High CO2 Atmospheres Research Articles

Cultivar Variation in Responses of Strawberry Fruit to High Carbon Dioxide Treatments

The tolerances of strawberry fruit to postharvest CO2 treatments is an important factor in assessing their potential for extended storage and marketing, but little information on variation among cultivars is available. We have assessed differences in responses of seven strawberry cultivars (`Annapolis', `Earliglow', `Kent', `Honeoye', `Cavendish', `Jewel', and `Governor Simcoe') to high-CO2 atmospheres. Fruit were harvested at the orange or white tip stage of ripeness, kept in air, or 20% CO2 (in air), and sampled after 1, 2, or 7 days for analysis of firmness, color, and volatile concentrations. Berries from each cultivar were collected on three separate harvest dates. Flesh firmness measurements of all cultivars tested were higher when treated with high CO2, but the degree of firming was affected by cultivar and assessment time. For example, firmness of `Annapolis', `Earliglow', `Honeoye', and `Jewel' was consistently enhanced by CO2, compared with air, during storage. In contrast, firmness of `Kent' was not affected by treatment after 1 day of storage and benefits were relatively slight at each subsequent removal. Red color development of the fruits was affected by cultivar and treatment period, but not by CO2 treatment. Volatile accumulation varied greatly among cultivars. `Annapolis' for example, appears very tolerant of high-CO2 treatment levels as indicated by low accumulations of ethanol, acetaldehyde, and ethyl acetate in the fruit. In contrast, `Kent' and `Governor Simcoe' accumulated large amounts of these compounds. This study indicates that differences in cultivar responses to CO2 should be considered by growers planning to store fruit under these conditions to extend marketing options. Research supported in part by the North American Strawberry Growers Association.

Ethanolic metabolism in cherimoya fruit during storage at ambient and under high CO2atmospheres

SummaryCherimoya fruits (Annona cherimola, Mill.) were kept in 20% O2 + 20% CO2 for up to 3 d at 20°C and then transferred to air to study the effect of high CO2 levels on fermentation enzymes, ethanol and acethaldehyde content and ripening evolution. Ethanol and acetaldehyde content increased during ripening in air mainly associated with the first respiration peak. At the end of the short-term high CO2 treatment, cherimoya fruit had a lower aerobic respiration rate while concentrations of acethaldehyde and ethanol were greatly increased compared with those of air-control fruit. The activation of fermentation pathway by high CO2 atmosphere is mainly due to an enhancement in pyruvate decarboxylase (PDC) activity. High CO2 treatment prevented the ripening process but, after transfer to air a decrease in fermentation metabolism was recorded and fruit was able to ripen, showing a typical decrease in tissue pH.

Respiration of Fresh-cut Carrots Stored in Low Oxygen or High Carbon Dioxide Atmosphere at Various Temperatures

Respiration of carrot slices, sticks, and shreds was monitored during storage in air, low O2 (0.5%, 1%, and 2%) or high CO2 (3%, 6%, and 10%) atmospheres at 0, 5, and 10°C. The respiration pattern differed with temperature and type of cuts. At 10°C, the rates of all cuts decreased with time. At the lower temperatures, the rate of sticks and shreds increased with the increase being greater at 5°C. Carbon dioxide production and O2 consumption of all cuts were lower when stored in either reduced O2 or elevated CO2 relative to those in air. Reduction was the greatest with cuts held in 0.5% O2 or 10% CO2 at 0°C. Low O2 was more effective than high CO2 atmosphere in reducing the rate at 10°C, but not at other temperatures. Respiratory quotient (RQ) of shreds were higher when held in low O2 and lower when held in high CO2 relative to those in air. RQ of other cuts were affected, but not consistently. The Q10 of all cuts ranged from 1.9 to 7.4 in the 0 to 10°C range and was lower with cuts in low O2 and greater with cuts in high CO2.

