Controlled Atmosphere Fruit Research Articles

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.

Controlled Atmosphere pO2 Alters Ripening Dynamics of 1-MCP treated ‘d’Anjou’ Pear (Pyrus communis L.) Fruit

Ripening and development of physiological disorders and decay were assessed in ‘d’Anjou’ pear fruit after 1-methylcyclopropene (1-MCP) treatment and cold storage in air or controlled atmosphere (CA). Fruit were exposed after harvest to 0 or 12.6 μmol·L−1 1-MCP and then stored at 0.5 °C in air or 1, 3, or 5 kPa O2 with 0.5 kPa CO2. Pears were held poststorage at 20 °C for 7 days before analysis. 1-MCP fruit usually had higher hue compared with controls. Softening after removal from storage was delayed in 1-MCP fruit regardless of storage atmosphere; however, control fruit stored in air or CA ripened to below 23 N, a minimum value for consumer acceptance, after all storage durations. 1-MCP fruit stored in air, 3, or 5 kPa O2 softened in the outer cortex (fruit surface to 8 mm into the cortex) to below 23 N only after 9 m, however, only fruit stored in air softened to less than 23 N in the inner cortex (8 mm to coreline). 1-MCP treatment also delayed deformation in cortex tissue tensile strength (TTS); after six or more months, 1-MCP fruit TTS was lower compared with those for control fruit. After 9 m, 1-MCP fruit stored in air had TTS values similar to those of controls whereas values for fruit stored in CA increased with CA O2 concentration. Titratable acidity was higher in 1-MCP-treated fruit stored in air (6 m only) or 3 or 5 kPa O2 compared with controls. Superficial scald developed after 6 m on control fruit stored in air or 5 kPa O2 and on control CA fruit regardless of O2 concentration after 9 m. No 1-MCP fruit developed scald. The results indicate ‘d’Anjou’ pear ripening in response to 1-MCP is influenced by storage pO2 as well as storage duration, and at the 1-MCP treatment concentration used, softening to a consumer standard for firmness occurred only in fruit cold stored in air for 9 months plus a 7-day poststorage ripening period. These fruit had peel hue less than 100, and the yellow peel color may not be consistent with current market expectations.

Avoiding Chilling Damage in ‘Hass’ Avocado Fruit by Controlled Atmosphere Storage at Higher Temperature

Sea-freight distribution of ‘Hass’ avocado (Persea americana) is by refrigerated containers, sometimes supplemented by controlled atmosphere (CA). With both refrigeration and CA prolonging the storage life of the fruit, there is a question as to whether the technologies can be traded. That is, by using CA at warmer temperatures to extend storage without the risk of chilling damage. In this project, the potential to avoid chilling damage by storing fruit at 7 °C in 2% O2/2% CO2 CA instead of 5 °C in 2% O2/2% CO2 CA or air has been investigated for fruit stored for 4 or 6 weeks. Increasing the storage temperature from 5 °C to 7 °C did not affect the quality of fruit immediately out of CA storage, with no significant difference in skin color, firmness, or skin disorders. Both CA storage regimes, at 5 °C or 7 °C, resulted in better fruit quality than for fruit that had been stored in air at 5 °C. Overall, CA at 7 °C was less effective at retarding the progression of ripening in storage than CA at 5 °C, although after 4 weeks of storage, fruit from both CA regimes took longer to ripen than the air-stored fruit. After 6 weeks of storage, there was no difference in ripening time between fruit that had been stored in CA at 7 °C or in air at 5 °C, with fruit that had been in CA at 5 °C still taking longest to ripen. However, the incidence of diffuse flesh discoloration (DFD) in the air-stored fruit was high compared with that in fruit from CA at 7 °C or 5 °C. The main negative aspect to storing fruit in CA at 7 °C rather than at 5 °C was the higher incidence of rots in ripe fruit. While it was lower in the air-stored fruit, the incidence in fruit that had been stored in CA at 7 °C tended to be higher than that of the fruit stored in CA at 5 °C. It therefore appears that the potential for using CA at slightly higher temperatures to avoid chilling damage rests on the storage duration required and the risk of rots in the fruit.

