Controlled Atmosphere Research Articles

1-Methylcyclopropene differentially regulates metabolic responses in the stem-end and calyx-end flesh tissues of ‘Empire’ apple during long-term controlled atmosphere storage

Firm flesh browning, a postharvest disorder of ‘Empire’ apples, can develop during controlled atmosphere (CA) storage. The disorder is initiated in tissues at the stem-end tissue and progressively develops through the calyx-end region of fruit. The susceptibility of fruit to the disorder can be provoked by the application of 1-methylcyclopropene (1-MCP) prior to storage. To gain a better understanding of the metabolic changes associated with disorder development, we coupled metabolic profiling with measures of flesh tissue color in partial least squares-discriminant analysis (PLS-DA) to determine changes in metabolic profile occurring in stem and calyx tissues of untreated and 1-MCP treated fruit during CA storage. Flesh tissues were less light (L*) in the stem-end tissues than in the calyx-end tissues and to a greater extent in 1-MCP treated than untreated fruit. Reduction in L* in 1-MCP treated fruit corresponded to metabolic divergence between stem-end and calyx-end tissues. Furthermore, tissues of 1-MCP treated fruit had lower levels of volatile aromatic compounds (VACs), but less so in the stem-end tissues than in the calyx-end tissues. The levels of most amino acids and VACs were higher in the stem-end tissues of 1-MCP treated fruit than in untreated fruit. Of the VACs, methanol, acetaldehyde and ethanol concentrations were much greater in the stem-end tissues than in the calyx-end tissues of untreated fruit but reduced by 1-MCP treatment, irrespective of tissues. In summary, metabolic profiling indicates that 1-MCP treatment induces greater physiological changes in the stem-end tissues than in the calyx-end ones under hypoxic storage condition. While the underlying metabolic processes that result in firm flesh browning remain to be elucidated, the accumulation of small molecule compounds, such as amino acids, in the stem-end tissues suggests that 1-MCP affects ethylene related pathways in this region to a greater extent, and may be associated with higher incidence of flesh browning during long-term CA storage.

Changes of Sensory Quality, Flavor-Related Metabolites and Gene Expression in Peach Fruit Treated by Controlled Atmosphere (CA) under Cold Storage.

Controlled atmosphere (CA) has been used to alleviate chilling injury (CI) of horticultural crops caused by cold storage. However, the effects of CA treatment on peach fruit sensory quality and flavor-related chemicals suffering from CI remain largely unknown. Here, we stored peach fruit under CA with 5% O2 and 10% CO2 at 0 °C up to 28 d followed by a subsequent 3 d shelf-life at 20 °C (28S3). CA significantly reduced flesh browning and improved sensory quality at 28S3. Though total volatiles declined during extended cold storage, CA accumulated higher content of volatile esters and lactones than control at 28S3. A total of 14 volatiles were positively correlated with consumer acceptability, mainly including three C6 compounds, three esters and four lactones derived from the fatty acid lipoxygenase (LOX) pathway. Correspondingly, the expression levels of genes including PpLOX1, hyperoxide lyase PpHPL1 and alcohol acyltransferase PpAAT1 were positively correlated with the change of esters and lactones. CA elevated the sucrose content and the degree of fatty acids unsaturation under cold storage, which gave us clues to clarify the mechanism of resistance to cold stress. The results suggested that CA treatment improved sensory quality by alleviating CI of peach fruits under cold storage.

Short vs. Long-Distance Avocado Supply Chains: Life Cycle Assessment Impact Associated to Transport and Effect of Fruit Origin and Supply Conditions Chain on Primary and Secondary Metabolites.

