CO2 Injury Research Articles

Impact of pre-harvest application of 1-methylcyclopropene (1-MCP) on fruit quality, physiological disorders and respiration rate of ‘Scilate’ apple

The ethylene inhibitor 1-methylcyclopropene (1-MCP) is widely used in the apple industry as a post-harvest fumigation application to slow down the ripening process and maintain fruit quality during storage. With the development of a sprayable formulation (Harvista™, Agrofresh Inc, USA), it is becoming increasingly common in the apple industry to apply 1-MCP as a pre-harvest spray. This study investigated the impact of pre-harvest 1-MCP applied 1 week prior to harvest as a foliar application at 11.4 L ha−1 in 1000 L water, on the quality and respiration rate of ‘Scilate’ apples grown in the Huon Valley, Southern Tasmania, Australia. Two trials were undertaken, trial 1 examined fruit quality, flesh browning (FB) and fruit softening in 1-MCP treated and untreated fruit while trial 2 compared the respiration rate of 1-MCP treated and untreated fruit. Despite no effect on fresh fruit quality attributes, pre-harvest spray application of 1-MCP influenced post-harvest fruit quality, storability, and respiration rate of apples. Fruit treated with 1-MCP showed higher malic acid concentration (1.2 g L−1 vs 0.9 g L−1) and lower juice pH (4.6 vs 4.9) even after 7.5 months of regular air cold-storage along with a six-fold reduction in fruit softening in comparison to untreated fruit (2% vs 13%). Pre-harvest treatment of 1-MCP reduced respiration rate by 32%, and incidence of CO2 injury by over 40%. The incidence of radial type (senescent related) FB was reduced by 100%. A significant proportion of treated apples still suffered from severe CO2 injury. This study has demonstrated that pre-harvest application of 1-MCP to ‘Scilate’ fruit can be useful in maintaining long-term fruit quality during storage, reducing respiration rate, and lowering the incidence of FB in general. However, the risk of severe CO2 injury remains, especially with larger fruit harvested from trees with lighter crop loads.

Study of the Characteristics of Mountain Apples Resisting Carbon Dioxide Damage Based on Water–Nitrogen Coupling

The apples are prone to CO2 damage during storage and damage the economic interest of fruit growers. Irrigation and nitrogen application can affect the quality of the fruit and the storage capacity of the fruit. The study was conducted to evaluate the effect of five irrigation levels (W0, 0; W1, 40–55% θf, where θf is the field water capacity; W2, 55–70% θf; W3, 70–85% θf; and W4, 85–100% θf) and four nitrogen applications levels (N0, 0; N1, 200 kg N hm–2; N2, 400 kg N hm–2; and N3, 600 kg N hm–2) on eating quality, physiological changes, phenolic acid content, and pulp microstructure of “Hanfu” apples damaged by CO2 stress during storage. Our results indicated that mild deficit irrigation (70–85% θf) and medium nitrogen (400 kg N hm–2) were recommended to better resist CO2 injury.

The response of ‘Monalisa’ apples to high CO2 storage conditions, harvest maturity and 1-MCP treatment

This study aimed to determine the effects of harvest maturity, 1-MCP treatment and storage conditions with high CO2 partial pressures on ‘Monalisa’ apples physicochemical quality and susceptibility to physiological disorders and decay during long-term storage, plus 7 d of shelf life at 22 °C. The study was composed by two experiments. In Experiment 1, fruit were harvested in one growing season (2011) at the same maturity stage and were treated or not treated with 1-MCP (1 µL L-1). In Experiment 2, fruit were harvested in two growing seasons (2019 and 2020), at two maturity stages. In both experiments, all fruit were stored under CA with four CO2 partial pressure (0.5, 1.5, 3.0 and 4.5 kPa) and regular air (RA, standard of comparison) for 6 or 7 months at 0.8 °C, plus 7 d shelf life at 22 °C. CA was very effective on delaying fruit ripening, senescent disorders and decay incidences, regardless of the CO2 partial pressure. However, under CA, ‘Monalisa’ apples were very susceptible to CO2 injury, expressed as dark flesh browning and cavities that were exacerbated with increasing CO2 partial pressures. Therefore, ‘Monalisa’ apples should be stored under CA with CO2 no higher than 0.5 kPa. The response of ‘Monalisa’ apples to high CO2 is more pronounced in late harvested fruit, which were also more prone to develop senescent flesh browning, cracking and rough skin. 1-MCP application had no effect on ‘Monalisa’ apple susceptibility to CO2 damages, while it reduced fruit softening and acidity loss in both RA and CA storages.

