Controlled Atmosphere Treatments Research Articles

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

1-Methylcyclopropene (1-MCP) is an inhibitor of ethylene reception used in post-harvest treatments to delay fruit ripening. Several factors affect the efficacy of 1-MCP treatments. The effect of a post-harvest treatment with 1-MCP on the quality of Pink Lady® apples as a function of 1-MCP dose, storage time and maturity at harvest was investigated. 1-MCP treatment was further tested in combination with controlled atmosphere (CA) storage. 1-MCP limited fruit respiration and softening during storage and was more effective on partially matured fruits and at prolonged storage times. The delaying of 1-MCP on the increase of ripening index was greater on matured fruits at prolonged storage times. The combination of 1-MCP and CA treatments positively affected quality indices of mature apples during 6 months of storage and 7 days of commercial life, with 1-MCP being more effective than CA. 1-MCP and CA showed positive combined effects on firmness and ripening index after 6 months of storage, and on firmness and CO₂ production after a further 7 days of commercial life. By knowing fruit maturity at harvest and expected storage time it is possible to choose the most suitable 1-MCP dose to meet the market requirements by applying a simple polynomial model.

Physicochemical Parameters and Antioxidant Compounds in Edible Squash (Cucurbita Pepo) Flower Stored under Controlled Atmospheres

AbstractEdible squash (Cucurbita pepo) flower is highly in demand in Mexico and internationally, but its high perishability limits marketing. An evaluation of the effect of storage under controlled atmosphere (CA) on physicochemical parameters and antioxidant compounds contents in squash flower was carried out. Male flowers were stored at 5C under a continuous flow of gas with one of four compositions: 5% O2 + N2 (CA1); 5% O2 + 10% CO2 + N2 (CA2); 10% CO2 + air (CA3); and air as a control. Compared with the control, the CA treatments had greater retention of total sugars, total soluble solids, pH, titratable acidity and lower physiological weight loss. At 16 days, CA2 retained the highest amount of ascorbic acid (49.5%), polyphenols (65.2%) and carotenoids (72.8%). Application of CA2 or CA3 could prolong postharvest life in squash flowers up to 16 days.Practical ApplicationsSquash plants are monoecious, bearing male and female flowers on the same plant. Female flowers produce the fruit, while male flowers are edible and used widely in a number of dishes, but their short shelf life limits marketability. The results demonstrate that storage of squash flowers in atmospheres with high (10%) CO2 concentration prolongs shelf life up to 16 days.

Effect of Controlled Atmosphere Storage Combined 1-Methylcyclopropene on Snap Bean for Alleviating Chilling Injury

Snap bean (Phaseolus vulgarisL.) is sensitive vegetable which can develop chilling injury when stored at low temperatures. This study was conducted to investigate the effect of controlled atmosphere (CA) (2.5±0.5 %O2, 5±0.5 %CO2) and 1-methylcyclopropene (1-MCP) (0.5 μL/L) on chilling injury (CI) of snap bean during 35 days storage at 0 °C. The results showed that CA and 1-MCP reduced chilling injury symptoms, however, the CA combined 1-MCP treatment which delayed the respiration peak appeared and the chilling injury index achieved 1.9. The treatment decreased electrolyte leakage, malondialdehyde content and activities of PPO, which were significantly lower than CA and 1-MCP singly. These results suggested that combination of CA and 1-MCP treatment is promising treatment for alleviating chilling injury of snap bean stored at 0 °C which extending the shelf-life.

Effect of controlled atmospheres with varying O2/CO2 levels on the postharvest senescence and quality of broccoli (Brassica oleracea L. var. italica) florets