Avocado consumption and trade are increasing worldwide, with North America and Europe being the main importing regions. Spain is the major European avocado producer (90% of the production), yet it only supplies 10% of the market. Consequently, more than 90% of the avocados consumed in Europe are imported from overseas, mainly from Chile and Peru. In this work, the Life Cycle Assessment (LCA) impact associated with the transport of two avocado supply chains (short (Spanish) and long (Chilean)) and the effect of the fruit origin and distance of both chains on primary and secondary metabolites from harvest to edible ripeness were evaluated using a gas chromatography-mass spectrometry (GC-MS) and liquid chromatography coupled to diode array detection (LC-DAD) based metabolite analysis. The LCA transport impact of the fresh supply chain from production centers in Chile (Quillota) and Spain (Malaga), and then the distribution to several cities in Europe, suggested road export from Spain to European capitals to have the lowest impact (0.14 to 0.22 kg CO2 eq/kg of avocado). When export from Chile was considered, the option of oceanic freight to European ports closer to final destinations was clearly a better option (0.21 to 0.26 kg CO2 eq/kg) than via the Algeciras port in Spain followed by road transport to final destinations in European capitals (0.34 to 0.43 kg CO2 eq/kg), although the situation could be somewhat different if the avocados are transported from the destination ports in northern Europe to long-distance capitals in other European countries. Fruit origin had a significant impact on avocado primary and secondary metabolites. The conditions of the supply chain itself (10 d in cold storage in regular conditions vs. 30 d cold storage + controlled atmosphere conditions) largely influence the fate of some metabolites that certainly affect the pool of metabolites at edible ripeness. The long-assumed hypothesis that the longer the supply chain the more negative impact on nutritional and functional compounds might not hold in this case, as long as transport conditions are adequate in terms of temperature, atmosphere conditions, and time considering distance from origin to destination.

Effects of controlled atmosphere and storage temperature on the quality of shelled ‘Barton’ pecan nuts during long-term storage

This study aimed to evaluate the effects of controlled atmosphere (CA) storage at a low oxygen partial pressure (pO2; 2 kPa of O2) and low pO2 associated with high pCO2 (2 kPa O2 + 15 kPa CO2) in relation to ambient atmospheric conditions (control), at different temperatures, on shelled ‘Barton’ pecan nuts quality after storage. Color, respiration rates, moisture content (MC), and oxidation markers, such as peroxide value (PV), acidity value (AV), and volatile compounds (VC), were evaluated. During six months of storage, the MC decreased in all CA treatments, and treatments at 10 °C had the lowest AVs and PVs. However, the treatment with high pCO2 levels also guaranteed lower AVs at 20 °C. The color parameter b* (yellow), which is related to the golden appearance of pecans and is a highly desirable visual attribute in the commercialization of nuts, was maintained high in treatments at 10 °C with CA treatments until six months of storage. The VCs, characteristic of lipid oxidation (aldehydes, acids, alcohols, and ketones), increase in all treatments with prolonging storage. When pCO2 was associated to 10 °C at six month of storage, it showed a larger area in the acids and unsaturated aldehyde classes, while it was relevant for alcohols, lactones, and esters at 20 °C, with sweet characteristics, including ethyl ethanoate, ethyl hexanoate, and butyrolactone. Thus, this study shows another advance in the storage techniques of shelled pecans, pointing to alternatives for reducing energy costs in the cooling chain.

The Use of Controlled Atmosphere Box in Sweet Cherry Storage

The aim of the study was to examine the use of controlled atmosphere (CA) box, a new technology, for sweet cherry storage. In addition, this technology was compared to normal (NA) and modified atmosphere (MAP) storages commonly used in sweet cherry preservation. The ‘0900 Ziraat’ sweet cherry variety, the most popular in Turkey, was used as the material. Fruit harvested at optimum stage were transported to the laboratory immediately, and pre-cooled at 1°C. After pre-cooling, fruit were stored at 0°C and 90±5% relative humidity (RH) for 5 weeks in NA, MAP conditions, and in CA box at 2°C. During the storage period, weight loss, fruit skin color, stem color, respiration rate, soluble solids content (SSC), titratable acidity (TA), gas composition of box and MAP were determined at weekly intervals. Fruit were also evaluated for sensory attributes during cold storage. Samples taken from cold storage in each week were stored for 2 days at 20°C for shelf life and then fruit were re-evaluated. According to evaluation criteria, the CA boxes gave better results than the other storage conditions at the end of the storage period of 35 days. Sweet cherry cv. ‘0900 Ziraat’ could be stored for 5 weeks in CA box and 4 weeks in MAP, with marketable quality.

