Chilling temperatures and controlled atmospheres alter key volatile compounds implicated in basil aroma and flavor

Use of basil in its fresh form is increasingly popular due to its unique aromatic and sensory properties. However, fresh basil has a short shelf life and high chilling sensitivity resulting in leaf browning and loss of characteristic aroma. Moderate CO₂ atmospheres have shown potential in alleviating symptoms of chilling injury in basil during short-term storage but its effect on the flavor volatiles is unclear. Moreover, studies on basil volatile profile as impacted by chilling temperatures are limited. We investigated the response of two basil genotypes to low temperatures and atmosphere modification, with emphasis on the volatile organic compounds responsible for basil aroma and flavor. Leaves were stored for 6 days at 5, 10, or 15°C combined with three different CO₂ atmospheres (0.04%, 5% or 10%). Basil volatile profile was assessed using headspace solid phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). Leaves suffered severe chilling injury and greater loss of aroma volatiles at 5°C compared to 10°C and 15°C. More than 70 volatiles were identified for each genotype, while supervised multivariate analysis revealed 26 and 10 differentially-accumulated volatiles for 'Genovese' and 'Lemon' basil, respectively, stored at different temperatures. Storage in 5% CO₂ ameliorated the symptoms of chilling injury for up to 3 days in 'Genovese', but not in 'Lemon' basil. Both chilling temperatures and controlled atmospheres altered key volatile compounds implicated in basil aroma and flavor, but temperature had a bigger influence on the observed changes in volatile profile.

Sorption and Desorption of Vapor of n-Pentane by Porphyrin Aluminum Metal-Organic Framework: Mechanism of Bonding, Kinetics and Stoichiometry by Complementary In-Situ Time-Dependent and Ex-Situ Methods

Metal-organic frameworks (MOFs) are highly nanostructured coordination polymers that contain metal cations and organic linkers and feature very large pore volumes and surface areas. The sorption and desorption of n-pentane vapor by porphyrin aluminum metal-organic framework Al-MOF-TCPPH₂ where TCPPH₂ is tetrakis(4-carboxyphenyl)porphyrin linker were studied by a novel method of in-situ time-dependent attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy in a controlled atmosphere and complementary in-situ and ex-situ methods. Sorption facilely occurs in the flow of dried air, and in the obtained adsorption complex the adsorbate molecules interact with phenyl and carboxylate groups of the linker and the O-H group. Sorption kinetics follows the pseudo-first-order rate law, as confirmed by in-situ time-dependent gravimetry. Further, an ex-situ (static) sorption of n-pentane vapor results in an adsorption complex with as much as 29.1 wt.% n-pentane with the stoichiometric formula [Al-MOF-TCPPH₂]₂(n-C₅H₁₂)₇ and a distinct XRD pattern. Finally, in the flow of dried air, the adsorption complex gradually desorbed n-pentane, following the pseudo-first-order rate law. The reversibility of sorption and desorption makes porphyrin aluminum MOF promising for the separation of light hydrocarbons and chemo-sensing. In-situ time-dependent ATR-FTIR spectroscopy in a controlled atmosphere, in combination with in-situ time-dependent gravimetry, is a new approach for the determination of binding sites of sorbents with adsorbate molecules, the stoichiometry of complexes, and chemical kinetics of "solid-gas" interactions.

Effect of Controlled Atmosphere Packaging on the Physiology and Quality of Fresh-Cut Dictyophora rubrovolvata

Dictyophora rubrovolvata is a typical edible fungus of Guizhou Province and is very popular due to its unique taste and texture. In this study, the effect of a controlled atmosphere (CA) on fresh-cut D. rubrovolvata shelf life was investigated. Firstly, this study addresses the influence of different O₂ concentrations (5%, 20%, 35%, 50%, 65%, 80%, or 95%) with N₂ balance on fresh-cut D. rubrovolvata quality while stored at 4 ± 1 °C for 7 d. Then, on the basis of the determined O₂ concentration (5%), CO₂ (0%, 5%, 10%, 15%, or 20%) was involved and stored for 8 d at 4 ± 1 °C. Evaluations of physiology parameters, texture, browning degree, nutritional, umami, volatile components, and total colony numbers were determined in fresh-cut D. rubrovolvata. From the results of water migration, the sample of 5% O₂/5% CO₂/90% N₂ was closer to 0 d than other groups at 8 days. Meanwhile, the polyphenol oxidase (2.26 ± 0.07 U/(g·min)), and catalase activity (4.66 ± 0.08 U/(g·min·FW)) were superior to the samples of other treatment groups on the eighth day (3.04 ± 0.06 to 3.84 ± 0.10 U/(g·min), 4.02 ± 0.07 to 4.07 ± 0.07 U/(g·min·FW)). Therefore, we found that a gas environment with 5% O₂/5% CO₂/90% N₂ could ensure the membrane integrity, oxidation, and prevent the browning of fresh-cut D. rubrovolvata, thus better maintaining the physiological parameters. Meanwhile, it also maintained the samples' texture, color, nutritional value, and umami taste. Furthermore, it inhibited the increase in total colony numbers. The volatile components were closer to the initial level compared with other groups. The results indicate that fresh-cut D. rubrovolvata could maintain its shelf life and quality when stored in 5% O₂/5% CO₂/90% N₂ at 4 ± 1 °C.

