Modified Atmosphere Treatments Research Articles

Comparative effects of hypoxia, hypercapnia, and hypoxia/hypercapnia on the mortality and survival of Acanthoscelides obtectus (Say) (Coleoptera: Chrysomelidae)

The bean beetle Acanthoscelides obtectus (Say) (Coleoptera: Chrysomelidae: Bruchinae) is one of the most damaging insects of Phaseolus bean worldwide, particularly in Africa. This study aimed to determine the effect of modified atmospheres (MAs) with CO2, N2 and its combination on the mortality and survival of all developmental stages of A. obtectus. All stages were exposed to three gas mixtures [99% N2 in air (hypoxia), 20% CO2 in air (hypercapnia), and 14% CO2 + 85% N2 + 1% O2 (combination)] at different exposure periods that lasted for 3 h or its duplicates until 100% mortality. The results revealed that the three gas mixtures had significant effects on the mortality of A. obtectus stages, which increased gradually with increasing exposure periods. Hypercapnia and hypoxia/hypercapnia effects were more severe on adult A. obtectus, which led to 100% mortality after 3 days of exposure for both treatments. No hatchability was recorded for both hypercapnia and hypoxia after 7 days of exposure, but hypoxia/hypercapnia led to 100% mortality after 5 days of exposure only. Also, the hypoxia/hypercapnia mixture was more effective on both larvae and pupae than hypoxia or hypercapnia alone. Hypoxia was also more effective on both larvae and pupae than hypercapnia. According to the LT50 and LT95 values, all stages of A. obtectus were more susceptible to hypoxia/hypercapnia than hypercapnia or hypoxia separately. Moreover, the sensitivity of all stages of A. obtectus to hypoxia/hypercapnia could be arranged as adult > egg = larva > pupa. The results showed that all gas mixtures led to fewer eggs per female, decreased of hatchability percentages, and less adult emergence percentages compared to the untreated control. Therefore, this study provides a greater understanding of hypercapnia, hypoxia, or hypoxia/hypercapnia in A. obtectus and shows the advantages of the hypoxia and hypercapnia combination in modified atmosphere treatments.

Combination of Modified Atmosphere and Irradiation for the Phytosanitary Disinfestation of Trogoderma granarium Everts (Coleoptera: Dermestidae).

Simple SummaryThe khapra beetle is defined as one of the most important quarantine pests globally, and fumigating by methyl bromide, one of the ozone-depleting substances under the Montreal Protocol, is a routine measure used for phytosanitary treatment. To protect the Ozone layer, an environmentally friendly measure is needed to be developed. The middle- to late-stage larvae and adults were treated with irradiation, modified atmosphere (MA) alone, and their combinations at room temperature of 24–26 ℃. As a result, late-stage larvae are determined as the most tolerant stage. Ionizing radiation was used to enhance the effects of 1% and 2% O2 MA treatments that the obvious synergistic effects are presented in all combinations, resulted in saving as high as 60% of the estimated exposure times comparing with MA treatment alone. A total of 111,366 late-stage larvae were exposed to a 1% O2 atmosphere for 14 or 15 days after a 200 Gy irradiation, resulted in no survivor in the validating tests. Therefore, the MA-irradiation combination treatment can provide quarantine security at a very high level, it may be combined with international transportation (train or sea container) to disinfest the commodities infested by khapra beetle and other stored products insect pests.The khapra beetle, Trogoderma granarium Everts, is defined as one of the most important quarantine pests globally, and fumigation with methyl bromide, an ozone-depleting substance, is a common phytosanitary measure currently used. The modified atmosphere (MA), irradiation, and their combination treatments of T. granarium larvae and adults were performed at room temperature (24–26 ℃) to develop an ecofriendly phytosanitary disinfestation measure and to shorten the exposure time and overcome treatment disadvantages of irradiation. Late-stage larvae are determined as the most tolerant stage resulted in large LT99.9968 values of 32.6 (29.2–37.5) and 38.0 (35.1–41.7) days treated under 1% and 2% O2 (with N2 balance) atmosphere, respectively. Ionizing radiation was used to enhance the effect of MA and the mortality was highly significantly affected by all the interaction effects, indicating that the synergistic effects present in all the combined treatments. The synergistic ratios, which is defined as the estimated lethal time for MA treatment (LD90, LD99, and LD99.9968), divided by that of combined treatment, were between 1.47 and 2.47. In the confirmatory tests, no individuals recovered from a sum of 111,366 late-stage larvae treated under 1% O2 atmosphere for 14- or 15-d after 200 Gy irradiation, which resulted in validating the probit estimations and achieving an efficacy of 99.9973% mortality at 95% confidence level. Therefore, these treatment schedules are recommended to disinfest T. granarium infecting commodities for phytosanitary purposes under the warehouse, MA packaging, or in combination with international transportation by train or sea container.