Shelf-life and sensory assessments reveal the effects of storage treatments with 1-methylcyclopropene on new and established apples

Stanich, K., Cliff, M. A., Hampson, C. R. and Toivonen, P. M. A. 2014. Shelf-life and sensory assessments reveal the effects of storage treatments with 1-methylcyclopropene on new and established apples. Can. J. Plant Sci. 94: 1427–1439. This research used shelf-life and sensory assessments to explore the influence of 1-methylcyclopropene (1-MCP) on four apples (Aurora, Fuji, Nicola™, Salish™). Maturity (internal ethylene concentration, starch clearing index), quality (soluble solids, titratable acidity, firmness) and sensory determinations were conducted on fruit that had undergone air (AIR) or controlled atmosphere (CA) storage treatments with and without 1-MCP. Trained panelists evaluated apples, along with industry standards (Gala, McIntosh and either Fuji or Ambrosia), for eight attributes (crispness, hardness, juiciness, skin toughness, sweetness, tartness, sweet–tart balance and flavour). Data were analyzed using analysis of variance and principal component analyses (PCA) to compare the treatment and cultivar responses. Cultivars responded very differently to CA and 1-MCP. Fruit from AIR with 1-MCP were very similar to CA fruit without 1-MCP; further improvements were not observed when 1-MCP was applied to CA fruit. PCA bi-plots of the shelf-life and sensory assessments revealed that treated Salish™ fruits were more similar to one another than to cultivars from other treatments. This work successfully documented the unique changes associated with the use of 1-MCP on new and established apple cultivars. It will assist industry in applying appropriate storage practices for new and established apple cultivars.

Upregulation of polyphenol-related genes prevents ‘skin burning’ of well-colored ‘Cameo’ apples stored under stressful controlled atmosphere conditions

‘Skin burning’ of ‘Cameo’ apples resulting in poorly colored fruit can occur in storage under high CO2 condition. To elucidate possible reasons for this physiological disorder, we assessed the differential expression of polyphenol-related genes. Poorly colored and well-colored mature ‘Cameo’ apples were stored under either high (3%) or low (0.7%) CO2 levels, both in combination with 1% O2, and monitored for seven months for ‘skin burning’. Samples were obtained by the end of storage period, and qPCR analyses were conducted using gene specific primers. We found expression levels of chalcone synthase (MdCHS), chalcone isomerase (MdCHI), anthocyanidin synthase (MdANS), flavonol synthase (MdFLS), dihydroflavonolreductase (MdDFR), and leucoanthocyanidinreductase (MdLAR1) genes to be substantially higher in well-colored compared to poorly colored apples. The delay in establishing the stressful controlled atmosphere (CA) storage condition (3% CO2 level) led to significantly higher expression levels of MdLAR1, MdCHI, anthocyanidinreductase (MdANR) and flavanone 3-hydroxylase (MdF3H), which may explain the lower incidence of ‘skin burning’ by delayed CA fruit. On the other hand, after seven months in storage, the expression levels of phenylalanine ammonia-lyase (MdPAL), MdCHS, MdCHI, MdDFR, MdFLS, and MdF3H, were significantly higher in poorly colored injured apples, which reflect a feedback mechanism to synthesize more polyphenols to counteract the stressful storage condition.

Diphenylamine Metabolism in ‘Braeburn’ Apples Stored under Conditions Conducive to the Development of Internal Browning

