Volatile fractions were prepared from four ripe commercial peach cultivars and two breeding lines by continuous vacuum steam distillation-hexane extraction and analyzed by capillary gas-liquid chromatography and gas-liquid chromatography/mass spectrometry. Thirty-three compounds were identified including five C, aldehydes and alcohols, six lactones, five monoterpenes, one sesquiterpene, one ester, three high molecular weight hydrocarbons (C,,, CZ3, C,,), and twelve other compounds.Major compounds identified were hexanal, (E)-a-hexenal, benzaldehyde, linalool, 6-pentyl-a-pyrone, y-and &decalactones, hexadecanoic acid, and three saturated hydrocarbons. By the use of threshold values and concentrations, odor units were calculated for the major low and medium molecular weight compounds to determine their contribution to peach aroma. Variations in the volatile constituents during maturation were also determined for two peach cultivars. Concentrations of most compounds increased with maturity of fruit. (E)-2-Hexenal increased in Cresthaven peaches but decreased in Monroe. Hexanal showed erratic behavior, increasing in Cresthaven and decreasing in Monroe.Many of the biochemical changes occurring during fruit ripening relate indirectly to quality. Quality was defined by Kramer and Twigg (1966) as the composite of those chemical and physical characteristics that make a product possess consumer appeal and acceptability. One of the most important aspects of these characteristics is fruit flavor.Several investigations on peach flavor have resulted in the identification of approximately 70 volatile compounds. Lactones have been implicated in peach aroma with informal sensory judgments by Jennings and Sevenants (1964), Jennings (1966,1971), Broderick (1966, 1975), and Do et al. (1969. Lim (1963), Lim and Romani (1964), and Do e t al. (1969) investigated volatile compounds from peaches at different maturity stages and during artificial ripening. Spencer et al. (1978) reported on the relationship between sensory characteristics and relative concentration of the volatile compounds of fresh and cooked peaches. Among the 10 peach varieties investigated, the major differences found were higher concentrations of esters and monoterpenes relative to lactones. However, she reported that the lactones made the major contribution to the "peachy" aroma.The present investigation was conducted to identify and quantitate the volatile constituents in peach cultivars by gas-liquid chromatography a n d gas-liquid chromatography/mass spectrometry. Also, the relative contributions of low and medium molecular weight compounds to peach aroma were evaluated.Variations in the volatile constituents during maturation for two peach cultivars were also determined. EXPERIMENTAL SECTIONMaterials. Tree-ripened peaches were obtained from the Appalachian Fruit Research Station, USDA-ARS, Kearneysville, WV, from the University of Georgia Horticultural Farm, Athens, GA, and from nearby commercial orchards. Fruits were analyzed within 24 h after harvest. Immedia...

Nonvolatile acids, sugars, and aroma volatiles from Majestic peaches were measured during maturation from 54 to 126 days after flowering. The highest levels of sucrose, lowest quinic acid levels, and second maximum malic/citric acid ratio occurred when mesocarp dry matter and seed reached their highest weight. Linalool, benzaldehyde, -decalactone, and -decalactone increased significantly during the final stages of maturation with -decalactone being the principal volatile compound. The increased levels of volatiles also closely paralleled seed and mesocarp growth. Pit lignification was complete about 50 days before the seed and mesocarp fully developed. Sucrose, quinic acid, malic/citric acid ratio, and major volatiles either singly or in combination appear to be useful indices for determining physiological maturity in the mesocarp and seed of Majestic peaches.

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Infection of tall fescue (Festuca arundinacea Schreb.) by a fungal endophyte (Acremonium coenophialum Morgan‐Jones & Gains) improves drought tolerance, but the mechanism is unknown. Research was conducted to determine if endophyte‐infected tall fescue subjected to drought stress accumulated sugar alcohols. An infected and uninfected clone of a ‘Kentucky 31’ tall fescue genotype was greenhouse grown in perlite at field capacity or −1.0 MPa for 7 d. Sugar alcohols and other soluble carbohydrates were identified in the leaf blades and sheath. Mannitol and arabitol were identified in sheaths of infected grasses, and arabitol accumulated in infected grasses under drought stress. Infected plants had greater concentrations of fructose and glucose in blades and higher glucose in sheaths than uninfected plants when grown under drought stress. We believe, therefore, that the higher carbohydrate accumulation in infected grasses contributes to osmotic potential and regrowth capacity of endophyte‐infected grasses.

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