Effects of different modified atmosphere treatments on lipid oxidation in spiced beef at different storage temperatures.

The high moisture and nutrient contents of spiced beef make it popular with consumers but present challenges for its storage, as spoilage is a common phenomenon. Therefore, for identifying packaging methods to reduce spoilage during storage, this study investigated the effects of 5% O2 (low oxygen), 70% CO2 (high carbon dioxide), and 5% O2/70% CO2/25% N2 (compound group) on lipid oxidation in spiced beef in the test groups and a vacuum‐packed group (control) at storage temperatures of 4, 25, and 60°C. The pH, thiobarbituric acid (TBA), anisidine value (AV), and peroxide value (POV) of the spiced beef were determined. Results indicated that 70% CO2 and storage at 4 and 25°C showed the strongest ability to inhibit the rancidity in spiced beef. The 5% O2 group delayed both initial oxidation and secondary oxidation of lipids. Although the compound group significantly inhibited the rancidity in spiced beef at 60°C, it could not maintain such inhibition for long. Among all the groups, the 70% CO2 group demonstrated maximum inhibition of initial lipid oxidation and suppressed the secondary oxidation of lipids for the longest time. Thus, the modified atmosphere packaging with O2 and CO2 can regulate the fat oxidation in meat products and effectively improve their flavor maintenance.

Effect of High CO2 Treatment and MA Packaging on Sensory Quality and Physiological-Biochemical Characteristics of Green Asparagus (Asparagus officinalis L.) during Postharvest Storage

Green asparagus is vulnerable to thrips that carry microorganisms and cause deterioration in quality. The effects of 60% CO2 treatment, which is used to kill thrips, combined with perforated (P) or modified atmosphere (MA) packages during cold storage, on the sensory quality and physiological–biochemical characteristics of asparagus were investigated. MA packaging yielded an asparagus shelf-life five days longer than P packaging. The 60% CO2 treatment for 48 h at 4 °C packaged with MA film (CO2-48 h-4 °C-MA) showed a lower number of aerobic bacteria, yeast, and mold. Yellowing of asparagus was retarded, as shown by higher hue angle and chlorophyll content and lower chlorophyllase activity. Also, CO2-48 h-4 °C-MA treatment inhibited the reduction of soluble solids content in asparagus. Likewise, all high CO2 treatments showed lower electrolyte leakage (EL), with CO2-48 h-4 °C-MA demonstrating the minimum EL. The effectiveness of high CO2 on maintaining sensory qualities was observed, with a score higher than 3.0. In conclusion, CO2-48 h-4 °C-MA treatment during cold storage was effective for maintaining post-harvest sensory qualities and physiological–biological traits of asparagus, and provided strong inhibition of microflora growth during the storage period.

Stress Response of Vibrio parahaemolyticus and Listeria monocytogenes Biofilms to Different Modified Atmospheres.

