Effects Of Storage Atmosphere Research Articles

Influence of storage temperature/time and atmosphere on survival and thermal inactivation of Escherichia coli ATCC 25922 inoculated to almond powder

The purposes of this study were to explore combined effects of storage temperature, time and atmosphere on survival and thermal inactivation of pathogenic Salmonella Enteritidis PT 30 with nonpathogenic E. coli ATCC 25922 as a surrogate inoculated to low-moisture almond powder. A thermal death time test heating block system (TDT-HBS) was used to rapidly determine thermal inactivation of E. coli ATCC 25922. Surviving populations and D75-values of E. coli ATCC 25922 in the almond powder with 6.0% w.b. were determined monthly for 12-month storage under three packaging atmosphere conditions at −20, 4, and 24 °C. The results showed that survival and thermal inactivation curves of E. coli ATCC 25922 fitted well to both Weibull and first-order-kinetic models, respectively. The effects of storage atmosphere on reducing surviving populations and D75-values of E. coli ATCC 25922 became more remarkable as the storage temperature increased. The reductions of 2.55 log CFU/g for surviving populations and 31.2% for D75-values were observed after 12-months storage at 24 °C under modified atmosphere packaging (MAP), and holding for 50.4 min at 75 °C could reach at least 4-log reductions of E. coli ATCC 25922, which are required by the USDA for safe exportation. Storage under MAP at ambient temperature may hold potential to inhibit surviving populations and reduce thermal resistance of S. Enteritidis PT 30 in low-moisture almond powder.

Effects of storage atmosphere and surface roughness on the hydrophobicity of Gd<sub>2</sub>O<sub>3</sub> thin film and sintered body

Effects of storage atmosphere and surface roughness on the hydrophobicity of Gd<sub>2</sub>O<sub>3</sub> thin film and sintered body

Effect of storage atmosphere and temperature on the oxidative stability of almond kernels during long term storage

In this study, the oxidative stability of almonds (Var. Mamaei) stored for a period of 10 months was examined. The influence of temperature (ambient and refrigeration), type of atmosphere (vacuum, CO2 and normal air) and the product physical shape (whole kernels and ground) on the oxidation stability were studied under conditions of darkness. Peroxide value (PV) and conjugated trienes (K268) were used as indicators for oxidation progress. Odor and flavor were also used for sensory evaluation. According to the results, effects of differing temperature, type of atmosphere or physical shape on PV and K268 were significantly different (P<0.05). At the end of storage with PV of 3.41 meqO2/kg and K268 of 3.42 μmol/g the ground almond sample exposed to air at ambient temperature was the least stable, and the whole kernels under vacuum kept in a refrigerator at 4 °C with PV of 0.69 meqO2/kg and K268 of 0.63 μmol/g were the most stable form against oxidation. As a result, with regard to PV, unpacked whole kernels and ground almonds stored at ambient temperature remained fresh for 8–9 and 7 months of storage, respectively, while the same samples in refrigeration had shelf lives above 10 months. The use of modified atmosphere packaging under vacuum and CO2 provided a shelf life of at least 10 months for all samples irrespective of storage temperature and physical shape of the nuts. Thus modified atmosphere packaging was a most effective method for protecting the almonds from oxidation.

Effects of Storage Atmosphere and Heme State on the Color and Visible Reflectance Spectra of Salmon (Salmo salar) Fillets

It has previously been observed that the color of mackerel muscle is dependent on the status of heme as myoglobin and hemoglobin and hence the storage atmosphere. This study gives strong indications of this being the case also in salmon. Three different storage conditions were used to promote the oxidized, reduced, and carbon monoxide (CO) bound forms of heme in salmon and mackerel fillets. Color determination (instrumental color analysis, imaging, and sensory evaluation) and spectroscopic measurements were performed to study how spectral changes corresponded to color variations. Storage in CO significantly increased the redness in mackerel. This was also seen in salmon to such a degree that it was visible over normal levels of salmon carotenoids. Air storage increased the yellowness and reduced the redness in mackerel, but this effect was partly concealed in salmon by the astaxanthin absorption. The spectral differences due to storage condition could be ascribed to the spectral features characterizing heme of different oxidation states and bound to different ligands. The status of heme should therefore always be considered when experiments related to salmon color are performed. The findings could help in the understanding, control, and prediction of color loss in salmon during processing, storage, and transport.

