Showing papers on "Neoxanthin published in 1971"

Quantitative Investigations of Leaf Pigments From Their Inception in Buds Through Autumn Coloration to Decomposition in Falling Leaves

Abstract: Pigments in hazel (Corylus americana), aspen (Populus tremuloides), and pin oak (Quercus ellipsoidalis) leaves were measured from their inception in buds to development of a summer maximum, and through the autumn coloration period to decomposition in dry falling leaves. Leaves contained generally high but varyingconcentrations of chlorophyll and carotenoid pigments throughout the summer months. The summer pigment variations among the three species are discussed in the light of the usefulness of chlorophyll content as an index of net primary productivity. During the autumn coloration period, preceding leaf desiccation and fall, chlorophyll decays rapidly, producing low levels of pheophytin with only occasional faint traces of pheophorbide and chlorophyllide during the period of most rapid chlorophyll breakdown. The levels of carotenoids begin declining at the same time as chlorophyll, but at a much slower rate. Violaxanthin disappears most rapidly, followed closely by neoxanthin. Lutein and Beta—carotene a...

Biochemistry of tea fermentation: the role of carotenes in black tea aroma formation

Abstract: — The carotenoid compounds present in fresh tea leaf were quantitatively extracted and separated by thin layer chromatography. Neoxanthin. Neoxanthin, violaxanthin, lutein, and β-carotene were identified and estimated by spectrophotometry. Quantitative studies showed that these carotenoid compounds decreased from about 0.053% (dry weight basis) in the fresh tea leaf to about 0.030% in the fermented (3 hr fermentation) leaf to about 0.026% in the fired black tea. This analytical study was followed by an investigation to determine how, and to what, these carotenoid compounds are altered during the black tea manufacturing process. The fate of β-carotene in tea fermentation was first studied in model systems. The model consisted of a crude soluble enzymes preparation extracted from fresh tea leaves, tea flavanols, and β-carotene. The model system was buffered at pH 5.4 and incubated for 30 min at 30°C. The volatile compounds formed in this system were studied by gas chromatographic analysis of headspace volatiles. It was found that β-ionone (identified by GLC retention time and mass spectrometry) was formed in this model tea fermentation system as a result of tea flavanol oxidation and drying of the reaction mixture after oxidation. Further, it was found that all three basic reaction mixture ingredients, i.e., active tea enzymes preparation, tea flavanol, and β-carotene were necessary for the production of β-ionone. While β-ionone was the major volatile product formed from β-carotene in these systems, experiments utilizing 15,15′.14C-β-carotene showed that several unidentified compounds also were formed. The formation of β-ionone from β-carotene during black tea manufacture was confirmed in separate experiments. Organoleptic and GLC headspace analyses showed that black teas made in the usual way except that β-carotene was added at the leaf maceration stage (stage which initiates fermentation) contained more β-ionone than control black teas. The results obtained with β-carotene have been generalized on paper for all of the carotenoid compounds known to be present in fresh tea leaf. The results of this work indicate that many of the important black tea aroma constituents are probably formed during the tea conversion process by oxidative degradation of the carotenoid compounds present in the system. The possible mechanism for these transformations is discussed.

Relationship between the Inhibitory Effects of 5,6–Epoxyxaiithophylls and Phototropism

Abstract: Using a range of assay systems, the effect of light on the inhibitory properties of several carotenoids were investigated. The 5,6-epoxyxanthophylls: violaxanthin, neoxanthin and 5,6-monoepoxylutein when illuminated were shown to cause inhibition in the various assays, while a certain amount of inhibition also occurred with the dark treatment. The suggestion that phototropism might be the result of light induced formation of inhibitory compounds was also investigated and there was no evidence that the inhibitors obtained by in vitro degradation of 5,6-epoxyxanthophylls play a part in phototropism.

The Biosynthesis of Astaxanthin—V* Interconversion of the Algal Carotenoids, Stigeoclonium sp. into Fish Carotenoids, Fancy Red Carps

Abstract: The carotenoids of fancy red carps (Cyprinus carpio Linne) have separated by ab sorption chromatography and further characterized by their absorption spectra and behavior on the column chromatography. In some cases melting points were measured and reactions for specific functional groups were performed. 2. The principal carotenoids of the integument were lutein, a-doradexanthin, astaxanthin, and £-doradexanthin and in the internal organs the existence of canthaxanthin, lutein, and zeaxanthin was confirmed. 3. The contents of the stomach of fancy red carps were examined and half-digested algae were found in them, the presence of chlorophylls was also confirmed. In the ponds where the carps were being raised, the algae, Stigeoclonium sp, was found. The carotenoids of the algae were separated and the presence of a-carotene, /9-carotene, ^-zeacarotene, echinenone, canthaxanthin, lutein, zeaxanthin, violaxanthin and neoxanthin was confirmed. The metabolic pathway from the plant carotenoid, into fish carotenoid, was proposed.