Physicochemical properties and transcriptional changes underlying the quality of 'Gala' apples (Malus × domestica Borkh.) under atmosphere manipulation in long-term storage

BACKGROUND

The year-round availability of apples (Malus × domestica Borkh.) depends on post-harvest technologies, which are essential for the retention of fruit sensory and chemical properties by delaying senescence. The effectiveness of strategies for preserving the quality of apples depends on complex interactions between the storage environment and endogenous biological factors. In the current work, we integrated instrumental, sensory, and transcriptional data to determine the role of conservation technologies cold storage, controlled atmosphere, and 1-methylcyclopropene-mediated ethylene blockage on the long-term conservation of apples.

RESULTS

The results demonstrated that inhibition of the consumer's perception of the apples' ethylene content is essential for long-term cold storage, and such quality conservation can be achieved by reducing oxygen pressure. Overall appreciation of apples after storage was determined mainly by their texture, with crispness and juiciness contributing favorably, and mealiness contributing negatively. Reduced oxygen pressure and inhibition of ethylene perception exerted distinct effects on the transcription of candidate genes associated with ripening in apple. Hexose and cell-wall carbohydrate metabolism genes exhibit distinct expression patterns under storage.

CONCLUSION

Inhibition of ethylene perception and reduction of relative oxygen pressure under cold storage both promote similar conservation of apple sensory traits under long-term cold storage. Texture was the main contributor to global appreciation of apples subjected to long-term storage. The conditions that were investigated were able to delay, but not fully prevent, senescence, as evidenced by physicochemical and gene expression analyses. The expression of gene-encoding enzymes involved in hexose metabolism was mainly developmentally regulated, whereas storage conditions exerted a stronger effect on the expression of genes associated with cell-wall metabolism. © 2022 Society of Chemical Industry.

A Review of Storage Temperature Recommendations for Apples and Pears

An exploration of the range of expert opinions on the optimum storage temperature for apples and pears in RA (refrigerated air), CA (controlled atmosphere), and DCA (dynamic controlled atmosphere) is provided, based on the accumulated postharvest data from the last 20 years. Apple cultivars have been divided into two storage temperature groups (0 to 1 °C and >1 °C), based on chilling sensitivity. Increasingly, gradual cooling, rather than rapid cooling, is recommended for apple cultivars, especially for chilling-sensitive cultivars. European pear cultivars are held at storage temperatures close to or just below 0 °C since they are not chilling-sensitive, and most cultivars require a cold temperature to induce ethylene production and ripening, especially if picked early for long-term storage. Asian pears apparently have higher temperature requirements in CA, compared with European pears. The temperature recommendations for RA and CA storage differ in some apple and European pear cultivars. In such cases, the CA recommendation is, on average, approximately 0.9 °C higher for apple cultivars and approximately 0.5 °C higher for pear cultivars, compared with RA. Research evidence suggests that some apple and pear cultivars can be stored at higher temperatures in DCA than in CA, and if the ethylene inhibitor, 1-methylcyclopropene (1-MCP), is applied in CA and/or DCA, leading to possible energy savings and quality benefits. A cool growing season may increase postharvest disorders, depending on cultivar and region. The store or packinghouse manager may choose to mitigate potential postharvest problems by maintaining the storage temperature at or above the temperature listed here and/or using stepwise (gradual) cooling. The storage temperature can affect the humidity and vapour pressure deficit (driving force) in the storage room. Altering the vapour pressure deficit controls the water loss in stored fruit, which can affect various quality parameters and the occurrence of several storage disorders.