The sessile biofilms of Vibrio parahaemolyticus and Listeria monocytogenes have increasingly become a critical threat in seafood safety. This study aimed to evaluate the effects of modified atmospheres on the formation ability of V. parahaemolyticus and L. monocytogenes biofilms. The stress responses of bacterial biofilm formation to modified atmospheres including anaerobiosis (20% carbon dioxide, 80% nitrogen), micro-aerobiosis (20% oxygen, 80% nitrogen), and aerobiosis (60% oxygen, 40% nitrogen) were illuminated by determining the live cells, chemical composition analysis, textural parameter changes, expression of regulatory genes, etc. Results showed that the biofilm formation ability of V. parahaemolyticus was efficiently decreased, supported by the fact that the modified atmospheres significantly reduced the key chemical composition [extracellular DNA (eDNA) and extracellular proteins] of the extracellular polymeric substance (EPS) and negatively altered the textural parameters (biovolume, thickness, and bio-roughness) of biofilms during the physiological conversion from anaerobiosis to aerobiosis, while the modified atmosphere treatment increased the key chemical composition of EPS and the textural parameters of L. monocytogenes biofilms from anaerobiosis to aerobiosis. Meanwhile, the expression of biofilm formation genes (luxS, aphA, mshA, oxyR, and opaR), EPS production genes (cpsA, cpsC, and cpsR), and virulence genes (vopS, vopD1, vcrD1, vopP2β, and vcrD2β) of V. parahaemolyticus was downregulated. For the L. monocytogenes cells, the expression of biofilm formation genes (flgA, flgU, and degU), EPS production genes (Imo2554, Imo2504, inlA, rmlB), and virulence genes (vopS, vopD1, vcrD1, vopP2β, and vcrD2β) was upregulated during the physiological conversion. All these results indicated that the modified atmospheres possessed significantly different regulation on the biofilm formation of Gram-negative V. parahaemolyticus and Gram-positive L. monocytogenes, which will provide a novel insight to unlock the efficient control of Gram-negative and Gram-positive bacteria in modified-atmosphere packaged food.

Mitochondrial response of the lesser grain borer Rhyzopertha dominica (F.) to modified atmospheres

Rhyzopertha dominica is an insect pest that feeds on a wide variety of grains and stored cereals, producing economical losses. Bioenergetics studies on insects are necessary to eventually plan strategies to reduce pest infestation on stored grains with methods other than insecticides. Modified atmosphere treatments, where insects are exposed to either low O2 or high CO2 concentrations, or both, can be used as alternatives. In this research, R. dominica was subjected to a modified atmosphere environment (MA) consisting of 5% O2 and 10% CO2 for 24 h and was compared with normoxia insects (21% O2 and 0.02% CO2). Mitochondria from the whole insect were isolated and their protein content was analyzed by two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) using OFFGEL Fractionator equipment and 12% polyacrylamide gels electrophoresis (SDS-PAGE). Lactate concentration, cytochrome c oxidase (COX) and ATPase activities were measured. Lactate concentration was 29% higher in R. dominica exposed to MA versus normoxia. 2-D PAGE and LC MS/MS revealed the presence of a heat shock protein (hsp60), an actin fragment, and ATP synthase α and β catalytic subunits. Activity levels of COX and ATPase were reduced by 58 and 59%, respectively, in MA versus normoxia. Therefore, R. dominica may have shifted into a hypo-metabolic state because oxygen intake was insufficient to maintain enzymatic activity. This scenario would ultimately result in a decrease in substrate concentration (oxygen) and a reduction in electron transport chain complex activity. Thus, eventually, this knowledge can be use to develop novel environmentally friendly alternatives to eradicate or reduce pests in stored grains.

Fumigant toxicity of mustard essential oil and its main compound alone and combinations with modified atmosphere treatments against Tribolium confusum du Val., 1863 (Coleoptera: Tenebrionidae)

