The changes in volatile-aroma of Penicillium expansium and Botrytis cinerea fungi and apple fruit inoculated with these fungi were studied using GC-MS. A specially designed chamber with raised end glass tubes with access ports fitted with Teflon-lined septa was used to determine the volatile profile for fungi on agar. Inoculated fruit were placed in glass flow-through chambers similarly fitted with sampling ports. Volatile collection from fruits or fungi was accomplished using solid phase micro-extraction (SPME) device (Supelco, Inc.). In fungi-inoculated fruits, volatiles not produced by uninfected fruit included formic acid, 2-cyano acetamide; 1-hydroxy-2-propanone, and 1-1-diethoxy-2-propanone, which were initially detected 6 hr after inoculation. These new volatiles are suggested to be synthesized specifically by the action of fungi on fruits as they were not detected from fungi that were grown on agar or bruised fruits. In general, esters, alcohols, aldehydes, ketones, acids, and hydrocarbons other than α-farnesene declined in fungi infected fruits.
N.A. Mir and R.M. Beaudry
P. Perkins-Veazie, C. Finn and E. Baldwin
Oregon produces most of the processing blackberries in the United States. `Marion' blackberry (Rubus hybrid) is a trailing, thorny plant type with fruit highly prized for its unique flavor and superior processing quality. Blackberries developed in other parts of the United States grow well in Oregon but differ in flavor from `Marion' fruit. `Marion' blackberry plants are thorny and highly susceptible to freeze injury; growers desire a thornless, higher yielding, and more winter tolerant plant with similar fruit flavor and quality. This experiment was done to identify volatiles unique to `Marion' that may be incorporated into new germplasm. Forty-two volatile peaks were identified in blackberries using headspace gas chromatography and known standards. Ethylacetate and trans-2-hexenol were present in very low amounts and nerilidol was present in an unusually high amount in fresh `Marion' homogenates relative to other blackberry cultivars. Nerilidol is a volatile commonly associated with raspberry flavor and may come from the raspberry germplasm in the breeding background of `Marion'. It appears that the flavor of `Marion' fruit results from proportional differences in several volatile compounds rather than the presence of volatiles unique to this cultivar.
S. Wee and R.M. Beaudry
Autoxidation products alpha-farnesene of have been implicated in superficial scald induction for apple (Malus domestica cv. Cortland Apple) fruit. We suspect the apple cuticle acts as a sink where α-farnesene can accumulate and eventually autoxidize into hydroperoxides, conjugated trienes, 6-methyl-5-hepten-2-one (ketone), and other compounds. These oxidized byproducts may diffuse back into the peel, thereby initiating the scald process. Cortland apples were stored at 0.8°C. Volatile cuticular components were analyzed at 2-week intervals by gas chromatography–mass spectroscopy. Only two scald-related volatiles were found, 6-methyl-5-hepten-2-one and α-farnesene. The identification of these compounds may allow the determination of cuticular involvement in superficial scald, as well as a possible correlation between the volatiles and apple scald development. α-farnesene concentrations initially increased and was followed by a decline, possibly due to its autoxidation.
T. R. Hamilton-Kemp, J. H. Loughrin and R. A. Andersen
Two methods for collecting headspace vapors produced by plant samples are presented. The first involves entraining volatiles in a stream of air and trapping the entrained compounds on a porous polymer such as Tenax. The volatiles are recovered from the trap by solvent extraction or heat desorption and analysed by gas chromatography. A second method entails removing headspace vapor above plant material with a gas-tight syringe and injecting the sample directly into the gas chromatograph. An evaluation of the usefulness of these techniques will be presented.