Controlled atmosphere (CA) has been widely used to help extend the shelf life and maintain the quality of horticultural products. In the present study, broccoli (Brassica oleracea L. cv. Youxiu) florets were stored under CA with high levels of O2/CO2 at 15 °C, including 100 % O2, 80 % O2 + 20 % CO2, 60 % O2 + 40 % CO2, 40 % O2 + 60 % CO2, and air (control), to determine the effects of CA on storage period and on some physiological properties during storage. The results showed that compared with the control, the treatments combining O2 and CO2 effectively extended the storage period and inhibited respiration rate, ethylene production, and reductions in weight loss, chlorophyll, and ascorbic acid levels. Moreover, the CA treatments inhibited the increases in both superoxide radicals (O2−·) production rate and hydrogen peroxide (H2O2) level and reduced malondialdehyde accumulation, which could be beneficial in delay of senescence by alleviation of oxidative damage. In addition, broccoli florets exposed to CA conditions maintained lower activities of superoxide dismutase and peroxidase that are responsible for scavenging of O2−· and H2O2 and alleviating lipid peroxidation. Among the treatments, the maximum efficacy was observed with a CA of 40 % O2 + 60 % CO2, which prolonged the storage period of broccoli heads to 17 days (d) compared with 4 d under air treatment. Conversely, 100 % O2 treatment accelerated senescence and deterioration in the quality of broccoli, resulting in a shorter storage period. These results suggest that the establishment of an appropriate CA condition with high levels of O2/CO2 may be an ideal strategy for maintaining the quality of broccoli florets during storage.

Controlled atmosphere treatment for control of grape mealybug, Pseudococcus maritimus (Ehrhorn) (Hemiptera: Pseudococcidae), on harvested table grapes

Controlled atmosphere (CA) treatments with ultralow oxygen (ULO) alone and in combinations with 50% carbon dioxide were studied to control grape mealybug, Pseudococcus maritimus (Ehrhorn) on harvested table grapes. Two ultralow oxygen levels, 30 and <0.01μLL−1, were tested in both ULO and ULO+50% CO2 treatments. The ULO treatments with the lower oxygen level were more effective than the ULO treatments at the higher oxygen level. The ULO+50% CO2 treatments were more effective than the ULO treatments. Grape mealybug eggs were significantly more tolerant of ULO and ULO+CO2 treatments than nymphs and adults. A 14day ULO treatment with 30μLL−1 O2 at 2°C did not achieve 100% mortalities of any life stage. In the presence of 50% CO2, the 14d treatment achieved complete mortality of all life stages of the grape mealybug. A 3d ULO treatment with <0.01μLL−1 O2 at 2°C resulted in 93.3% mortality of nymphs and adults. The 3d ULO treatment in combination with 50% CO2 treatments, however, achieved complete control of grape mealybug nymphs and adults and caused 70.5% relative egg mortality. Complete egg mortality was achieved in a 10d ULO+50% CO2 treatment with <0.01μLL−1 O2 at 2°C. Both the 14d CA treatment with 30μLL−1 O2 and 50% CO2 and the 10d CA treatment with <0.01μLL−1 O2 and 50% CO2 were tested on table grapes and grape quality was evaluated after two weeks of post-treatment storage. The CA treatments did not have a significant negative impact on grape quality and were safe for table grapes. The study indicated that CA treatments have potential to be developed for postharvest control of grape mealybug on harvested table grapes.

Fruit maturity, controlled atmosphere delays and storage temperature affect fruit quality and incidence of storage disorders of ‘Fuji’ apples

The effects of storage temperature, harvest maturity, controlled atmosphere (CA) storage regime, and CA strategies on fruit quality and the incidence of storage disorders during storage of ‘Fuji’ apples [Malus sylvestris (L.) Mill var. domestica (Borkh.) Mansf.] were investigated. Flesh browning incidence was lower in fruit stored at 2°C than at 0°C, but fruit were also softer and had lower titratable acidity (TA) at the higher storage temperature. All subsequent studies were carried out at 0°C. High partial pressures of CO2 (pCO2) of 2.5kPa compared with <1kPa did not consistently affect flesh firmness, soluble solids concentration (SSC), and TA. The incidence of flesh browning was higher in more mature fruit and it was further aggravated by higher pCO2 in the storage atmosphere, irrespective of pO2, while watercore disappearance was more rapid at <1kPa CO2 than at 2.5kPa CO2. Flesh browning was also higher at 1.5kPa CO2 than at <1kPa CO2, although ethylene production was lowest at 1.5kPa pCO2. Stepwise delay of high CO2 or low O2 CA storage did not affect flesh firmness, TA, internal ethylene concentration, respiration rate, and ethylene production, but watercore disappearance was more rapid, compared with standard CA storage at 2 months. Flesh browning was not detected in the stepwise CO2 delayed CA treatment and low CO2 CA storage (<0.2kPa CO2), but a low (<4%) incidence of flesh browning was found in a delayed CA treatment and standard CA storage. These results indicate that ‘Fuji’ apples could be stored at 0°C in 1–2kPa O2/<1kPa CO2 if harvested at less than 190 days after full bloom. Stepwise CO2 delay CA or low CO2 CA storage regimes are recommended to retard the loss of fruit quality factors and reduce development of CA-related storage disorders.

