Determining the disinfection of textiles in compressed carbon dioxide using various indicator microbes

Aims: This paper presents a research on the disinfection efficiency of inoculated textile swatches by compressed carbon dioxide, an environmental friendly way to disinfect textiles as opposed to the conventional laundering procedures using water. The disinfection efficiency was determined by using the following microbes inoculated on cotton test fabrics: Enterococcus faecium, Enterobacter aerogenes and Candida albicans. Methods and Results: The experiments were performed using the high pressure extraction device with a maximum pressure of 50 MPa and a small extraction vessel of 500 ml. Pure CO₂ and CO₂ with added disinfection agent or commercial detergent were used. The chosen disinfecting agent was hydrogen peroxide, a widespread disinfecting chemical. It was found that treatment with CO₂ for 25 min at 5 MPa and 40°C (313K) and the addition of 4 ml of specific detergent per litre of CO₂ assures at least a five log step reduction of Enterobacter aerogenes and C. albicans, whilst treatment at 50°C (323K) with CO₂ for 25 min at 5 MPa is sufficient for at least a five log step reduction for Enterococcus faecium. It was also found that a 15‐min CO₂ treatment at 7 MPa and 20°C (293K) was sufficient for the inactivation of the yeast C. albicans, whilst these conditions were not rigorous enough for the challenge bacteria. On the other hand, the labscale treatment with CO₂ for 25 min at pressure 4 and 6 MPa with the addition of detergent or hydrogen peroxide only yields a log step reduction of up to 4 log steps, thus proving the slightly disinfective properties of the CO₂ treatment with added agents, but not reaching efficient results as a 5 log step reduction was not reached. Conclusions: Addition of heat to the compressed CO₂ treatment of textiles inoculated with microorganisms proved more effective than the addition of detergent or disinfectant with compressed CO₂ treatment at temperature of 20°C. Significance and Impact of the Study: CO₂ treatment of textiles is a promising ecological alternative dry‐cleaning method for the disinfection of medical textiles.     

Isolation of off-flavors and odors from tuna fish oil using supercritical carbon dioxide

Off-flavors and unfavorable odors in tuna fish oil were successfully removed and identified using supercritical carbon dioxide extraction, while retaining variable compounds, polyunsaturated fatty acids such as EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). Samples of oil were extracted in a 100 mL semi-batch stainless steel vessel under conditions which ranged from 8 to 20 MPa and 20 to 60°C with solvent (CO₂) flows from 10 g/min. GC-MS was used to identify the main volatile components contributing to the off-flavors and odors which included 2-methyl-1-propanol, 2,4-hexadienal, cyclopropane, and octadiene. Analyses of oil extracted at 40°C, 20 MPa showed a 99.8% reduction in dimethyl disulfide. Other significant off-flavors identified were 2-methyl-butene, 3-hydroxy butanal and ethylbenzene.     

Increased shelf life of a bioherbicide through combining modified atmosphere packaging and low temperatures

The effects of air temperatures (4, 14 and 24°C) and modified atmosphere packaging (MAP) (0% CO₂/100% N₂; 20% CO₂/80% N₂ or 40% CO₂/60% N₂) on vigour of a Sclerotinia minor barley formulation during 6 months storage were evaluated. The study was performed using a multilevel factorial experimental design and response surface methodology (RSM) and aimed to determine the optimum combination of the above factors that resulted in retention of S. minor vigour during storage. Temperature and storage duration are the main factors that affect S. minor vigour. CO₂ concentration had no effect on S. minor vigour during storage. However, oxygen displacement from storage containers by CO₂ and N₂ resulted in significant decrease of vigour reduction of S. minor as compared to ambient air control. An acceptable level of S. minor vigour reduction (ALVR) during storage was developed and determined to be ALVR=31.7±14.8% (mean±95% CI). Contour plot analysis indicated that the S. minor barley formulation at 0.4 water activity could be stored for 6, 12 or 26 weeks without exceeding the upper ALVR threshold (ca. 46%) at air temperatures not higher than 20, 17 or 11°C, respectively.     