カットニンジンのエチレン処理による苦味発現の誘導ならびに環境ガス組成変更による制御

カットニンジンのエチレン処理による苦味発現の誘導ならびに環境ガス組成変更による制御

Optimum O2 or CO2 Atmosphere for Storing Broccoli Florets at Various Temperatures

`Marathon' broccoli (Brassica oleracea L. var. italica) florets were stored in air, low O2(0.25%, 0.5%, and 1 %) or high CO2(3%,6%, and 10%) at 0, 5, and 10C. Oxygen consumption and CO2 production were reduced under low O2 or high CO2atmosphere, the reduction being greater at lower O2 and higher CO2 levels. No differences were found in ethylene production among the different atmospheres. Low O2 and high CO2 retained color of broccoli florets to about the same extent at 10C but had no effect at 0 and 5C. Development of soft rot and browning was suppressed by low O2 or high CO2, but offensive off-odor occurred in 0.25%02 at all temperatures and 0.5% O2 at 10C. These results indicate that the best O2 and CO2 levels seem to be 0.5% O2 and 10% CO2 at 0 and 5C, and 1% O2 and 10% CO2 at 10C.

Interactive Effects of Atmospheric CO2 Enrichment and Soil N on Growth and Ectomycorrhizal Colonization of Ponderosa Pine Seedlings

Abstract Interactive effects of elevated atmospheric CO2 and soil N fertility on above- and below-ground development of juvenile ponderosa pine (Pinus ponderosa Dougl. ex Laws.) were examined. Seedlings were grown from seed in atmospheres containing 700 μl l-1, 525 μl l-1, or ambient CO2. Medium and high soil N treatments were created by adding sufficient (NH4)2SO4 to the potting mix to increase total N by 100 μg g-1 and 200 μg g-1, respectively, while unamended mix, which had a total N concentration of approximately 300, μg g-1, served as the low N treatment. Three whole-seedling harvests at 4-month intervals permitted assessment of shoot and root growth and ectomycorrhizal formation resulting from inoculation with Pisolithus tinctorius (Pers.) Coker and Couch. After 4 months, CO2 enrichment increased shoot volume and dry weight of seedlings grown in high soil N, but this result was not evident in the other N treatments and did not persist to the second harvest. Root weight, however, increased, and shoot/root ratio decreased as the CO2 concentration increased within all three N treatments at the first harvest. At the second harvest, root weights within the high and intermediate N treatments were lowest in seedlings grown in ambient CO2 and shoot/root ratios decreased as CO2 increased in these two N treatments as well. Although the ectomycorrhizal infection percentage of seedlings grown in 700 μl l-1 CO2 was highest among the seedlings grown in high N after 4 months, mycorrhizal colonization was variable overall at the first and second harvests. After 1 yr, the 525 μl l-1 CO2 concentration stimulated above- and belowground growth more than the high CO2 atmosphere in both high and medium soil N. These seedlings also had relatively extensive ectomycorrhizal formation, but colonization was again variable. Results presented here suggest the response of juvenile ponderosa pine to CO2 enrichment is ephemeral, with the effects on roots more pronounced and persistent overall than those on shoots, and that the response is dependent on N availability. For Sci. 41(3):491-500.

Controlled-atmosphere Storage of Shredded Carrots

Quality and physiology of carrot shreds were monitored during storage in air, low O2 (0.5%, 1%, and 2%), or high CO2 (3%, 6%, and 10%) at 0, 5, and 10C to evaluate the response to controlled-atmosphere (CA) storage. Oxygen uptake and CO2 production from respiration were reduced under low-O2 or high-CO2 atmosphere, the reduction being greater at lower O2 and higher CO2 levels. The respiratory quotient was about 1 with samples in air, more than 1 in low-O2, and less than 1 in high-CO2 atmosphere during storage at all temperatures. No differences were found in ethylene production, which were less than 0.2 μl·kg–1·h–1 with all samples. The CA containing 0.5% O2 and 10% CO2 reduced weight loss and formation of white-colored tissue and decreased pH, but did not affect microbial count and texture at all temperatures. Off-odor and black root rot were not detected in both CA and air atmospheres.

