A metabolomics approach to elucidate apple fruit responses to static and dynamic controlled atmosphere storage

Stefano Brizzolara a,*, Claudio Santucci b, Leonardo Tenori c, Maarten Hertog d,
Bart Nicolaid,e, Stefan Stürz f, Angelo Zanella f, Pietro Tonutti a

a Istituto di Scienze della Vita, Scuola Superiore Sant’Anna, Pisa, Italy
b CERM, University of Firenze, Firenze, Italy
c Fondazione FiorGen ONLUS, Firenze, Italy
d Division of Mechatronics, Biostatistics and Sensors (MeBioS), Department of Biosystems (BIOSYST), KU Leuven, Leuven, Belgium
e Flanders Centre of Postharvest Technology (VCBT), Leuven, Belgium
f Laimburg Research Centre for Agriculture and Forestry, Ora, Bolzano, Italy

The response of apple fruit to storage conditions based on low oxygen protocols depends on their genetic
background. In order to elucidate common and divergent processes characterizing the metabolic changes
under hypoxia, fruit of two apple (Malus domestica) varieties (‘Granny Smith’, GS, and ‘Red Delicious’, RD)
were stored under two different low oxygen protocols (Ultra Low Oxygen, ULO, at 0.9 kPa oxygen, and
Dynamic Controlled Atmosphere based on chlorophyll
fluorescence, DCA-CF, between 0.2 and 0.55 kPa
oxygen) for up to 200 and 214 days of storage for GS and RD samples, respectively. Through an integrated
metabolomics approach (1H NMR, GC–MS, HS-SPME-GC–MS analyses) a total of 130 metabolites
(volatiles and non-volatiles) were identified. Most of them (117) were common to both cultivars; 95 were
significantly different between both cultivars when comparing the whole set of data (ULO + DCA-CF),
whereas 13 volatile compounds, identified via HS-SPME-GC–MS, were specific for either GS or RD.
Multivariate analyses (PCA and PLS) of the whole dataset allowed to clearly discriminate between GS and
RD samples. When storage condition was used as a categorical response variable, a lower percentage
explained variance was obtained as this effect was overshadowed by the large effect of storage time. After
4 months of storage, RD underwent more pronounced metabolic compositional changes of the cortex,
possibly associated with the evolution of ripening. Based on the accumulation pattern of pyruvate-
derived metabolites (ethanol, acetaldehyde, lactate, alanine) it can be hypothesized that there are two
main metabolic reconfiguration strategies in GS and RD to regenerate NAD+ and cope with energy crisis
under hypoxia. GS showed more pronounced responses through changes in the nitrogen metabolism and
limited induction of the ethanol fermentation while the latter was highly induced in RD under both ULO
and DCA-CF. Marked differences were detected between the VOC profiles of the two cultivars regardless
storage conditions. Ethyl esters and 2-methylbutyl derivatives appeared
finely modulated by the Oxygen level in GS and RD apples, respectively.
Activity type
Publication in scientific journal (peer review)
Activity work package
Fruit quality; improvement of fruit handling/storage
Activity number
Activity contact
Dr. Angelo Zanella
Laimburg Research Centre
Laimburg 6 - Pfatten
I-39040 Post Auer (BZ), Italy
[email protected]
Activity partner
Laimburg Research Centre
Activity country
Last edit
The EUFRUIT thematic network has received funding from the
European Union's Horizon 2020 research and innovation programme
under grant agreement No 696337.