Internal Flesh Browning in Apple and Its Predisposing Factors—A Review

This review article is focused on internal flesh browning (IFB)-related physiological disorders affecting apple (Malus domestica Borkh.) fruit. The expression of different physiological and metabolic IFB-related disorders during post-harvest storage are investigated along with the pre-harvest factors contributing to development. The effectiveness of commercially available pre-harvest technologies for preventing IFB-related disorders are also examined. Internal flesh browning-related disorders are erratic and devastating disorders that result in post-harvest deterioration of fruit quality in apples. Internal flesh browning-related disorders can result in severe economic losses to the apple industry through reduced consumer trust and market acceptability of susceptible cultivars. There are several IFB-related disorders and incidence can range from 0 to 100% of a crop, with severity ranging from no brown flesh to browning of the entire fruit flesh. While IFB-related disorders are found in several apple cultivars, some cultivars are more prone than others. The development of IFB-related disorders involve complex mechanisms depending upon the different types and causes, or factors involved in loss of structural integrity and functional stability of the cell membranes and cell components. Membrane disruption followed by enzymatic oxidation of fruit phenolic compounds by polyphenol oxidases and the production of brown polymers is considered to be the general underlying mechanism causing the browning of flesh tissue. It can be observed in different patterns based on the injured portion of the fruit flesh and the cause of membrane disruption. Three broad categories of IFB-related disorders, including chilling injury, internal CO2 injury, and senescent-related browning disorders, are discussed along with their sub-types. The development of IFB-related disorders can be influenced by both pre-harvest factors and post-harvest conditions and their interactions. Although commonly associated with storage, IFB can also be found immediately after harvest and sometimes in unharvested fruit prior to full maturity. As pre-harvest conditions are a strong contributor to IFB-related disorders, the influence of several pre-harvest orchard conditions, including fruit size, crop load, maturity at harvest, cultivar, climatic conditions, seasonal temperatures, growing degree days, and major mineral nutrients, such as nitrogen (N), phosphorus (P), potassium (K), and calcium (Ca) are reported. Although there are contradictory findings in the studies reported, in general, factors such as larger fruit size, light crop load and delayed harvesting, along with cool temperatures after bloom and warmer temperatures before harvest, increase the risk of IFB-related disorders. In relation to fruit mineral concentrations, high N and low Ca have been associated with increasing IFB, while there is conflicting evidence in relation to the impact of both P and K. This review also examines the effectiveness of commercial pre-harvest technologies such as 1-methylcyclopropene, aminoethoxyvinylglycine and diphenylamine in the prevention of IFB-related disorders, but none of these technologies were found promising due to varied and contradictory results.

Preharvest debagging alleviates external CO2 injury of ‘Fuji’ apple during storage by improving antioxidant capacity and energy status

‘Fuji’ apples that are commercially debagged before harvest are more resistant to external CO2 injury, a physiological disorder, than without debagging. In this study, debagged (bags removed 30 d before harvest) and bagged (bags not removed until harvest) apple fruit were stored in air and in controlled atmosphere storage regimes of 4 kPa O2/0 kPa CO2 and 4 kPa O2/5 kPa CO2 to explore the effects of preharvest debagging on the occurrence of external CO2 injury and the underlying mechanism of the injury. Debagging reduced disorder occurrence of the fruit from 8 d to at least 60 d. Preharvest debagging suppressed the accumulation of reactive oxygen species and malondialdehyde under CO2 stress by increasing the concentrations of antioxidant substances, including phenolics and ascorbic acid, and the activities of superoxide dismutase and catalase. In vitro free radicals scavenging activities further confirmed that the debagged fruit had higher antioxidant activity than the bagged fruit under elevated-CO2 storage conditions. Compared with the bagged fruit, the debagged fruit had higher contents of adenosine triphosphate (ATP) and adenosine diphosphate, level of energy charge, and activities of energy metabolism-related enzymes, including succinate dehydrogenase, cytochrome C oxidase, and Ca2+-ATPase under CO2 stress. ATP treatment inhibited the disorder occurrence ‘Fuji’ apple. These results reveal that the effect of preharvest debagging on inhibiting the occurrence of external CO2 injury of ‘Fuji’ apple was associated with the improvement of antioxidant capacity and energy status of apple peels under CO2 stress.