Potential of Initial CA Condition on Quality Maintenance of 'Fuji' Apples during Export Simulation after Long-term Storage

Effects of initial controlled atmosphere (CA) treatment on quality maintenance of ‘Fuji’ apples were assessed and compared with 1-methylcyclopropene (1-MCP) treatment and continuous CA storage. Apples were harvested twice at different maturity, treated with 1 μLㆍL -1 1-MCP and then stored for 8 months at 0℃ under 3 conditions: air, CA for the first month followed by air (initial CA), and continuous CA (full CA). CA storage was performed with 1.5 ㎪ O₂ and ＜1.0 ㎪ (N₂ balance). Following long-term storage, export simulation, refrigerated shipment and local distribution, were performed by holding apples at 0℃ for 2 weeks and on the shelf at 20℃ for 7 days. Both the application of 1-MCP and CA storage reduced ethylene production and respiration rates. Initial CA storage was also effective on reducing the metabolism although the effects were not as noticeable as full CA. Full CA storage with or without 1-MCP treatment maintained titratable acidity, flesh firmness, and sensory quality at the acceptable to excellent level even after the export simulation following 8-month storage regardless of harvest maturity. In contrast, effects of initial CA storage were limited to the maintenance of firmness and texture in early-harvested apples. Overall results indicated that harvest maturity is the critical factor for export fruit quality after long-term storage when separate treatment of initial CA storage or 1-MCP treatment is applied as a postharvest program.

Influence of preharvest calcium applications, fruit injury, and storage atmospheres on postharvest brown rot of apple

In a three year study, the effect of preharvest calcium applications on postharvest losses of apple fruit (cultivar ‘Idared’) caused by Monilinia fructigena was evaluated in fruit under air storage, controlled atmosphere (CA), and ultra low oxygen (ULO) conditions. Injured and noninjured fruit were used and storage was at 1°C for all three storage conditions. In addition, temporal dynamics of postharvest brown rot development were assessed monthly over four months storage and the spread of brown rot infection amongst fruit was assessed at the final assessment date. For all years, disease development, final brown rot incidence and the area under curves of disease progress were lower amongst calcium-treated than in the nontreated controls (mean values of 3.6 and 11.1%, respectively). CA and ULO treatments reduced rot incidence (mean values of 12.4, 6.3, and 0.7%, for air, CA and ULO fruit respectively). In addition, with regard to injury–inoculation combinations, final brown rot incidence increased in the order noninjured–noninoculated, noninjured–inoculated, injured–noninoculated and injured–inoculated treatments (mean values of 3.6, 5.0, 7.3, and 11.4%, respectively). The number of infected fruit was generally higher in the first layer of neighbouring fruit in storage boxes than in the second one. Calcium treatment significantly reduced the number of infected fruit both in the first and second layers compared to the controls (mean values of 45.5 and 75, respectively). CA and ULO treatments also reduced the number of infected fruit both in the first and second layers of neighbouring fruit (mean values of 94, 69.5, and 10.5, for air, CA and ULO respectively). With regard to injury treatments, the number of infected fruit increased in both the first and second layers of neighbouring fruit in the order of noninjured–inoculated and injured–inoculated treatments (mean values of 51.5 and 75.5, respectively). This study suggests that integration of preharvest calcium applications and CA storage, along with minimization of fruit injury/infection, may reduce brown rot incidence during long term storage.

