Group Title: Flavor research investigations, 1962
Title: Flavor research investigations
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Permanent Link: http://ufdc.ufl.edu/UF00072343/00001
 Material Information
Title: Flavor research investigations
Series Title: Citrus Station mimeo series
Alternate Title: Present status on analysis of flavor and aroma of orange juices by gas chromatography
Identification of some alcohols and acids in orange essences
Physical Description: 4, 5 leaves : ill. ; 28 cm.
Language: English
Creator: Wolford, R. W
Alberding, Gilbert E
Attaway, John A., 1930-
Citrus Experiment Station (Lake Alfred, Fla.)
Florida Citrus Commission
Publisher: Florida Citrus Experiment Station :
Florida Citrus Commission
Place of Publication: Lake Alfred FL
Publication Date: 1962
 Subjects
Subject: Orange juice -- Flavor and odor -- Testing -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: Richard W. Wolford, Gilbert E. Alberding, and John A. Attaway.
General Note: Caption title.
General Note: "October 2, 1962."
Funding: Citrus Station mimeo report ;
 Record Information
Bibliographic ID: UF00072343
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 75262397

Full Text






Citrus Station Mimeo Series 63-1
October 2, 1962

Flavor Research Investigations

I. Present Status on Analysis of Flavor and Aroma of Orange Juices
by Gas Chromatography

Richard W. Wolford, Gilbert E. Alberding, and John A. Attaway
Florida Citrus Commission
Lake Alfred, Florida


Previous discussions on investigations concerning the volatile flavor
components of citrus juices, with particular emphasis on orange juices, have
appeared in the Annual Citrus Processors' Meeting reports for 1959, 1960,
and 1961. While much of the published data resulting from these investi-
gations have been concerned with methodology, a significant number of chemical
identifications have been confirmed and some new compounds have been reported.

Through the continued application of new developments in programmed
temperature gas chromatography (PTGC) improved resolution of the complex mixture
of components contributing to the flavor of orange juice has been possible. Like-
wise, the development of supplementary methods for analysis, including paper and
column chromatography, for identification of carbonyls, alcohols, and acids, has
extended the knowledge of the chemical composition of the compounds responsible
for the flavor of orange juices. Some later studies concerning the alcohols and
acids are outlined in the second paper in this series.

Efforts toward tentative identification of components separated by PTGC
where multiple column systems were utilized brought about the effective use of
retention temperatures for chromatographic peak assignments. The validity of
that procedure has been proven in the case of a large number of compounds,
especially the carbonyls and alcohols. The analysis of esters using retention
temperatures for peak assignments in conjunction with a determination of the
alcohol and acid portions will also assist in their identification. In addition,
the application of subtractive methods to the analysis of extracts of recovered
orange essences has permitted identification of compounds in a less complex
mixture.

With the established use of these techniques, another phase of investigation
was immediately undertaken. While commercially recovered orange essences have
continued to serve as the principal source of volatile flavor components in these
studies, it became evident that the volatile component spectrum of specially pre-
pared essences from some established orange varieties was desirable so that they
could be compared. Normally, the organic extracts which have been studied con-
tained significant quantities of terpene hydrocarbons and other materials which
apparently came from the peel oil. Entrainment of oil would be expected in juices
and subsequently recovered essences where commercial juice extraction procedures
are employed. Therefore, it was desired that analyses of volatiles from peel oil-
free juice and the recovered peel oil be made for comparative purposes. In


Florida Citrus Commission and
Florida Citrus Experiment Station,
Lake Alfred, Florida.
10/2/62 RWW







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addition to analyses using PTGC with thermal conductivity detection on liquid
injections of essence extracts, aroma analyses of the fresh orange juices and
their recovered volatiles also have been undertaken.

Some of the aims in this study were (1) to examine the compositional
differences in control juice simulating commercially extracted juice, peel oil-
free prepared juice, and peel oil of three varieties of oranges; (2) to deter-
mine the contribution to the flavor of extracted juice by volatile components
inherently present in the juice and/or peel oil; (3) to define any qualitative
or relative quantitative changes in flavor components with advancing maturity;
and (4) to compare analyses of the constituents responsible for the fresh aroma
of the juices of each variety.