Bu calisma 2017 yilinda Kahramanmaras Sutcu Imam Universitesi’nin Entomoloji Laboratuvari’nda hardal ucucu yagi ve bunun ana bilesigi olan allyl isothiocyanate’in yuksek CO 2 veya N 2 ile kombinasyonunun Tribolium confusum du Val., 1863 (Coleoptera: Tenebrionidae)’un tum biyolojik donemlerine karsi fumigant etkinlikleri belirlemek amaciyla yurutulmustur. On biyolojik etkinlik test sonuclari, hardal ucucu yagi veya allyl isothiocyanate’in tek basina 10 µl/l konsantrasyonda T. confusum ’un tum biyolojik donemlerinde %100 olumune neden oldugunu gostermistir. Hardal ucucu yagi veya allyl isothiocyanate’in %92 oranindaki CO 2 veya N 2 ile birlikte uygulanmasi T. confusum ’un larva, pupa ve erginlerine ait LC 90 degerlerinde 1.8-7.3 arasinda degisen oranlarda azalmalara neden olmustur. Genel olarak hardal ucucu yagi veya allyl isothiocyanate’in %92 CO 2 ile kombinasyonun T. confusum ’un larva, pupa ve erginlerine karsi bunlarin %92 N 2 ile kombinasyonuna kiyasla daha toksik oldugu belirlenmistir. Biyolojik etkinlik testleri sonunda hardal ucucu yagi ve bunun ana bilesigi olan allyl isothiocyanate’in yuksek konsantrasyonda CO 2 veya N 2 gaziyla birlikte uygulanmasinin T. confusum ’un larva, pupa ve erginlerine ait toksisite degerlerinde onemli azalmalara neden oldugu ve dolayisiyla CO 2 veya N 2 kullaniminin sinerjik etki gosterebilecegi gorulmustur. Sonuc olarak, hardal ucucu yagi ve ana bilesigi olan allyl isothiocyanate’in degistirilmis atmosfer ile kombinasyon halinde uygulanmasinin depolanmis urun zararlilarinin mucadelesinde konvansiyonel fumigantlara potansiyel alternatif olabilecegi degerlendirilmistir.

Influence of modified atmosphere treatment on post-harvest reactive oxygen metabolism of pomegranate peels

Modified atmosphere storage can regulate the reactive oxygen metabolism of fruits and vegetables, reduce the accumulation of hazardous free radicals, and mitigate the peroxidation degree of fruit membrane lipids. In this study, different gas matching ratios were adopted for the modified atmosphere treatment of pomegranate fruits. Up to 120 d of storage, compared with the control treatment, the H2O2 and malonaldehyde (MDA) contents in treatment 2 decreased by 8.88% and 18.28%, respectively, when the activities of superoxide dismutase (SOD), catalase (CAT) and ascorbic acid peroxidase (APX) in treatment 2 increased by 21.44%, 117.38% and 114.95%, the ascorbic acid (ASA) and glutathione (GSH) contents in treatment 2 also increased by 116.83% and 50%, these results showed that treatment 2 (6.0% O2, 6.0% CO2) could effectively regulate various indexes of the reactive oxygen metabolism of pomegranate peels, maintain the normal physiological actions of the fruits, and postpone the ripening and senescence of histocytes. Under treatment 4 (10.0% O2, 10.0% CO2), H2O2 contents in the pomegranate peel significantly increased, and the activities of SOD, CAT and APX significantly reduced. ASA and GSH were degraded, the MDA content abruptly increased, the membrane lipid peroxidation accelerated, and the cytomembrane structure was destroyed.

Effects of pure oxygen and reduced oxygen modified atmosphere packaging on the quality and microbial characteristics of fresh-cut pineapple

Introduction. Modified atmosphere packaging (MAP) is a preservation technique currently used by the fresh-cut fruit industry. Fruit quality may vary according to the concentration of oxygen (O2 ) in the packaging. However, there is no published research on the effects of a pure O2 modified atmosphere in the packaging of fresh-cut pineapple. There are also no comparative studies of the differences between pure O2 and conventional low O2 MAP on the quality of fresh-cut pineapple. Materials and methods. Pineapple slices were sealed with a tray sealer using a polyethylene (PE) / polypropylene (PP) composite film and one of the following atmosphere treatments: (4% O2 + 5% CO2 ), (100% O2 ), and ambient air (control). We evaluated the effects on quality and microbial spoilage of fresh-cut pineapple. Results and discussion. Both modified atmosphere treatments delayed decreases in firmness, soluble solid contents (SSC), reducing sugar, and ascorbic acid. Pineapple slices packaged in pure O2 contained lower amounts of sugar and ascorbic acid and displayed more browning than the slices in the low O2 concentration. Additionally, both modified atmosphere treatments strongly delayed the growth of microorganisms. Aerobic bacteria, yeast and mold levels in pineapple slices packaged in pure O2 were higher than those packaged with the low O2 atmosphere during long-term storage. Conclusion. Modified atmosphere packaging using low O2 concentration (4% O2 + 5% CO2 ) was better able to maintain the quality of fresh-cut pineapple than packaging with pure O2 atmosphere.