Diphenylamine metabolism and ethylene action were evaluated as factors influencing the development of 'Braeburn' apple internal browning and cavitation during cold storage. Apples treated with the antioxidant diphenylamine (DPA) and/or the ethylene action inhibitor 1-methylcyclopropene (1-MCP) were held at 1 degrees C for up to 6 months in air or a controlled atmosphere (CA) containing 1 kPa of O2 and 3 kPa of CO2. Cortex tissues from fruit without disorders as well as from symptomatic and asymptomatic areas of fruit with disorders were analyzed for DPA and DPA derivative content. Internal browning and cavities developed in control and 1-MCP-treated fruit stored in CA, whereas air-stored and CA fruit treated with DPA or with DPA and 1-MCP prior to storage did not develop disorders. Depending on the storage regimen and duration, less DPA was detected in 1-MCP-treated fruit. The 4-hydroxydiphenylamine (4OHDPA) content of control fruit decreased during air storage duration but increased between 2 and 4 months in CA storage. 4OHDPA content in 1-MCP-treated fruit increased with storage duration in CA but not air. N-Nitrosodiphenylamine (NODPA) was detected after 2 months in control fruit stored in air or CA and in 1-MCP-treated fruit stored in CA, and NODPA content in control fruit was higher compared to that in 1-MCP-treated fruit. Accumulation of 4-methoxydiphenylamine (4MeODPA) in control fruit stored in air increased with storage duration, but 4MeODPA content did not change in 1-MCP-treated fruit stored in air or CA. 2-Nitrodiphenylamine content was reduced by prestorage treatment with 1-MCP, but storage environment and duration had no effect on its accumulation. The results indicate that CA storage increases the risk of disorder development in 'Braeburn' apples, that DPA can prevent disorder development, and that the content of DPA and DPA derivatives is influenced by storage environment and ethylene action. A clear relationship between DPA derivative formation and storage conditions that promote internal browning was not apparent.

EFFECTS OF LOW OXYGEN ON ACTIVE OXYGEN METABOLISM AND INTERNAL BROWNING IN 'BRAEBURN' APPLE FRUIT

'Braeburn' apple fruit were held in low oxygen (0.5 kPa O2 +0.05 kPa CO2) controlled atmosphere (CA) at 0 °C for two months, or sealed in polyethylene bags (Pa) at 20 °C for 10 days to obtain anaerobic conditions. Control fruit (CK) were stored in air at 0 or 20 °C. Activity of xanthine oxidase (XOD), NADH and NADPH oxidase, superoxide dismutase (SOD) and the incidence of physiological disorders were investigated. The activities of XOD, NADH oxidase were highest in apples stored in CA or Pa. SOD activity was similar in CA and CK fruit, but lower in Pa apples. Acetaldehyde (AA) treatment (120 ppm, at 0 °C for 24 h) prior to CA or addition of AA (1 ml of a 1% solution) to polyethylene bags stimulated NAD(P)H oxidase activity. AA pre-treatment resulted in lower SOD activity, and this response was detectable through two months storage in CA. The physiological disorder, internal browning, occurred in apples stored in CA or Pa, and the disorder development was enhanced by AA treatments. The results suggest that development of internal browning in 'Braeburn' apples may be associated with superoxide accumulation due to enhanced activity of XOD and NAD(P)H oxidase with reduced SOD activity under low oxygen or anaerobic conditions.

Ethylene biosynthesis and ripening behaviour of ‘Hayward’ kiwifruit subjected to some controlled atmospheres

The effects of storage in air (AS), controlled atmosphere (CA) or ultra low oxygen (ULO) on ethylene biosynthesis and ripening of ‘Hayward’ kiwifruit during storage at 0 °C and post-storage at 20 °C, were investigated. Fruit were stored for 60, 120 and 180 days at 0 °C in AS, CA (2%O 2 +5%CO 2 ) and ULO (0.7%O 2 +0.7%CO 2 and 1%O 2 +1%CO 2 ). Freshly harvested fruit and fruit removed from storage were treated with 130 μl/l propylene or propylene-free air for 9 days at 20 °C. Fruit treated with propylene at 20 °C at harvest produced ethylene with a lag period of 3 days, had concomitant 1-aminocyclopropane-1-carboxylic acid (ACC) production, 1-aminocyclopropane-1-carboxylate synthase (ACC synthase) and 1-aminocyclopropane-1-carboxylate oxidase (ACC oxidase) activities, and were ripe after 3–5 days while fruit not treated with propylene were not able to produce ethylene and ripen during the 9 days experiment. AS fruit softened faster during the first 60 days of storage. This effect was reduced in CA and ULO treatments. The soluble solids content (SSC) increased markedly during the first 60 days of storage and remained almost constant thereafter in all treatments. After 9 days shelf life, only AS and CA stored fruit were ripe. Fruit from ULO storage required propylene treatment to ripen fully. When kiwifruit were placed at 20 °C, after 60, 120 or 180 days storage at 0 °C, there was an induction of ethylene production with no lag period in fruit from AS or CA, with or without propylene. There was some ACC content and ACC synthase activity after 60 days storage for all treatments, while ACC oxidase activity increased only upon rewarming of the fruit in AS or CA. Kiwifruit removed from ULO-storage showed drastically reduced capacity to produce ethylene mainly due to low ACC oxidase activity rather than reduced ACC production or ACC synthase activity. Respiration increased upon rewarming of the fruit in all treatments. With storage time, there was a decrease in the capacity of the warmed fruit to produce ethylene and CO 2 as well as in the activities of ACC synthase and ACC oxidase, mostly after 60 days storage.