Temporary Team Performance and Knowledge Hiding: Mediated by Interpersonal Mistrust.

Although scholars have acknowledged that knowledge hiding is negatively with team performance, none of the extant research has revealed the relationship between knowledge hiding and the performance of temporary teams. To fill this gap, we will explore whether and how knowledge hiding influences temporary team performance. Following a literature review, the correlation between knowledge hiding, interpersonal distrust, and temporary team performance is explored, and the theoretical model between variables is constructed, along with four hypotheses. Then, a quantitative analysis is conducted through a QS (Questionnaire Survey) design on the proposed hypotheses. Specifically, test is conducted on the collected data, and then SPSS and AMOS are used to integrate and analyze the data of 102 teams. The results show that knowledge hiding and its two dimensions (active and passive hiding) have a negative impact on the work efficiency of temporary teams. Interpersonal distrust plays a mediating role between knowledge hiding and temporary team performance. The incentive atmosphere, including control atmosphere and performance atmosphere, can regulate the performance of a temporary team efficiently. Control atmosphere is favorable to improving interpersonal trust and team performance, and performance atmosphere is inverted U-shaped regulation between interpersonal distrust and temporary team performance. Based on the above conclusions, the corresponding management suggestions that encouraging members in temporary teams to share actively and confronting the passive concealment of knowledge are put forward to enhance interpersonal trust and improve the efficiency of the temporary team.

Impact of Modified Atmosphere Packaging and Controlled Atmosphere Applications on ‘Seval F1’ Tomato Fruit Quality and Marketability

This study was carried out at the Postharvest Physiology Laboratory of the Department of Horticulture of Isparta University of Applied Sciences with the ‘Seval F1’ table tomato variety. Tomato fruits are stored in normal atmospheric storage (NA), modified atmosphere packages (MAPs) (MAP1 and MAP2) and in controlled atmosphere (CA) cabinets (5% O2+5% CO2) at 12±1°C temperature and 90% ± 5 relative humidity (RH) conditions. After removing the fruits from cold storage at each analysis period they were kept at room conditions for 2 days for shelf life evaluation. Weight loss, peel color, fruit firmness, soluble solids content, pH, titratable acidity, respiration rate (RR), ethylene production (EP), MAPs’ gas composition and sensorial analyzes were carried out for fruits taken randomly from cold storage and subsequent 2 days in shelf life conditions. According to the mean values, CA and MAPs maintained fruit firmness better than NA. The lowest RR (11.3 mLCO2 kg -1 h -1) was recorded in NA followed by MAP1 (13.2 mLCO2 kg -1 h -1). EP values of NA and CA were closer to each other’s and lower than those of the others (2.7 and 2.8 µL.kg-1h-1, respectively). CA had the highest taste-aroma value at 25+2 days of storage, followed by MAP1 and NA. The highest O2 (18.98 %) and the lowest CO2 (2.90 %) values were recorded in MAP1. In conclusion, CA and MAP1 storage conditions successfully extended the postharvest life of ‘Seval F1’ tomato fruits and maintained their marketable quality for 25+2 days.

Ultra-Low Oxygen and Preconditioning Storage Regulate Ethylene Synthesis to Prevent Corky Disorders in 'Fuji' Apple.

Corky disorders in apples represent a significant problem for long-term storage where controlled atmosphere (CA) is mainly used. Ultra-low oxygen (ULO) is an alternative to CA, which consists of low partial pressure of O2 to maintain a low metabolism in the apple fruit, achieving an effective decrease in the ethylene production and physiological disorders. The aim of this research was to study the effectiveness of a short hypoxia period on the development of cork physiological disorders during the storage of apple. ‘Fuji’ apples were prestored under ULO (0.5 kPa O2) for two periods of time (15 and 30 days) and at two temperatures (0 or 5°C). Corky physiological disorders increased at 5°C prestorage temperature; however, ULO treatments for 15 or 30 days at 0 or 5°C achieved a significant reduction in corky disorders near to 1%, compared with control treatments. In addition, a considerable reduction in ethylene production for up to 30 days was observed in ULO-treated fruit at 0 and 5°C. ULO for 30 days at 0 and 5°C increased the internal production of ethanol and acetaldehyde, causing a lower sensory quality due to the presence of fermentative flavors in fruit stored at 5°C. ULO of 15 days of conditioning decreased the relative expression of ethylene biosynthesis genes MdACS1 and MdACO1, resulting in lower ethylene production.