Effects of vacuum and modified atmosphere on textural parameters and structural proteins of cultured meagre (Argyrosomus regius) fillets.

The influence of two preservation strategies (vacuum package and modified atmosphere package) on the post-mortem changes of textural parameters, pH, water holding capacity, sarcoplasmic and myofibrillar proteins, and collagen content of meagre (Argyrosomus regius) fillets was studied. Fillets were stored in a cold room in aerobic (control, C), vacuum (V) and modified atmosphere (MA) package. Samples were withdrawn at six sampling points throughout 15-day storage, and post-mortem changes were assessed. The textural parameters were significantly enhanced in V and MA compared to C. Both V and MA treatments reduced the intensity of a group of myofibrillar protein fractions (140-195 kDa) and increased insoluble collagen compared to C. Consequently, the post-mortem flesh softening in C was attributed to increased proteolysis in both intracellular and extracellular structural proteins. The preservation of the textural and biochemical characteristics of meagre fillets subjected to V and MA treatments makes these two treatments highly recommendable for the commercialization of meagre fillets.

Growth behavior prediction of fresh catfish fillet with Pseudomonas aeruginosa under stresses of allyl isothiocyanate, temperature and modified atmosphere

Abstract Pseudomonas aeruginosa, an opportunistic pathogen which can be found on fresh catfish fillet, grows rapidly when temperature rises above 4 °C. The combination of allyl isothiocyanate (AIT) and modified atmosphere (MA) was applied and proved effective to retard the growth of P. aeruginosa. The objective of this research was to develop simple mathematical models to predict the growth behavior of P. aeruginosa in catfish fillet and its potential storage time (in abuse temperature condition) as a function of AIT and temperature with/without MA treatment. The antimicrobial effect of gaseous AIT (0, 18 and 36 μL/L) on the growth of P. aeruginosa cocktail was evaluated at 8, 15 and 20 °C. Furthermore, the effects of MA (49% CO2, 50.5% N2 and 0.5% O2) alone and AIT/MA combination were also investigated. These data obtained through an experimental design were used for model development. The regression models for lag phase, growth rate and “shelf life” (based on P. aeruginosa which closely related to Pseudomonas fluorescens and Pseudomonas pudita and all belong to the same RNA group used to classify the Pseudomonas at the subgenus level) were validated experimentally. Surface plot of models was also drawn to lucidly represent the interaction of AIT and temperature. The developed models may provide useful information for food industry in designing or selecting the proper packaging system with incorporation of AIT to attain the food safety with acceptable “shelf life” of fresh fish products under specified and potential abuse (with temperature deviation) distribution and storage conditions.

Effect of time of day for harvest and postharvest treatments on the sugar metabolism of broccoli (Brassica oleracea var. italica)

Loss of sugars contributes to accelerate postharvest senescence of broccoli. Several treatments have been developed to delay senescence, but in many cases their effects on sugar metabolism were not analyzed. We studied the effect of harvest at different times of day (08:00, 13:00 and 18:00 h) and of several postharvest treatments as heat treatment (HT), modified atmosphere (MA) and 1-methylcylcopropene (1-MCP) on sugar levels and activities of enzymes related to sucrose and starch degradation. Harvesting at the end of day delayed the loss of chlorophylls and caused the lowest decrement in sugars, although no differences in invertase, sucrose synthase and β-amylase activities were detected among samples. Treatments of MA and 1-MCP caused a lower loss of glucose and fructose, while HT caused a lower decrement of sucrose. Treated samples maintained higher levels of chlorophylls. The treatments reduced the activity of invertase and sucrose synthase and induced higher levels of β-amylase activity. Harvesting at the end of day and performing simultaneously a MA treatment could be a good combination to maintain the green color of the inflorescence and sugar levels during postharvest of broccoli.