Comparative evaluations of the flavor and aroma patterns by PTGC of three
varieties of Florida oranges, namely, Hamlin, Pineapple, and Valencia, were
conducted. Preliminary investigations revealed no significant qualitative dif-
ferences in gross analyses conducted on either the liquid or vapor. However,
it was indicated that relative quantitative differences were responsible for
the flavor differences noted among varieties.

Analyses of control juices, peel oil-free juices, their respective juice
essences, and peel oils from each variety of orange studied showed some com-
positional differences. The presence of certain chemical constituents in the
juice was directly related to the peel oil. No significant qualitative dif-
ferences existed in similarly prepared samples from different varieties.

The principal components in the peel oil from each of the three varieties
were identified as alpha-pinene, myrcene, d-limonene, n-octanal, n-nonanal, n-
decanal, linaloOl, and n-octanol, confirming results reported by other investi-
gators. Those in the higher boiling region of oxygenated components were indi-
cated to be neral, geranial, and carvone. Future work will require deterpe-
nation of the oil and specific study of the oxygenated components.

Those major components identified in the juice of each variety were methanol,
ethanol, n-hexanal, d-limonene, 1-hexanol, and 3-hexenol, There were large
concentrations of components in the higher retention temperature range of 1930
and 2370C. which are presently unidentified. Also, included in the chromatographic
peak assignments were neral and geranial.

Of the three varieties, the Valencia juice had the highest recoverable oil.
This was reflected in the chromatograms of the simulated commercially extracted
juices where the terpenes had a quantitative effect on the oxygenated components.
However, the peel oil-free juice volatiles were qualitatively identical with
those in the other varieties.

The following observations indicated certain trends in the quantitative
changes in some components with advancing maturity. In Hamlin juice from
oranges picked on 2/1/62 increases in concentration of ethyl butyrate, n-hexa-
nal, 1-hexanol, 3-hexenol, geraniol, and attendant reductions in the amounts of


Florida Citrus Commission and
Florida Citrus Experiment Station,
Lake Alfred, Florida.
10/2/62 RWW








-3-


acetaldehyde, n-octanal, linalool, 1-octanol, and neral were observed compared
to Hamlin juice from fruit picked at an earlier date, 11/28/61. Pineapple orange
juice from more mature fruit, picked on 2/1/62 exhibited increases in concen-
tration of ethyl butyrate, n-hexanal, 1-hexanol, linalo'l, and the citral isomers,
neral and geranial. There appeared to be some reduction in the terpene hydro-
carbons, myrcene and d-limonene. However, n-octanal contributed by the oil did
not appear to change with maturity. In the Valencia juice significant increases
in concentrations of ethyl butyrate, linalool, and 1-octanol were related to
change in maturity between the picking dates 3/21/62 and 5/1/62.

The following components, in particular, appeared to provide some character-
ization for the juices of each of the three varieties: ethyl butyrate, n-hexanal,
n-octanal, 3-hexenol, linalool, and possibly some of the higher boiling terpene
carbonyls, alcohols, and esters. The constituent exhibiting the most consistent
concentration change with advancing maturity was ethyl butyrate.

In Table 1 are shown the volatile chemical components in Pineapple orange
juice which have been given peak assignments, based on retention temperatures
and peak coincidence with known compounds.

Aroma chromatograms obtained on 4 ml samples of vapor, removed from a sealed
headspace above fresh juice at room temperature, showed 35 flavor components.
Some of the components separated from the vapor sample were identified as follows:
acetaldehyde, possibly ethyl format, acetone, methanol, ethanol, ethyl butyrate,
alpha-pinene, n-hexanal, myrcene, d-limonene, 2-hexenal, and n-octanal.