Modelling the effects of modified atmosphere onSalmonella typhimurium in packaged meat during storage in the refrigerator and at 12°C

The effects of storage atmosphere and temperatures onSalmonella typhimurium and aerobic plate count (APC) in meat were studied. Experimental results were analysed by non-linear regression of modified-Gompertz and logistic equations to generate “best fit”. In the absence of CO2 in package (with air and 40% O2+60% N2), in the refrigerator and at 12°C,S. typhimurium had higher growth rate and reached to higher number, whereas the presence of CO2 from 40 to 100% reduced the number ofS. typhimurium by 0.2 to 1.6 logs unit in the refrigerator. CO2 dissolves in water to form carbonic acid which reduces pH of meat and bacterial cytoplasm. This would be reduced the bacteria or inhibited their growth. The effects of the modified atmospheres on microorganisms in meat seems to be responsible for the data obtained, together with a probable contribution from pH which in turns is likely to be influenced by the gas atmosphere. It is known that CO2 has a bacteriostatic effect. Parameters of non-linear modified-Gompertz and logistic models of theS. typhimurium and APC in meat stored at variaus atmospheres were matched in a satisfactory way. Both the modified-Gompertz and logistic models showed good fit to all curves as assessed using the root mean square error and the correlation coefficient between the experimental and predicted values.

DOES ´ACOUSTIC FIRMNESS´ RELATE TO SENSORY PERCEPTION OF APPLE TEXTURE?

Apple samples covering a wide range in texture were produced by storage in different regimes and by using two cultivars ('Queen Cox' and 'Royal Gala'). Fruit were graded into 3 size bands prior to storage. 'Acoustic firmness' was measured using an AFS unit (AWETA BV) and penetrometer measurements were made using a Lloyd LRX materials testing machine fitted with an 11 mm probe. A trained panel at Leatherhead Food International Ltd UK carried out the sensory assessments. Measurements were made on three replicate sets of samples to correspond with three sensory panel sessions. Separate samples were used for penetrometer measurements and sensory tests but 'acoustic firmness' was measured on all samples of fruit. In 'Cox' the penetrometer measurements showed a general decline with increasing fruit size and with increasing store oxygen concentration. A decline in acoustic firmness index with increasing fruit size and oxygen concentration was observed though with a reduced sensitivity compared to the penetrometer measure. The sensory assessment of crispness showed a similar overall trend with oxygen concentration, but without a consistent effect of fruit size. For 'Gala' apples similar trends with storage atmosphere for sensory crispness and penetrometer measurements were observed, though there was a clear trend of declining values with increasing fruit size for the penetrometer which was not evident for sensory crispness. There appeared to be little effect of storage atmosphere or fruit size on 'acoustic firmness' index for this variety. For 'Cox' there was a good relationship between penetrometer readings and scores for sensory crispness but a less good relationship for 'Gala'. The relationship between 'acoustic firmness' and sensory crispness was poor, particularly for 'Gala'. In 'Cox' there was a strong correlation between 'acoustic firmness' and penetrometer readings but no correlation in 'Gala'. Increasing water loss in stored New Zealand 'Cox' apples tended to increase sensory scores for crispness and hardness but acoustic firmness index showed an opposite trend indicating that turgidity of the tissue is a confounding factor in the acoustic measurement of apple firmness.

Enzymatic changes in minimally processed apples

The impacts of chemical treatment and modified atmosphere on enzymatic changes in minimally processed apples were evaluated. Slices of apple cultivars Golden Delicious and Red Delicious were packed in plastic bags with modified atmospheres: 85% N&lt;sub&gt;2&lt;/sub&gt;, 5% O&lt;sub&gt;2&lt;/sub&gt;, 10% CO&lt;sub&gt;2&lt;/sub&gt; (MA) and 78% N&lt;sub&gt;2&lt;/sub&gt;, 21% O&lt;sub&gt;2&lt;/sub&gt;, 1% other gases (NA). The changes in colour, firmness, polyphenoloxidase activity, total phenols content and concentration of single phenols during storage were measured. It has been found that the effects of storage atmosphere and antioxidant treatment were not as important as the choice of apple cultivar. Red Delicious is a cultivar with high concentration of phenolic compounds and high activity of polyphenoloxidase; therefore it is difficult to limit the very fast enzymatic changes and subsequent discoloration.