Timing of Ethylene Inhibition Affects Internal Browning and Quality of 'Gala' Apples in Long-Term Low Oxygen Storage.

The objective of this study was to evaluate the timing of ethylene inhibition with preharvest and postharvest 1-methylcyclopropene (1-MCP) treatments on internal browning and quality of ‘Gala’ apples in long-term low O2 storage. ‘Gala’ apples were obtained from the same commercial orchard during their harvesting period for 2 years of study. Preharvest 1-MCP orchard spray (3.8% a.i) was applied at the label rate of 60 g 1-MCP per acre in the first year. Postharvest 1-MCP (1 μl L−1) treatments were made for 24 h at 0.5°C either at harvest time (1 day after harvest) or after storage in controlled atmosphere (CA) in both years. Apples were stored in 1.5 kPa O2 + 0.5 kPa CO2 or 0.6 kPa O2 + <0.5 kPa CO2 for 9 months in the first year and 1.5, 1.0, or 0.5 kPa O2 + 0.5 kPa CO2 for 8 months in the second year. Storage regimes with O2 concentrations less than 1 kPa were based on fruit respiration using SafePod™ technology. After removal from storage, all apples were then evaluated for internal browning and other quality attributes after 1, 7, and 14 days at room temperature (RT, 21–22°C). Internal browning developed in ‘Gala’ apples during both years of study, with up to 16% incidence across treatments in the first year and up to 84% in the second year. Apples stored in 0.5–0.6 kPa O2 had significantly less internal browning during both years of study, compared to apples stored in higher O2. The effect of 1-MCP on internal browning was negligible in 0.5–0.6 kPa O2 storage. ‘Gala’ stored in 1.5 kPa O2 and treated with postharvest 1-MCP after storage had significantly less internal browning with preharvest 1-MCP than those without preharvest treatment. Apples treated with postharvest 1-MCP at harvest time, instead of after storage, did not exhibit this same effect. Preharvest 1-MCP-treated fruit maintained greater firmness retention than those without preharvest 1-MCP, and this effect was further enhanced when 1-MCP was applied after storage. Postharvest 1-MCP had no effect on firmness retention in fruit without preharvest 1-MCP, but lower O2 maintained greater firmness in those apples. Preharvest 1-MCP had no significant effect on internal ethylene concentration, whereas it was reduced by postharvest 1-MCP at harvest time in the first year of study, regardless of storage regimes. However, internal ethylene was only affected by storage regime in the second year, with lower concentration in fruit from 0.5 kPa O2 than in those from higher O2. Greasiness developed only in the second year and postharvest 1-MCP consistently reduced it, regardless of treatment timing and storage regime. There was no greasiness in apples treated with postharvest 1-MCP at harvest and then held in 0.5 kPa O2 for 8 months plus 14 days at room temperature. Soluble solids concentration and malic acid content were slightly higher in ‘Gala’ apples with preharvest 1-MCP compared to those without, whereas there was little and inconsistent effect of postharvest 1-MCP on these attributes. Overall, storage regimes with less than 1 kPa O2 provided the least amount of internal browning and best quality attributes. Ethylene inhibition provided further benefits, but this was dependent on the timing of 1-MCP treatment.