Fruit quality of ‘Gala’ and ‘Fuji’ apples cultivated under different environmental conditions

This study evaluated the effect of growing site environmental conditions on apple fruit quality. Experimental orchards with ‘Gala’ and ‘Fuji’ apple strains were established in the subtropical humid climate in Southern Brazil, between 26° and 28°S, in the growing sites of São Joaquim, Caçador and Vacaria, located 1415, 960, and 971 m, respectively, above sea level. Fruit quality was assessed at harvest and after storage from the 5th through 8th year after planting. At each growing site, ‘Gala’ apples were harvested at one maturity stage and stored in a controlled atmosphere (CA). ‘Fuji’ apples were harvested at two maturity stages, with early harvested fruit stored in air and late harvested fruit stored in CA. For the São Joaquim site compared with those of Caçador and Vacaria, average temperature during the growing season was lower whereas the number of winter chilling hours and the number of days from bloom to harvest were higher. Fruit weight and red skin area were higher and russeting skin index lower in fruit from the coldest site (São Joaquim) for both cultivars. At harvest, flesh firmness and starch index of fruit from the coldest site were higher or the same as those of the warmest sites (Caçador and Vacaria), depending on cultivar and harvest date. The rate of flesh firmness loss during storage was greater in fruit from the coldest growing site for both cultivars and harvest maturities. Titratable acidity (TA) and soluble solids content (SSC) in fruit from the warmest site were higher or the same as the fruit from the coldest site, depending on when fruit analysis were performed. Although ‘Gala’ apples produced in all three growing sites were equally affected by external fungal decay, fruit from the warmest site had the highest incidence of Glomerella cingulata spot. ‘Fuji’ apples produced in the coldest site had the highest length/diameter ratio and watercore index at harvest and developed more CO2 injury and diffuse flesh browning. External fungal decay index for ‘Fuji’ was the same for the three growing sites for fruit harvested at early maturity, but the decay index was higher for fruit from the warmest site when harvested at an advanced maturity. The study shows the influence of environmental conditions on apple fruit growth and development and the need to adjust production and storage practices to achieve high fruit quality based on pre-harvest environment.

Prestorage High CO2 and 1-MCP Treatment Reduce Chilling Injury, Prolong Storability, and Maintain Sensory Qualities and Antioxidant Activities of "Madoka" Peach Fruit.

Cold storage is widely used to prolong the storability of peach fruit. However, prolonged storage at low temperatures results in chilling injury (CI) in some susceptible peach cultivars during or after cold storage. Prestorage high CO2 and 1-methylcyclopropene (1-MCP) treatments are among the methods reported to alleviate CI and maintain the firmness of peach fruit. Hence, this study investigated CI, ripening-related physicochemical parameters, sensory qualities, total phenolics and flavonoids, and antioxidant activities of “Madoka” peach fruit to observe the effectiveness of prestorage treatment with high CO2 and 1-MCP during the storage at 0 and 5°C. Based on the CI index, control fruits were acceptable for marketing up to 20 and 16 days of storage at 0 and 5°C, respectively, while the treated fruits could be marketable up to 28 days of storage. The results of firmness and firmness-related parameters [pectin content and polygalacturonase (PG) activity] also revealed that both high CO2 and 1-MCP treatments were effective in delaying the ripening process of Madoka peach, and the storage at 0°C showed better results than at 5°C. However, based on the overall sensory evaluation results, the treated and control fruits were acceptable for marketing up to 20 and 12 days of storage, respectively, in both storage conditions. After deciding on fruit marketability based on the combined objective postharvest quality parameters and subjective sensory qualities, we analyzed the changes in total phenolics, flavonoids, and antioxidant activities at harvest, on the 12 and 20th days of cold storage. Storage of Madoka peach at 0°C maintained total phenolics, flavonoids, and antioxidant activities regardless of prestorage treatment with high CO2 and 1-MCP. In summary, storing Madoka peach fruit at 0°C after treating it with 30% CO2 for 6 h or 0.5 μl L–1 1-MCP for 24 h reduces CI, prolongs storability, and maintains sensory quality and antioxidant properties.

