temperature storage for retention of -carotene, ascorbic acid, chlorophyll content and enhancement of shelf life.     

In Vitro Accessibility and Intake of β-Carotene From Cooked Green Leafy Vegetables and Their Estimated Contribution to Vitamin A Requirements

Provitamin A carotenoids from green leafy vegetables constitute a major dietary source of vitamin A in Tanzania. The efficiency of different vegetable preparations in contributing to the daily safe intake level of vitamin A for children was evaluated in the present study. The amount of bioaccessible (available for absorption) all-trans--carotene from green leafy vegetable dishes prepared either traditionally in households or with an improved method was estimated by an in vitro digestion method that simulates human digestion. The median vegetable portion size consumed by 34 children (2--12 years old) in the surveyed households was determined by weighing. The amount of all-trans--carotene available for absorption from the same type of vegetables cooked without oil by traditional or a modified method ranged from 5 to 12% and 4 to 15%, respectively. Vegetables cooked with modified method with oil had 2–5 times higher amount of in vitro accessible all-trans--carotene than vegetables cooked without oil. A median portion (84 g) of such a relish then provided 88–477% of the daily safe intake level of vitamin A, while portions cooked without oil only provided between 23 and 46%. In this study, a wide variation in all-trans--carotene content and bioaccessibility among studied green leaves was obtained. Still, to supply daily safe intake level of vitamin A for children from a median vegetable relish portion it is necessary to add oil in the preparation.     

Some preliminary observations on treatments which increase and decrease the stability of β-carotene in preserved,moist leaf protein

-carotene in leaf protein extracted from some species is destroyed in a few days when incubated with salt as a preservative. Its shelf-life can be greatly extended by pretreatment with oxalate, ascorbate mercaptans, phenolic substances, extracts made from leaves in which carotene is more stable, and by tight compaction. Treatment with alum reverses the protective effect of these chemical pretreatments, it also increases the lability of carotene in leaf protein extracted from species which usually give a relatively stable product. In these preparations of leaf protein, which were heated to 90 °C during preparation, carotene is only partially extractable into some solvents which are miscible with water. It seems therefore to be present in more than one state, but differences in extractability could not be correlated with differences in lability.     

Nutritional composition of selected green leafy vegetables,herbs and carrots

Six green leafy vegetables and herbs – spinach, amaranth, bengal gram, cauliflower, mint, coriander and carrots – were analyzed for moisture, protein,ascorbic acid, -carotene, total iron, ionizable iron (as % of total iron) in vitro iron (% of total iron), copper, manganese and zinc. Moisture content of the leaves and carrots varied from 75.1 percent (bengal gram) to 95.4 percent (carrot) and protein from 9.83 percent (carrots) to 30.9 (mint) percent. Ascorbic acid, -carotene, total iron and ionizable iron contents were at a maximum in case of bengal gram leaves whereas level of ionizable iron and in vitro iron as a percent of total iron was highest in carrots. Copper, manganese and zinc contents were maximum in spinach.     

Seed globulins of Cajanus cajan

Seed globulins ofCajanus cajan a widely cultivated legume were purified and characterised. About 78% of the seed proteins were salt soluble, out of which 61% were globulins which were further separated into three fractions. The fraction was insoluble at pH 4.7 and consisted of two subfractions. Fraction and were soluble at pH 4.7. All the fractions were characterised as glycoproteins by cesium chloride centrifugation. The proteins consisted of subunits which were not held together by covalent disulphide linkages. Amino acid analysis of the different globulin fractions showed that the fraction was comparatively rich in sulphur amino acids.     

Les caroténoïdes du maïs

Résumé L'extraction du maïs (variétés INRA 258 et 420) par l'hexane, permet de mettre en évidence des caroténoïdes carbures, colorés: carotène, zéacarotène, carotène, ou incolores (phytofluène) et des caroténoïdes alcools: lutéol, zéaxanthol; le cryptoxanthol est tres difficile à mettre en évidence.Il subsiste un tourteau jaune; le méthanol en extrait un ensemble de colorants, qui sont aussi des caroténoïdes, et dont a masse est plus importante que celle des colorants solubles dans l'hexane. Ces caroténoïdes ne sont pas libres, mais combinés à une matière protéique, sans doute une prolamine, qui précipite en milieu acide, en entraînant 25 à 30% de lipides. Une saponification de 3 h. à 100° en milieu normal de soude de ce complexe lipidoprotéique (qui représente de l'ordre de 2% du poids du grain) libère les acides palmitique et oléique, un peu de phytofluène, de carotène, un caroténoïde alcool ayant un pic à 424 m µ et un petit pic à 444 mµ, non identifiable à un caroténo de connu, et un acide caroténoïque, ayant le spectre de l'acide apo 8 caroténoïque, (pics à 442 et 470 dans l'hexane, 446 et 473 dans le cyclohexane), en quantité du même ordre que les caroténoïdes solubles dans l'hexane.