Kwang Jin Kim, Hyun Hwan Jung, Hyo Won Seo, Jung A. Lee and Stanley J. Kays
indoor plants that can metabolize and live exclusively on volatile toluene as a carbon source underscores the importance of the rhizosphere microbe community in phytoremediation ( Zhang et al., 2013 ). It is highly probable that the microbe population has
Charles F. Forney and Michael A. Jordan
Heat can induce physiological changes in plant tissues, including the inhibition of broccoli senescence. Hot water treatments at 52C for 3 or more minutes may induce off-odors in fresh broccoli. The objective of this study was to identify heat-induced volatiles that may indicate physiological injury and/or be responsible for off-odors. Heads of fresh broccoli (Brassica oleracea L. Italica group cv. `Paragon') were immersed in water at 25C for 10 min (control); 45C for 10, 15, or 20 min; or 52C for 1, 2, or 3 min. Following treatment broccoli was held at 20C in the dark. Volatiles in the headspace above treated broccoli were trapped on Tenax-GR 2, 24, and 72 h after treatment and analyzed on a GC-MS. Heat treatments increased the production of ethanol, dimethyl disulfide (DMDS), dimethyl sulfide (DMS), dimethyl trisulfide (DMTS), hexenol, methyl thiocyanate, and several other unidentified compounds. Two hours after treatment, ethanol and hexenol concentrations in the headspace of all heat-treated broccoli were greater than those of the 25C/10 min controls. In the 52C/3 min-treated broccoli, headspace concentrations of ethanol, hexenol, DMDS, and methyl thiocyanate were 600-, 42-, 4-, and 4-fold greater than those of controls. After 72 h at 20C, concentrations of DMDS, DMS, and DMTS in broccoli from all six heat treatments were 10- to 200- fold, 8- to 35-fold, and 1.5- to 23- fold greater than those of controls, respectively. Concentrations of ethanol and methyl thiocyanate did not change relative to the controls during the additional 70 h at 20C. Concentrations of hexenol decreased in heat-treated broccoli during this time. The relationship of these volatiles to physiological changes and off-odor development in treated broccoli will be discussed.
David Obenland, Sue Collin, James Sievert and Mary Lu Arpaia
of volatile compounds that are known to be very important in determining their flavor ( Nisperos-Carriedo and Shaw, 1990 ). The volatile composition of these fruit is known to be influenced by maturity and by postharvest conditions ( Obenland et al
Yan Li, Hongyan Qi, Yazhong Jin, Xiaobin Tian, Linlin Sui and Yan Qiu
identified in oriental sweet melon is attributed to several volatile compounds including alcohols, acids, aldehydes, and esters that are biosynthetically derived from FAs, amino acids, carotenoids, and terpenes ( Aubert and Bourger, 2004 ; Beaulieu and Grimm
Denys J. Charles and James E. Simon
The curry plant [Helichrysum italicum (Roth) G. Don in Loudon ssp. italicum or H. angustifolium (Lam.) DC (Asteraceae)], a popular ornamental herb with a curry-like aroma, was chemically evaluated to identify the essential oil constituents responsible for its aroma. Leaves and flowers from greenhouse-grown plants were harvested at full bloom. Essential oils were extracted from the dried leaves via hydrodistillation and the chemical constituents analyzed by gas chromatography (GC) and GC/mass spectrometry. The essential oil content was 0.67% (v/w). Sixteen compounds were identified in the oil and included: neryl acetate (51.4%), pinene (17.2%), eudesmol (6.9%), geranyl propionate (3.8%),β-eudesmol (1.8%), limonene (1.7%), and camphene (1.6%). While the aroma of the curry plant is similar to that of a mild curry powder, the volatile chemical profile of the curry plant does not resemble that reported for commercial curry mixtures.
Rufino Perez and Randolph M. Beaudry
Volatile production is known to change with stages of plant organ development. Research has primarily focused on ripening-related volatiles; however, the potential exists to use volatiles as markers of organ damage and senescence. We have employed gas chromatography/mass spectrometry to establish stages of senescence based on volatile profiles of whole and lightly processed broccoli and carrot. An air-tight chopping apparatus was used as a flow-through chamber system and the exit gas stream analyzed for each commodity with and without tissue disruption. For carrot, isoprenoid pathway volatiles, such as 3-carene, caryophellene, α-caryophellene, and β-pinene, increase with damage and tissue senescence. Similar trends were obtained for broccoli with volatiles characteristic of β-oxidation and shikimic acid pathways. Time and condition-related volatile profile changes will be presented for carrot, broccoli, and strawberry.