Effects of Long Term Exposure to High-CO2 During Storage at 0°C on Biology and Infectivity of Botrytis cinerea in Red Chicory

The effects on Botrytis cinerea of prolonged exposures to CO₂‐enriched atmospheres were studied in vitro and in vivo at 0°C. Mycelial growth on potato dextrose agar decreased linearly with increasing CO₂ concentrations from 5, 10, 15 and 20% CO₂. The growth reduction was greater after 30–40 days of incubation. A reduced production of sclerotia in air by the colonies formerly exposed to various CO₂ concentrations was also detected. Conidial germination was delayed and the amount of germinated conidia decreased with increased CO₂ and at 20% CO₂ it was inhibited. Germ tube elongation was affected in the same way. In artificially inoculated red chicory, lesion area caused by B. cinerea decreased with increasing concentrations of CO₂ up to 60 days storage, later only 10 and 15% CO₂ were really effective, while in the final inspection after 120 days all the concentration tested showed a low efficacy. Similar results were obtained in naturally infected chicory where the severity of the disease decreased by increasing CO₂ from 5 to 10%, higher values did not improve the suppressive effect or determined, after 150 days of storage, an increased vulnerability of the tissues to disease due to the phytotoxic effects of the gas. An atmosphere enriched with 10% CO₂ is advised to suppress Botrytis rot during storage at 0°C of red chicory.     

Physiological responses of Opuntia ficus-indica to growth temperature

The influences of various day/night air temperatures on net CO₂ uptake and nocturnal acid accumulation were determined for Opuntia ficus-indica, complementing previous studies on the water relations and responses to photosynthetically active radiation (PAR) for this widely cultivated cactus. As for other Crassulacean acid metabolism (CAM) plants, net nocturnal CO₂ uptake had a relatively low optimal temperature, ranging from 11°C for plants grown at day/night air temperatures of 10°C/0°C to 23°C at 45°C/35°C. Stomatal opening, which occurred essentially only at night and was measured by changes in water vapor conductance, progressively decreased as the measurement temperature was raised. The CO₂ residual conductance, which describes chlorenchyma properties, had a temperature optimum a few degrees higher than the optimum for net CO₂ uptake at all growth temperatures. Nocturnal CO₂ uptake and acid accumulation summed over the whole night were maximal for growth temperatures near 25°C/15°C, CO₂ uptake decreasing more rapidly than acid accumulation as the growth temperature was raised. At day/night air temperatures that led to substantial nocturnal acid accumulation (25°C/15°C.). 90% saturation of acid accumulation required a higher total daily PAR than at non-optimal growth temperatures (10°C/0°C and 35°C/25°C). Also, the optimal temperature of net CO₂ uptake shifted downward when the plants were under drought conditions at all three growth temperatures tested, possibly reflecting an increased fractional importance of respiration at the higher temperatures during drought. Thus, water status, ambient PAR, and growth temperatures must all be considered when predicting the temperature response of gas exchange for O. ficus-indica and presumably for other CAM plants.     

Interactive effects of low atmospheric CO2 and elevated temperature on growth, photosynthesis and respiration in Phaseolus vulgaris

For most of the past 250 000 years, atmospheric CO₂ has been 30–50% lower than the current level of 360 μmol CO₂ mol^–1 air. Although the effects of CO₂ on plant performance are well recognized, the effects of low CO₂ in combination with abiotic stress remain poorly understood. In this study, a growth chamber experiment using a two-by-two factorial design of CO₂ (380 μmol mol^–1, 200 μmol mol^–1) and temperature (25/20 °C day/night, 36/29 °C) was conducted to evaluate the interactive effects of CO₂ and temperature variation on growth, tissue chemistry and leaf gas exchange of Phaseolus vulgaris. Relative to plants grown at 380 μmol mol^–1 and 25/20 °C, whole plant biomass was 36% less at 380 μmol mol^–1× 36/29 °C, and 37% less at 200 μmol mol^–1× 25/20 °C. Most significantly, growth at 200 μmol mol^–1× 36/29 °C resulted in 77% less biomass relative to plants grown at 380 μmol mol^–1× 25/20 °C. The net CO₂ assimilation rate of leaves grown in 200 μmol mol^–1× 25/20 °C was 40% lower than in leaves from 380 μmol mol^–1× 25/20 °C, but similar to leaves in 200 μmol mol^–1× 36/29 °C. The leaves produced in low CO₂ and high temperature respired at a rate that was double that of leaves from the 380μmol mol^–1× 25/20 °C treatment. Despite this, there was little evidence that leaves at low CO₂ and high temperature were carbohydrate deficient, because soluble sugars, starch and total non-structural carbohydrates of leaves from the 200μmol mol^–1× 36/29 °C treatment were not significantly different in leaves from the 380μmol mol^–1× 25/20 °C treatment. Similarly, there was no significant difference in percentage root carbon, leaf chlorophyll and leaf/root nitrogen between the low CO₂× high temperature treatment and ambient CO₂ controls. Decreased plant growth was correlated with neither leaf gas exchange nor tissue chemistry. Rather, leaf and root growth were the most affected responses, declining in equivalent proportions as total biomass production. Because of this close association, the mechanisms controlling leaf and root growth appear to have the greatest control over the response to heat stress and CO₂ reduction in P. vulgaris.     

