Carotinoidgehalt und-zusammensetzung verschiedener deutscher Kartoffelsorten und deren Bedeutung für die Fleischfarbe der Knolle

Barley (Hordeum vulgare), corn (Zea mays), bean (Phaseolus vulgaris), and radish (Raphanus sativus) seedlings were continuously irradiated under a lighting device for 5-10 d at an increased ultraviolet (UV)-B fluence rate. In their growth parameters, composition, and leaf surface, these four species responded differently to the increased UV-B exposure. Bean seedlings suffered the most serious effects, radish and barley less, and corn was hardly influenced at all. In all plant species, the fresh weight, the leaf area, the amounts of chlorophylls, carotenoids and the galactolipids of the chloroplasts were reduced. The lipid content of the corn and bean seedlings also diminished. But all the irradiated plants showed a rise in their protein content compared to the control plants. The content of flavonoids increased in barley and radish seedlings by about 50%. The effects on growth parameters and composition were more extensive with increasing UV-B fluence rates, at least as shown in the case of barley seedlings. The fresh weights fell proportionally with the chlorophylls and carotenoids. In contrast, the flavonoid content of barley leaves rose parallel to the increasing UV-B fluence rates and reached 180% of the value in the control plants with the highest UV-B fluence rate. Scorching appeared regularly in the form of bronze leaf discoloration at the highest UV-B fluence rates. Scanning electron micrographs of the leaf surface of UV-B irradiated plants showed deformed epidermal structures. Show more

Methods for a rapid quantitative determination of chlorophylls and carotenoids are decribed.The extraction of pigments was carried out with different kinds of plant material, such as algae, leaves and chloroplasts. The separation of the carotenoids from these extracts was succeeded by an adsorptionchromatographic process in which the thin-layer consists of anorganic adsorbents (CaCO3, MgO, Ca(OH)2). The basicity of the layer is further increased by the addition of KOH; thereby the chlorophylls are retained at the starting line and the overlapping of chlorophylls and xanthophylls on the chromatogram can be avoided.With this method even those carotenoids can be separated which differ only in the position of a double bond, as for instance α- and β-carotene, and lutein and zeaxanthin. Thus the separation of all the principal carotenoids on a single chromatogram is possible, for example from a Chlorella extract (in order of decreasing Rf-value): α-carotene, β-carotene, lutein-5,6-epoxide (traces), violaxathin, lutein, antheraxanthin, neoxanthin neo A, neoxanthin and zeaxanthin. Furthermore the chromatographic behaviour of the carotenoids ζ-carotene, γ-carotene, lycopene and rhodoxanthin, which are found only rarely, is described.The chlorophylls a and b are separated by a partition chromatographic process on the second thin-layer; this layer consists of silica gel mixed with ascorbic acid as an antioxidant. An apparatus for an equal spreading of defined quantities of the extract on the starting line and new methods for a rapid quantitative elution of the pigments from the adsorbent are described.The specific extinction coefficients E 1 cm (1 %) for antheraxanthin in ethanol and for α-carotene in chloroform, which were needed for the calculation of the pigment quantity were determined. Show more