Interactions between controlled atmospheres and low temperature tolerance: a review of biochemical mechanisms

Controlled atmosphere treatments using carbon dioxide, oxygen, and/or nitrogen, together with controlled temperature and humidity, form an important method for post-harvest sterilization against insect-infested fruit. However, in insects, the cross tolerance and biochemical interactions between the various stresses of modified gas conditions and low temperature may either elicit or block standard stress responses which can potentiate (or limit) lethal low temperature exposure. Thus, the success of such treatments is sometimes erratic and does not always result in the desired pest mortality. This review focuses on the biochemical modes of action whereby controlled atmospheres affect insects low temperature tolerance, making them more (or occasionally, less) susceptible to cold sterilization. Insights into the integrated biochemical modes of action may be used together with the pests’ low temperature tolerance physiology to determine which treatments may be of value in post-harvest sterilization.

CONTROLLED ATMOSPHERE EFFECTS ON SUGAR CONTENT AND RESPIRATORY ACTIVITY OF GREEN CELERY

Green celery stalks could be stored at 0 to 4°C and about 95% RH in air for between 2 to 6 weeks. In those conditions undesirable quality changes reducing shelf life occur, and controlled atmosphere (CA) has been shown as useful for lowering those processes. Celery is an important source of mannitol, an uncommon sugar for vegetables and useful for pharmaceutical industries. Moreover, celery sugars, especially mannitol, may be used as a reduced-calorie sweetener. As far as we know there are no reports about the effect of CA on the main sugars present in celery. Horticulturally mature 'Trinova' celery stalks, free from defects and of uniform size were washed with chlorinated water, drained and stored in hermetic glass jars at 4°C during 35 days. Continuous humidified flows through air (as control), 5 kPa O 2 + 5 kPa CO 2 (CA5), 5 kPa O 2 + 15 kPa CO 2 (CA15) or 5 kPa O 2 + 25 kPa CO 2 (CA25) were applied. Throughout cold storage the respiration rate was monitored by using a closed system. At the beginning of the experiment and at the end of cold storage sugar content was measured by liquid chromatography with a refractive index detector. The respiration rate was high at the beginning of storage, decreasing rapidly and being stable until the end. Compared to air, CA storage reduced respiratory activity. The reduction was mainly related to O 2 level, and with almost no impact of varying CO 2 , with no differences among CA treatments. Mannose was the predominant sugar followed by fructose and glucose. After storage, total sugar content decreased for air but not for CA5 and CA15, probably related to lower respiration rate which would retard loss of sugar. Fructose decreased for CA25 and non significant changes were detected for remaining sugars in any CA treatment. After 5 weeks of cold storage, a CO 2 level of 25 kPa was detrimental to sugar maintenance, and CA5 and CA15 provided the best results.

Ultralow Oxygen Treatment for Control of &lt;I&gt;Planococcus ficus&lt;/I&gt; (Hemiptera: Pseudococcidae) on Grape Benchgrafts

Controlled atmosphere treatments with ultralow oxygen (ULO treatments) were developed successfully for control of vine mealybug, Planococcusflcus Signoret (Hemiptera: Pseudococcidae), on dormant grape (Vitis spp.) benchgrafts. At 30 ppm oxygen, 3-d ULO treatment at 25 degrees C and 4-d ULO treatment at 150C achieved complete control of all life stages of P. ficus. At a much lower oxygen level (<1 ppm), the two ULO treatments with the same exposure periods of 3 d at 25 degrees C and 4 d at 15 degrees C were tested on six table and wine grape cultivars grafted on rootstocks along with P. ficus. The benchgrafts were then potted in a greenhouse, together with untreated controls, to determine treatment effects on rootstock viability. Both ULO treatments achieved complete control of P. ficus and did not have any negative effects on vine growth, compared with the control. Results indicate that ULO treatments can be used to control P. ficus on dormant grape benchgrafts. The advantages of the ULO treatments are also discussed with respect to hot water treatments.

EFFECTS OF OXYGEN CONCENTRATIONS IN CONTROLLED ATMOSPHERE STORAGE ON PHYSIOLOGICAL CHANGES IN CUCUMBER FRUIT (CUCUMIS SATIVUS)

The effects of controlled atmosphere (CA) at 5%, 21 % (air, control), and 100% O 2 on chilling injury, respiratory and hydrogen peroxide formation at 5°C in cucumber fruit were determined. The appearance of chilling injury symptoms in cucumber was delayed in both CA treatments; 100% O 2 effectively reduced pitting as did the 5% O 2 treatment. Respiration and ethylene production rates were suppressed in cucumber fruit stored at 5°C to a greater extent in 100% O 2 than in 5% O 2 and air. The increase of membrane permeability and weight loss from cucumber was not significantly different among treatments. Hydrogen peroxide concentration in flesh tissue of cucumber fruit stored in 5% and 100% O 2 temporarily increased on day 1 and thereafter declined to concentrations less than in control fruit for the remainder of the storage period. These results revealed that both CA conditions might suppress oxidative processes in cucumber fruit during cold storage.