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.

Manutenção da qualidade de maçã ‘Luiza’ em função de práticas pós-colheita

Abstract This study was carried out to examine the response of ‘Luiza’ apple to different storage atmospheres, durations, and chemical inhibition of ethylene action by 1-MCP. Analysis of fruit quality and physiological disorder incidence were performed every two months during eight months of storage for Exp. 1 and 2, and after eight months for Exp. 3. Both CA storage and 1-MCP treatment reduced fruit ethylene production and respiration and prevented the rapid fruit softening, flesh browning incidence and fungal decay of ‘Luiza’ apple. The combination of 1-MCP treatment before storage in CA provided an additional benefit in firmness retention after simulated marketing conditions at 22oC. Based on the time to reach a firmness of 53 N, the storage life of ‘Luiza’ apple is less than four months in air-storage and more than six months under CA-storage. ‘Luiza’ fruit did not develop symptoms of CO2 injury when stored under high CO2 partial pressures (up to 4.5 kPa). However, we observed increased flesh browning and fungal decay incidence for CA-stored fruit between six and eight months of storage. Therefore, the storage potential of ‘Luiza’ apple fruit may be limited to six months under CA-storage (1.5 kPa O2 and 2.5 kPa CO2).

Analysis of apple postharment damage under high CO₂ concentration by transcriptome combined with metabolome

The environmental gas concentration affects the storage period and quality of fruits and vegetables. High concentration CO₂ treating for a long time will cause damage to fruits, However, the specific molecular mechanism is unclear. To analyze the mechanism of CO₂ injury in apple, high-throughput sequencing technology of Illumina Hiseq 4000 and non-targeted metabolism technology were used to analyze the transcriptome sequencing and metabolomics analysis of browning flesh tissue of damage fruit and normal pulp tissue of the control group. A total of 6 332 differentially expressed genes were obtained, including 4 187 up-regulated genes and 2 145 down regulated genes. Functional analysis of the differentially expressed genes confirmed that the occurrence of CO₂ injury in apple was related to redox process, lipid metabolism, hormone signal transduction process and energy metabolism process. Twenty candidate browning genes were successfully screened, among which grxcr1 (md14g1137800) and gpx (md06g1081300) participated in the reactive oxygen species scavenging process, and pld1_ 2 (md15g1125000) and plcd (md07g1221900) participated in phospholipid acid synthesis and affected membrane metabolism. mdh1 (md05g1238800) participated in TCA cycle and affected energy metabolism. A total of 77 differential metabolites were obtained by metabolomic analysis, mainly organic acids, lipids, sugars and polyketones, including 35 metabolites related to browning. The metabolism of flavonoids was involved in the browning process of apple. Compared with the control tissue, the content of flavonoids such as catechin and quercetin decreased significantly in the damaged apple tissue, the antioxidant capacity of cells decreased, the redox state was unbalanced, and the cell structure was destroyed, resulting in browning. The results of this study further enrich the theoretical basis of CO₂ damage, and provide reference for the practical application of high concentration CO₂ preservation technology.

