Combined analysis of primary metabolites and phenolic compounds to authenticate commercial monovarietal peach purees and pear juices

Here we authenticated single-varietal peach purees and pear juices on the basis of primary metabolite and phenolic compound analysis by Proton Nuclear Magnetic Resonance (1H-NMR) and Ultra Performance Liquid Chromatography coupled to Photodiode Array and Tandem Mass Spectrometry (UPLC-PDA-MS/MS), respectively. After suitable preprocessing, the 1H-NMR and chromatographic data were evaluated by principal component analysis (PCA). The PCA combining data from primary metabolites and phenolic compounds allowed the separation of the clusters in all cases, allowing discrimination of processed and unprocessed peach purees, both separately and pooled. The PCA of primary metabolites allowed the cluster separation of purees of distinct peach varieties but not between processed and non-processed purees. The PCA of phenolic compounds allowed better cluster separation than of primary metabolites. For pear juices, both PCA approaches allowed satisfactory discrimination of Alejandrina, Conference, and Blanquilla cultivars. These approaches may help to better control cultivar authenticity in fruit products. It could therefore contribute to the development of a process to achieve products characterized by a quality characteristic of a given cultivar.This research was funded by the Catalan Government, grant number [2017 SGR 828]

Ripening-related cell wall modifications in olive (Olea europaea L.) fruit: A survey of nine genotypes

The production of olive (Olea europaea L.) is very important economically in many areas of the world, and particularly in countries around the Mediterranean basin. Ripening-associated modifications in cell wall composition and structure of fruits play an important role in attributes like firmness or susceptibility to infestations, rots and mechanical damage, but limited information on these aspects is currently available for olive. In this work, cell wall metabolism was studied in fruits from nine olive cultivars ('Arbequina', 'Argudell', 'Empeltre', 'Farga', 'Manzanilla', 'Marfil', 'Morrut', 'Picual' and 'Sevillenca') picked at three maturity stages (green, turning and ripe). Yields of alcohol-insoluble residue (AIR) recovered from fruits, as well as calcium content in fruit pericarp, decreased along ripening. Cultivar-specific diversity was observed in time-course change patterns of enzyme activity, particularly for those acting on arabinosyl- and galactosyl-rich pectin side chains. Even so, fruit firmness levels were associated to higher pectin methylesterase (PME) activity and calcium contents. In turn, fruit firmness correlated inversely with ascorbate content and with α-L-arabinofuranosidase (AFase) and β-galactosidase (β-Gal) activities, resulting in preferential loss of neutral sugars from cell wall polymers.This work was funded by grant AGL2015-64235-R from the Plan Nacional de I+D, Ministry of Education and Science, Spain. CD is the recipient of a predoctoral scholarship granted by the Universitat de Lleida

Insights into olive fruit surface functions: a comparison of cuticular composition, water permeability, and surface topography in nine cultivars during maturation

Olive (Olea europaea L.) growing has outstanding economic relevance in Spain, the main olive oil producer and exporter in the world. Fruit skin properties are very relevant for fruit and oil quality, water loss, and susceptibility to mechanical damage, rots, and infestations, but limited research focus has been placed on the cuticle of intact olive fruit. In this work, fruit samples from nine olive cultivars ('Arbequina,' 'Argudell,' 'Empeltre,' 'Farga,' 'Manzanilla,' 'Marfil,' 'Morrut,' 'Picual,' and 'Sevillenca') were harvested from an experimental orchard at three different ripening stages (green, turning, and ripe), and cuticular membranes were enzymatically isolated from fruit skin. The total contents of cuticular wax and cutin significantly differed among cultivars both in absolute and in relative terms. The wax to cutin ratio generally decreased along fruit maturation, with the exception of 'Marfil' and 'Picual.' In contrast, increased water permeance values in ripe fruit were observed uniquely for 'Argudell,' 'Morrut,' and 'Marfil' fruit. The toluidine blue test revealed surface discontinuities on green samples of 'Argudell,' 'Empeltre,' 'Manzanilla,' 'Marfil,' and 'Sevillenca' fruit, but not on 'Arbequina,' 'Farga,' 'Morrut,' or 'Picual.' No apparent relationship was found between water permeability and total wax coverage or the results of the toluidine blue test. The composition of cuticular waxes and cutin monomers was analyzed in detail, and sections of fruit pericarp were stained in Sudan IV for microscopy observations. Skin surface topography was also studied by means of fringe projection, showing large differences in surface roughness among the cultivars, 'Farga' and 'Morrut' fruits displaying the most irregular surfaces. Cultivarrelated differences in cuticle and surface features of fruit are presented and discussed.This work was funded by grant AGL2015-64235-R from the Plan Nacional de I+D, Ministry of Education and Science, Spain. CD is the recipient of a predoctoral scholarship granted by the Universitat de Lleida. PH-L was recipient of a PhD scholarship from Zespri™ International. HH was supported by an Oversea Study Program, Guangzhou Elite Project, China