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Summary Extraction of maize-Kernels (cultivar INRA 258 and 420) with hexane yield carotenoids, coloured hydrocarbons, -carotene, -zeacarotene and -carotene or the colourless phytofluene as well as carotene-alkohols, luteol and zeaxanthol. The cryptoxanthol is very difficult to trace.There remains a yellow residue; a mixture of colouring substances consisting of carotenoids can be extracted in higher amounts than those gained by extraction with hexane by the aid of anhydrated methanol. Those carotenoids are not free, but combined with protein — doubtless a prolamine — which yield additionally 25 to 30 % lipids, when precipitated in an acid medium. A three hours saponification in a normal alcaline medium supplies from the lipoproteid-complex (the seed contains about 2 %) plamitic- and oleic acid, a small amount of phytofluen, -coratene, a carotenoid alcohol (peak at 424 mµ and a smaller one at 444 mµ) not being identified by a known carotenoid, furthermore, a carotenoid-acid, having the spectra of the -Apo-8 carotenoid-acid (Peaks at 442 and 470 mµ in hexane and at 446 and 473 mµ in Cyclohexane) ranging in quantity as high as found in carotenoids soluable in hexane.

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Zusammenfassung Extraktion von Mais-Caryopsen (Sorten INRA 258 und 420) mit Hexan gestattet den Nachweis von Carotinoiden, und zwar der farbigen Kohlenwasserstoffe -Carotin, -Zeacarotin und -Carotin oder des farblosen Phytofluens sowie der Carotin-Alkohole, Lutein und Zeaxanthin; das Kryptoxanthin nachzuweisen, ist sehr schwierig.Es verbleibt ein gelber Rückstand, aus diesem extrahiert man mit wasserhaltigem Methanol ein Farbstoffgemisch, das auch aus Carotinoiden besteht und dessen Mengenanteil bedeutsamer ist als jener der in Hexan löslichen Farbstoffe. Diese Carotinoide sind nicht frei, sondern an eine Eiweißsubstanz gebunden, die zweifelsohne ein Prolamin ist und die, im sauren Milieu gefällt, 25 bis 30 % Lipide mitreißt. Eine dreistündige Verseifung im normalen alkalischen Milieu liefert aus dem Lipoproteid-Komplex (das in einer Größenordnung von 2 % im Samen vorliegt) Palmitin- und Ölsäure, ein wenig Phytofluen, -Carotin, einen Carotinoid-Alkohol mit einem Peak bei 424 mµ und einem kleineren bei 444 mµ — der nicht über ein bekanntes Carotinoid zu identifizieren ist — sowie eine Carotinoid-Säure, die das Spektrum der -Apo8 Carotinoidsäure (Peaks bei 442 und 470 mµ in Hexan und bei 446 und 473 mµ in Cyclohexan) aufweist, in einer Menge, die größenordnungsmäßig der der in Hexan löslichen Carotinoide entspricht.

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avec 3 Fig.

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Exposé présenté le 16 Juillet 1965 à Lund, Suède à l'occasion du congrès EUCARPIA-CIQ (14–17 Juillet 1965).     

Inheritance of carotenoid differences in the tomato

Summary The effects of five genes which affect carotenoid differences in the fruits ofLycopersicon are discussed. Green and orange-fruited species contain a gene which, when introduced intoesculentum can cause production of -carotene, as shown first withhirsutum hybrids byLincoln &Porter at Purdue. A gene, ghost, gives rise to a form of albinism, and phytoene accumulation is observed. The interpretation of the data in terms of a biochemical sequence involving phytoene, lycopene and -carotene is by no means self-evident and at this juncture, explanations must be considered only as working hypotheses.

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Zusammenfassung Die Wirkung von fünf Genen, die die Differenzierung von Karotinoiden in Früchten vonLycopersicum beeinflussen, wird diskutiert. Die Sorten mit grünen oder mit orangefarbigen Früchten enthalten ein Gen, das, in die Art esculentum eingeführt, in der Lage ist, die Bildung von -Karotin zu veranlassen, wie als ersteLincoln &Porter für Hybriden von hirsutum festgestellt haben. Ein Gen Ghost bewirkt eine gewisse Form von Albinismus; dabei beobachtet man eine Anhäufung von Phytoen.Aus diesen Tatsachen kann man nicht schliessen, dass ein biochemischer Zusammenhang zwischen Phytoen, Lycopin und -Karotin bestände; bei dem heutigen Tatbestand kann man dies höchstens als Arbeitshypothese betrachten.