920 PB 461 CONTROLLED ATMOSPHERE AFFECT STORAGE QUALITY OF ZUCCHINI SQUASH SLICES

Physiology and quality of CaCl2 treated or nontreated `Elite' zucchini squash slices were monitored during storage in air, low O2 (0.25, 0.5 and 1%) or high CO2 (3, 6, and 10%) atmosphere at 10C. O2 consumption and CO2 production were reduced under low O2 and high CO2 atmospheres and the reduction was greater with low O2. C2H4 production was reduced with low O2 and initially with high CO2. After day 2 or 4, C2H4 production under high CO2 increased with the increase being greater at the lower CO2 level. The amount and severity of injury/decay were less under low O2 and high CO2 than air atmosphere. Slices stored under 0.25% O2 atmosphere had less weight loss and injury/decay and greater shear force and ascorbic acid content than those held in air atmosphere. Microbial count, pH, and color were affected by the low O2 only on the last day. CaCl2 had no additive effect.

CONTROLLED ATMOSPHERIC ENVIRONMENTS AND THEIR EFFECTS ON APHIDS AND WESTERN FLOWER THRIPS ON FLORAL PRODUCTS

Shipments of floral products to Pacific rim markets must meet stringent pest-free requirements. Conventional fumigation methods with methyl bromide will soon become unavailable. Studies show that controlled atmosphere (CA) environments can offer effective insect control. Currently, CA overseas marine shipping is occuring with fresh fruits and vegetables. These shipments use microprocessors to precisely control O2, CO2, temperature and relative humidity. This study is evaluating similar commercial shipments with fresh flowers and foliage under low temperature and low O2 and high CO2 atmospheres. Preliminary results with shipments conducted by TransFresh to Guam indicate that properly maintained CA shipments of 0.5 % O2 kill insects and that flowers in properly maintained atmospheres can withstand 14 days of marine shipment with minimum effect on post-harvest life. Adequate regulation of CA storage during transit seems to be the primary limitation to the expansion of floral markets using this method of shipment.

135 LOW TEMPERATURES AND CONTROLLED ATMOSPHERES MAINTAIN QUALITY OF FRESH CUT BELL PEPPER

Bell pepper fruits (green and red) were stored intact or prepared in dices (1 × 1 cm), washed with chlorinated water, biot dried, and stored in air or controlled atmospheres (air or 3% O2 with 0, 5 or 10% CO2) at 0, 5 or 10C for up to 20 days. Dicing resulted in respiration rates 2-3 times higher than those of intact peppers, but did not result in measureable increases in ethylene production. Samples were periodically transferred to 15C for 12 h before evaluation for visual quality, decay, discoloration, aroma, flavor, texture, and sugar content. Quality changes were similar for green and red fruit of the same cultivar. Intact peppers are chilling sensitive, but the quality of diced peppers was maintained best at 0C. The shelf-life of diced pepper at 10 and 5C was 1/2 to 2/3 that of intact peppers. Atmospheres containing 5 or 10% CO2 reduced decay and increased the shelf-life of diced peppers, but were not as effective as storage in air at 0C. Storage at 0C also resulted in greater retention of sugars than storage under other conditions. High CO2 atmospheres resulted in softening of pepper tissue and increased electrolyte leakage. Aroma and flavor scores declined more rapidly in CA than in air storage.

Storage of Shredded Cabbage under a Dynamically Controlled Atmosphere of High O2 and High CO2.

Shredded cabbage (Brassica oleracea L., Capitata group) was stored under a dynamically controlled atmosphere (DCA) and modified atmosphere (MA) at 5°C. Quality factors were measured every 2 days. Browning was suppressed as the CO2 concentration was increased (0% to 15%), with no influence from O2 concentration (2.5% to 10%). The development of an off-odor was markedly delayed with an increase in O2 concentration, such an odor being detected after 6 days at 2.5% O2,8 to 10 days at 5% to 7.5% O2, and not at all above 10 days at 10% O2, while the off-odor development was little affected by CO2 concentration (5% to 15%). Total sugar, polyphenolics, total ascorbate, and total microbial count were little influenced by O2 and CO2. These results show that shredded cabbage can be kept in good condition with a combined high O2 and high CO2 atmosphere. These findings are largely different from those for MA storage.