Controlled Atmosphere Improves the Quality, Antioxidant Activity and Phenolic Content of Yellow Peach during the Shelf Life

Controlled atmosphere (CA) has been demonstrated to maintain the shelf-life quality of fruits, but its effect on the antioxidant activities and phenolic content of yellow peach is not comprehensive. This study analyzed the role of CA on the quality of shelf period, phenolic content and antioxidant activity of "Jinxiu" yellow peach. Yellow peach was left under specific aeration conditions (3.5-4% CO2, 2-3% O2, 92-95.5% N2, 1 ± 0.5 °C) and the control (1 ± 0.5 °C) for 21 d, to observe changes in physiological parameters of the fruit during 10 d of the shelf life (25 ± 1 °C). The result showed that CA reduced the weight loss rate (WLR), decay rate (DR), and browning index (BI) of yellow peaches. Furthermore, the CA held a high level of total flavonoid content (TFC), total phenol content (TPC) and phenolic content in the fruit. Antioxidant analysis showed that polyphenol oxidase (PPO) enzyme activity was lower and free radical scavenging capacity (DPPH, ABTS, and FRAP) and antioxidant enzyme activities (POD and PAL) were higher in the CA group. Combining the results of significance analysis, correlation analysis, principal component analysis (PCA) and hierarchical cluster analysis (HCA) clearly identified the differences between the CA group and the control group. The results showed that the CA could maintain higher phenolic content and reduce the oxidation of yellow peach fruit and enhance fruit quality by affecting the antioxidant activities of yellow peach.

Effects of Long-Term Low Oxygen Storage Treatment on Survival of Rice Weevil (Sitophilus oryzae) and Confused Flour Beetle (Tribolium confusum)

There is a need for alternative treatments for postharvest pests on stored products. In this study, 45-d long-term controlled atmosphere (CA) treatments with 3, 5, 6.5, and 8% O2 were studied to determine effects on survival and development of rice weevil (Sitophilus oryzae) and confused flour beetle (Tribolium confusum) eggs and susceptibility of different life stages to a 14-d 5% O2 treatment. Low oxygen treatments were effective against S. oryzae and T. confusum. The 45-d CA treatments with 6.5, 5, and 3% O2 resulted in 0.26, 0.004, and 0% survival rates from egg to adult respectively for S. oryzae and 6.51, 0.14, and 0% survival rates from egg to later stages respectively for T. confusum. For both species, eggs were more susceptible to low oxygen treatment than larvae or pupae. A 14-d CA treatment with 5% O2 resulted in 4.9 and 3.3% survival of eggs of S. oryzae and T. confusum, respectively, as compared with over 50% survival of larvae and pupae for both species. S. oryzae adults, however, were very susceptible to low oxygen treatment and 14-d exposure to 5% O2 atmosphere resulted in zero survival. In contrast, the 14-d exposure to 5% O2 atmosphere resulted in over 94% survival for T. confusum adults. This study suggested there were considerable differences between stored product insects in susceptibility to low oxygen treatment and that long-term CA storage treatments with a low oxygen level of ≤6.5 and ≤5% have potential in controlling S. oryzae and T. confusum, respectively.

Effect of Drying Methods on Peanut Quality during Storage

Storage is an important step after peanut harvest and drying. Many factors could affect the peanut quality during storage. The quality change differences of peanut after being dried by solar radiation and at 35℃, 40℃, 45℃, 50℃ during later storage were investigated, including moisture content (MC) and germination percentage (GP) of peanut kernels, acid value (AV), peroxide value (PV), iodine value (IV), vitamin E (VE) content and fatty acid composition (FAC) of extracted peanut oil. And the impact of four storage conditions, air-room temperature (A-RT), air-low temperature (A-LT), vacuum-room temperature (V-RT) and nitrogen-room temperature (N-RT) on peanut quality after 10 months' storage were also studied in this paper. The results revealed that drying conditions had only a little influence on peanut quality during later storage. Peanut dried by solar radiation was more easily oxidized than that dried under other drying conditions. The effects of storage time were much greater. The GP, AV, PV, VE content and FAC, showed significantly changes along with storage. GP and VE content decreased, AV and PV increased, and some linoleic acid was oxidized to oleic acid after 10 months' storage. In addition, A-LT exhibited best performance in keeping peanut quality than A-RT, V-RT and N-RT, which demonstrated that low temperature was more advantageous for peanut storage than controlled atmosphere. These results above would provide useful information and reference for the peanut storage to apply in food industry.

