1,721,086 research outputs found
Identificazione e applicazione di marcatori fisiologici, biochimici e molecolari della qualità di prodotti ortofrutticoli
No full textI prodotti ortofrutticoli durante il postraccolta, dal punto di vista biologico sono vivi e manifestano delle risposte fisiologiche ai processi di lavorazione, alla manipolazione, ai trattamenti e all’atmosfera interna alle confezioni. La fisiologia postraccolta è di conseguenza facilmente assimilabile alla fisiologia di piante sottoposte a stress di vario tipo. Alcuni esempi di stress abiotici ai quali il prodotto può andare incontro includono la disidratazione, le alte e basse temperature, la mancanza (o eccesso) di luce, il taglio, l’esposizione a etilene, ecc. La capacità delle piante di adattarsi ad ambienti e condizioni sfavorevoli diverse è, direttamente o indirettamente, connessa a risposte fisiologiche complesse che coinvolgono la sintesi e la degradazione di metaboliti, l’espressione di geni, l’attività di enzimi, l’azione di ormoni e la sintesi di proteine specifiche.
L’insieme complesso di questi fenomeni, unitamente alla presenza di contaminazioni di tipo ambientale e microbiologico, determinano la qualità postraccolta del prodotto ortoflorofrutticolo.
Durante l'ultimo decennio, i gruppi di ricerca hanno focalizzato la loro attività di ricerca sulle diverse componenti della qualità dei prodotti durante la fase postraccolta attraverso l’applicazione delle più moderne tecniche di indagine come la trascrittomica, la proteomica e la metabolomica.
Lo scopo di questa presentazione è quello di fornire un quadro generale dei risultati ottenuti in tale campo per il monitoraggio e la valutazione della qualità. Verrà brevemente illustrato come le diverse tecnologie di indagine scientifica possano essere combinate al fine di sviluppare metodi multidisciplinari e sistemi di valutazione della qualità affidabili, rapidi, e di semplice esecuzione da poter applicare lungo tutta la filiera.
Durante la presentazione saranno mostrati alcuni esempi di ricerche basate sulla identificazione di potenziali marcatori fisiologici, biochimici e molecolari della qualità dei prodotti ortofrutticoli durante la fase postraccolta. Come caso di studio saranno presentati in particolare i risultati più recenti ottenuti nel corso del progetto Europeo QUAFETY
Effects of postharvest treatments on quality and vase life of cut rose (Rosa hybirida)
No full textRose (Rosa hybrida) is among the most important species sold as cut flower. Its vase life is quite short and ranges from 6 to 10 days, depending on postharvest conditions. Flower and leaf senescence are the main responsible for quality losses and strongly affects the marketability of this ornamental item.
The aim of this work was to evaluate the effects of different postharvest treatments on the quality and on the vase life of cut-rose flowers. Cut roses (flowers and leaves) were treated for 24 h with different classes of compounds including chemical elicitors (salicylic acid - SA, benzothiodiazole - BTH, methyl jasmonate - MJ), signal molecules (nitric oxide, hydrogen peroxide) and ethylene-suppressor (selenium). During vase life, gas exchanges, chlorophyll contend and chlorophyll a fluorescence were monitored non-destructively in leaves. Samples were collected at harvest (T0) and after 7 (T7) and 10 (T10) days of vase life at 25 °C and destructive analyses (sugars, phenolic compounds) were conducted.
Results showed that the treatments with BTH and SA increased chlorophyll content in leaves after 4 days. Chlorophyll a fluorescence data showed that BTH was able to preserve leaf functionality and delay senescence in cut roses after 7 days of vase life
CHARACTERIZATION OF BIOACTIVE COMPOUNDS AND QUALITY ATTRIBUTES IN VACCINIUM SPP. DURING DEVELOPMENT RIPENING AND STORAGE.
Full text linkBlueberries belong to the genus Vaccinium , a widespread genus with over 200 species of evergreen and deciduous woody plants varying in size from dwarf shrubs to trees.
Blueberry possesses one of the highest antioxidant capacities in berries due to the high contents of anthocyanin pigments; it is also a moderate source of ascorbic acid (AsA). It is accepted that the content of phenolics and ascorbic acid in berries is not only affected by genetic differences and pre-harvest environmental conditions, but also by the degree of maturity at harvest. In postharvest, different storage conditions may also strongly influence antioxidant capacity of this produce and there are many factors who contribute to improve fruit quality maintenance such as temperature, gas concentration and cultivar.