Growth Kinetics, Carbohydrate, and Leaf Phosphate Content of Clover (Trifolium subterraneum L.) after Transfer to a High CO2 Atmosphere or to High Light and Ambient Air

Intact air-grown (photosynthetic photon flux density, 400 microeinsteins per square meter per second) clover plants (Trifolium subterraneum L.) were transfered to high CO(2) (4000 microliters CO(2) per liter; photosynthetic photon flux density, 400 microeinsteins per square meter per second) or to high light (340 microliters CO(2) per liter; photosynthetic photon flux density, 800 microeinsteins per square meter per second) to similarly stimulate photosynthetic net CO(2) uptake. The daily increment of net CO(2) uptake declined transiently in high CO(2), but not in high light, below the values in air/standard light. After about 3 days in high CO(2), the daily increment of net CO(2) uptake increased but did not reach the high light values. Nightly CO(2) release increased immediately in high light, whereas there was a 3-day lag phase in high CO(2). During this time, starch accumulated to a high level, and leaf deterioration was observed only in high CO(2). After 12 days, starch was two- to threefold higher in high CO(2) than in high light, whereas sucrose was similar. Leaf carbohydrates were determined during the first and fourth day in high CO(2). Starch increased rapidly throughout the day. Early in the day, sucrose was low and similar in high CO(2) and ambient air (same light). Later, sucrose increased considerably in high CO(2). The findings that (a) much more photosynthetic carbon was partitioned into the leaf starch pool in high CO(2) than in high light, although net CO(2) uptake was similar, and that (b) rapid starch formation occurred in high CO(2) even when leaf sucrose was only slightly elevated suggest that low sink capacity was not the main constraint in high CO(2). It is proposed that carbon partitioning between starch (chloroplast) and sucrose (cytosol) was perturbed by high CO(2) because of the lack of photorespiration. Total phosphate pools were determined in leaves. Concentrations based on fresh weight of orthophosphate, soluble esterified phosphate, and total phosphate markedly declined during 13 days of exposure of the plants to high CO(2) but changed little in high light/ambient air. During this time, the ratio of orthophosphate to soluble esterified phosphate decreased considerably in high CO(2) and increased slightly in high light/ambient air. It appears that phosphate uptake and growth were similarly stimulated by high light, whereas the coordination was weak in high CO(2).

Effect of modification of storage atmosphere on phospholipids and ultrastructure of cauliflower mitochondria

Differences in mitochondrial membrane composition and ultrastructure were studied after storage of cauliflower (Brassica oleracea, L., Botrytis group) for 5 days at 25°C in air or under controlled atmospheres: 3% O2, 21% O2+ 15% CO2 or 3% O2+ 15% CO2. In air, postharvest senescence involved a 20% decrease in mitochondrial phospholipid content. A large reduction in the relative abundance of phosphati-dylcholine (PC) and in the degree of unsaturation of PC and phosphatidyl ethanolamine (PE) was observed. However, the degree of unsaturation increased in cardiolipin (CL). Storage under 3% O2 did not prevent phospholipid breakdown. Low O2 prevented the relative decrease in PC observed during storage in air and the loss of linoleic acid from PC, but not from PE. This relative protection offered by the low O2 atmosphere was lost under 3% O2+ 15% CO2. The high CO2 atmospheres caused twice as much loss in phospholipids as that observed during storage in air. Extensive loss of mitochondrial protein, a marked decrease in phospholipid to protein ratio, and electron micrograph observations suggest structural alterations in the presence of high CO2.