Environmental stresses affect tomato microsomal membrane function differently than natural ripening and senescence

Abstract On the premise that environmental stresses may induce changes in microsomal membrane function characteristic of accelerated senescence, the effects of physical damage (PD), chilling injury (CI), heat shock (HS) and controlled atmosphere (CA) on tomato fruit ( Lycopersicon esculentum cv. Trust) were compared to changes occurring during normal ripening and senescence. A physiological pattern for ripening and senescence of tomato fruit was established based on weight loss patterns, colour development, ion leakage, lipid fatty acid profiles of microsomal membrane lipids, microsomal K + stimulated ATPase activity and electrophoretically separated protein patterns of microsomal membranes. Control fruit displayed increases in redness, weight loss, ion leakage and saturation index (SI) of membrane lipids, as well as the appearance of membrane-associated polygalacturonase (polygalacturonase isozyme II—PGII) and its β-subunit and decreased microsomal membrane K + stimulated ATPase activity during a three-week storage period. Relative to controls, PD and CI fruit displayed increased ion leakage and a decreased rate of red colour development, increased ATPase activity and SI. Membrane-associated PGII appeared sooner in PD fruit, but its appearance was delayed in CA and CI fruit, relative to controls. Tomatoes exposed to HS and CA treatments, however, displayed ripening and senescence physiological symptoms similar to control fruit. Thus, environmental stresses induced membrane changes that were expressed differently than seen during senescence.

Ester biosynthesis in “Rome” apples subjected to low-oxygen atmospheres

Abstract The relationship between acetate ester-forming activity of acetyl CoA alcohol transferase (ACAT), non-ethylene volatile emission, and flesh volatile content of “Rome” apples ( Malus domestica Borkh.) after removal from 9 months storage in low-oxygen environments was investigated. Apple samples held at 0–1°C were removed from refrigerated air (RA) or controlled-atmosphere (CA) storage at 1.0 or 0.5% v/v O 2 /1% CO 2 and placed in ambient laboratory conditions. Every three days fruit flesh and headspace were analyzed for volatile compounds using capillary gas chromatography. Acetate ester forming activity was assayed spectrophotometrically on partially-purified extracts of cortical tissue. Patterns of acetate ester formation depended upon storage environment and alcohol moiety precursor. Ethyl acetate content was always higher in the headspace and flesh of RA fruit, regardless of time after storage. Propyl acetate concentrations in CA stored apple flesh were higher until post-storage day 12 when they decreased. Headspace propyl acetate levels were higher in RA controls until days 9–15 when more emanated from CA fruit. Butyl acetate concentrations were lower in flesh and headspace of CA fruit until day 15, when RA fruit headspace levels decreased. Headspace and flesh concentrations of 2-methyl-1-butyl acetate were higher in CA apples. Acetate ester-forming activity was detectable at day 0 in 1.0% oxygen-stored fruits, but not in 0.5% oxygen-stored fruits. By post-storage day 9, ACAT activity in CA apples reached maximal levels, only to decrease by day 15. RA-stored apples had more ACAT activity at day 0, but did not substantially increase in activity like the 0.5% oxygen-stored apples removed from CA storage. It is unknown whether the ACAT protein is reactivated by exposure to ambient oxygen or synthesized de novo.