The aroma chromatograms, using ionization detection methods, have shown the
following results: (1) the volatile constituents that cause the aroma of orange
juice can be shown qualitatively and the potentiality of semi-quantitative deter-
mination is good. A satisfactory chromatogram of volatile components from a
limited headspace over one liter of orange juice at temperatures as low as 100C.
can be obtained, indicating adequate vapor pressures of components through d-
limonene and including n-octanal in some samples. As would be expected, increas-
ing the temperature of the juice increases the overall concentration of the
components in the headspace; (2) the aroma chromatograms of recovered dilute
essences from Hamlin, Pineapple, and Valencia orange juices are directly comparable
with the aroma analyses of the fresh juices themselves. Except for the slightly
higher concentrations in the experimentally recovered volatile essences, no
chemical changes resulting from the recovery procedure were indicated; and (3)
distinct qualitative similarities were shown in the aroma chromatograms of the
juices from three varieties of Florida oranges. Some quantitative differences
throughout the spectrum might be used to differentiate among varieties.

Present studies of the aroma of orange juices are being accelerated to meet
the need for direct analysis. Some particular phases of this work are concerned
with improved columns, greater sensitivity at the higher temperatures, the eval-
uation of dual column dual flame systems, and adjustment of operating para-
meters for maximum resolution of components in the vapor.


Florida Citrus Commission and
Florida Citrus Experiment Station,
Lake Alfred, Florida.
10/2/62 RWW









Table 1. Component peak assignments (Fig. 1) on chromatograms
of Pineapple orange juice volatile flavor components.

Compound Peak assignments
Acetaldehyde 5
Acetone 7
(Ethyl formate1 7
(Ethyl acetate) 8
Methanol 9
Ethanol 9
(Methyl isovalerate) 13
(1-Propanol) 13
Ethyl butyrate 14
(o< -Pinene) 15
n-Hexanal 16
Myrcene 20
A3 -Carene 20
o( -Terpinene 21
d-Limonene 22
(n-Amyl alcohol) 22
2-Hexenal 22
Ir -Terpinene 24
n-Octanal 25
2-Hexenal 25
Terpinolene 25
(p-Cymene) 25
n-Hexanol 26
3-Hexenol 27
(2-Octenal) 27
n-Nonanal 29
(Methyl heptenol) 30
Ethyl n-caprylate 30
2-Nonanol 32
n-Decanal 34
Linaloil 35
n-Octanol 36
(n-Undecanal) 39
(Terpinen-4-ol) 40
(n-Octyl butyrate) 42
1-Nonanol 42
(n-Octyl isovalerate) 43
Neral 44
<( -Terpineol 44
Terpinyl acetate 45
Geranial 46
(Methyl-n-methyl anthranilate) 46
Citronellol 46
1-Carvone 48
Nerol 50
Geraniol 50
(Trans-Carveol) 51
1The components in parentheses either received study on
only one column or did not show agreement in peak assign-
ment by analysis on two columns. All other peak assignments
have been either positively or tentatively identified.
Florida Citrus Commission and Florida Citrus Experiment Station,
Lake Alfred, Florida. 10/2/62 RWW











The study of the flavor and aroma components in juices of established
varieties of oranges will also be repeated during the 1962-63 season. It is
desirable that a more critical comparison between varieties will be possible
with the accumulation of identified components for the use in interpretation
of chromatograms.

Acknowledgments

The suggestions and assistance of Mr. C. P. Atkins in the recovery of
the orange juice volatiles, using pilot plant equipment, was very much
appreciated.

The authors wish to thank Libby, McNeill, and Libby for supplying samples
of orange essence used in the flavor research investigations.


































Florida Citrus Commission and
Florida Citrus Experiment Station,
Lake Alfred, Florida.
10/2/62 RWW




























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RETENTION TEMPERATURE, C.
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Figure 1. PIGC chrnatograms of A- Pineapple (late) control juice volatile,
B- Aeel oil-free juice volatiles, C- t3el oil.
B- Feel oil-free juice volatiles, C- Feel oil.




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