Elevated CO2 alleviates browning development by modulating metabolisms of membrane lipids, proline, and GABA in fresh-cut Asian pear fruit

Enzymatic browning is a major problem of fresh-cut pear, which severely limits the shelf life. In the current study, elevated carbon dioxide (CO2) was applied to investigate its effects on quality maintenance and browning repression. The results showed that 5% and 10 % CO2 treatment maintained quality attributes, including firmness, color, and total soluble solids. Browning development was also inhibited by elevated CO2. Elevated CO2 delayed the decrease of unsaturated fatty acid in membranes by decreasing the activities of lipoxygenase (LOX) and phospholipase D (PLD), maintained the integrity of membrane, and therefore alleviate enzymatic browning. In addition, elevated CO2 triggered the accumulation of two stress adaptor molecules, proline and γ-aminobutyric acid (GABA), by improving their biosynthesis and repressing their degradation, which finally contributed to browning repression. However, excessive concentration (15 %) showed adverse effects because of CO2 injury. Our current study suggested a potential strategy for browning repression in fresh-cut pear fruit.

Physiological responses and quality attributes of muscadine grape (Vitis rotundifolia Michx) to CO2-enriched atmosphere storage

Abstract Muscadine grape (Vitis rotundifolia Michx) is a non-climacteric fruit that rapidly loses quality during storage. This study aimed to assess the effect of controlled atmosphere (CA) on quality parameters and muscadine grapes decay. Berries of two muscadine grape cultivars, Triumph, and Supreme, were stored at 4 °C with 95 % relative humidity in either regular air (AIR), regular CA (RCA) (6 % O2 + 10 % CO2), or CA with extreme CO2 level (ECA; 4 % O2 + 30 % CO2) for up to 42 d. Treated berries with either RCA or ECA provided better control of weight loss. Both CA treatments reduced decay incidence, but there was no decay in ECA berries after 42 d for both cultivars and no evidence of CO2 injury. The results showed that berry softening was significantly delayed by RCA and ECA, which had a lower ethylene production rate than berries exposed to AIR. Application of RCA and ECA also retained greater total antioxidant activity, total phenolic compounds, and firmness compared to AIR. These results demonstrate that maintaining CA conditions postharvest leads to improved preservation of compositional quality and delayed softening and decay of harvested muscadine grapes compared with AIR storage.

Effect of pulsed controlled atmosphere with CO2 on the quality of watercored apple during storage

Watercored 'Fuji' apple with special water core and unique flavor is a characteristic fruit. However, the problems of water core disappearance and browning in the apples are outstanding during postharvest storage. In this study, pulsed controlled atmosphere (pCA) with CO2 was used to protect the water-core and resist browning of apples. Effects of different concentrations of CO2 on the quality of apple fruits was investigated, and CO2 injury characteristic to apple fruits were studied as well. Results showed that pCA with CO2 could effectively maintain the sensory and texture qualities of watercored apples. Treated with pulsed controlled CO2, the degree of membrane lipid peroxidation of the apples was effectively reduced and the membrane system was well maintained. Meanwhile, the activity of polyphenol oxidase (PPO) and phenylalanine ammonia-lyase (PAL) of the apples were inhibited and the browning was reduced. On the whole, pCA with 1% CO2 presented the most significant effects on the quality preservation of watercored apples while higher CO2 showed negative effects on the quality of the samples. Under the condition of pCA with 5% CO2, the endurance of watercored apples was less than 45 days and the internal browning was serious. In conclusion, 2%～3% O2 and pCA with 1% CO2 was the best and most effective in the long-term preservation of watercored apples, and it is beneficial to guide for the preservation of apple fruits.

Comparison of fruit attributes of ‘Fuji’ apple strains at harvest and after storage