High pressure homogenization inactivation of Escherichia coli and Staphylococcus aureus in phosphate buffered saline,milk and apple juice

High pressure homogenization (HPH) offers new opportunities for food pasteurization/sterilization. Escherichia coli and Staphylococcus aureus suspended in phosphate buffered saline (PBS) buffer, milk and apple juice at initial concentration of ~10⁶ log₁₀ CFU per ml were subjected to HPH treatments up to 200 MPa with inlet temperatures at 4–40°C. After HPH at 200 MPa with the inlet temperature at 40°C, the count of E. coli suspended in PBS, milk and apple juice reduced by 3·42, 3·67 and 3·19 log₁₀ CFU per ml respectively while the count of S. aureus decreased by 2·21, 1·02 and 2·33 log₁₀ CFU per ml respectively suggesting that S. aureus was more resistant. The inactivation data were well fitted by the polynomial equation. Milk could provide a protective effect for S. aureus against HPH. After HPH at 200 MPa with the inlet temperature at 20°C, the cell structure of E. coli was destroyed, while no obvious damages were found for S. aureus.     

Disinfestations of the oriental tobacco budworm in green hot pepper by ultra high carbon dioxide: Implications for postharvest fruit quality

To develop environmentally amenable insect disinfestations, effects of a carbon dioxide (CO₂) controlled atmosphere (CA) on the control of the oriental tobacco budwormHelicoverpa assulta were investigated in green hot peppers. Green hot peppers (cv. Nokgwang) were exposed to CO₂. at 80% and 100% in 0.08-mm polyethylene film bags for 24 and 48 h at 20°C. Mortality percentages of oriental tobacco budworm larvae were determined after gas exposure. The CO₂-CA at both concentrations for 24 h greatly reduced survival of the larvae, showing approximately 65% mortality when compared with control fruit. Prolonged exposure at both concentrations up to 48 h completely disinfested the larvae. To evaluate plausible deleterious effects of the ultra high CO₂-CA on green hot peppers, the fruit were stored at 10°C, and postharvest quality was analyzed in terms of firmness, electrolyte leakage, respiration rate, and content of vitamin C and capsaicin. There were no significant differences in postharvest fruit quality up to 20 days of storage, compared with control fruit. Meanwhile, respiration rates of exposed pepper fruit were approximately half the control’s rate after 20 days of storage. These results suggested that ultra high CO₂ CA could disinfestH. assulta without significant differences in postharvest quality of green hot peppers, compared with control fruit. Exposure of 80% CO₂ for 24 h would be recommended as a reliable control means that is harmless to humans and can alleviate concern regarding pesticide residues.     

The transmission of European wheat striate mosaic virus by Javesella pellucida (Fabr.) injected with extracts of plants and plant-hoppers

Virus-free individuals of the plant-hopper Javesella pellucida (Fabr.) infected plants with European wheat striate mosaic virus (EWSMV) after being injected at 5° C. with extracts of either plants or hoppers, but extracts of hoppers provided a better inoculum. Hoppers were unable to infect plants until at least 8 days at 20–25° C. after they were injected, and nymphs fed on infected plants similarly required 8 days before they gave infective extracts. Few hoppers survived more than a week after injection with untreated extracts of hoppers or with material sedimented from them by centrifuging the extracts at 8000g, but 60–70% survived injection with purer virus preparations. Injection of the virus seemed harmless, because as many hoppers survived CO₂ anaesthesis + injection, whether or not they later infected plants, as survived anaesthesis without injection. Attempts to determine the properties of the virus in vitro gave inconsistent results, but virus from hoppers was still infective after 10 min. at 30° C, 36 hr. at 5° C, precipitation at pH 4.0, storage for several months at -15° C, or at a dilution equivalent to 0.0014 g. hopper/ml. The best extraction medium contained 0.2 M-Na₂HPO₄+ ascorbic acid + 0.01 M-DIECA at pH 7.0–7.3. In sucrose density-gradients, EWSMV sedimented more slowly than tobacco mosaic virus. No specific particle with which infectivity could be correlated was seen by electron microscopy.     