RESPONSES OF “KEITT” MANGO TO SHORT TERM INSECTICIDAL O2 AND CO2 ATMOSPHERES

The tolerance of “Keitt” mango to a modified atmosphere (MA) of < 0.5% O2 + 70-80% CO2 for 0 to 4 days and a controlled atmosphere (CA) of 2% O2 + 50% CO2 for 0 to 5 days was evaluated. MA and CA delayed the respiratory climacteric of the fruit. There was no significant fruit injury due to the low O2 or high CO2 atmosphere, Sensory evaluation tests did not indicate the presence of any off-flavors. Both CA and MA increased the activity of the enzyme ATP: Phosphofructokinase, did not effect the activity of pyruvate kinase, and MA reduced the activity of PPi: phosphofructokinase. MA reduced the levels of frutose 6-phosphate, while phosphoenolpyruvate and pyruvic acid were not effected by both atmosphere treatments Although insecticidal O2 and CO2 atmosphere resulted in changes in the glycolitic activity, there was no indication of any injury and fruits were ripened normally, This work indicates the potential of the application of M/CA for postharvest insect control in mango.

RESPONSES OF “KEITT” MANGO TO SHORT TERM INSECTICIDAL O2 AND CO2 ATMOSPHERES

The tolerance of “Keitt” mango to a modified atmosphere (MA) of < 0.5% O2 + 70-80% CO2 for 0 to 4 days and a controlled atmosphere (CA) of 2% O2 + 50% CO2 for 0 to 5 days was evaluated. MA and CA delayed the respiratory climacteric of the fruit. There was no significant fruit injury due to the low O2 or high CO2 atmosphere, Sensory evaluation tests did not indicate the presence of any off-flavors. Both CA and MA increased the activity of the enzyme ATP: Phosphofructokinase, did not effect the activity of pyruvate kinase, and MA reduced the activity of PPi: phosphofructokinase. MA reduced the levels of frutose 6-phosphate, while phosphoenolpyruvate and pyruvic acid were not effected by both atmosphere treatments Although insecticidal O2 and CO2 atmosphere resulted in changes in the glycolitic activity, there was no indication of any injury and fruits were ripened normally, This work indicates the potential of the application of M/CA for postharvest insect control in mango.

CA STORAGE INHIBITS CHILL INJURY OF MUSCADINE GRAPE

`Fry' and `Granny Val' muscadine grapes (Vitis rotundifilia) were stored at 1C for two, four, and six weeks in himidified flow-through atmospheres of air, 0% CO2 - 5% O2, 5% CO2 - 5% O2, 10% CO2 - 5% O2, and 15% CO2 - 5% O2. Weight loss, grade, pH, acidity, soluble solids, sugars and sensory evaluations were made upon removal from 1C storage. Chill injury ratings were made after 0, 24, and 48 hours at 27C. `Fry' muscadine grapes had a better storage life than did `Granny Val'. High CO2 atmospheres extended the storage life of both cultivars. Severe chill injury symptoms resulted after 4 or 6 weeks of 1C storage in air. High CO2 atmospheres inhibited chill injury of both `Fry' and `Granny Val' grapes. No chill injury to either cultivar occurred after six weeks of storage in the 15% CO2 - 5% O2 atmosphere.

The effects of enriched CO2 atmospheres on plant-insect herbivore interactions: growth responses of larvae of the specialist butterfly, Junonia coenia (Lepidoptera: Nymphalidae).

Little is known about the effects of enriched CO2 environments, which are anticipated to exist in the next century, on natural plant-insect herbivore interactions. To begin to understand such effects on insect growth and survival, I reared both early and penultimate instar larvae of the buckeye, Junonia coenia (Lepidoptera: Nymphalidae), on leaves from one of their major hostplants, plantain, Plantago lanceolata (Plantaginaceae), grown in either ambient (350 PPM) or high (700 PPM) CO2 atmospheres. Despite consuming more foliage, early instar larvae experienced reduced growth on high CO2-grown compared to ambient CO2-grown leaves. However, survivorship of early instar larvae was unaffected by the CO2 treatment. Larval weight gain was positively correlated with the nitrogen concentration of the plant material and consumption was negatively correlated with foliar nitrogen concentration, whereas neither larval weight gain nor consumption were significantly correlated with foliar water or allelochemical concentrations. In contrast, penultimate instar larvae had similar growth rates on ambient and high CO2-grown leaves. Significantly higher consumption rates on high CO2-grown plants enabled penultimate instar larvae to obtain similar amounts of nitrogen in both treatments. These larvae grew at similar rates on foliage from the two CO2 treatments, despite a reduced efficiency of conversion of ingested food (ECI) on the low nitrogen, high CO2-grown plants. However, nitrogen utilization efficiencies (NUE) were unaffected by CO2 treatment. Again, for late instar larvae, consumption rates were negatively correlated with foliar nitrogen concentrations, and ECI was also very highly correlated with leaf nitrogen; foliar water or allelochemical concentrations did not affect either of these parameters. Differences in growth responses of early and late instar larvae to lower nitrogen, high-CO2 grown foliage may be due to the inability of early instar larvae to efficiently process the increased flow of food through the gut caused by additional consumption of high CO2 foliage.