The aim of these studies is to improve the product quality, by acquiring a better understanding about the evolution of bioactive compounds during maturation and storage and to define the optimal conditions to extend the shelf life of fresh produce while ensuring both commercial and nutraceutical quality.
The work consists in the identification and evaluation of antioxidant compounds (such as phenolics and ascorbic acid) of potential use for their functional and bioactive properties during maturation and ripening and under different pre- and postharvest conditions in different blueberry cultivar and species.
Shelf-life trials were performed along three years in order to test different controlled atmosphere (C.A.) conditions on three blueberry varieties (‘Brigitta’, ‘Legacy’ and ‘Duke’). Analyses on phenolic compounds and ascorbic acid content were performed, moreover, we performed analyses aiming to estimate the oxidative status of fruits during storage, by measuring the malondyhaldeide content expressed as TBARs equivalents.
We have individuated the storage conditions that guarantee both the longest shelf life and the highest phenolic content during storage. Among the considered varieties, ‘Brigitta’ showed the best attitude to C.A. storage with the lowest degradation rate, and the highest quality keeping during the storage period.
Benzothiadiazole (BTH) is a functional analogue of salicylic acid that acts as an elicitor of the phenolic metabolism and of systemic acquired resistence (SAR). Pre-harvest treatments with BTH were performed on two different varieties (‘Duke’ and ‘Brigitta’) during fruit development and ripening. We measured ascorbic acid content, total phenols, total anthocyanins and total flavonoids at four different stages of maturation and ripening. We also measured APX, DHAR, MDHAR and GR enzymatic specific activities.
A substantial positive effect of BTH treatment on phenolics and ascorbic acid content was observed in blueberry with different behavior depending on the cultivar studied. A positive effect was also observed on the activity of the enzymes involved in ascorbate recycling.
Pre-harvest treatments using the phytohormone Methyl Jasmonate (MeJa) were performed. Plants from two cultivar (‘Blue Ray’ and ‘Duke’) were treated with a MeJa solution. Berries nearly expanded after colour breaking were picked 3, 6, 9 and 24 hours after treatment for molecular analyses. After one week from the treatment all fruit from the plants were picked up and stored at -80°C. The whole experimental plan was repeated for two growing seasons.
Total RNA was extracted from tissues for gene expression analyses on key enzymes of the phenylpropanoid pathway. Our results showed that the treatment was effective in stimulating the expression of some of the key genes in phenylpropanoids metabolism (such as CHS and PAL). We measured the changes in levels of different classes of phenolic compounds by HPLC.
Data obtained from transcripts and metabolite analyses resulted to be well-paralleled and allowed us to make comparisons and observe good correlations in the so called gene-to-metabolite networks for secondary metabolism in blueberry. However more detailed analyses, for example on the regulatory factors of this pathway remains to be performed as an interesting challenge for future analyses.
Ascorbic acid (AsA) accumulation and the expression of the genes encoding the enzymes of the main AsA biosynthetic and recycling routes as well as the activities of the enzymes involved in AsA recycling were investigated for the first time during the development and ripening of bilberry (Vaccinium Myrtillus) fruit. The results showed that the AsA level was highest in unripe green berries but decreased slightly during the maturation. This was supported by the expression data of the genes encoding the key enzymes in the main AsA biosynthetic route, particularly in the early ripening stages. Activities of the studied enzymes were mainly consistent with the AsA levels. In over-ripe berries, both AsA content and gene expression were markedly higher in skin than in pulp
Effects of long-term storage on highbush blueberry (Vaccinium Corymbosum L.) antioxidant quality
No full textBlueberry (Vaccinium corymbosum L.) is a fruit crop rich in antioxidants.
The quality of this fruit and the content of health-promoting compounds are
influenced by many factors, such as environmental conditions, genetic diversity and
degree of maturity at harvest. Blueberry has often been reported to be a highly
perishable fruit, thus its commercial value could be strongly affected by storage
conditions. After harvest, blueberry quality and product losses are mainly due to
dehydration, weight loss, shrivel and fungal spoilage. Little is known so far about the
effects of long-term storage on the antioxidant components of blueberry. We
investigated the effects of two different conditions of controlled atmosphere (CA1:
4 kPa O2 plus 10 kPa CO2; CA2: 1 kPa O2 plus 9 kPa CO2) on a mid/late season
blueberry cultivar (‘Legacy’) during long-term storage, by measuring the incidence
of decay, total polyphenols, total flavonoids, total anthocyanins and the antioxidant
capacity using the DPPH ̇ radical-scavenging assay. Sampling was for a period much
longer than normally expected for storage of this product. Controlled atmosphere
unexpectedly did not retard decay. During storage an irregular pattern was
observed in the levels of total polyphenols, but at the end of the trial, the content had
not changed, with respect to the beginning, in the control and CA2 stored samples.