Preservation of cv. Jubileu peaches in a conventional cold storage system under a dynamic controlled atmosphere

The peach tree (Prunus persica) has a considerable global economic impact because its fruits are consumed worldwide. As climacteric fruits, peaches ripen after harvest and are also highly perishable postharvest. The aim of this study was to investigate alternatives for extending storage time and preventing a decline in quality in peaches using conventional cold storage (CS) compared with controlled atmosphere (CA) and ultralow oxygen (ULO) systems. A completely randomized design was used, with a 3 x 6 factorial scheme (3 storage systems x 6 storage times), thirteen parameters assessed by analysis of variances and significance by Tukey’s test and regression. Total soluble solids (TSS) varied from 12.72 to 16.07ºBrix, titratable acidity (TA) declined during storage and pH varied significantly among the systems used from 40 days of storage onwards. The best TSS/TA ratio was obtained under ULO after 40 days, while firmness and weight loss declined in CA and ULO, contrasting with the brightly colored pulp. Reducing and non-reducing sugars decreased under CA and ULO at 30 and 40 days of storage, whereas phenolic compounds and antioxidant activity remained similar in these systems at 30, 40 and 50 days. Carotenoids remained stable for up to 40 days in ULO.CA and ULO maintained the best physical and chemical quality parameters, both systems being the most recommended. The phytochemical compounds analyzed in this study changed little during storage in the systems analyzed.

Quality of ‘Baigent’ apples as a function of pre-harvest application of aminoethoxyvinylglycine and ethephon stored in controlled atmosphere

– The objective of this work was to evaluate the effects of pre-harvest application on ‘Baigent’ apple trees cultivated under black anti-hail nets with aminoethoxyvinylglycine (AVG), in a single or split dose, combined or not with ethephon, on the quality, the antioxidant activity, and the content of phenolic compounds of the fruits after storage in controlled atmosphere (CA). The pre-harvest applications of AVG alone, both at a dose of 0.125 g L−1, as well as in split dose and at a dose of 0.0625 g L−1, reduced the rate of ethylene production, showed less yellowing fruits and a lower incidence of cracks, maintaining high flesh firmness, texture attributes, and fruit acidity, without causing negative effects on the incidence of mealiness and decay. The pre-harvest applications of AVG at a dose of 0.125 g L−1 and in split dose combined with ethephon also contributed to the reduction of the ethylene production rate and yellowing, showed high flesh firmness and texture, however, it showed a high incidence of decay and cracking when ethephon was combined with AVG at a dose of 0.125 g L−1. In the skin, application of AVG only at a dose of 0.125 g L−1 reduced the total phenolic compounds values, however, total antioxidant activity was reduced with any form of AVG application. In the flesh, there was no effect of pre-harvest application of AVG. Regardless of the dose and form of application, AVG reduced the contents of chlorogenic acid, phloridizin, and epicatechin in the skin of fruits harvested at commercial harvest.

Effect of controlled atmospheric conditions combined with salt acid immersion on trimmed young coconut qualities during cold storage

Trimmed young coconut (TYC) contributes to global economic trade but is impacted by microbial and browning spoilage during the cold chain operation. TYCs were dipped in salt/acid solution (SA; 10% sodium chloride and 10% citric acid) and stored at 2 °C for 8 weeks in three different controlled atmosphere (CA) conditions with normal atmospheric condition as the control. Qualities and bacterial profiles of TYCs were determined. TYC treated with SA+CA (5% O2 + 7.5% CO2) showed the lowest average browning index of 29.13. Titratable acidity, total soluble solid content and pH ranged 0.026–0.071%, 6.86–8.96 °Brix and 5.38–6.51, respectively. Aerobic plate count and total yeast and mold counts were less than 4 log CFU/area of each shoulder, body and bottom area of TYCs. Leuconostoc mesenteroides and Pseudomonas sp. were undetected by PCR-DGGE analysis. Results suggested that SA+CA (5% O2 + 7.5% CO2) offered a non-allergenic hurdle technology to prolong the shelf life of TYC.

High CO2 Reduces Spoilage Caused by Botrytis cinerea in Strawberry Without Impairing Fruit Quality.