Effect of Hypoxia on the Lethal Mortality Time of Adult Sitophilus oryzae L

Simple Summary

The rice weevil is a major pest of stored grains that leads to losses resulting in food and income insecurity among farmers. Pesticides, often used by farmers to control insect pests of stored products, are becoming unattractive due to health risks to applicators, consumers, and the environment. Hermetic (airtight) storage methods have been used as alternatives to pesticides. Understanding when insects die during hermetic storage is vital, in order to improve pest management. We conducted experiments to assess the time required to attain mortality of adult rice weevils when the oxygen levels reached below 5% in airtight containers. Results revealed that it required 69.7, 187.8, and 386.6 h to kill 50% of adult rice weevils exposed to 1%, 3%, and 5% oxygen levels, respectively. No adult emerged from infested grains following exposure to 1 and 3% oxygen levels, but some did at 5% oxygen level. Based on these results, we recommend that grain be kept in hermetic airtight conditions for at least 39 days to achieve adult rice weevil mortality and minimize grain reinfestation.

Abstract

Sitophilus oryzae is one of the most destructive pests of stored grains. It leads to significant quantitative and qualitative losses, resulting in food and income insecurity among farmers. Chemical pesticides are the most common methods used by farmers and other grain value chain actors to manage this pest. However, pesticides are increasingly becoming unattractive for pest control due to health hazards posed to applicators, consumers, the environment, and insect resistance. Modified atmospheres have the potential to manage stored insect pests as an alternative to pesticides. There is limited understanding of when insect pests die when grain is stored in airtight containers. This experiment was conducted to assess the time required to reach mortality of adult S. oryzae when exposed to 1, 3, and 5% oxygen levels. Results revealed that the LT50 for 1, 3, and 5% of oxygen were reached after 69.7 h, 187.8 h, and 386.6 h of exposure, respectively. No adult emergence was observed on infested grains following exposure to 1 and 3% oxygen levels. This result provides vital rationale for storing grain in hermetic storage conditions for at least 39 days to achieve adult S. oryzae mortality and minimize grain reinfestation.

Low Oxygen Storage Improves Tomato Postharvest Cold Tolerance, Especially for Tomatoes Cultivated with Far-Red LED Light

We investigated the effects of low oxygen storage on chilling injury development, colour development, respiration and H₂O₂ levels of ‘Merlice’ tomatoes cultivated with and without far red (FR) LED lighting during 20 days of shelf-life. Mature green (MG) and red (R) tomatoes were stored at 2 °C in combination with 0.5, 2.5, 5 and 21 kPa O₂ for 15 days (experiment 1). MG tomatoes cultivated under either white LED or white LED light with FR LED light were stored at 2 °C in combination with 1, 5 and 21 O₂ kPa for 14 days (experiment 2). Chilled MG and R tomatoes from experiment 1 showed decay, firmness loss and higher weight loss during shelf-life which were reduced under low oxygen conditions. FR during cultivation improved chilling tolerance of MG tomatoes. Fastest colour development and lowest respiration rate during shelf-life were observed for MG fruit cultivated with FR lighting prior to storage at 1 kPa O₂/0 kPa CO₂. H₂O₂ levels during the shelf-life were not affected during cold storage. The improved cold tolerance of MG tomatoes cultivated with FR lighting is likely due to lower oxygen uptake that led to both higher lycopene synthesis and less softening.

Low storage temperature for tree ripe mangoes under controlled atmospheres with elevated CO2 concentrations

BACKGROUND

Tree-ripe mangoes are of a better quality than the more commonly marketed mature-green fruit. However, the postharvest life of tree-ripe mangoes at the chilling threshold temperature for mature-green fruit of 12 °C is insufficient to allow long distance transport for international marketing. Because the chilling sensitivity often decreases as fruit ripen, lower temperatures (5 and 8 °C) in combination with a controlled atmosphere of 5 kPa O₂ plus 10 or 25 kPa CO₂ were tested to determine whether the quality of tree-ripe mangoes could be maintained longer without chilling injury (CI).