Commercial apples are graded primarily by appearance and many new 'Fuji' apple strains have been planted in commercial orchards because of the enhanced red color of their skin. The fruit of most apple strains selected for skin color do not differ; however, some apple strains may produce fruit with different firmness and soluble solid content (SSC). This study compared the fruit quality and maturity of three 'Fuji' apple strains ('Fuji Suprema', 'Mishima', and ‘Fuji Select') grown in experimental orchards in southern Brazil. Fruit were harvested at two maturity stages: early, which were stored in air; and advanced, which were stored in a controlled atmosphere (CA). Storage conditions were selected to induce the development of different physiological disorders. Fruit quality was assessed one day after harvest and after 210 days of storage at 0.8 °C plus seven days at 22 °C, over three growing seasons. Skin color was the main variable that distinguished fruits of the three strains. The extent of red coloration was greater on the surface of 'Fuji Suprema’ apples than on 'Mishima’ or 'Fuji Select’, especially for early-harvest fruit. The pattern of fruit maturation on the tree was the same for the three strains and they showed similar starch index, SSC, and titratable acidity; flesh firmness was slightly (<2.5 N) lower in 'Fuji Select' for both maturity stages. At harvest, fruits of the three strains were also similar in terms of fruit weight and development of russeting disorder. 'Fuji Select' apples were least affected by watercore. The three strains showed similar rates of loss of firmness and were equally affected by fungal decay, core rot, superficial scald, calcium deficiency disorders, shrivel, and diffuse flesh browning during storage, indicating that they did not differ in terms of storability. 'Fuji Suprema’ had the lowest susceptibility to CO2 injury, suggesting that distinct CA protocols could be applied for the different 'Fuji’ strains. The results show that planting of 'Fuji Suprema' could increase fruit production of high quality grades based on red skin color and reduce the expenses associated with CO2 removal from storage facilities.

Microbiological and Quality Responses of Strawberry Fruit to High CO2 Controlled Atmosphere and Modified Atmosphere Storage

‘Minomusume’ strawberries were stored in high CO2 atmospheres (20%, 30%, and 40%) by means of a controlled atmosphere (CA) and active modified atmosphere packaging (MAP) for 10 days at 5 °C. The CA of 20% to 40% CO2 was effective in delaying an increase in fungal count and preventing the external formation of mold mycelia, but a CA of &gt;30% CO2 induced black discoloration on the surface of strawberry due to CO2 injury. When strawberry fruit were stored in a MAP flushed with either air or high CO2, all packages approached an equilibrium of ≈20% CO2 and 2% O2 by the end of storage. Fungal counts of strawberry fruit stored in a MAP remained constant throughout the storage period and the diversity of fungal flora was partially similar regardless of the difference in the MAP method. Visual quality (mold incidence and severity of black discoloration) and physicochemical quality (weight loss, firmness, pH, and total ascorbic acid content) were unaffected by CO2 atmospheres as the flushing gas during active MAP storage, except that the fruit in a MAP flushed with 20% and 30% CO2 were firmer than those with air and 40% CO2. After transfer to ambient conditions for 6 days at 10 °C, however, external formation of mold mycelia identified as Botrytis cinerea and surface black discoloration were induced in strawberry fruit in MAP flushed with 30% and 40% CO2.

Carbon Dioxide Injury Prediction Model for Fresh-Cut Apples

Abstract Carbon dioxide (CO2) injury is one of the key cause affecting the sales of fresh-cut apples during the sales period. The method to warn the time till occurring CO2 injury would be convenient for businesses and consumers, but so far, no one has paid attention. This research aimed to study the change rule of the mechanism of carbon dioxide injury of fresh-cut apples treated with high CO2 concentration. The experiment was conducted at 5, 15, 25 and 35°C for 4 days. Every twelve hours, the fresh-cut apple was analyzed by measuring the changes of firmness, soluble solids concentration, browning index and sensory evaluation. The results showed that sensory scores, firmness and soluble solids concentration decreased over time, while the browning index of freshly cut apple increased rapidly with time. Based on the dynamic model of the browning index, with the CO2 Injury warning model of ready-to-eat apples treated with high CO2 concentration was determined.

Effect of high carbon dioxide injury on the physiological characteristics of fresh-cut garlic scapes

Garlic scapes (flower stalks of garlic) exhibited symptoms of CO2 injury when exposed to high CO2 conditions during storage. This study aimed to investigate and compare the physiological characteristics of fresh-cut garlic scapes stored in air or in a high CO2 atmosphere (21 % CO2 and 5% O2) at 25 °C. High levels of CO2 promoted the production of several enzymes associated with anaerobic metabolism, particularly PDC and ADH, which lead to the accumulation of ethanol. The content of ethanol in fresh-cut garlic scapes stored in a high CO2 atmosphere was about 5.9 times greater than that of those stored in air. High CO2 also enhanced the accumulation of other volatile compounds, alcohols, aldehydes and esters, often the primary cause of off-flavor development. The cell membrane-bound Ca2+ content of the fresh-cut garlic scapes stored in a high CO2 atmosphere was significantly lower than of those stored in air, because it had combined with CO2 thus making the content of calcium carbonate higher. This sharp decline in cell membrane-bound Ca2+ aggravated the damage to the tissue structure. The activity of PPO also increased when fresh-cut garlic scapes were stored in a high CO2 atmosphere.