Antimicrobial Effects of Vapor Phase Thymol, Modified Atmosphere, and Their Combination against Salmonella spp. on Raw Shrimp

Salmonella contamination on raw shrimp is a big food safety concern in the United States currently. This research evaluated the inhibition effects of vapor phase thymol, modified atmosphere (MA), and their combination against Salmonella spp. on raw shrimp. Growth profiles of a Salmonella spp. cocktail (6 strains), inoculated onto the surface of raw shrimp, treated with vapor phase thymol at 3 levels (0, 0.8, and 1.6 mg/L), or MA (59.5% CO2 + 39.5% N2 + 1% O2 ), both alone and in combination, at 3 temperatures (8, 12, and 16 ºC), were determined. Lag time and maximum growth rate of Salmonella spp. under each treatment were obtained using Baranyi and Roberts models. Results indicated that both vapor phase thymol and MA treatments alone inhibited the growth potential of Salmonella spp. effectively, extending the lag time by 10% to 100% and reducing the maximum growth rate by 14% to 71% compared with controlled samples at experimental temperatures (8, 12, and 16 ºC). Combination treatments of vapor phase thymol and MA exhibited greater inhibition effectiveness than each individual treatment and a synergistic antimicrobial effectiveness could be observed on the lag time extension. To the maximum, at 12 ºC, lag time of Salmonella spp. was extended 59.6% more by the combination treatment of 0.8 mg/L thymol + MA (36.97 h) than those effects combined from 0.8 mg/L thymol treatment and MA treatment alone (23.16 h in total). This combination strategy could be potentially utilized for Salmonella inhibition during the long distance and temperature-abused raw shrimp import process.

1-MCP, low O2 and high CO2 reduce disorders and extend vase life of “Rosalin” gerberas during storage

The hormone ethylene performs an important function in the processes related to the senescence of cut flowers, and, in particular, anti-ethylene treatments are recommended to extend the vase life of orchids. Among the treatments currently used for such postharvest treatment, 1-methylcyclopropene (1-MCP) is an efficient inhibitor of the autocatalytic production of ethylene. Although postharvest 1-MCP treatment is used to counter ethylene activity and delay senescence in fresh produce, its potential application in cut flowers has not been adequately tested. The objective of this study was to investigate the effect of 1-MCP treatment with modified atmosphere packaging on the shelf life of cut “Rosalin” gerberas. To this end, gerberas harvested at commercial maturity were divided into two groups: 1-MCP treatment (625 ppb at 4±1°C for 4 hours) and no treatment. Both groups of flowers were stored under normal and modified atmosphere conditions at 4±1°C and 80±5% relative humidity. The flowers were covered with materials of different characteristics for the modified atmosphere. To determine the differences between the treatments, quality parameters were examined in the flowers at 7-day intervals during the storage. The 1-MCP treatment with both the normal and modified atmosphere significantly reduced the overall postharvest loss in quality. The best results for the quality characteristics determined were obtained from the 1-MCP and 30 µm polyvinylchloride combined treatment. These results indicate that 1-MCP and a modified atmosphere treatment are good methods for extending the vase life, maintaining the visual quality, and reducing the loss of quality of gerberas.

The use of modified atmospheres to control Sitophilus zeamais and Sitophilus oryzae on stored rice in Portugal

This study reports the efficacy of using CO2 against Sitophilus zeamais and Sitophilus oryzae as an alternative treatment to fumigation for rice stored in a rice mill in Portugal. The trials were conducted in a silo containing 40 tonnes of polished rice and in four hermetic big bags of 1 tonne capacity; two with paddy and two with polished rice. The composition of the atmosphere ranged from 90 to 95% CO2 and 0.7–2.1% O2. Three trials were carried out at different temperatures and treatment times; stored rice in the silo at 29.6 ± 0.1 °C for 26 days (first trial), at 34.1 ± 0.2 °C for 10 days (second trial), and in big bags at 22 °C for 26 days (third trial).To evaluate the efficacy of each treatment, metal cages with 16 g of infested rice where placed at bottom, middle, top and surface of the polished rice in the silo. Four replications of each type of infested rice containing one-week-old S. zeamais adults, or eggs of S. zeamais or S. oryzae, were incubated in the laboratory, at the same temperature as in the silo, to serve as a control.In all modified atmosphere treatments adults of S. zeamais, and eggs of both S. oryzae and S. zeamais, showed mortality close to 100% and no F1 emergence was recorded in any treatment sample. This was the first time that a Portuguese rice mill used modified atmospheres.