CO2 uptake by the cultivated hemiepiphytic cactus, Hylocereus undatus

The climate of the native tropical forest habitats of Hylocereus undatus, a hemiepiphytic cactus cultivated in 20 countries for its fruit, can help explain the response of its net CO2 uptake to environmental factors. Under wet conditions, about 85% of the total daily net CO₂ uptake occurs at night via Crassulacean acid metabolism, leading to a high water‐use efficiency. Total daily net CO₂ uptake is reduced 57% by only 10 days of drought, possibly involving stomatal closure induced by abscisic acid produced in the roots, which typically occupy a small substrate volume. Total daily net CO₂ uptake for H. undatus is maximal at day/night air temperatures of 30/20°C, optimal temperatures that are higher than those for desert cacti but representative of ambient temperatures in the tropics; its total daily net CO₂ uptake becomes zero at day/night air temperatures of 42/32°C. Stem damage occurs at 45°C for H. undatus, whose photosynthetic cells show little acclimation to high temperatures compared with other cacti and are also sensitive to low temperatures, ‐1.5°C killing half of these cells. Consistent with its shaded habitat, total daily net CO2 uptake is appreciable at a total daily PPF of only 2 mol m2 day' and is maximal at 20 mol m^?2 day^?1, above which photoinhibition reduces net CO₂ uptake. Net CO₂ uptake ability, which is highly correlated with stem nitrogen and chlorophyll contents, changes only gradually (halftimes of 2–3 months) as the concentration of applied N is changed. Doubling the atmospheric CO₂ concentration raises the total daily net CO₂ uptake of H. undatus by 34% under optimal conditions and by even larger percentages under adverse environmental conditions.     

The effects of development at sub-optimal growth temperatures on photosynthetic capacity and susceptibility to chilling-dependent photoinhibition in Zea mays

When plants of Zea mays L. cv. LG11 that have been grown at optimal temperatures are transferred to chilling temperatures (0–12°C) photoinhibition of photosynthetic CO₂ assimilation can occur. This study examines how growth at sub-optimal temperatures alters both photosynthetic capacity and resistance to chilling-dependent photoinhibition. Plants of Z. mays cv. LG11 were grown in controlled environments at 14, 17, 20 and 25°C. As a measure of the capacity for photosynthesis under light limiting conditions, the maximum quantum yields of CO₂ assimilation (φ^a.c) and O₂ evolution (φ^a.o) were determined for the laminae of the second leaves at photon fluxes of 50–150 μmol m^-2s^-1. To determine photosynthetic capacity at photon fluxes approaching light saturation, rates of CO₂ uptake (A₁₅₀₀) and O₂ evolution (A₁₅₀₀) were determined in a photon flux of 1500 μmol m^-2s^-1. In leaves developed at 14°C, φ and φ were 26 and 43%, respectively, of the values for leaves grown at 25°C. Leaves grown at 17°C showed intermediate reductions in φ and φ, whilst leaves developed at 20°C showed no significant differences from those grown at 25°C. Similar patterns of decrease were observed for A₁₅₀₀ and A_1500.0 with decreasing growth temperature. Leaves developed at 25°C showed higher rates of CO₂ assimilation at all light levels and measurement temperatures in comparison to leaves developed at 17 and 14°C. A greater reduction in A₁₅₀₀ relative to A_1500.0 with decreasing growth temperature was attributed to increased stomatal limitation. Exposure of leaves to 800–1000 μmol m^-2 s^-1 when plant temperature was depressed to ca 6.5°C produced a photoinhibition of photosynthetic CO₂ assimilation in all leaves. However, in leaves developed at 17°C the decrease in A₁₅₀₀ following this chilling treatment was only 25% compared to 90% in leaves developed at 25°C. Recovery following chilling was completed earlier in leaves developed at 17°C. The results suggest that growth at sub-optimal temperatures induces increased tolerance to exposure to high light at chilling temperatures. This is offset by the large loss in photosynthetic capacity imposed by leaf development at sub-optimal temperatures.     