Outcome of peroral endoscopic myotomy in children with achalasia.

Achalasia cardia is rare in children and optimum endoscopic management options are not well known. Peroral endoscopic myotomy (POEM) is a novel treatment modality for achalasia with excellent results in adult patients. The long-term outcomes of POEM are not well known in children. In this study, we aim to evaluate the outcome of POEM in children with idiopathic achalasia. We analyzed the data of children (≤ 18years) diagnosed with achalasia from September 2013 to January 2018. Technical success, clinical success, and adverse events were assessed. Post-POEM, gastroesophageal reflux (GER) was assessed with 24-h pH-impedance study and esophagogastroduodenoscopy. A total of 44 children (boys-23, girls-21) with mean age of 14.5 ± 3.41years (4-18) were diagnosed with achalasia during the study period. Of these, 43 children underwent POEM. The subtypes of achalasia according to Chicago classification were type I-11, type II-29, type III-2, and unclassified-2. Eighteen children (40.9%) had history of prior treatment. POEM was successfully performed in 43 children (technical success-97.72%). Intra-operative adverse events occurred in 11 (25.6%) children including retroperitoneal CO2 (7), capnoperitoneum (3), and mucosal injury (1). Clinical success at 1, 2, 3, and 4 years' follow-up was 92.8%, 94.4%, 92.3%, and 83.3%, respectively. Erosive esophagitis was detected in 55% (11/20) children. On 24-h pH study, GER was detected in 53.8% (7/13) children. POEM is a safe, effective, and durable treatment for achalasia in children. However, GER is a potential concern and should be evaluated in prospective studies before adopting POEM for the management of achalasia in children.

Recent developments on dynamic controlled atmosphere storage of apples—A review

Abstract The potential of dynamic controlled atmospheres (DCA) as a non-chemical treatment for maintaining the postharvest quality of apples during long-term cold storage has been an interest of researchers for decades. This article reviews the recent developments in DCA technology for storage of apples. The effects of DCA on physiological disorders, physico-chemical and sensory quality are discussed. Moreover, negative effects associated with DCA technology are also discussed. The study has shown that DCA maintains apple postharvest quality by reducing respiration rate and ethylene production. Ethylene-mediated physiological disorders such as superficial scald are completely suppressed by DCA storage. However, the effect of DCA on bitter pit incidence needs further investigation. The review also showed that fruit firmness and colour retention is considerable high in DCA stored apples. Although DCA maintains both the physico-chemical and organoleptic quality of apples, the high risk of CO2 and low O2 injury in DCA stored fruit remains a concern. Further research is required to refine and improve the DCA technology in order to minimize the risk of CO2 and low O2 injury during longterm storage.

Effect of carbon dioxide (CO2) and oxygen (O2) levels on quality of 'Palmer' mangoes under controlled atmosphere storage.

With the objective to evaluate the modifications in the fruit quality, 'Palmer' mangoes were stored at 12.8°C for 30days in controlled atmosphere storage that contained a low level of oxygen (5kPa) which was associated with increasing levels of carbon dioxide CO2 (0, 1, 5, 10, 15 and 20kPa CO2). Controlled atmosphere storage did not effect mango respiration. However, transfer mangoes, that were previously stored at high levels of CO2 (5kPa O2+15kPa CO2 and 5kPa O2+20kPa CO2) to ambient temperature presented higher respiratory rates. No significant effects of increasing CO2 levels on color (L*, chromaticity, and hue angle), firmness, physical-chemical parameter and carbohydrate metabolism (total and reducing sugars, soluble pectin) were observed. After transfer to ambient temperature the mangoes ripened normally without any signs of CO2 injury. Therefore, the increment levels of CO2 neither improved the quality of the 'Palmer' mangoes nor presented a synergistic effect with low-oxygen when compared to 5kPa O2-control.