Effects of storage atmosphere on Listeria monocytogenes and competing microflora using a surface model system

A solid‐surface model system was used to study the effects of gas atmospheres encountered in modified atmosphere packaging of vegetables on the survival and growth of Listeria monocytogenes and competing micro‐organisms. The effects of increasing CO2 levels (from 5% to 20%), 100% N2 and 3% O2 were determined. The model system allowed for estimation of the growth of L. monocytogenes alone or in the presence of competing microflora. CO2 concentrations of 5–10% (with 5% O2 in N2) had no inhibitory effect, by comparison with air, on the growth and survival of pure cultures of L. monocytogenes. At 20% CO2 population densities were reduced up to day 8, but the final population densities reached were not. An atmosphere of 100% N2 allowed survival of pure cultures of L. monocytogenes, but populations did not significantly change (P &gt; 0.05) during storage, whereas a low O2 (3%, balance N2) atmosphere allowed significant growth (P &lt; 0.05) of L. monocytogenes. Growth and inhibitory activities of Enterobacter cloacae and E. agglomerans were inversely related to the concentration of CO2. By contrast, the growth and anti‐listerial activities of Leuconostoc citreum increased with elevated CO2 concentrations. In the low O2 atmosphere, L. monocytogenes grew considerably better in the presence of populations from the indigenous microflora of lettuce than when in pure culture. The results indicate that the gas atmospheres present within modified atmosphere packages of minimally processed vegetables may affect the interactions between the pathogen and the natural competitive microflora sufficiently to indirectly enhance L. monocytogenes growth.

Quality of Fundy and Blomidon lowbush blueberries: Effects of storage atmosphere, duration and fungal inoculation

This study investigated the response of two cultivars of lowbush blueberries, Vaccinium angustifolium Ait., cultivars Fundy and Blomidon, to controlled atmosphere (CA) storage in all combinations of 1, 2, and 5% O2 and 0, 5, 10, and 15% CO2, and storage in air. A second set of samples was inoculated with a Botrytis-infected raspberry prior to storage to determine the effect of CA storage on decay development. The berries were held at 0 °C in air-tight chambers flushed each day for 30 min. Half-liter samples were stored for 2,4, and 6 wk in air or CA storage and then evaluated for percent unmarketable berries, firmness, titratable acids and percent decayed berries. This was followed by 7 d in air at 10 or 20 °C and recording of percent unmarketable berries. The experiment was replicated over 2 yr. Both cultivars responded positively to CA storage. Increasing CO2 in the presence of 1–5% O2 reduced decay and the percent unmarketable berries and maintained titratable acids and berry firmness levels. After 42 d of storage, Fundy had 30.5% unmarketable berries in air storage, compared with 8.7% in 15% CO2. Blomidon had 36.0% and 6.8% unmarketable berries in air and 15% CO2, respectively. Decreasing O2 reduced the percentage decayed berries and maintained titratable acids. Botrytis inoculation before storage reduced berry quality, but cultivars responded differently. The quality of berries 7 d after removal from storage was influenced primarily by cultivar, storage time and shelf temperature and not by storage atmosphere. Key words:Vaccinium angustifolium, oxygen, carbon dioxide, shelf-life, firmness, titratable acidity, decay, CA storage

The effects of storage atmosphere on the keeping quality of ‘Idared’ apples

SummaryThe response of ‘Idared’ apples to storage in atmospheres containing less carbon dioxide than the recommended 8% was investigated after it was found that core flush could develop in 8% CO2 + 13% O2 at 3.5°C. Storage in <1 % CO2 and 1 or 2% O2 resulted in less core flush than storage in 5% CO2 + 3% O2, but apples from 2% O2 were softer, as determined by both a sensory panel and a penetrometer, than those from 5% CO2 + 3% O2. Jonathan spot developed in both low oxygen regimes. A pre-harvest application of daminozide increased the surface area coloured red, increased firmness at harvest and reduced the incidence of core flush in samples stored in 8% CO2 + 13% O2. It was concluded that to minimize losses from physiological disorders, ‘Idared’ grown in UK should be picked no later than the beginning of November and stored in <1% CO2 +1% O2 for no more than three months.

Elimination of Pathogens of Significance in Food by Low-dose Irradiation: A Review

Food irradiation is a processing technology that has been shown to be a wholesome process by many scientific studies conducted worldwide during the past 40 years. The research has been supported by the World Health Organization, the Food and Agricultural Organization, and govemmental agencies in many different countries. Industrial support also has been substantial. Some of the benefits ascribed to this technology include improved shelf life, reduced use of Chemicals as preservatives, and reduced levels of pathogens in foods. Pathogens such as Listeria monocytogenes, Yersinia enterocolitica, and Aeromonas hydrophila are capable of growing at temperatures as low as 0°C and are considered to pose a threat to the safety of refrigerated products. The number of cases of foodborne illness caused by contamination by Salmonella and Campylobacter spp. continues to increase. Researchers have been investigating ways in which food safety can be improved without sacrificing product quality and wholesomeness. The sensitivity of these pathogens to low-dose irradiation has been studied in several food products. Survival curves have been elucidated, and some studies on the effects of storage atmosphere, storage temperature, heating, and various treatments in combination with irradiation have been conducted. This review presents background information on this technology, with an emphasis on the radiation sensitivity of some pathogens of importance. Suggestions for future work in this area are also discussed.

