Ewald Swinny

Edible Coatings Influence Fruit Ripening, Quality, and Aroma Biosynthesis in Mango Fruit

The effects of different edible coatings on mango fruit ripening and ripe fruit quality parameters including color, firmness, soluble solids concentrations, total acidity, ascorbic acid, total carotenoids, fatty acids, and aroma volatiles were investigated. Hard mature green mango (Mangifera indica L. cv. Kensigton Pride) fruits were coated with aqueous mango carnauba (1:1 v/v), Semperfresh (0.6%), Aloe vera gel (1:1, v/v), or A. vera gel (100%). Untreated fruit served as the control. Following the coating, fruits were allowed to dry at room temperature and packed in soft-board trays to ripen at 21+/-1 degrees C and 55.2+/-11.1% relative humidity until the eating soft stage. Mango carnauba was effective in retarding fruit ripening, retaining fruit firmness, and improving fruit quality attributes including levels of fatty acids and aroma volatiles. Semperfresh and A. vera gel (1:1 or 100%) slightly delayed fruit ripening but reduced fruit aroma volatile development. A. vera gel coating did not exceed the commercial mango carnauba and Semperfresh in retarding fruit ripening and improving aroma volatile biosynthesis.

Substituted bibenzyls, phenanthrenes and 9,10-dihydrophenanthrenes from the heartwood of Combretum Apiculatum

Abstract 3,5,4′-, 3,4,3′,5′-, 3,4,5,4′- and 3,4,5,3′,4′-substituted dihydrostilbenes, 2,3,4,6,7- substituted phenanthrenes and its 9,10-dihydro analogues were isolated and identified in the acetone extract from the heartwood of Combretum apiculatum . Growth inhibition and fungitoxic screening tests were conducted on 4,7-dihydroxy-2,3,6-trimethoxyphenanthrene, 2,7-dihydroxy-2,4,6-trimethoxy-9, 10-dihydrophenanthrene and 4,4′-dihydroxy-3,5-dimethoxydihydrostilbene.

Red clover Trifolium pratense L. phytoestrogens : UV-B radiation increases isoflavone yield, and postharvest drying methods change the glucoside conjugate profiles

Isoflavone extracts of red clover Trifolium pratense L. (cv. Pawera) with dissimilar glucoside conjugate profiles were obtained by employing different postharvest drying methods. The most prominent isoflavones found were formononetin and biochanin A and their corresponding glucosides and malonyl glucoside esters. Postharvest freeze drying inhibited the conversion of the glycosides to the aglycones, while vacuum drying allowed for maximum conversion of the glycosides to their corresponding aglycones. Air drying produced a low level of the aglycones formononetin and biochanin A, and oven drying promoted decarboxylation of the malonyl glucosides to the acetyl glucosides. Exposure to enhanced UV-B radiation resulted in an increase in total formononetin and biochanin A isoflavone levels, indicating that harvest during a period of high ambient UV-B radiation may be appropriate for maximum yield. The levels of caffeic acid and flavonols also increased by about 40 and 250%, respectively, on exposure to enhanced UV-B radiation.

The structure and synthesis of proguibourtinidins from Cassia abbreviata

Abstract An acetone extract of the bark of Cassia abbreviata yielded guibourtinidol-(4β → 8)-epicfzelechin, guibourtinidol-(4α → 8)-epiafzelechin, guibourtinidol-(4α → 8)-catechin, guibourtinidol-(4β → 8)-epicatechin and ent-guibourtinidol-(4β → 8)-epicatechin. The structures of the proguibourtinidin dimers were confirmed by synthesis via mild acid-condensation. Guibourtinidol-(4α → 8)-afzelechin, previously isolated from Acacia leuderitzii, was also synthesized. Another two proguibourtinidol oligomers, namely, guibourtinidol-(4β → 8)-afzelechin and guibourtinidol-(4α → 6)-afzelechin were products of the previous synthesis but neither of them have been reported to date.

The structure and synthesis of a 7,8,4′-trihydroxyflavan-epioritin dimer from Acacia caffra

Abstract The first (2 S )-7,8,4′-trihydroxyflavan-epioritin-4 α -ol dimer was isolated from the heartwood of Acacia caffra . Reduction of 7,8,4′-trihydroxyflavanone to the flavan-4-ol was subsequently used in an acid-catalysed condensation with epioritin-4α-ol to synthesize the dimer.

The fluorescence and photostabilities of naturally occurring isoflavonesDedicated to the memory of Nobel Laureate, Lord George Porter FRSC FRS OM.

The 5,7-dihydroxyisoflavones do not emit detectable fluorescence and are significantly more photostable than the two 7-hydroxy-5-deoxyisoflavones, daidzein and formononetin. The latter isoflavones emit fluorescence that depends on the basicity of the solution and the polarity of the solvent. Comparison of the spectral distributions of the emission in methanol in the presence and absence of base indicates that it originates from the conjugate anion excited singlet states. The fluorescence of daidzein and formononetin exhibit large Stokes shifts to longer wavelengths in methanol, ethanol, hexanol and acetonitrile and the magnitudes of these shifts increase with solvent polarity. This indicates that the emission originates from excited singlet states with much larger dipole moments than those of the corresponding ground states. Values of 8.3 D and 6.5 D were determined for daidzein and formononetin respectively. The photostabilities of formononetin and daidzein both increase with increasing solvent polarity and in corresponding solvents, the photostability of daidzein is higher than that of formononetin, behaviour which is attributed to the greater antioxidant activity of daidzein.

Metabolites from Chlorophora excelsa: Possible intermediates in the biogenesis of a pentasubstituted stilbene

Abstract A series comprising substituted hydroxyl-geranylstilbenes, substituted benzenoid compounds and quercitin-type flavones were isolated and characterized from the acetone extract of the heartwood of Chlorophora excelsa .

Flavonoids and isoflavonoids from the heartwood ofVirgilia oroboides

Abstract The heartwood of Virgilia oroboides contains 3-hydroxy-8,9-methylenedioxypterocarp-6a-ene, (2 R ,3 R )-3,7-dihydroxyflavanone, (α R )-4-methoxy-α,2′,4′-trihydroxydihydrochalcone, two pterocarpans and several other flavonoids and isoflavonoids.

A 3-oxygenated flavonolignoid fromDistemonanthus benthamianus

A new flavonolignan, 2,3-trans-2-(4-hydroxy-2,3-dimethoxyphenyl)-9-(5-hydroxy-2-methoxyphenyl)-2-hydroxymethyl-2,3-dihydro-7H-1,4-dioxino[2,3-h]chromen-7-one with a rare 1,2,3,4-tetrasubstituted D-ring was isolated from the heartwood of Distemonanthus benthyamianus

5,5′-Dihydroxy-3,7,2′,4′-tetramethoxyflavone from Chlorophora excelsa

Abstract 5,5′-Dihydroxy-3,7,2′,4′-tetramethoxyflavone was isolated from the acetone extract of the heartwood of Chlorophora excelsa .