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Résumé Discussion sur l'action des cinq gènes qui déterminent la différenciation des caroténoïdes dans les fruits deLycopersicum. Les espèces à fruits verts ou oranges contiennent un gène qui, introduit dans l'espèceesculentum, peut déterminer la production de -carotène, ainsi queLincoln &Porter l'ont montré les premiers pour les hybrides dehirsutum. Un gène phantome détermine une certaine forme d'albinisme, et corrélativement s'observe l'accumulation de phytoène.L'interprétation de ces données comme preuve d'une filiation biochimique phytoène-lycopène--carotène n'est nullement évidente; dans l'étant actuel des faits, il ne peut être question que d'une hypothèse de travail.

     

Proximate composition and mineral content of two edible species of Cnidoscolus (tree spinach)

Proximate composition and mineral content of raw and cooked leaves of two edible tree spinach species (Cnidoscolus chayamansa and C. aconitifolius), known locally as chaya, were determined and compared with that of a traditional green vegetable, spinach (Spinicia oleraceae). Results of the study indicated that the edible leafy parts of the two chaya species contained significantly (p<0.05) greater amounts of crude protein, crude fiber, Ca, K, Fe, ascorbic acid and -carotene than the spinach leaf. However, no significant (p>0.05) differences were found in nutritional composition and mineral content between the chaya species, except minor differences in the relative composition of fatty acids, protein and amino acids. Cooking of chaya leaves slightly reduced nutritional composition of both chaya species. Cooking is essential prior to consumption to inactivate the toxic hydrocyanic glycosides present in chaya leaves. Based on the results of this study, the edible chaya leaves may be good dietary sources of minerals (Ca, K and Fe) and vitamins (ascorbic acid and -carotene).     

Oat β-glucan-amylodextrins: Preliminary preparations and biological properties

Amylodextrins with soluble -glucan contents from 1 to 10% were prepared from oats and the hypocholesterolemic properties of the latter were evaluated. The products are called OATRIM and can lower blood cholesterol by replacing animal fats rich in cholesterol in food products and, possibly, by the action of -glucan in the body after consumption. In the chick model, decreased total blood cholesterol also resulted in increases of HDL cholesterol and decreases of LDL cholesterol. Processing conditions were found that gave the maximum amount of -glucan and desirable fat-replacement qualities with the least amount of color and flavor.The mention of firm names or trade products does not imply that they are endorsed or recommended by the US Department of Agriculture over other firms or similar products not mentioned.     

Changes in carbohydrate and nitrogenous components and amylase activities during germination of grain amaranth

Grain amaranth (Amaranthus hypochondriacus), Yercaud local variety, was soaked overnight and germinated for 192 h taking the soaked grains as the zero time (0 h) sample. The changes in the activities of - and -amylases, starch, sugar, protein and lysine contents during germination are reported. Activity of -amylase was high in the 0 h soaked grains, while -amylase activity was high in 72 h germinated grains. The joint action of the amylases resulted in a decrease of starch content from 0 to 192 h in germinated grains and an increase in total sugars during the initial period of germination.Protein nitrogen was found to decrease from 48 h to 192 h accompanied by an increase in free amino acid and non-protein nitrogen contents. Total lysine content was found to be increased by 31% in 24 h germinated grain amaranth. Protein fractionation of raw, soaked and 24 h germinated grain amaranth showed that the distribution of different types of proteins varied during germination of the grains. An increase of water soluble protein content was noticed in 24 h germinated grains.     

Retention of quality characteristics of dehydrated green leaves during storage

Green leafy vegetables are the most underexploited class of vegetablesdespite high nutritional value. Reports on nutritional composition andstorage of some of the fresh leaves are available but the storage behaviorof dehydrated leaves apparently has not been studied. Therefore, in thepresent study, two green leafy vegetables, savoy beets (Beta vulgarisvar. bengalensis) and fenugreek (Trigonella foenumgraecum) were dehydrated in a low temperature drier and stored for9 months under ambient and cold stored conditions after packaging insingle or double layers of high density polyethylene film (200 gauge). Thequality was determined on the basis of retention of -carotene,ascorbic acid and chlorophyll, and the extent of browning during storage.Retention of these quality characteristics depended on the crop and storageconditions. Double packed and cold stored samples of fenugreek retained67% -carotene, whereas savoy beet leaves retained only 57% ofthe initial -carotene under similar conditions. Similarly, higherretention of ascorbic acid and chlorophyll, and lower browning wasobserved in double packed, cold stored samples. Results indicated theefficacy of double packed and cold stored samples over other combinations.     