Carbon Dioxide-induced Brown Stain Development as Related to Phenolic Metabolism in Iceberg Lettuce

Abstract Controlled atmospheres containing air + 11% CO2 caused tissue injury and induced phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) activity in iceberg lettuce (Lactuca sativa L.) midrib tissue. Injury symptoms included brown stain (browning of epidermal tissue) and sunken epidermal areas (pitting) a few millimeters in diameter. Pitting occurred in high-CO2 atmospheres at 5C with no increase in phenolic content, but browning did not develop until the tissue had been transferred to air at 25C. Browning developed within several hours of transfer to air and the degree of browning was correlated with the soluble phenolic content. The oxidation of soluble phenolic compounds to brown substances by polyphenol oxidase (PPO, EC 1.10.3.2) could account for tissue browning. Lignification was associated with cell wall thickening in discolored tissue and was accompanied by an increase in ionically bound and soluble peroxidase (POD, EC 1.11.1.7) activities. Exposure of tissue to elevated CO2 increased ionically bound indoleacetic acid (IAA) oxidase activity, but reduced soluble IAA oxidase activity. Application of an aqueous solution of 1.0 mm IAA to the tissue before treatment did not significantly reduce browning. Lettuce tissue exposed to 1.5% O2 + 11% CO2 had reduced PAL activity and lower soluble phenolic content than lettuce exposed to air + 11% CO2. Depending on the sensitivity of the lettuce tissue to CO2 injury, low-O2 atmospheres either reduced or slightly retarded browning induced by 11% CO2.

Rabbiteye Blueberry Storage Life and Fruit Quality in Controlled Atmospheres and Air Storage

Abstract Fruits of rabbiteye blueberries (Vaccinium ashei Read cvs. Climax and Woodard) harvested by hand in 1984 and machine in 1985 were stored in air, 100% N2, and in 10%, 15%, or 20% CO2 with 5% O2. Storage of either blueberry cultivars in high-CO2 atmospheres resulted in greater percentages of marketable and firm fruit, and better sensory ratings, than did storage in air. Fruit of ‘Climax’ lost less weight, were firmer, and developed less decay after 21 or 42 days of storage than ‘Woodard’ fruit. Fruit quality characteristics of hand-harvested ‘Climax’ stored for 42 days and machine-harvested ‘Climax’ stored for 21 days in 20% CO2 with 5% O2 were similar to those of freshly harvested fruit.

Effect of High CO2 Atmospheres on Stored Zucchini Squash

Abstract Zucchini squash (Cucurbita pepo L. cv. Romanesco) were stored 19 days at 5°C in 21% ± 1% O2 plus 0.0%, 2.5%, 5.0%, or 10.0% CO2 and then stored an additional 4 days at 13° in air. High CO2 levels inhibited the rate of CO2 production and reduced the development of chilling injury symptoms at all three maturities (16, 20, and 22 cm fruit). There was a high negative correlation between CO2 levels and reduction of chilling injury. At the end of the 23-day storage period, 82% of the 22-cm squash held in 10% CO2 appeared salable, but they had a slight off-flavor and were soft; 79% of the fruit held in 5% CO2 were salable, firm, and free of off-flavors; samples from 2.5% CO2 and air were unacceptable because of decay and pitting. The percentage of unsalable fruit increased from 16- to 20-cm squash. Carbon dioxide concentrations around 5% may be useful for storing zucchini squash at about 5°, a temperature that normally causes chilling injury in zucchini.