ABSTRACT: The effects of genotype, root size, storage, and processing on the content of bioactive compounds in carrots were determined to investigate the possibilities for optimizing the health‐promoting properties of this vegetable. The content of polyacetylenes (falcarinol, falcarindiol, falcarindiol‐3‐acetate), carotenoids (α‐and β‐carotene), and isocoumarin 6‐methoxymellein (6‐MM) varied significantly between 6 genotypes of the Nantes type. The content of falcarindiol, falcarindiol‐3‐acetate, and 6‐MM was significantly higher in small (50‐ to 100‐g root size) than in extra large root sizes (>250‐g root size). Refrigerated storage of the roots for 4 mo at 1 °C before processing resulted in a significantly higher content of polyacetylenes and no differences in the content of carotenoids and 6‐MM compared with frozen storage of processed carrots. The content of falcarinol increased and that of falcarindiol and falcarindiol‐3‐acetate decreased during steam blanching of the carrots before freezing. No changes were observed in the content of carotenoids and 6‐MM.

Dehydrodimers of hydroxycinnamates play an important role in the cross-linking of plant cell walls. An aqueous solution of quaternary ammonium salts with a long aliphatic chain is known to spontaneously organize itself into micelles with the ionic part at the outer sphere. It is shown that regioisomeric ferulic acid dehydrodimers can be obtained in one step from trans-ferulic acid after attachment to these micelles and using the biomimetic peroxidase-H2O2 system. The surfactant hexadecyltrimethylammonium hydroxide yielded trans-4-(4-hydroxy-3-methoxybenzylidene)-2-(4-hydroxy-3-methoxyphenyl)-5-oxotetrahydrofuran-3-carboxylic acid (25%), (E,E)-4,4'-dihydroxy-5,5'-dimethoxy-3,3'-bicinnamic acid (21%), and trans-5-[(E)-2-carboxyvinyl]-2-(4-hydroxy-3-methoxyphenyl)-7-methoxy-2,3-dihydrobenzofuran-3-carboxylic acid (14%), whereas the surfactant tetradecyltrimethylammonium bromide gave 4-cis, 8-cis-bis(4-hydroxy-3-methoxyphenyl)-3,7-dioxabicyclo[3.3.0]octane-2,6-dione (18%) as the main product. The use of micelles appears to be not only a new way to synthesize regioisomeric ferulic acid dehydrodimers but may also help to understand the regiospecificity of dimeric hydroxycinnamate formation in vivo.

The 2-beta-O-D-glucoside of the cyclic arylhydroxamic acid 2, 4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA) that occurs in large amounts in young maize shoots (Zea mays L.) is converted enzymatically to its aglycone upon tissue damage. The aglycone DIMBOA possesses strong biologically activity toward various organisms whereas the glucoside is almost biologically inactive. A simple procedure yielding DIMBOA in gram quantities, from 7-day-old maize seedlings, was developed by using solid-phase extraction.

The allergen primin and its precursor miconidin were collected by dynamic headspace technique from Primula obconica Hance and quantified and identified by gas chromatography (GC) and gas chromatography‐mass spectrometry (GC‐MS). The primin concentrations in leaves/stems and flowers (including pedicel and calyx) of P. obconica were 262 μg and 531 μg (g fresh plant material)−1, respectively, whereas miconidin concentrations were 92 μg (g fresh plant material)−1 in leaves/stems and 194 μg (g fresh plant material)−1 in flowers. The amounts of primin released from unchopped leaves/stems and flowers were 65.3 ng and 18.8 ng (g fresh plant material)−1 h−1, respectively. Dynamic headspace analysis of intact P. obconica plants showed that primin is also directly emitted from undamaged plants, although in smaller concentrations (6.2 ng (g fresh plant material)−1 h−1), whereas miconidin was only emitted in minute amounts (less than 0.4 ng (g fresh plant material)−1 h−1) both from intact plants and from unchopped plant parts. The possibility that primin from P. obconica could be a potential airborne allergen and therefore a source of airborne contact dermatitis is discussed.