Armazenamento de sementes de palmiteiro sob atmosfera modificada

Este trabalho objetivou avaliar o efeito do armazenamento sob atmosfera modificada (AM), passiva e ativa, sobre o desempenho de sementes de Euterpe edulis Martius. Os tratamentos avaliados foram: T1 - controle (sem embalagem); T2 - polietileno de baixa densidade (PEBD); T3 - PEBD + absorvedor de CO2, T4 - PEBD + N2; e T5 - PEBD + absorvedor de CO2 + N2. O tratamento T2 consistiu no armazenamento em AM passiva e os tratamentos T3, T4 e T5 no armazenamento em AM ativa. As sementes foram armazenadas por 150 e 480 dias a 7 ºC. Após 150 dias de armazenamento, as sementes dos tratamentos com AM (passiva ou ativa) mantiveram germinação (%), velocidade de emergência (VE), grau de umidade e vigor (comprimento da parte aérea e da raiz primária e menor condutividade elétrica) superiores ao tratamento controle. Após 480 dias de armazenamento, as sementes armazenadas nos tratamentos PEBD, PEBD + N2 e PEBD + absorvedor de CO2 + N2 estavam com maior germinação e menor condutividade elétrica, enquanto as sementes dos tratamentos PEBD e PEBD + N2, maior VE, comprimento da parte aérea e da raiz. O grau de umidade não variou significativamente entre os tratamentos de AM, mas esses foram superiores ao controle. A AM contribui para preservar o desempenho das sementes de Euterpe edulis por um período de até 150 dias de armazenamento. Quando há extensão desse período para 480 dias, tanto sob AM passiva como AM ativa, a injeção de N2 é benéfica à conservação de sementes de Euterpe edulis.

MODIFIED ATMOSPHERE EXTENDS STORAGE PERIOD AND MAINTAINS QUALITY OF ´BARHI´ DATE FRUITS

Mature yellow 'Barhi' date fruits (Phoenix dactylifera) were stored under modified atmosphere (MA) conditions at cold storage (0°C). Fruits were exposed to three carbon dioxide concentrations (5, 10, or 20%). The control fruits were stored at cold storage (0°C) under the common air components conditions (0.03% CO 2 ). Fruits storage ability, as well as changes in fruit quality during the storage period were studied. MA conditions improved significantly fruit storage ability, and maintained fruit quality. Fruits stored under 20% CO 2 showed significantly longer storage period (lasted for 182 days) than all other treatments (i.e. 5 and 10% CO 2 which lasted for 119 days) and the control (lasted for 49 days). At the end of the experiment, MA treatment with 20% CO 2 maintained fruit soluble solid content %, and total tannins. In addition, CO 2 treatment retarded significantly the degradation of caffeoylshikimic acid, which is one of the major phenolic compound of date fruits. This study indicated that 'Barhi' date fruits could be stored successfully under modified atmosphere conditions in cold storage (at 0°C) to achieve the longest possible storage period (371.4% more than the control) with the best fruit color and firmness, and most proper eating quality, which ultimately improves market ability.

Quality of Modified Atmosphere Packaged `Hedelfingen' and `Lapins' Sweet Cherries