High CO2 (> 20 kPa) conditions are beneficial for suppressing spoilage caused by Botrytis cinerea in strawberry fruit; however, these conditions are often accompanied by discoloration, off-flavors, and faster softening. Stepwise increments of CO2 concentrations have been proposed to alleviate injuries in fruits caused by high CO2. In this study, we investigated whether stepwise increments of CO2, up to 30 kPa and under a reduced O2 concentration, are beneficial for reducing fungal spoilage without inducing CO2 injury symptoms in strawberry fruit. Based on recommended settings (5–10 kPa O2 with 15–20 kPa CO2), we first selected optimal O2 and CO2 concentrations that best-reduced spoilage caused by B. cinerea in red ripe “Sonsation” strawberry fruit. We found that higher O2 (10 kPa) and CO2 (20 kPa) concentrations were most beneficial for prolonging strawberry fruit shelf life. Subsequently, we studied the performance of red ripe “Arabella” strawberry fruit stored at 5°C under different controlled atmosphere (CA) conditions (10 kPa O2 with either 0, 20, or 30 kPa CO2). The CO2 concentrations were achieved either within 8 h or in a stepwise manner within the first 4 days of storage. As a control, 21 kPa O2 and 0 kPa CO2 were used. Following storage for up to 11 days, the spoilage incidence was assessed at 12°C for 5 days. The application of high CO2 (20 and 30 kPa) combined with 10 kPa O2 greatly suppressed fruit spoilage during storage and subsequent shelf life. High CO2 suppressed respiration as well as maintained a higher pH and firmness in treated fruit. The level of total sugars did not change, but during storage, a substantial part of sucrose was converted into glucose and fructose, especially under high CO2 conditions. High CO2 did not affect ascorbic acid and anthocyanin levels. The stepwise increments of CO2 did not result in beneficial effects compared to the static application of high CO2. Our results show that “Arabella” strawberry fruit are highly tolerant to elevated CO2 and can be stored under 30 kPa CO2 to prolong the shelf life.

Quality Evolution and Aroma Profile of Pointed Cabbage in Different Storage Regimes.

With its increasing popularity, the need for optimal storage conditions of pointed cabbages becomes more important to meet the year-round demand. Storage of the pointed varieties, however, is more difficult compared to the traditional, round varieties and is limited to a few weeks in normal air. Pointed cabbages are more susceptible to quality loss (shriveling, yellowing of leaves, weight loss, fungal, and bacterial infections) and tend to spoil much faster. In order to provide a year-round availability of the fresh product, storage under controlled atmosphere (CA) could offer a solution. In this study, pointed, white cabbage heads (Brassica oleracea var. capitata for. alba L. subv. Conica cv. ‘Caraflex’) were stored at 1°C from November 2018 to May 2019 under four different CA conditions (1 kPa O2 + 1.5 kPa CO2, 1 kPa O2 + 5 kPa CO2, 3 kPa O2 + 1.5 kPa CO2, and 3 kPa O2 + 5 kPa CO2), and compared to storage under normal air. Results showed that CA storage resulted in a prolonged storage life with a good quality retention for both texture and aroma. CA-stored cabbages showed less weight loss, shriveling, and yellowing. Internal quality parameters [color, soluble solids content (SSC)] were stable over the whole storage period for all objects. The aroma profiles of both the storage atmosphere and cabbage samples were impacted by storage duration. The aroma of cabbage juice was also affected by the storage regime. A clear separation was found for cabbage stored under CA compared to the reference group. From the CA-treatments studied, a combination of low oxygen (1 kPa O2) and elevated carbon dioxide levels (5 kPa CO2) showed the best results maintaining quality. Storage under CA resulted in a better resemblance to the aroma of freshly, harvested produce compared to cabbages stored in normal air.

Research and development of a pilot continuous annealing and MgO coating line for grain-oriented silicon steel

ABSTRACT To investigate the processes of continuous annealing and MgO coating of grain-oriented silicon steel (GO), a pilot-scale line was developed, which could realize functions such as cleaning, heating, decarburization, reduction, nitriding, and MgO coating in a coil-to-coil manner. A significant feature of the pilot line is the integrated furnace consisting of six furnace units and the in-between separating devices, which work collaboratively to adjust the lengths, and to separate the annealing atmospheres and temperatures of the different process sections. A series of test runs and experiments was carried out on the line. The results showed that the pilot line had the characteristics of flexible process, accurate process parameters control and reliable atmosphere separation. The results of decarburization, reduction, nitriding, and coating met the requirements of GO. The pilot line provided an excellent platform for the experimental study of the processes of continuous annealing and MgO coating of GO.

