Root volatile organic compounds (VOCs), their chemistry and ecological functions have garnered less attention than aboveground emitted plant VOCs. We report here on the identification of VOCs emitted by barley roots (Hordeum vulgare L.). Twenty nine VOCs were identified from isolated 21-d-old roots. The detection was dependent on the medium used for root cultivation. We identified 24 VOCs from 7-d-old roots when plants were cultivated on sterile Hoagland gelified medium, 33 when grown on sterile vermiculite, and 34 on non-sterile vermiculite. The major VOCs were fatty acid derived compounds, including hexanal, methyl hexanoate, (E)-non-2-en-1-ol, nona-3,6-dien-1-ol, and nona-2,6-dien-1-ol. In an olfactometer assay, wireworms (larvae of Agriotes sordidus Illiger, Coleoptera: Elateridae) were attracted to cues emanating from barley seedlings. We discuss the role of individual root volatiles or a blend of the root volatiles detected here and their interaction with CO 2 for wireworm attraction.

Aroma is one of the essential parameters that determine fruit quality. It is also an important feature of varietal characterization and so valuable for agro-biodiversity identification and preservation. In order to characterize changes in the aroma fingerprint through fig development, the main objective of the present research was to study the volatile organic compound (VOC) profiles of figs (Ficus carica L.) from three cultivars, Taamriwthe (TH), Azegzaw (AZ), and Averkane (AV), at three ripening stages (unripe, ripe, and fully ripe). Analyses was performed using Headspace Solid-phase Microextraction and gas chromatography coupled with mass spectrometry. Results revealed the presence of 29 compounds that were grouped into different chemical classes. Aldehydes comprised the most abundant VOCs identified in all the studied figs, while alcohols, ketones, and terpenes comprised the minor compounds found in TH, AZ, and AV figs, respectively. Different aroma descriptors were identified throughout the ripening stages of figs; fruity and green aromas were dominant in all cultivars, while a fatty aroma scarcely occurred in figs. A gallery plot representation demonstrated that certain VOCs differentiate the studied cultivars and the different ripening stages of figs. Principal component analysis findings demonstrated characteristic VOCs of distinct ripening stages and cultivars, those VOCs can be used as fingerprints to distinguish different cultivars and/or ripening stages.

Alcalase was scarcely immobilized on monoaminoethyl‐N‐aminoethyl (MANAE)‐agarose beads at different pH values (<20% at pH 7). The enzyme did not immobilize on MANAE‐agarose activated with glutaraldehyde at high ionic strength, suggesting a low reactivity of the enzyme with the support functionalized in this manner. However, the immobilization is relatively rapid when using low ionic strength and glutaraldehyde activated support. Using these conditions, the enzyme was immobilized at pH 5, 7, and 9, and in all cases, the activity vs. Boc‐Ala‐ONp decreased to around 50%. However, the activity vs. casein greatly depends on the immobilization pH, while at pH 5 it is also 50%, at pH 7 it is around 200%, and at pH 9 it is around 140%. All immobilized enzymes were significantly stabilized compared to the free enzyme when inactivated at pH 5, 7, or 9. The highest stability was always observed when the enzyme was immobilized at pH 9, and the worst stability occurred when the enzyme was immobilized at pH 5, in agreement with the reactivity of the amino groups of the enzyme. Stabilization was lower for the three preparations when the inactivation was performed at pH 5. Thus, this is a practical example on how the cooperative effect of ion exchange and covalent immobilization may be used to immobilize an enzyme when only one independent cause of immobilization is unable to immobilize the enzyme, while adjusting the immobilization pH leads to very different properties of the final immobilized enzyme preparation. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2768, 2019.