particularly fiber aging. This is a critical issue for data normalization when extracting volatile compounds with SPME.
14. Make sure that all the samples are at the same ripening stage.
The production of volatile compounds, including those
derived from carotenoids, changes dramatically during the
process of ripening. Additionally, biological material should
be manipulated with care. Any stress, such as physical damage,
will have a remarkable effect on the volatile profile.
15. When comparing different types of samples, analysis of pericarp
produces better comparable metabolomic profiles than using
the whole fruit, which also includes other tissues with a quite
different chemical composition, such as seeds or locular tissue.
These other tissues tend to be in different proportions,
depending on many reasons such as fruit size, locule number
or seed content, among others. Nevertheless, the same method
can be used with other tissues or the whole fruit, if preferred.
16. Fruit should be cut into pieces small enough to be introduced
in the container, but preferably not smaller.
17. Freeze-drying is an adequate technique for the storage of plant
material for some other metabolomic analysis, but not for
volatile analysis. The freeze-drying process produces depletion
in the levels of most volatile compounds.
18. When the frozen tomato powder is thawed, it tends to form
aggregates. Therefore, the end of the tip should be cut to ease
pipetting.
19. When prepared as indicated, the composition in most of the
volatile compounds in the samples is rather stable for about
10–12 h [12].
20. High incubation temperature favours the detection of semivolatile apocarotenoids. Nevertheless, it needs to be verified that
they are not produced by thermal degradation from carotenoids present in the matrix.
References
1. Rubio A, Rambla JL, Santaella M, Gomez MD,
Orzaez D, Granell A, Gomez-Gomez L (2008)
Cytosolic and plastoglobule-targeted carotenoid dioxygenases from Crocus sativus are both
involved in beta-ionone release. J Biol Chem
283:24816–24825
2. Rubio-Moraga A, Rambla JL, Ferna ´ndez-delCarmen A, Trapero-Mozos A, Ahrazem O,
Orza ´ez D, Granell A, Go ´ mez-Go ´ mez L
(2014) New target carotenoids for CCD4
enzymes are revealed with the characterization
of a novel stress-induced carotenoid cleavage
dioxygenase gene from Crocus sativus. Plant
Mol Biol 86:555–569
3. Boon CS, Mc Clements DJ, Weiss J, Decker EA
(2010) Factors influencing the chemical stability of carotenoids in foods. Crit Rev Food Sci
Nutr 50:515–532
4. Lo ´ pez-Gresa MP, Liso ´ n P, Campos L,
Rodrigo I, Rambla JL, Granell A, Conejero V,
Belle ´s JM (2017) A non-targeted metabolomics approach unravels the VOCs associated
with the tomato immune response against
pseudomonas syringae. Front Plant Sci
174
Jose ´ L. Rambla and Antonio Granell
14. Make sure that all the samples are at the same ripening stage.
The production of volatile compounds, including those
derived from carotenoids, changes dramatically during the
process of ripening. Additionally, biological material should
be manipulated with care. Any stress, such as physical damage,
will have a remarkable effect on the volatile profile.
15. When comparing different types of samples, analysis of pericarp
produces better comparable metabolomic profiles than using
the whole fruit, which also includes other tissues with a quite
different chemical composition, such as seeds or locular tissue.
These other tissues tend to be in different proportions,
depending on many reasons such as fruit size, locule number
or seed content, among others. Nevertheless, the same method
can be used with other tissues or the whole fruit, if preferred.
16. Fruit should be cut into pieces small enough to be introduced
in the container, but preferably not smaller.
17. Freeze-drying is an adequate technique for the storage of plant
material for some other metabolomic analysis, but not for
volatile analysis. The freeze-drying process produces depletion
in the levels of most volatile compounds.
18. When the frozen tomato powder is thawed, it tends to form
aggregates. Therefore, the end of the tip should be cut to ease
pipetting.
19. When prepared as indicated, the composition in most of the
volatile compounds in the samples is rather stable for about
10–12 h [12].
20. High incubation temperature favours the detection of semivolatile apocarotenoids. Nevertheless, it needs to be verified that
they are not produced by thermal degradation from carotenoids present in the matrix.
References
1. Rubio A, Rambla JL, Santaella M, Gomez MD,
Orzaez D, Granell A, Gomez-Gomez L (2008)
Cytosolic and plastoglobule-targeted carotenoid dioxygenases from Crocus sativus are both
involved in beta-ionone release. J Biol Chem
283:24816–24825
2. Rubio-Moraga A, Rambla JL, Ferna ´ndez-delCarmen A, Trapero-Mozos A, Ahrazem O,
Orza ´ez D, Granell A, Go ´ mez-Go ´ mez L
(2014) New target carotenoids for CCD4
enzymes are revealed with the characterization
of a novel stress-induced carotenoid cleavage
dioxygenase gene from Crocus sativus. Plant
Mol Biol 86:555–569
3. Boon CS, Mc Clements DJ, Weiss J, Decker EA
(2010) Factors influencing the chemical stability of carotenoids in foods. Crit Rev Food Sci
Nutr 50:515–532
4. Lo ´ pez-Gresa MP, Liso ´ n P, Campos L,
Rodrigo I, Rambla JL, Granell A, Conejero V,
Belle ´s JM (2017) A non-targeted metabolomics approach unravels the VOCs associated
with the tomato immune response against
pseudomonas syringae. Front Plant Sci
174
Jose ´ L. Rambla and Antonio Granell