Juan Pablo Fernández-Trujillo

Aroma volatiles obtained at harvest by HS-SPME/GC-MS and INDEX/MS-E-nose fingerprint discriminate climacteric behaviour in melon fruit.

BACKGROUND Melon aroma volatiles were extracted at harvest from juice of a climacteric near-isogenic line (NIL) SC3-5-1 with two quantitative trait loci (QTLs) introgressed which produced climacteric behaviour and its non-climacteric parental (PS) using two methodologies of analysis: static headspace solid phase micro-extraction (HS-SPME) by gas chromatography-mass spectrometry (GC-MS) and inside needle dynamic extraction (INDEX) by MS-based electronic nose (MS-E-nose). RESULTS Of the 137 volatiles compounds identified, most were found at significantly higher concentrations in SC3-5-1 than in PS in both seasons. These volatiles were mostly esters, alcohols, sulfur-derived esters and even some aldehydes and others. The number of variables with high correlation values was reduced by using correlation network analysis. Partial least squares-discriminant analysis (PLS-DA) achieved the correct classification of PS and SC3-5-1. The ions m/z 74, 91, 104, 105, 106 and 108, mainly volatile derivatives precursor phenylalanine, were the most discriminant in SC3-5-1 and PS. As many as 104 QTLs were mapped in season 1 and at least 78 QTLs in each season with an effect above the PS mean. CONCLUSION GC-MS gave better discrimination than E-nose. Most of the QTLs that mapped in both seasons enhanced aroma volatiles associated with climacteric behaviour.

Fruit flesh volatile and carotenoid profile analysis within the Cucumis melo L. species reveals unexploited variability for future genetic breeding: Fruit flesh volatile and carotenoid profile variability within the Cucumis melo L. species

BACKGROUND Aroma profile and carotenoids content of melon flesh are two important aspects influencing the quality of this fruit that have been characterized using only selected genotypes. However, the extant variability of the whole species remains unknown. RESULTS A complete view of the volatile/carotenoid profiles of melon flesh was obtained analyzing 71 accessions, representing the whole diversity of the species. Gas chromatography-mass spectrometry and high-performance liquid chromatography were used to analyze 200 volatile compounds and five carotenoids. Genotypes were classified into two main clusters (high/low aroma), but with a large diversity of differential profiles within each cluster, consistent with the ripening behavior, flesh color and proposed evolutionary and breeding history of the different horticultural groups. CONCLUSION Our results highlight the huge amount of untapped aroma diversity of melon germplasm, especially of non-commercial types. Also, landraces with high nutritional value with regard to carotenoids have been identified. All this knowledge will encourage melon breeding, facilitating the selection of the genetic resources more appropriate to develop cultivars with new aromatic profiles or to minimize the impact of breeding on melon quality. The newly characterized sources provide the basis for further investigations into specific genes/alleles contributing to melon flesh quality.

Non-Destructive Assessment of Aroma Volatiles from a Climacteric Near-Isogenic Line of Melon Obtained by Headspace Stir-Bar Sorptive Extraction.

A climacteric aromatic near-isogenic line (NIL) of melon (Cucumis melo L.) SC3-5-1 contained an introgression of the non-climacteric Korean cultivar “Shongwan Charmi” accession PI 161375 (SC) in the genetic background of the non-climacteric cultivar “Piel de Sapo” (PS). The aroma production was monitored during ripening at 21 °C in intact fruit using headspace sorptive bar extraction (HSSE). Bars were composed of polydimethylsiloxane (PDMS) and aromas were desorbed and analyzed by gas-chromatography mass-spectrometry. The aromatic profile was composed of 70 aromatic compounds plus 21 alkanes with a predominance of esters, particularly acetate (2-methylbutyl acetate, 2-methylpropyl acetate, hexyl acetate, and phenylmethyl acetate). Some compounds were severely affected by postharvest time. The acetate esters (3-methylbutyl acetate, butan-2-yl acetate and phenylmethyl acetate) decreased with ripening and sulfur-derived compounds (S-methyl butanethioate and S-methyl 3-methylbutanethioate) increased gradually with ripening. A few compounds increased at the senescence phase (propyl ethanoate). Other compounds such as hexadecanoic acid showed a marked decrease after harvest, some decreasing from a relative maximum at harvest (2-methylpropyl hexanoate; n-hexanoic acid; nonanoic acid).

Camu-camu (Myrciaria dubia Kunth McVaugh)

Abstract: Camu-camu is a small wild berry from the Amazon river region which shows sigmoid growth and has an acid and astringent taste and the highest L-ascorbic acid content known in the fruit world. The development of a red skin is the most widely used harvest index. Camu-camu has an apparent climacteric behaviour without a detectable peak of ethylene production. Camu-camu is susceptible to shrivelling, loss of ascorbic acid and, at low temperatures, to chilling injury. For this reason, it is recommended that fruit at the turning or red colour stage be stored at temperatures around 10°C in modified atmosphere packaging (MAP). The local fresh fruit market uses MAP with low-density polyethylene bags for short storage periods. The fruit is consumed fresh or in the form of juice, while the pulp is also processed for beverages and lyophilized capsules, or to extract health-promoting compounds.

Uncommon disorders and decay in near-isogenic lines of melon and reference cultivars

Postharvest disorders and rots can produce important economic losses in fruits stored for long time for exportation. The genetic and physiological basis of some disorders in melon (Cucumis melo L.) are unknown and particularly the possible relation with climacteric behavior. A collection of melon near-isogenic lines (NILs) (SC3-5 and seven more showing climacteric and two non-climacteric ripening pattern) were analyzed to study genetic and physiological aspects of fruit disorders and rots. Two non-climacteric (Nicolas; Inodorus Group; and Shongwan Charmi PI161375, Conomon Group) and two climacteric cultivars (Fado, Reticulatus Group; Vedrantais, Cantaloupensis Group) were used as reference. The field was divided in eight blocks containing one three-plant replication for each NIL, two for the parental cultivar Piel de Sapo and one or two for the reference cultivars. Replications evaluated were more than six in the cultivars studied. Plant problems included aphids, powdery mildew, and leaf wind injury. Preharvest fruit disorders included whole fruit cracking in cultivar Vedrantais and NIL 5M2, and stylar-end cracking in cultivar Fado. Climacteric NILs with yellow skin were particularly affected by over-ripening, stylar-end cracking, and sunburn during cultivation. At harvest, two NILs showed slight placental tissue necrosis which was inherited from SC and were also detected after storage. Other uncommon disorders seen at harvest or 30 days after storage at 8oC included warted skin (scarring), flesh discoloration (light brown or translucent areas), hollow flesh disorder, and deep furrow netting inherited from SC. Less common rots included grey mould, bacterial soft rot, Penicillium rot, cottony leak and internal Cladosporium rot. Stylar-end hardness below 20 N·mm-1 was associated with cracking and softening. The incidence of the disorders and rots was too low to confirm that the genetic component played a role in their development.