RESULTS

Tree-ripe 'Tommy Atkins' and 'Keitt' mangoes were stored for 14 or 21 days, respectively, in air or controlled atmosphere (CA) at 5 or 8 °C. Respiration rates were below 10 mL kg^-1 h^-1 during CA storage and increased three-fold during a 3-day shelf life period at 20 °C. Ethanol synthesis of fruit stored in 25 kPa CO₂ , but not 10 kPa CO₂ , increased during storage and remained high during shelf life, indicating physiological stress. Elevated electrolyte leakage and 1-aminocyclopropane-1-carboxylic acid concentrations in both cultivars stored in 25 kPa CO₂ also indicated that mesocarp tissues were injured by the higher CO₂ level. No CI symptoms were observed in air or CA at either 5 or 8 °C.

CONCLUSION

Storage of tree-ripe mangoes in 5 kPa O₂ plus 10 kPa CO₂ at either 5 or 8 °C best maintained the quality of Tommy Atkins and Keitt fruit for 14 or 21 days, respectively, without evidence of either atmosphere injury or CI. © 2020 Society of Chemical Industry.

Responses of Pigs to Stunning with Nitrogen Filled High-Expansion Foam

Nitrogen gas (N2) delivered in high expansion foam in a closed container could be a feasible method for humanely stunning pigs. This study aimed to evaluate potential aversion in pigs to the N2 foam method and its effect on stun quality. Furthermore, the study aimed to assess potential aversion to the foam itself. Sixty pigs (27.8 ± 4.4 kg) were divided into three treatments and were exposed to either N2-filled foam, air-filled foam, or no foam air. The N2 foam was effective at purging the air from the container and quickly created stable anoxic conditions. The pigs did not show any strong aversive behaviours when exposed to foam. However, they seemed to avoid putting their heads and snouts into the foam when foam levels became high. Escape attempts through the lid also increased when the foam started covering their heads. The mean time to loss of posture was 57.9 s. Based on the results, stunning with the N2 foam technique could be a viable alternative to high concentration CO2 stunning and potentially lead to improved animal welfare at slaughter.

Health technology assessment: Choice between a cytotoxic safety cabinet and an isolator for oncology drug reconstitution in Tunisia

INTRODUCTION

In order to implement a centralized cytotoxic reconstitution unit (CCRU), a study was conducted to compare the implementation costs of a CCRU equipped with a cytotoxic safety cabinet (CSC) and one equipped with an isolator with negative pressure.

MATERIALS AND METHODS

This study compares items such as infrastructure, air treatment and CCRU qualification costs, equipment's purchase and qualifications costs, as well as staff dressing costs. Two plans were elaborated according to the international recommendations in a way that they respond to the necessary requirements in both cases. Requests for quotes for the compared items were sent to different suppliers.

RESULTS

The implementations' cost of a CCRU equipped with a CSC is cheaper than the one equipped with an isolator. The price of an isolator is much higher than a CSC; its qualification is also more expensive. However, the requirements and the costs for the air treatment and the dressing of the staff are less in the case of an isolator. The overall cost of the CCRU's implementation is approximately 1.3 times higher in the case of an isolator. However, by excluding the equipment purchase cost, the overall cost of a CSC's implementation becomes higher.

CONCLUSION

For Tunisia, it seems that the CSC is the most adapted. However, this work should be completed by the comparison of the CCRU's operating costs in order to optimize the resources and figure out the cheapest system.

Graduated Controlled Atmosphere: A Novel Approach to Increase "Duke" Blueberry Storage Life

Blueberries (Vaccinium corymbosum L.) are highly valued for their health-promoting potential, yet they are extremely perishable. Controlled atmosphere (CA) strategies reduce blueberry respiratory metabolism, slowing down senescence. However, the sudden change of atmosphere could elicit a physical abiotic stress in the fruit, negatively affecting quality. We propose an innovative approach based on controlled graduation to slowly reach optimum gas storage conditions as an alternative to standard CA. For two consecutive seasons, "Duke" blueberries were subjected to four different storage conditions: control (air); standard CA (sudden exposure to 5 kPa O₂ and 10 kPa CO₂ across the experiment); GCA3 and GCA7 (gradually reaching 5 kPa O₂ and 10 kPa CO₂ in 3 and 7 days, respectively). Fruit were stored for 28 days at 0 ± 0.5°C. Real-time respirometry provided an in-depth insight to the respiratory response of blueberries to their gas environment. Blueberries subjected to the graduated application of CA (GCA) treatments had a lower steady-state respiration rate compared to control and standard CA fruit. This indicated a reduction in metabolic activity that positively impacted quality and storage life extension. For example, GCA3 and GCA7 blueberries had a 25% longer storage life when compared to control, based on reduced decay incidence. In addition, GCA fruit were 27% firmer than control and CA fruit after 28 days of cold storage. GCA3 had a positive effect on maintaining individual sugars concentrations throughout the experiment, and both GCA treatments maintained ascorbic acid content close to initial values compared to a decrease of 44% in the control fruit at the end of the experiment. This work provides a paradigm shift in how CA could be applied and a better understanding of blueberry physiology and postharvest behavior.