Genetic aspects of some carotenoids synthesis in tomatoes

Summary The wild species of tomato,Lycopersicon minutum, carries a factor which after introduction into cultivated varieties ofL. esculentum results in an increasing concentration of -carotene in fruits. The factor is closely linked to the sp⁺ gene in chromosome 6 (0.12 % c.o.). This allows to conclude that it is either the B gene or a very similar allele. (The fruit flesh ofL. minutum is greenish white and contains very small quantities of carotenoids; this is perhaps due to the absence of the r⁺ gene). The results of the present study and findings of other workers suggest that the gene B occurs in all species of the genusLycopersicon and only a part ofL. esculentum and a part ofL. pimpinellifolium are the exceptions in having the allele B+.Some segregants characterised by remarkably increased amount of both -carotene and lycopene have been isolated from the cross between high -carotene line and the hp mutant.

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Zusammenfassung Die WildtomateLycopersicum minutum enthält einen Faktor, der, auf KulturtomatenL. esculentum übertragen, eine beträchtliche Zunahme des Gehaltes an -Carotin in den Früchten verursacht. Dieser Faktor ist eng verbunden mit dem sp⁺-Gen im 6. Chromosom (0,12 % c.o.). Dies läßt vermuten, daß es entweder das B-Gen oder ein sehr ähnliches Allel ist. (Die Früchte vonL. minutum haben grünlich-weißes Fleisch und enthalten sehr kleine Mengen von Karotinoiden; das hängt höchstwahrscheinlich mit der Abwesenheit des r⁺-Gens zusammen). Auf Grund von eigenen Arbeiten und Arbeiten anderer Autoren kann man vermuten, daß das B-Gen in allen Arten der GattungLycopersicum anwesend ist und nur einige Varietäten vonL. esculentum undL. pimpinellifolium ausnahmsweise das B+-Allel besitzen.Als Ergebnis einer Kreuzung zwischen der Linie mit erhöhtem Gehalt an -Carotin und den Mutanten hp hat man Segreganten erhalten, welche sich durch einen erhöhten Gehalt sowohl an -Carotin wie an Lykopin auszeichnen.

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Résumé Une espèce de tomate sauvage,Lycopersicon minutum, contient un facteur qui — après avoir été introduit dans les variétés cultivées — détermine un taux élevé de -carotene dans les fruits. Ce facteur est étroitement associé avec le gène sp⁺ du chromosome 6 (0.12 % c.o.), ce qui permet de supposer qu'il s'agit ou bien du gène B ou d'un allèle très ressemblant. (La pulpe du fruitL. minutum est d'un blanc verdâtre et contient de très petites quantités de caroténoides, peutêtre à cause de l'absence du gène r⁺). Il résulte de cette étude ainsi que des données puisées dans d'autres, qu'on peut supposer que le gène B se trouve dans toutes les espèces du genreLycopersicon et seulement une partie de l'espèceL. esculentum et une partie de l'espèceL. pimpinellifolium sont des exceptions qui possèdent l'allèle B+.Par croisement entre la lignée enrichie de -carotene et le mutant hp, on a obtenu des ségrégants caractérisés par une plus forte concentration aussi bien de -caroténe que de lycopène.

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Paper read in Lund, Sweden (EUCARPIA-CIQ Congress, 14th to 17th July 1965) on 17/7/1965.     

Sur l'obtention d'un β-sitostérol pur par chromatographie sur plaque d'alumine imprégnée de nitrate d'argent

Résumé Nous avons obtenu avec un rendement acceptable des échantillons de -sitostérol purs par le procédé suivant: la double liaison en 22 d'un propionate de stigmastérol de pureté 95% est hydrogénée en présence de Pd/C. Le propionate de -sitostérol formé est isolé par chromatographie préparative sur couche mince d'alumine imprégnée de nitrate d'argent.Nous avons contrôlé la pureté du produit obtenu par spectrométrie de masse.

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Summary Samples of pure -sitosterol have been obtained with a satisfactory yield by the following method.The double linkage in 22 of a stigmasterol propionate of 95% purity is hydrogenated in the presence of Pd/C. The -sitosterol propionate is isolated by preparatory thin layer chromatography on silver nitrate impregnated aluminium.The purity of the product has been verified by mass spectrometry.

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Zusammenfassung Wir erhielten mit annehmbarem Wirkungsgrad Muster von reinem -Sitosterin nach folgender Methode:In Gegenwart von Pd/C wird die Doppelbindung bei 22 eines Stigmasterin-Propionates mit 95%-er Reinheit hydriert. Das gebildete -Sitosterin-propionat wird durch präparative DC auf mit Silbernitrat imprägnierter Aluminiumoxidschicht isoliert.Die Reinheit des erhaltenen Produktes wurde mit dem Massenspektrometer geprüft.

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Note de laboratoire