Yeasts were isolated from frozen concentrated orange juice, grown in Sabouraud dextrose broth at 25 degrees C, and tested for the ability to cometabolize ferulic acid. Strains of Rhodotorula sp., ...Candida lambica, Trichosporon pullulans, and Candida intermedia decarboxylated ferulic acid nonoxidatively to an off-flavor compound, 4-vinylguaiacol. By decarboxylating naturally occurring ferulic acid, these and other yeasts have the potential to contribute to off flavors in improperly stored fruit juices
Ambient concentrations of the hydroxyl (OH), hydroperoxyl (HO
2
), and total peroxy (ΣRO
2
) radicals were measured as part of the Tropospheric OH Photochemistry Experiment at Idaho Hill, Colorado, ...during August and September of 1993. OH radicals were measured using ion‐assisted mass spectroscopy and low‐pressure laser‐induced fluorescence (LIF) detection techniques. HO
2
was measured using chemical conversion and LIF detection of OH. ΣRO
2
radicals were measured using a chemical amplifier technique. The simultaneous measurements of these key species provide an opportunity to test our present understanding of the fast photochemistry of the troposphere. Measured HO
2
/OH ratios were typically between 15 and 80, and agreed well with predictions under conditions where NO mixing ratios were greater than 100 pptv. However, under clean conditions the measured ratio was a factor of 3–4 lower than predicted. The RO
2
/HO
2
ratio was typically a factor of 4–15 larger than predicted by present theories of tropospheric chemistry. A steady state model was used in an attempt to analyze the discrepancies between the measured HO
2
/OH and RO
2
/HO
2
ratios with present theories of hydrocarbon oxidation in the troposphere.
Ambient concentrations of the hydroxyl (OH), hydroperoxyl (HO sub(2) ), and total peroxy (summation RO sub(2) ) radicals were measured as part of the Tropospheric OH Photochemistry Experiment at ...Idaho Hill, Colorado, during August and September of 1993. OH radicals were measured using ion-assisted mass spectroscopy and low-pressure laser-induced fluorescence (LIF) detection techniques. HO sub(2) was measured using chemical conversion and LIF detection of OH. summation RO sub(2) radicals were measured using a chemical amplifier technique. The simultaneous measurements of these key species provide an opportunity to test our present understanding of the fast photochemistry of the troposphere. Measured HO sub(2) /OH ratios were typically between 15 and 80, and agreed well with predictions under conditions where NO mixing ratios were greater than 100 pptv. However, under clean conditions the measured ratio was a factor of 3-4 lower than predicted. The RO sub(2) /HO sub(2) ratio was typically a factor of 4-15 larger than predicted by present theories of tropospheric chemistry. A steady state model was used in an attempt to analyze the discrepancies between the measured HO sub(2) /OH and RO sub(2) /HO sub(2) ratios with present theories of hydrocarbon oxidation in the troposphere.
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