The content of total flavonoids and total anthocyanins changed in a similar way
during storage and no marked effect can be linked to any gas composition. In
conclusion ‘Legacy’ blueberry fruit demonstrated stability in quality attributes and
marketability during the whole cold storage period (almost 5 months). ‘Legacy’
appeared to be a rich source of phenolic compounds.
Among the different applied CA conditions, CA2 was slightly more effective
in maintaining high levels of flavonoids and anthocyanins
Ascorbic Acid Content in ‘Passe-Crassane’ Winter Pear as Affected by 1-Methylcyclopropene during Cold Storage and Shelf Life
No full text‘Passe-Crassane’ is a winter pear which requires a cold storage period to produce
ethylene and properly ripen. In this study, the effects of 1-methylcyclopropene (1-MCP), an
ethylene perception inhibitor,were studied during cold storage (30, 60, 90, and 135 days) and
shelf life at 20 8C (30 days) of ‘Passe-Crassane’ pears. Ethylene accumulation was monitored
and quality parametersweremeasured.Oxidative stress of fruitwas estimated bymeasuring
lipid peroxidation. The cell antioxidant status was assayed determining ascorbic acid (AsA)
content and the activities of the enzymes ascorbate peroxidase (APX), monodehyroascorbate
reductase (MDHAR), dehydroascorbate reductase (DHAR), and glutathione reductase (GR)
involved in its oxidation and recycling. AsA content was positively affected by higher
temperature (20 8C) and by 1-MCP after 90 days of storage. This effect was more evident
after shelf life. Thiobarbituric acid reactive substances (TBARS) increased in pears kept at
20 8C and in treated pears, starting from 60 days of cold storage and remained elevated after
shelf life. Although during storage 1-MCP enhanced the activities of APX and DHAR only at
90 days, after shelf life the effect on APX, MDHAR, and DHAR activities was more
pronounced and enzyme activities were higher in treated pears sampled after 60 and 90 days
of storage. The results indicate that 1-MCP has a beneficial effect on the antioxidant potential
of winter pears: it maintained high AsA levels throughout storage and shelf life and
improved the enzymatic mechanisms of AsA recycling, especially after shelf life. The effect of
1-MCP on pear ripeningmay not be solely due to its action on ethylene but also to an increase
in antioxidant defense. A stress response linked to lipid peroxidation is triggered by the
interaction of cold temperatures and treatment as ‘Passe-Crassane’ pears acquires ripening
competence. However, it may be compensated by the high AsA content
Transcriptome analysis of transcription factors in rocket (Diplotaxis tenuifolia L.) under postharvest stress
No full textRocket (Diplotaxis tenuifolia L.) is widely used in fresh-cut salads and it is appreciated by consumers for its nutraceutical and sensorial properties. The evaluation of quality in ready-to-eat vegetables over the production pipeline is a crucial need for the fresh-cut industry. Analysis of the transcriptome allows studying the transcriptional events that take place in an organism under different physiological conditions. In this study rocket has been subjected to different postharvest stress conditions, and transcriptome analysis was employed to study the changes induced in specific pathways or gene families. Plants were grown using hydroponic systems in controlled growth chambers for 3 weeks prior to stress treatment. Post-harvest stresses included chilling, wounding, dark and water deprivation. Sampling was performed after 24 h and total RNA was extracted from stressed and control plants and sequenced with a two paired-end Illumina sequencing platform. Preliminary results from the analysis of the transcription factors which were influenced by stresses are presented. Among the 33874 transcripts found, 2188 were identified as putative transcription factor genes and were clustered into groups corresponding to the most representative transcription factors families.
Results suggest an involvement of transcription factors in plant stress responses. The data obtained from this work will help to shed more light on the mechanisms of stress response in rocket, with regards to the regulatory network and to the involvement of specific pathways which cover important roles in plant physiology and in human nutrition
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