Efficacy of Hypoxia Against Tribolium castaneum (Coleoptera: Tenebrionidae) Throughout Ontogeny

Hermetic grain storage technology offers a viable chemical-free approach to control storage insects. However, there is limited knowledge on how hypoxia affects the survival of insect life stages during grain storage in hermetic bags. We exposed Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) eggs (2 d), young larvae (7 d), old larvae (21 d), pupae (28 d), and adults (2 d after emergence) to 2, 4, 8, and 20.9% oxygen levels for 1, 3, 5, 10, and 15 d and assessed subsequent mortality. At 2% oxygen, complete mortality was achieved in 3 d for eggs and young larvae, 10 d for old larvae and pupae, and 15 d for adults. At 4% oxygen, 15 d were required to kill all eggs and old larvae but not the other insect life stages. At 8% oxygen after 15 d, complete mortality of any insect life stage was not observed; but even a relatively short exposure (1-3 d) caused significant developmental delays in immature insects. Our study shows potential utility of hermetic technology for control of T. castaneum, but internal oxygen should be maintained below 2% level for at least 15 d for complete control. Increased oxygen levels improved the development of all insect life stages leading to increased adult emergence. There is a need to explore exposure time required to achieve complete mortality of all insect life stage above the 2% oxygen level.

Metabolic Alterations in Postharvest Pear Fruit As Influenced by 1-Methylcyclopropene and Controlled Atmosphere Storage

This study assessed the impact of 1-methylcyclopropene (1-MCP) and controlled atmosphere (CA) on the metabolism of targeted amino acids, organic acids, and antioxidants in stored 'AC Harrow Crisp' pears and their relationships to storage disorders. Pears were treated with 0 or 300 nL L^-1 1-MCP and stored at 0 °C under ambient air or CA. Spectrophotometric assays demonstrated that glutathione levels fluctuated with storage and were most preserved by 1-MCP under ambient air. HPLC analysis revealed that ascorbate concentrations declined with storage and were little affected by 1-MCP and CA. Citrate, lactate, and fumarate accumulated with storage but were differentially affected by 1-MCP. Aspartate and glutamate concentrations were greater with 1-MCP; γ-aminobutyrate accumulated in disordered fruit. Principal component analysis demonstrated that alterations in citrate and fumarate were, respectively, correlated with internal breakdown and senescent scald. γ-Aminobutyrate and alanine were associated with internal cavities. All disorders were associated with antioxidant depletion.

Hydrothermal One-Step Synthesis of Highly Dispersed M-Phase VO2 Nanocrystals and Application to Flexible Thermochromic Film

Preparation of ultrafine highly dispersed VO₂(M) nanoparticles that are essential materials to fabricate thermochromic flexible films remains a challenge, preventing effective use of their promising properties. Here, we report an original hydrothermal approach by controlling oxidizing atmosphere of reaction with hydrogen peroxide to prepare ultrafine VO₂(M) nanoparticles free from annealing. Hydrogen peroxide is separated from precursor solution in a reactor, which creates a moderate oxygenation environment, enabling the formation of stoichiometric VO₂(M) nanoparticles. The obtained VO₂(M) nanoparticles are well-dispersed, highly uniform, and single-phase, with an average particle size ∼30 nm. The flexible thermochromic films fabricated with the VO₂(M) nanoparticles exhibit excellent thermochromic performance with a solar modulation efficiency of 12.34% and luminous transmittance of 54.26%. While the films prepared with annealed nanoparticles show reduced transmittance due to light scattering of the large size particles resulting from agglomeration and growth during annealing. This work demonstrates a promising technique to realize moderate oxidizing atmosphere by hydrothermal process for preparing well-dispersed stoichiometric nano-oxides.