SHORT-TERM EXPOSURES TO REDUCED O2 AND ELEVATED CO2 ATMOSPHERES DIFFERENTLY AFFECT THE RESPIRATORY CHARACTERISTICS OF GRAPEFRUIT AND MANDARIN

Respiratory responses of citrus fruit to controlled atmospheres (CA) are of great importance, since CA treatments can be used in postharvest handling only as long as they do not cause any detrimental effects on fruit quality. In this study, we evaluated the physiological responses of 'Star Ruby' grapefruit (Citrus paradisi Macf., 'Star Ruby') and 'Murcott' mandarin (Citrus reticulata Blanco, 'Murcott') to different concentrations of O 2 (5, 10, 15, and 21%) or CO 2 (0, 5, 10, and 20%) at 20°C for a short-term period (1 week). Exposure to reduced O 2 atmospheres greatly reduced respiration rates and internal CO 2 levels, but 5% O 2 dramatically increased juice ethanol, and to a lesser extent, acetaldehyde (AA) levels. Exposure to 5% and 10% O 2 reduced ethylene evolution rates in grapefruit but increased their levels in mandarin. Exposure to 10% and 20% CO 2 markedly increased respiration rates and internal CO 2 levels, but reduced ethylene production. Exposure to 20% CO 2 substantially increased juice ethanol and AA levels as compared with air controls, but to a less extent as compared with exposure to 5% O 2 atmosphere. Mandarin exhibited stronger and more rapid responses to reduced O 2 than grapefruit, as revealed by the accumulation of juice ethanol and AA, two important indicators of anaerobic respiration. Mandarin also showed earlier and higher increases in respiration rates and internal CO 2 levels than grapefruit following exposure to elevated CO 2 . Results indicate that reduced O 2 and elevated CO 2 atmospheres affect citrus fruit' respiratory characteristics differently. The possible mechanisms involved are briefly discussed.

Recent advances in development of ultralow oxygen treatment for postharvest pest control on perishable commodities

Purpose of review: This review summarises and discusses recent research progress in controlled atmosphere (CA) treatment with ultralow oxygen (ULO) for postharvest pest control on perishable commodities. Findings: In the last 10 years few studies have been conducted on ULO treatment for postharvest pest control. However, significant progress has been made and several ULO treatments were developed for postharvest pest control on different types of perishable prod� ucts. Complete control of green peach aphid, sweetpotato whitefly, twopotted spider mite and western flower thrips was achieved with 18 h fumigation using >99% nitrogen without injury to begonia seedlings. Lettuce aphid, western flower thrips and black widow spi� ders were successfully controlled on head lettuce, broccoli and table grapes, respectively, without negative impact on product quality. Vine mealybug was successfully controlled without reducing the vitality of grape benchgrafts. The tolerance of lettuce to ULO treat� ment was increased through postharvest storage to improve the safety of ULO treatment. ULO treatment is promising for controlling selected pests on selected fresh commodities, especially on those that are evaluated for their vitality rather than appearance. Directions for future research: More research efforts should be directed towards identifying suitable pests and fresh commodities for ULO treatment. Emphasis should also be given to pest control on products such as rootstocks, bulbs and tubers, which are evaluated by vitality rather than appearance. Research should also be directed at enhancing the tolerance of commodities to CA treatment in order to make ULO and other CA treatments safer to product quality. Large scale studies and collaboration with industry are also vital for in� dustrial adaptation of ULO treatment.

