The Technical Evolution of CA Storage Protocols and the Advancements in Elucidating the Fruit Responses to Low Oxygen Stress

Abstract 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

Metabolomics approach to studying minimally processed peach (Prunus persica) fruit

Fresh-cut fruit products for both retail and food service applications have increasingly appeared in the market place in recent years. Among different fruit types, peaches can be used and are highly appreciated as fresh-cut product although their commercial success is limited due to their short shelf-life and the quick onset of wounding-related physiological reactions. In this work we analyzed the technological and physiological changes induced by fresh-cut preparation in three different types of peach cultivars: 'Fayette' (melting), 'Wilhelmina' (non-melting) and 'Ghiaccio3' (stony hard). We performed a metabolite targeting profiling to focus on the changes in organic acid levels, important components of fruit taste and organoleptic quality of peaches. Interestingly, 'Ghiaccio3' showed an increase of several organic acids after cutting while 'Fayette' and 'Wilhelmina' showed unchanged amounts or a general reduction. Cutting induces a similar pattern of change in important metabolites (i.e., dehydroascorbate, alanine) in all the three peach types while other metabolites (i.e., citric acid) appeared to be differentially regulated in the considered peach cultivars

Charge Transfer and Charge Broadening of GEM Structures in High Magnetic Fields

We report on measurements of charge transfer in GEM structures in high magnetic fields. These were performed in the framework of the R&D work for a Time Projection Chamber at a future Linear Collider. A small test chamber has been installed into the aperture of a superconducting magnet with the GEM structures mounted perpendicular to the B field direction. The charge transfer is derived from the electrical currents monitored during irradiation with an ${}^{55}$Fe source. No severe loss of primary ionisation charge is observed, but an improved ion feedback suppression is achieved for high magnetic fields. Additionally, the width of the charge cloud released by individual ${}^{55}$Fe photons is measured using a finely segmented strip readout after the triple GEM structure. Charge widths between 0.3 and 0.5 mm RMS are observed, which originate from the charge broadening inside the GEM readout. This charge broadening is only partly suppressed at high magnetic fields.Comment: 11 pages, 9 figure

Rapid and non-destructive method to assess in the vineyardgrape berry anthocyanins under different seasonal andwater conditions

Abstract Background and Aims: Monitoring of anthocyanins (Anth) in winegrape (Vitis vinifera L.) is fundamental for the production of top-quality red wines. This work was aimed at testing a new fluorescence-based sensor for Anth detection in the vineyard. Significance of the Study: The present study showed a new important innovative technology for viticulture. The sensor evaluation of the large spatial and temporal heterogeneity in Anth accumulation can be useful as support parameter in the harvest date decision or for vineyard zoning of phenolic maturity. Methods and Results: Anth in grape (cv. Aleatico) bunches attached to the vine were monitored non-destructively in the field using a fluorescence-based sensor during the 2008 and 2009 seasons and under different water regimes. The ANTHRG index = log(far-red-fluorescenceR/far-red-fluorescenceG), with fluorescence signals excited with red (R) and green (G) light, was inversely correlated through an exponential function (r2 = 0.875) to the Anth concentration derived from the HPLC analysis of berry skin extracts. ANTHRG was effective in detecting the earlier ripening process in 2009 with respect to 2008 and differences in the Anth accumulation between seasons and in relation to different water regimes.Water deficit imposed in 2009 enhanced Anth concentration in berries because of a reduction in berry size but also an increase of Anth biosynthesis. This effect was observed by both destructive and ANTHRG non-destructive measurements. Conclusions: Our results show that the employed fluorescence sensor represents a reliable, rapid and non-invasive tool for monitoring and determining Anth accumulation in situ

Ethanol fermentation- and ethylene physiology-related gene expression profiles in Red Delicious apples stored under variable hypoxic conditions and protocols

Dynamic Controlled Atmosphere (DCA) is beneficial in maintaining specific quality parameters but, due to the extreme oxygen levels applied, can cause adverse effects on the fruit by inducing excessive anaerobic metabolism and the production of off­flavors. The metabolic adaptation and responses of apples (Malus domestica Borkh.) cv. Red Delicious to static or dynamic oxygen concentrations (0.3 and 0.8%, with sequential shifts) during cold storage for 7 months were studied by monitoring quality parameters and the expression of genes involved in sugar, fermentative metabolism, and ethylene physiology. Ethanol content reached the highest levels (around 400 mg/kg FW) under 0.3% oxygen concentration and fruit firmness appeared to be reduced in samples accumulating the highest levels of ethanol. The oxygen switch was effective in reducing the ethanol concentrations with timing­dependent variable effects. The expression of fermentative (alcohol dehydrogenase, lactate dehydroge‐nase, pyruvate decarboxylase) and sugar metabolism (β‐amylase; phosphofruc‐tokinase; sucrose synthase) genes resulted to be differently affected by the hypoxic conditions imposed, in particular during the early stages of storage. Sucrose synthase expression appeared to be highly sensitive to changes in low oxygen concentration. Ethylene biosynthesis (ACC synthase and oxidase) genes showed marked differences in their expression in relation to the static and dynamic protocols and the hypoxic conditions, as well as six Ethylene Responsive Factors (ERF) genes, some of them possibly involved in the oxygen sensing mechanism operating in fruit tissues

Postharvest Ozone Fumigation of Grapes (cv Sangiovese) Differently Affects Volatile Organic Compounds and Polyphenol Profiles of Berries and Wine

Consumers are more and more oriented towards the purchase of safer food and beverages, which is pushing the wine sector to find alternatives to the use of sulfur dioxide. Ozone (O3) is already applied in the wine industry to produce sulfur dioxide-free wines through the patented method Purovino®. The aim of this two-year study was that of evaluating whether the postharvest treatment of grapes with ozone affects volatile organic compounds (VOCs) and polyphenol profile in berries, and in turn, wine composition. Grape bunches (Vitis vinifera L.) of cv Sangiovese were fumigated overnight with gaseous ozone (max 20 g·h−1 with 6% w.w−1 of ozone) in a cold room at 4°C (±0.5). After treatment, grapes were processed into wine. In grapes, ozone treatments increased total polyphenol and flavonoid content and upregulated specific genes (phenylalanine ammonia lyase, VvPAL, flavanol synthase 1, and VvFLS1) involved in polyphenol biosynthesis. Wine obtained from ozone-treated grapes had higher flavanol content than the control. Fumigation only slightly affected the different VOC classes of grapes and wine, including aroma compounds derived from the lipoxygenase (LOX) pathway. Although a season-dependent effect was observed, results showed that postharvest ozone treatments applied to avoid the use of sulfur dioxide introduced limited but, in general, positive modifications to grape and wine composition. This information provides assurance to winemakers that the maintenance of wine quality and typicity will be guaranteed when using ozone treatments

Effects of Selenium Enrichment of Tomato Plants on Ripe Fruit Metabolism and Composition

The effects of selenium (Se) addition on production and quality traits of Solanum lycopersicon ‘Red Bunch’ were investigated. Se was added as sodium selenate at the rate of 0, 0.5 and 1 mg Se L-1 to the nutrient solution. Se was absorbed by roots and accumulated in leaves and fruits, and at the tested concentrations, it did not affect yield. Se concentration followed a gradient, decreasing from the basal to the apical part of the plant. At red ripe stage, the fruits on the lower trusses accumulated higher amount of Se than the fruits of the higher trusses. ß-carotene and lutein significantly decreased only at 1.0 mg Se L-1. Lycopene increased either in 0.5 and, less markedly, 1.0 mg Se L-1-treated fruits where a pronounced increase in quercetin was also observed