Synergistic Effects of Oxygen on Phosphine and Ethyl Formate for the Control of Phthorimaea operculella (Lepidoptera: Gelechiidae)

Phosphine (PH3) and ethyl formate (EF) are two potentially powerful postharvest fumigant insecticides. We investigated the effectiveness of both PH3 and EF as fumigants at all developmental stages of the potato tuber moth Phthorimaea operculella Zeller, and we also studied the synergistic effects of these fumigants under controlled atmospheres of 50 and 80% oxygen (O2). The larval stage of P. operculella was the most susceptible to fumigation with PH3 at both 5°C and 20°C. All of the developmental stages showed greater susceptibility to PH3 at 20°C than at 5°C, whereas the susceptibility of adult P. operculella to this fumigant was not affected by temperature. The toxicity of EF did not differ with temperature for any of the P. operculella developmental stages. The atmospheric oxidation of PH3 increased the toxicity of this fumigant toward all developmental stages at both temperatures. In contrast, no differences in toxicity were observed for oxidized EF compared with EF alone at any developmental stage. In conclusion, using fumigation tests, we showed that atmospherically oxidized PH3 was much more effective against P. operculella than PH3 alone, demonstrating a synergistic effect for this fumigant and O2. Therefore, treatment with PH3 and high concentrations of O2, as described in this study, could be useful for managing the postharvest pest P. operculella.

Response of Pink Lady® apples to post-harvest application of 1-methylcyclopropene as a function of applied dose, maturity at harvest, storage time and controlled atmosphere storage

BACKGROUND

1-Methylcyclopropene (1-MCP) is an inhibitor of ethylene reception used in post-harvest treatments to delay fruit ripening. Several factors affect the efficacy of 1-MCP treatments. The effect of a post-harvest treatment with 1-MCP on the quality of Pink Lady® apples as a function of 1-MCP dose, storage time and maturity at harvest was investigated. 1-MCP treatment was further tested in combination with controlled atmosphere (CA) storage.

RESULTS

1-MCP limited fruit respiration and softening during storage and was more effective on partially matured fruits and at prolonged storage times. The delaying of 1-MCP on the increase of ripening index was greater on matured fruits at prolonged storage times. The combination of 1-MCP and CA treatments positively affected quality indices of mature apples during 6 months of storage and 7 days of commercial life, with 1-MCP being more effective than CA. 1-MCP and CA showed positive combined effects on firmness and ripening index after 6 months of storage, and on firmness and CO₂ production after a further 7 days of commercial life.

CONCLUSION

By knowing fruit maturity at harvest and expected storage time it is possible to choose the most suitable 1-MCP dose to meet the market requirements by applying a simple polynomial model.

Biomarker development for external CO2 injury prediction in apples through exploration of both transcriptome and DNA methylation changes

Several apple cultivars are susceptible to CO2 injury, a physiological disorder that can be expressed either externally or internally, and which can cause major losses of fruit during controlled atmosphere (CA) storage. Disorder development can also be enhanced using SmartFresh™ technology, based on the inhibition of ethylene perception by 1-methylcyclopropene (1-MCP). Injury development is associated with less mature fruit with lower ethylene production, but the aetiology of the disorder is poorly understood. Here we report on the progress made using mRNAseq approaches to explore the transcriptome during the development of external CO2 injury. Next-generation sequencing was used to mine the apple transcriptome for gene expression changes that are associated with the development of external CO2 injury. 'Empire' apples from a single orchard were treated with either 1 µL L(-1) 1-MCP or 1 g L(-1) diphenylamine or left untreated, and then stored in a CA of 5 kPa CO2 and 2 kPa O2. In addition, susceptibility to the disorder in the 'Empire' apples from five different orchards was investigated and the methylation state of the ACS1 promoter investigated using McrBC endonuclease digestion and real-time quantitative polymerase chain reaction. Expression of over 30 000 genes, aligned to the apple genome, was monitored, with clear divergence of expression among treatments after 1 day of CA storage. Symptom development, internal ethylene concentrations (IECs) and methylation state of the ACS1 promoter were different for each of five orchards. With transcriptomic changes affected by treatment, this dataset will be useful in discovering biomarkers that assess disorder susceptibility. An inverse correlation between the frequency of this disorder and the IEC was detected in a multiple orchard trial. Differential methylation state of the ACS1 promoter correlated with both IEC and injury occurrence, indicating epigenetic regulation of ethylene biosynthesis and possibly events leading to disorder development.