Effects of short-term controlled atmosphere treatment at elevated temperature on dried fig fruit

Commercial sun-drying has been practiced around the Mediterranean Basin for many centuries. Dried fruit are goods with a long shelf life but many factors including storage pests may limit their marketability. Before the decision to phase it out under the Montreal Protocol, methyl bromide (MB) was the most widely used fumigant to control storage pests due to its efficacy and relatively low cost. Now there is an urgent need to find MB alternatives for post-harvest use. The present research work comprised 3 experiments in 2005–6 carried out in a pilot fumigation chamber designed by EcO 2 (EcO 2 B.V., AG Numansdorp, The Netherlands). The objective was to test the effectiveness of controlled atmosphere (CA) (decreased O 2 at 1 ± 0.5%) at elevated temperature (41 °C) in controlling the major storage pests, fig moth ( Ephestia cautella), Indian meal moth ( Plodia interpunctella), and dried fruit beetle ( Carpophilus spp.). In addition, major quality parameters of the hosts, dried figs, were analyzed soon after the treatments, and after 4 months of storage under ambient conditions, in comparison with MB-treated controls (60 g/m 3 for 24 h). The CA treatment can be recommended as a post-harvest MB alternative for dried figs since it provided 100% control of the pest species tested, had neutral or positive effects on dried fruit quality and required comparatively short (c.26 h) treatment times compared with other MB alternatives.

Controlled atmosphere storage at high CO 2 and low O 2 levels affects stomatal conductance and influence root formation in kalanchoe cuttings

Since the response of cuttings to raised CO 2 concentration is not documented, controlled atmosphere (CA) storage of kalanchoe cuttings at combinations of high carbon dioxide and low oxygen levels was investigated to study the feasibility of using CA to sustain quality of cuttings prior to planting. During storage, stomata opening and plant fresh weight (FW) were measured, and root formation (RF) was recorded post storage. Storage atmosphere composition (10/2, 15/2, or 15/5; kPa CO 2/kPa O 2), storage duration (9 or 19 days), and cutting type (rooted or un-rooted) affected stomata conductance ( G s), and influenced FW and subsequent RF in cuttings of kalanchoe ‘Yellow Josefine’. In CA stored plants, G s was high, 60–160 mmol m −2 s −1, indicating open stomata, whereas in control plants G s was low, 5–14 mmol m −2 s −1, indicating closed stomata. Generally G s values were higher for un-rooted than for rooted cuttings. Overall, cutting FW was reduced by CA storage with no significant differences in FW reduction between the CA treatments. RF of un-rooted CA stored cuttings was comparable to that of controls, whereas for rooted cuttings controls grew better than CA stored cuttings. CA at 10 kPa CO 2 and 2 kPa O 2 for 2–3 weeks could sustain un-rooted cuttings, in a pests-free state whilst retaining the ability of the cuttings RF. The results showed that stomata aperture may be altered by high CO 2 concentration combined with low O 2, and results indicated that this effect was not only caused by high CO 2 but also by low O 2 concentration. In addition, the results indicated that CA storage, stomata conductance, and water stress of kalanchoe cuttings may be correlated. Monitoring G s of leaves of cuttings could be used as a non-destructive indicator of storability and quality status. Based on the novel positive preliminary results reported here, a protocol that focuses on minimising water loss should be developed and optimised for kalanchoe.

Effect of Pre-processing Controlled Atmosphere Storage on the Quality of Fresh-cut Galia Melons

The effects of controlled atmosphere (CA) storage of whole Galia melon on its physical, chemical, and sensory quality after minimal processing were evaluated. High quality fruits washed with 200 mg/L NaClO water solution were stored at 8 °C and 95% RH under CA of 4 kPa O2 + 15 kPa CO2 (T1), 4 kPa O 2 + 10 kPa CO2 (T2) and 21 kPa O2 + 0 kPa CO 2 (T3, air as control). Melons were removed from CA after 10 and 28 days, kept in air at 5 °C for 24 h and then minimally processed in a disinfected cold room at 5 °C. Trapezoidal sections were washed with 100 mg/L NaClO, rinsed and drained. Melon pieces were placed in polypropylene (PP) trays which were heat sealed with an oriented PP film of 35 μm thickness and stored at 5 °C. After 9 days the atmosphere within packages was dependent of pre-storage time, but very similar for the three pre-storage CA treatments: around 2 kPa O2 + 21 kPa CO2 for those stored 10 days and 3 kPa O2 + 31 kPa CO2 for those stored during 28 days. Overall quality of minimally processed Galia melon was affected by pre-processing conditions. Trapezoidal sections obtained from melons previously stored during 28 days at 8 °C under 4 kPa O2 + 15 kPa CO 2 and MAP stored for 7 days at 5 °C showed the highest firmness and the best sensory quality. However, for all the cases, microbial counts were over the legal limits. Alternative disinfection procedures should be developed to guarantee safety of the product.