Redistribution of minerals in apple fruit during storage: Effects of storage atmosphere on magnesium and phosphorus concentrations

AbstractThe median transverse redistribution of magnesium and phosphorus in Cox's Orange Pippin apples stored at 2·8°C or 4°C was investigated. The more detailed investigation at 4°C showed that phosphorus accumulated in the core zone throughout storage in air, but that the inward movement of magnesium was delayed in the early weeks when magnesium concentration increased in the peel. Storage atmospheres of 2 or 1·25% oxygen (&lt;1% carbon dioxide) inhibited movement of both elements to the core zone and, for a few weeks following the establishment of a 1·25% oxygen atmosphere, magnesium was withdrawn from the core zone. An inward shift of magnesium from the peel to the inner cortex occurred several weeks prior to the development of visible low temperature breakdown symptoms in apples stored in 1·25% oxygen.Similarities between the effects of low oxygen and low temperature storage on the redistribution of magnesium and phosphorus and on the induction of low temperature breakdown are discussed.

Redistribution of minerals in apple fruit during storage: The effect of storage atmosphere on calcium concentration

AbstractCalcium concentrations in median transverse sections of Cox's Orange Pippin apples stored at 4°C in either air or 1.25% oxygen (&lt; 0.3% carbon dioxide) were measured at weekly intervals for 25 weeks. Large fluctuations of calcium concentration occurred in all zones of fruit from both stores throughout storage. The low oxygen atmosphere had little effect on the concentration of calcium in the cortex and redistribution of calcium from the core zone to the outer zones other than causing a decline in calcium concentration in the peel towards the end of storage when calcium concentration was generally rising in the peel of the air‐stored fruit. The results are discussed in relation to the suppression of calcium deficiency disorders by low oxygen storage and to earlier experiments on calcium redistribution and bitter pit development.

The effects of storage atmosphere and temperature on the keeping quality of Spartan apples

SUMMARYThe rate of softening of apples of the variety Spartan was reduced by addition of 6 or 8% CO2 to a storage atmosphere of 2% O2 at 1 ‐5 oC. This effect was observed in three seasons and in samples from five sources. Sensory assessments suggested that addition of carbon dioxide to the storage atmosphere had no adverse effect on eating quality.Storage in 2% O2 at – 1 oC was as effective in maintaining flesh firmness as 8% CO2+ 2%O2 at 1–5 oC.Strategies for further reductions in firmness loss during storage of Spartan apples are discussed.

Effects of storage atmosphere, temperature and calcium on low-temperature injury of peach fruit

Peach fruit ( Prunus persica (L.) Batsch., cultivar ‘J.H. Hale’) stored at 1° C in an atmosphere of 20% carbon dioxide (CO 2) added to air were almost entirely free of low-temperature injury when ripened after 42 days storage, whilst incipient injury occurred in air-stored controls after 21 days. Withdrawal of 20% CO 2 after 14 days of storage abolished the beneficial response. The ability of peaches to evolve CO 2 and ethylene (C 2H 4) normally upon removal from storage at 1° C to air at 20° C was preserved when 20% CO 2 was applied during storage. Incubation of fruit at 20° C for 60 h before cold storage gave slight control of injury, and warming the fruit at 20° C for 72-h periods after 14 and 28 days of storage gave good control of injury. Post-harvest treatment of peaches with calcium chloride solutions before storage reduced low-temperature injury, but caused severe skin damage.

Effect of Storage Atmosphere on Postharvest Growth of Mushrooms1

Abstract Controlled atmosphere (CA) storage prolonged the shelf life of mushrooms (Agaricus bisporus, [Lange] Sing.) if the O2 concentration was 9% or the CO2 concentration was 25 or 50%. Concentrations of 2 to 10% O2 stimulated pileus expansion and stipe elongation with maximal stimulation of growth occurring at 5% O2. Levels of CO2 above 5% markedly inhibited growth, even after air was substituted for the CO2 treatment. Five percent CO2 stimulated stipe elongation and suppressed pileus expansion. Protein degradation, as indicated by protease activity and the level of a-amino N in the tissue, increased during postharvest maturation of mushrooms. As in starving bacteria, it is suggested that the main physiological function of proteolysis in the postharvest maturation of mushrooms is as a source of C and N.