Investigating the role of abscisic acid and its catabolites on senescence processes in green asparagus under controlled atmosphere (CA) storage regimes

Asparagus (Asparagus officinalis) is a highly perishable crop with a short postharvest life. Although some research has been done on the application of controlled atmosphere (CA), it has not been sufficiently explored and the underlying mechanisms controlling asparagus senescence processes are not well understood, restricting its potential for commercial application. The aim of this study was to investigate for the first time the link between abscisic acid (ABA) and ABA catabolites and senescence in asparagus stored under a range of different CA conditions. Two different set-ups were run in parallel; a traditional CA delivered by an International Controlled Atmosphere (ICA) system with continuous gas supply and LabPods™ fitted with sensors for real time monitoring of respiration rate (RR) and respiratory quotient (RQ) and able to retain established CA conditions with minimum gas supply requirements. The role of genetic variability was also studied by including two UK grown asparagus cultivars ‘Gijnlim’ and ‘Jaleo’ adapted for different climatic conditions. The results indicated that ABA and its catabolites were present in significantly higher concentrations in the air stored spears (control) compared to CA throughout storage, irrespective of cultivar, and were associated with accelerated senescence processes observed in control samples, such as textural changes indicative of spear toughening, discolouration, sugar depletion and asparagine accumulation. Furthermore, partial least squares regression (pls-r) applied for both cultivars, successfully differentiated samples based on O2 and CO2 concentrations and storage duration, both in cold storage and during shelf-life with the separation being driven primarily by ABA and its catabolites. Physiological and biochemical results indicated that all three CA conditions tested ([CA1] 2.5% O2, 3% CO2, [CA2] 2.5% O2, 6% CO2 and [CA3] 2.5% O2, 10% CO2) successfully retained quality parameters including texture, colour, moisture content and visual appearance longer compared to air (control); however, they did not completely suppress the development of ‘tip-breakdown’ (a physiological disorder also known as tip rot) towards the end of storage, which coincided with rising concentrations of phaseic acid indicating an activation of the abscisic biosynthetic and catabolic pathway. It can be concluded that CA conditions can delay senescence for at least 3-weeks (2 weeks cold storage and 1 week shelf-life), by lowering metabolic rate and respiratory quotient (RQ) within the spears compared to control, and through successfully regulating ABA biosynthetic and catabolic pathways.

Automatic periodical sulfur dioxide fumigation in combination with CO 2 ‐enriched atmosphere extends the storage life of durian ( Durio zibethinus Murr.)

The postharvest decay of durian (Durio zibethinus Murr.) increases rapidly when the storage time is extended, which seriously limits the commercial value. In this research, the effects of appropriate periodical SO2 fumigation and different CO2-enriched atmospheres (3% O2 + 10%–13%, 14%–17%, or 18%–21% CO2) on the storage quality of durian stored at 14°C were investigated. Results showed that SO2 fumigation in combination with enriched CO2 atmosphere (14%–17%) could maintain firmness (16.37 N), retard weight loss (10.24%), reduce decay rate (11%), and inhibit the production of ethylene (9.2 μl kg−1 h−1) and malondialdehyde (12.10 μmol/g). Moreover, the treatment consolidated the disease resistance of durian by, first, enhancing peroxidase (POD) and catalase (CAT) activities, and, second, by restraining polyphenol oxidase (PPO) activity, which helped to maintain the cell integrity structures. More importantly, this treatment retained a high sensory score (41.35) and extended the storage life up to 60 days. Therefore, a combination of 1,500 mg/L SO2 fumigation and controlled atmosphere storage (3% O2 + 14%–17% CO2) was the more effective method to delay maturation and senescence and improve the storage quality of durian. Novelty impact statement Durian (Durio zibethinus Murr.) is susceptible to rapid water loss, softening, browning, and chemical deterioration after harvest, which greatly limits the storage quality and commercial value of fruits. Automatic periodical SO2 fumigation of 1,500 mg/L in conjunction with CO2-enriched controlled atmosphere storage (3% O2 + 14%–17% CO2) will be a promising postharvest strategy to reduce decay and extend the storage life of fresh durian.