Combined effects of chemical dip and/or carrageenan coating and/or controlled atmosphere on quality of fresh-cut banana

The combined effect of chemical dip and/or edible coating and/or controlled atmosphere (CA) on quality of fresh-cut banana was investigated. Banana slices were subject to a 3-min dip into a solution containing 1% (w/v) calcium chloride, 0.75% (w/v) ascorbic acid and 0.75% (w/v) cysteine and/or combined with a carrageenan coating and/or combined with controlled atmosphere (3% O 2 + 10% CO 2). Physico-chemical and microbiological qualities were evaluated during 5 days of storage at 5 °C. Dip combined with CA treatment prevented product weight loss and increase of polyphenol oxidase activity during the 5 days of storage. Colour, firmness, pH, tritatable acidity and total soluble solids values and total phenolic content presented the smallest changes. Microbial analysis showed that minimally processed bananas were within the acceptable limits during 5 days of storage at 5 °C.

Development of a Model System for Rapid Assessment of Insect Mortality in Heated Controlled Atmosphere Quarantine Treatments

The development of postharvest quarantine treatments can be both expensive and time-consuming. It is necessary to determine the species and stage of the pest most tolerant to the treatment, if more than one species is the target of the treatment. Initial laboratory studies often include infesting the commodity with various egg and larval stages of the pest and performing treatments and evaluations of the fruit. In collaboration with others, I have previously developed combination high temperature under controlled atmosphere treatments against two quarantine pests in apples (Malus spp.) and peaches and nectarines (both Prunus spp.). I decided to develop an artificial system that can be used for these initial tests without the need for infesting large quantities of the fruit. I tested the system on the immature stages of the pests under regular air and controlled atmospheres by using the controlled atmosphere water bath system. This system can be used for rapid assessment of the most tolerant stage and species of a pest to a combination heat and controlled atmosphere treatment without the expense of infesting, treating, and evaluating the commodity.

Organic Apple Production in Two Humid Regions: Comparing Progress in Pest Management Strategies in Iowa and New Zealand

By 2003, organic apple [Malus sylvestris (L.) Mill var. domestica (Borkh.) Mansf.] production had increased to 5626 ha in the United States and to 2964 ha in New Zealand by 2002. Common problems facing organic apple growers in the humid regions of New Zealand and the United States include effective management strategies for apple scab [Venturia inaequalis (Cooke)] and insect pests. Experiments conducted in Iowa in 2003–2004 demonstrated the effectiveness of a kaolin clay- and spinosad-based insecticide program in maintaining codling moth [Cydia pomonella (L.)] damage levels to less than 5% in the scab-resistant cultivars Enterprise, Liberty, Redfree, and Gold Rush. Similar pest management systems have been developed in New Zealand to comply with export standards and quarantines. The use of codling moth granulosis virus and a spinosad-based insecticide have led to reduced pest pressure and to an increase in organic exports with a 41% premium price over conventional apples. However, an association between spinosad use and woolly apple aphid [Eriosoma lanigerum (Hausmann)] population increase was observed in organic orchard surveys in 2006. An alternative to spinosad applications, insect disinfestation through controlled atmosphere (CA) treatment, was investigated to control quarantined pests and to extend the storage potential of scab-resistant cultivars. A CA treatment of 9 weeks of 2% O2 and 2% CO2 at 0.5 °C was determined to maintain firmness ratings to export standards in CA-stored, scab-resistant ‘Pinkie’ apples and to decrease internal ethylene concentration by 84% compared with apples stored in air. In addition, new scab-resistant cultivars with ‘Pinkie’ background under development in New Zealand show promise for organic production in humid regions. Few fruit quality differences were determined between ‘Pinkie’ fruits from integrated fruit production and organic production systems, although premium prices exist only for certified organic apples.