`Hedelfingen' and `Lapins' sweet cherries (Prunus avium) were stored in air or in two types of modified atmosphere (MA) bags (LifeSpan 204 and 208) at 3 °C (37.4 °F) and 90% relative humidity for 4 weeks. Various analytical and quality measurements were conducted weekly on `Hedelfingen' cherries, whereas on `Lapins' these were done initially and at the end of 4 weeks. For `Hedelfingen' cherries, there were differences in carbon dioxide (CO2) and oxygen (O2) composition within the MA bags, depending on the bag used. This resulted in slightly better cherry quality for the bag with lower O2 permeability (L204), which equilibrated at 4% to 5% O2 and 7% to 8% CO2. For `Lapins', the two MA bags showed concentrations of 9% to 10% O2 and 8% to 9% CO2 and similar final fruit quality. There was a significant weight loss for the control treatments over time (6% to 13%), whereas the MA treatments showed minimal losses. A higher incidence of cracking and decay was observed in MA treatments of `Hedelfingen' but not in `Lapins'. Control cherries had significant shriveling and browning of stems; MA-stored cherries had green and healthy stems after 4 weeks. No significant differences were observed in pH, acidity, soluble solids, firmness, and hue angle among the storage treatments. MA packaged cherries seemed to maintain better color than control cherries over time. Similarly, MA cherries had better appearance and eating quality after 4 weeks when compared to control cherries.

Modified atmosphere treatments as a potential disinfestation technique for arthropod pests in greenhouses.

Incidental transport of arthropods on plant material can be a significant mode of pest entry into greenhouses. We evaluated the use of controlled atmosphere treatments as a potential way to eliminate arthropod pests on plant propagules (i.e., cuttings or small rooted plants). Lethal exposures to CO2 or N2 were determined for common greenhouse pests including fungus gnat larvae, Bradysia sp.; green peach aphid, Myzus persicae (Sulzer); sweetpotato whitefly, Bemisia sp.; twospotted spider mite, Tetranychus urticae Koch; and western flower thrips, Frankliniella occidentalis (Pergande). We also studied the effect of pest species, life stage, and presence or absence of plants on efficacy of modified atmosphere treatments. Finally, effects of modified atmospheres on plant quality were evaluated for several bedding plant species including begonia, Begonia semperflorens-cultorum Hort. 'Cocktail Series', chrysanthemum, Dendranthema grandiflora Tzvelev., geranium, Pelargonium X hortorum L.H. Bailey, and impatiens, Impatiens wallerana Hook f., and among cultivars of geranium and chrysanthemum. Exposure for 12-18 h to >99% N2 or CO2 caused complete mortality of aphids, mites, thrips, and whiteflies. Fungus gnat larvae were more tolerant of hypoxic conditions. Adult mites and eggs were equally susceptible. For most pests, there was no difference in response to atmospheres modified by CO2 or N2. However, there was variation in response among plant species and cultivars, with effects ranging from delayed flowering to mortality. Despite the possibility of adverse effects on some plants, this work indicates that use of modified atmospheres has potential to eliminate arthropod pests on plant propagules before they are introduced into greenhouses.

Nonproteolytic Clostridium botulinum Toxigenesis in Cooked Turkey Stored under Modified Atmospheres

The ability of nonproteolytic Clostridium botulinum type B spores to grow and produce toxin in cooked, uncured turkey packaged under modified atmospheres was investigated at refrigeration and mild to moderate abuse temperatures. Cook-in-bag turkey breast was carved into small chunks, surface-inoculated with a mixture of nonproteolytic C. botulinum type B spores, packaged in O2-impermeable bags under two modified atmospheres (100% N2 and 30% CO2:70% N2), and stored at 4, 10, and 15°C. Samples were analyzed for botulinal toxin and indigenous microorganisms, as well as subjected to sensory evaluation, on days 0, 7, 14, 28, 42, and 60. Given sufficient incubation time, nonproteolytic C. botulinum type B grew and produced toxin in all temperature and modified atmosphere treatment combinations. At moderate temperature abuse (15°C), toxin was detected by day 7, independent of packaging atmosphere. At mild temperature abuse (10°C), toxin was detected by day 14, also independent of packaging atmosphere. At refrigeration temperature (4°C), toxin was detected by day 14 in product packaged under 100% N2 and by day 28 in product packaged under 30% CO2:70% N2. Reduced storage temperature significantly delayed toxin production and extended the period of sensory acceptability of cooked turkey, but even strict refrigeration did not prevent growth and toxigenesis by nonproteolytic C. botulinum. At all three storage temperatures, toxin detection preceded or coincided with development of sensory characteristics of spoilage, demonstrating the potential for consumption of toxic product when spoilage-signaling sensory cues are absent.