EFFECT OF TEMPERATURE AND 1-METHYLCICLOPROPENE ON THE STORABILITY OF ‘ALEXANDER LUCAS’ PEAR

ABSTRACT The storage life of ‘Alexander Lucas’ pear is limited by the occurrence of internal storage disorders during controlled atmosphere (CA). 1-Methylcyclopropene (1-MCP) can be used to delay pear ripening, however, its interaction with CA conditions is not well understood. ‘Alexander Lucas’ fruit were treated with 1-MCP at 300 nL L-1 for 24 h in air at-0.5 or 1.0 °C before being stored. Fruit were kept at-0.5 or 1.0 °C in normal air or CA (2.0 kPa O2 plus &lt;0.7 kPa CO2). After six months of storage, superficial scald did not develop in fruit. The highest incidence of flesh browning (72.2 %) was found in air-stored fruit at-0.5 °C without 1-MCP treatment. Storage in air at 1.0 °C plus 300 nL L-1 1-MCP produced 88.8 % of healthy fruit. In contrast, 1-MCP increased the incidence of flesh and core browning under CA conditions. 1-MCP and CA maintained greener skin color and higher titratable acidity. No significant differences were found for fruit firmness, total soluble solids and ascorbic acid content between the treatments. In conclusion, the quality of ‘Alexander Lucas’ pear was best maintained during six months storage under normal air at 1.0 °C combined with 300 nL L-1 1-MCP treatment.

Effects of cuticular wax on the postharvest physiology in fragrant pear at different storages.

Epidermal wax is an important factor affecting the storage quality of fruits and vegetables. Previous studies have shown that the epidermal wax of fruits undergoes significant changes during storage, but there are few studies on the effects of different storage methods on the changes in waxes and the relationship with storage quality. To investigate the effect of cuticular wax on the postharvest physiology in fragrant pear, equal numbers of fragrant pear fruits were stored in room temperature storage (control), cold storage and controlled atmosphere (CA) storage environs, respectively. Gas chromatography-mass spectrometry analysis revealed that the prevailing compositions of cuticular wax of fragrant pear were alkanes, alkenes, alcohols, aldehydes, esters and fatty acids. Compared with the control, cold storage and CA storage significantly inhibited changes in postharvest physiology, total wax contents and wax compositions of fragrant pear, and the effects of CA storage were more pronounced than cold storage. Under different storage methods, total wax contents and wax compositions show different correlations with various physiological indicators. The results obtained in the present study indicate that cold storage and CA storage altered the fragrant pear cuticular wax contents and constituents, thus changing the postharvest physiology quality. The changes in the metabolism of wax components caused by the changes in storage environment mainly affect the changes in the hardness of fragrant pears. The present study provides a theoretical basis for the preservation and storage of fruits. © 2022 Society of Chemical Industry.

Carpophilus hemipterus (L.) Pupasının Düşük Oksijenli Yüksek Karbondioksit Uygulamasına Duyarlılığı Üzerinde Yaşın ve Uygulama Süresinin Etkisi

Modified/controlled atmosphere applications, as an alternative to the chemical treatments, are an effective technique in controlling pest of stored products, especially dried fruits. In gas tight units, it is applied with the principle of preventing the insect respiration by changing the oxygen (O2), carbon dioxide (CO2) and nitrogen (N2) gas levels of the atmosphere. In the study, 1-, 2- and 3- d-old pupae of dried fruit beetle, Carpophilus hemipterus (L.), which is an important dried fruit pest, were exposed to the modified / controlled atmosphere. The modified/controlled atmosphere consisting of 2.1% O2 + 90% CO2 + 7.9% N2 gas mixture was applied for 48, 72, 96 and 120 h at 20°C and 75 ± 5% relative humidity. One, two and three d old pupae responded similarly to modified/controlled atmosphere application. Mortality rates remained close in each exposure time and no significant difference was found between age groups. Unlike the age factor, the exposure time was found to be statistically significant and the mortality rates increased as the exposure time increased in each age group. The highest mortality rates were found as 38, 60 and 47% in 1-, 2- and 3-d old pupae after 120 h of application, respectively.