Effects of Delays in Establishing Controlled Atmospheres on Kiwifruit Softening during and Following Storage

Abstract Establishment of a controlled atmosphere (CA) of 2% O2 + 5% CO2 within one day of harvest (no delay) or after a one-week delay in 0°C air retarded rapid softening of CA-stored kiwifruit (Actinidia chinensis Planch. ‘Hayward’) during the 1st 6 weeks of 0° storage, relative to those kept in air or in CA established after a 2-week delay. Between the 6th and 24th week of storage, further softening in air-stored fruit was suppressed in all CA treatments, and the 2-week delay CA fruit always were significantly softer than those placed in CA within one day of harvest. The one-week delay treatment resulted in an intermediate flesh firmness. The rates of fruit softening at 0°-air after 12, 16, or 24 weeks of CA storage were comparable to those of fruit stored continuously in 0° air.

Fruit quality and respiration of ‘McIntosh’ apples in response to ethylene, very low oxygen and carbon dioxide storage atmospheres

Storage of ‘McIntosh’ Apples ( Malus domestica Borkh.) in a controlled atmosphere (CA) with very low O 2 (1.5% CO 2 + 1.0% O 2, 2.8°C) retained greater fruit firmness and titratable acids during storage and during subsequent air storage than apples stored in conventional CA (5.0% CO 2 + 3.0% O 2, 2.8°C). The rate of firmness loss during subsequent 0°C air storage decreased with length of storage in CA. Storage of apples in very low O 2 for 40 or 80 days decreased the rate of firmness loss in subsequent 0°C air storage as compared to the rate of firmness loss in conventional CA fruit, but the rate of firmness loss in 0°C air storage subsequent to 160 or 320 days of conventional CA was significantly less than the loss in similar fruit stored in very low O 2 atmospheres. A modified atmosphere with 1.0% O 2 decreased the rate of C 2H 4 accumulation in storage, and fruit production of both C 2H 4 and CO 2 after storage opening in comparison with similar fruit in conventional CA. The accumulation of C 2H 4 in storage chambers was increased with increasing O 2 levels, but the rate of increase depended upon the CO 2 level. C 2H 4 storage accumulation was stimulated by the presence of CO 2 at 0.5% O 2, but was suppressed by CO 2 when 3.0% O 2 was maintained. Retention of fruit firmness and titratable acids in apples stored in 1.5% CO 2 + 1.0% O 2 were insensitive to very low (0.231 ml l −1) or very high (2440 ml l −1) C 2H 4 levels in storage. Scrubbing C 2H 4 (0.304 ml l −1) from chambers held at 5.0% CO 2 + 3.0% O 2 resulted in significantly firmer fruit after storage, but this effect was not significant after shelf life of 7 days at 20°C.

The Influence of Controlled Atmosphere Storage and Processing Conditions on the Quality of Applesauce from ‘Golden Delicious’ Apples1

Abstract Type of storage influenced yield and quality of applesauce. The yield of applesauce from controlled atmosphere (CA) storage was significantly less than from cold stored apples. Applesauce color was superior when the sauce was made from CA stored apples. Increased cooking time reduced total sauce yield but had no effect on yield at the pulper-finisher or on the color of the sauce. The addition of acid to the applesauce improved color. Acid addition had a stronger influence on the applesauce color of cold stored apples than of CA fruit. The addition of extra water beyond 30% by weight reduced quality regardless of storage type, cook time or addition of acid.

Influence of Controlled-Atmosphere Storage on Respiration of McIntosh Apples

1. McIntosh apples respired approximately one-third as fast in controlled-atmosphere storage at 40⚬ F. as in ordinary cold storage at 32⚬ F. The residual effect of controlled-atmosphere storage on apples after their removal to high temperatures can be partially explained by a reduction in respiration rate following the storage treatment. The residual effect cannot be accounted for by persistence of a high carbon dioxide level in the tissues of the fruit. 2. McIntosh held in cold storage at 32⚬ F. evolved two and one-half to three times as much carbon dioxide during the same time period in storage as controlled-atmosphere fruit. The value and limitations of cumulative respiration curves for this type of study are indicated.