The volatile constituents of the essential oils of the peel, flower (neroli) and leaves (petitgrain) of bitter orange (Citrus aurantium L.) growing in Greece were studied by GC-MS. The analytical procedures enabled the quantitative determination of 31 components. More specifically, the components of the essential oils identified were: twelve in the peel, twenty-six in the flowers, and twenty and sixteen in old and young leaves, respectively. The major constituents of the different parts of Citrus aurantium L. essential oils were: β-pinene (0.62%–19.08%), limonene (0.53%–94.67%), trans-β-ocimene (3.11%–6.06%), linalool (0.76%–58.21%), and α-terpineol (0.13%–12.89%). The DPPH test demonstrated that the essential oils in the old leaves had the maximum antioxidant activity, followed by the flowers, young leaves and the peel in that order. This study updates the data in the literature on the essential oils of bitter orange, and provides information on the composition of the oils for a further evaluation of this product.

Doi:10.3906/bot-1302-55 Melatonin and other factors that promote rooting and sprouting of shoot cuttings in Punica granatum cv. Wonderfu

An investigation was carried out in order to estimate the biochemical changes occurring in bitter orange (Citrus aurantium L.) leaves in response to melatonin (MEL), gibberellic acid (GA) and salicylic acid (SA) treatments. We examined the effect of MEL, GA and SA on the essential oil (EO), the total phenolic (TPC) and total flavonoid content (TFC), and the antioxidant activity of bitter orange leaves from 1-year-old plants. 15 μMMEL, 1 mMSA and 1.44 mMGA increased the total leaf phenolic and flavonoid content and enhanced FRAP and DPPH activity of leaf methanolic extracts. Salicylic acid and GA promoted the leaf essential oil content and affected significantly the concentration of limonene, linalool and linalyl acetate.

Sustainability, circular economy and alternative production systems are urgent imperatives for humanity and animal husbandry. Unless wasted, agri-food by-products can offer a promising source of high value. We evaluated the effect of rice bran (RB), corncob (CC), potato peels (PP), solid biogas residues (BR), and olive-oil processing residuals (OR), as alternative substrates to wheat bran (WB as control), on the growth and nutritional value of Tenebrio molitor during its breeding for animal feeds and/or human consumption. Innovation-wise, we further investigated the substrate supplementation (0, 10, 20%) with post-distillation residues of Mediterranean aromatic-medicinal plants (MAPs: lavender, Greek oregano, rosemary, olive; 1:1:1:1 ratio). Tenebrio molitor larvae (TML) were reared in all the studied substrates, and TML and diets’ proximate and fatty acid compositions as well as total phenol and flavonoid content and antioxidant potential were assessed using standard procedures. After statistical analysis of correlations, we observed that CC promoted oviposition and progeny survival; larval weight and dry matter were positively affected mainly by dietary energy and fat content; number of TML and/or larval weight increased using 10% MAPs inclusion in WB, RB and OR or RB, OR, BR and PP, respectively, which did not affect protein content; TML fatty acid composition decreased the content of saturated ones and increased that of mono-unsaturated ones; MAPs residues had an apparent favorable impact on total phenolic content and antioxidant activity of each substrate, with RB displaying the highest capacity and content. These findings indicate that alternative substrates can be exploited and their enrichment with natural phenolics is able to influence T. molitor growth, offering highly beneficial and nutritional value.