Characterization of volatile substances in apples from Rosaceae family by headspace solid‐phase microextraction followed by GC‐qMS

Abstract

The volatile composition of different apple varieties of Malus domestica Borkh. species from different geographic regions at Madeira Islands, namely Ponta do Pargo (PP), Porto Santo (PS), and Santo da Serra (SS) was established by headspace solid-phase microextraction (HS-SPME) procedure followed by GC-MS (GC-qMS) analysis. Significant parameters affecting sorption process such as fiber coating, extraction temperature, extraction time, sample amount, dilution factor, ionic strength, and desorption time, were optimized and discussed. The SPME fiber coated with 50/30 microm divinylbenzene/carboxen/PDMS (DVB/CAR/PDMS) afforded highest extraction efficiency of volatile compounds, providing the best sensitivity for the target volatiles, particularly when the samples were extracted at 50 degrees C for 30 min with constant magnetic stirring. A qualitative and semi-quantitative analysis between the investigated apple species has been established. It was possible to identify about 100 of volatile compounds among pulp (46, 45, and 39), peel (64, 60, and 64), and entire fruit (65, 43, and 50) in PP, PS, and SS apples, respectively. Ethyl esters, terpenes, and higher alcohols were found to be the most representative volatiles. Alpha-farnesene, hexan-1-ol and hexyl 2-methylbutyrate were the compounds found in the volatile profile of studied apples with the largest GC area, representing, on average, 24.71, 14.06, and 10.80% of the total volatile fraction from PP, PS, and SS apples. In PP entire apple, the most abundant compounds identified were alpha-farnesene (30.49%), the unknown compound m/z (69, 101, 157) (21.82%) and hexyl acetate (6.57%). Regarding PS entire apple the major compounds were alpha-farnesene (16.87%), estragole (15.43%), hexan-1-ol (10.94), and E-2-hexenal (10.67). Alpha-farnesene (30.3%), hexan-1-ol (18.90%), 2-methylbutanoic acid (4.7%), and pentan-1-ol (4.6%) were also found as SS entire apple volatiles present in a higher relative content. Principal component analysis (PCA) of the results clustered the apples into three groups according to geographic origin. Linear discriminant analysis (LDA) was performed in order to detect the volatile compounds able to differentiate the three kinds of apples investigated. The most important contributions to the differentiation of the PP, PS, and SS apples were ethyl hexanoate, hexyl 2-methylbutyrate, E,E-2,4-heptadienal, p-ethyl styrene, and E-2-hexenal.

Effectiveness of different solid-phase microextraction fibres for differentiation of selected Madeira island fruits based on their volatile metabolite profile—Identification of novel compounds

“…Different reports show that in some fruit species like apple, pear, annona and banana [35], as well as other tropical fruit [36], esters are the major volatile compounds on their characteristic aroma profile. Our previous work confirms this feature in annona [31], apples [32] and banana (our unpublished work). In this study we show that papaya and kiwi belong to this group of fruits with high content of esters in their aroma profile, but not plum.…”

“…The same result was previously obtained in the characterization of annona [31] and apples [32] volatiles.…”

“…17.71 1399 Cis-linalool oxide P P P P ABDEFI 22.24 1482 in Madeira island, was done with the best HS-SPME methodology conditions previously reported [31][32][33]. In those reports, we have also shown that the selection of the appropriate fibre depends on the target compounds and the matrix studied.…”

“…5-Hydroxymethylfurfural and furfural are usually associated to the sweet flavour of fruits and have been identified in several other fruits aroma, including annona [31], apples [32] and banana (our unpublished results), as well as different Prunus species [37]. The volatiles composition of different kiwi species has been evaluated by different methods, but to our knowledge, only the report from Wan et al [34] used SPME to characterize kiwi aroma profile in the same A. deliciosa specie.…”

Biochemistry of apple aroma: A review

“…In Ponta do Pargo, Porto Santo and Santo da Serra apples, terpenes constituted a signifi cant fraction of total volatile compounds, with α-farnesene as the main compound (an average of 25 %). Other terpenes identifi ed were β-farnesene, germacrene, farnesol and estragole (161). In Royal Gala, a low terpene producer, (E,E)-farnesol was the predominant terpene (84 % of total terpenes), while in King David, Wilmot, Russet, Belle et Bonne, Adam's Pearmain and Merton Russet apples, (E,E)-α--farnesene was by far the most prevalent (161).…”