1,721,147 research outputs found
Innovations in Storage Technology and Postharvest Science
No full textNovel or improved postharvest technologies have been developed in the last 10-15 years. Some of them (e.g., 1-MCP) are already being used in several storage facilities and commercial applications, others (e.g., DCA) are just targeted for specific horticultural crops, some others are still at a preliminary or pilot-scale level and currently under evaluation. The integration of different treatments and the
optimization of already existing protocols, a trend observed for the storage of several commodities, need to be assessed and validated through the combination of basic and applied research with the aim of elucidating metabolic processes and regulatory mechanisms affected by the imposed postharvest conditions. The development of
“omics” technologies and the increasing number of horticultural crop genomes that have been sequenced and annotated are facilitating this new approach in postharvest science. Information and descriptions of storage-related processes at the level of transcripts, proteins and metabolites are starting to be available concerning the responses to low temperature storage including the different aptitudes to develop
chilling injuries. Similarly, the biological basis of the effects of hypoxic conditions on the maintenance of quality and the onset of the related physiological disorders (superficial scald, browning) are going to be elucidated by means of integrated and systemic approaches
The Technical Evolution of CA Storage Protocols and the Advancements in Elucidating the Fruit Responses to Low Oxygen Stress
No full textAbstract
Innovations in postharvest technology also deal with the modulation of gas
composition in storage rooms and/or packaging, in particular concerning oxygen
levels, which, for some storage protocols and fruit crops, is set at extremely low
concentrations (less than 1 kPa). Since the establishment of the first commercial CA rooms,
the oxygen concentration showed a constant decrease throughout decades, reaching
the lowest levels used in ULO (Ultra Low Oxygen), ILOS (Initial Low Oxygen
Stress), and DCA (Dynamic Controlled Atmosphere) applications. This decreasing
trend in oxygen concentrations used in storage rooms resulted in a general
improvement of the quality parameters and the marketable life of the commodities
(apples, in particular). The optimization of these techniques and the reduction of the
risks (development of physiological disorders, off-odors, off-flavors) associated with
keeping the fruit at such extreme conditions need to be based on a better knowledge
of the metabolic responses to hypoxia. The metabolic responses of fruit tissues to
low-oxygen stress are, as observed in model plants, mainly related to dramatic
changes in mitochondrial respiration and the activation of the fermentative
metabolism that appear to be differently affected (resulting in different levels of
ethanol accumulation) by different low oxygen levels and in relation to the genetic
background. Among others, ethanol, alanine, asparagine and aspartate
concentrations in cortex tissue markedly change in relation to hypoxic conditions,
thus representing possible metabolic markers of this kind of stress. Specific volatile
compounds of apples are also differentially affected, whereas other volatile classes
appear more stable. Using large-scale transcriptomic approaches coupled with
metabolic profiling analyses it is now possible to better describe the global fruit
responses to low oxygen conditions. In apples, in addition to the expression of genes
involved in primary metabolism (major CHO, fermentation), hypoxia also affects
specific secondary metabolic pathways that appear to be selectively modulated by
different low oxygen treatments. Members of the ERF-VII transcription factors
(TFs) gene family displayed differential expression suggesting their involvement in
the modulation or controlling mechanisms of hypoxic responses, as observed in
model species
Heat and hypoxia stress and their effects on stored fruits
No full textPurpose of review: This review gives an overview of the current knowledge of metabolic and molecular responses of fruit commodities to pre-storage heat treatment and to low oxygen conditions (hypoxia) during storage.
Main findings: Both hot water and hot air treatments have been used on citrus fruit and peaches to control fungal pathogens and prevent chilling injury during storage. Proteomic and metabolomic studies of these two commodities found that the heat treatment led to the accumulation of stress and defense proteins, and caused an increase in sugars and a decrease in organic acids. Some studies also found increases in polyphenols and polyamines, which have antioxidative activity and protective effects against stress. The transcriptomic studies corroborated these findings and found that heat treatment led to changes in transcripts that were similar to those that occurred in cold storage. Hypoxia produced by decreasing oxygen concentration (generally together with increase in the carbon dioxide levels) is the basis for controlled and modified atmosphere (CA and MA) storage. As observed in vegetative tissues and model species, as well as in fruits, the responses to modified O2 levels include changes in primary and secondary metabolism as result of modifications at the levels of gene expression and mRNA translation. Recently, some molecular elements of low oxygen sensing and signaling in Arabidopsis have been elucidated, and similar sensing mechanisms are postulated to be present in fruit tissues to modulate the metabolic responses in relation to the different oxygen levels present in the storage rooms.
Directions for future research: Integrated 'omics' approaches will result in a more precise understanding of postharvest stress physiology and adaptive mechanisms present in fruit crops, and elucidate the major pathways involved in the responses. This may lead to strategies that will allow commodities to resist stresses through targeting specific genes in a pathway, either by conventional breeding or other methods
Il ruolo del postraccolta per il mantenimento della qualità e l'innovazione dei prodotti ortofrutticoli: l'Italia in primo piano
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