Quantitation using a stable isotope dilution assay (SIDA) and thresholds of taste-active pyroglutamyl decapeptide ethyl esters (PGDPEs) in sake

A stable isotope dilution assay (SIDA) for two taste-active pyroglutamyl decapeptide ethyl esters (PGDPE1; (pGlu)LFGPNVNPWCOOC₂H₅, PGDPE2; (pGlu)LFNPSTNPWCOOC₂H₅) in sake was developed using deuterated isotopes and high-resolution mass spectrometry. Recognition thresholds of PGDPEs in sake were estimated as 3.8 μg/L for PGDPE1 and 8.1 μg/L for PGDPE2, evaluated using 11 student panelists aged in their twenties. Quantitated concentrations in 18 commercial sake samples ranged from 0 to 27 μg/L for PGDPE1 and from 0 to 202 μg/L for PGDPE2. The maximum levels of PGDPE1 and PGDPE2 in the sake samples were approximately 8 and 25 times higher than the estimated recognition thresholds, respectively. The results indicated that PGDPEs may play significant sensory roles in the sake. The level of PGDPEs in unpasteurized sake samples decreased during storage for 50 days at 6 °C, suggesting PGDPEs may be enzymatically decomposed.     

An analysis of photosynthetic response and adaptation to temperature in higher plants: temperature acclimation in the desert evergreen Nerium oleander L*

Abstract. Factors underlying the process of photosynthetic acclimation to temperature were investigated for the shrub Nerium oleander L. Ramets of a single clone were grown under day/night temperature regimes of 20°C/15°C or 45°C/32°C. Plants grown at the lower temperature regime possessed rates of photosynthesis twice that of the high-temperature grown plants when CO₂ fixation was measured at 20°C. In contrast, the plants grown at the high-temperature regime had twice the rate of CO₂ fixation of the 20°C/l 5°C-grown plants at a measurement temperature of 45° C. It was determined that the ability to acclimate to changes in temperature regime was present in fully mature leaves. A reciprocal transfer of plants between the two growth regimes resulted in the appearance of the CO₂ fixation characteristics appropriate to the new growth temperature after 12–14d. The response of CO₂ fixation to light, temperature, and CO₂ partial pressure and the temperature responses of soluble and membrane-bound photosynthetic enzyme systems were analysed to determine which components might be responsible for the superior photosynthetic performance of the 20°C/I5°C-grown plants at 20°C, and the enhanced high-temperature stability of the 45°C/32°C plants. The measured photosynthetic capacity of the 20°C/15°C plants could not be attributed to gross morphological, stomatal, or other physical changes, or to a general increase in the concentration of components of the photosynthetic process. Only a single enzyme, Fru-P₂ phosphatase, was affected to an extent similar to that of photosynthesis. The enhanced thermal stability of the 45°C/32°C plants may be attributed primarily to an enhanced stability of the chloroplast membrane-bound enzymatic activities and the stability of the photosynthetic carbon metabolism enzymes which require lighl for activation.     

Inhibition of whole plant respiration by elevated CO2 as modified by growth temperature

Plants of alfalfa (Medicago sativa) and orchard grass (Dactylus glomerata) were grown in controlled environment chambers at two CO₂ concentrations (350 and 700 μmol mol^-1) and 4 constant day/night growth temperatures of 15, 20, 25 and 30°C for 50–90 days to determine changes in growth and whole plant CO₂ efflux (dark respiration). To facilitate comparisons with other studies, respiration data were expressed on the basis of leaf area, dry weight and protein. Growth at elevated CO₂ increased total plant biomass at all temperatures relative to ambient CO₂, but the relative enhancement declined (P≤0.05) as temperature increased. Whole plant respiration (R_d) at elevated CO₂ declined at 15 and 20°C in D. glomerata on an area, weight or protein basis and in M. sativa on a weight or protein basis when compared to ambient CO₂. Separation of R_d into respiration required for growth (R_g) and maintenance (R_m) showed a significant effect of elevated CO₂ on both components. R_m was reduced in both species but only at lower temperatures (15°C in M. sativa and 15 and 20°C in D. glomerata). The effect on R_m could not be accounted for by protein content in either species. R_g was also reduced with elevated CO₂; however no particular effect of temperature was observed, i. e. R_g was reduced at 20, 25 and 30°C in M. sativa and at 15 and 25°C in D. glomerata. For the two perennial species used in the present study, the data suggest that both R_g and R_m can be reduced by anticipated increases in atmospheric CO₂; however, CO₂ inhibition of total plant respiration may decline as a function of increasing temperature     

Determination of L-ascorbic acid levels in culture medium: Concentrations in commercial media and maintenance of levels under conditions of organ culture

Summary The method of Deutsch and Weeks was modified to provide a reliable and reasonably quick method for assaying the L-ascorbic acid content of culture medium. The modified method was used to determine the decay of L-ascorbic acid under various conditions of culture and the concentration of the vitamin in commercially prepared media. The half-life of L-ascorbic acid in a modified New circulator gassed with 95% O₂+5% CO₂ was 1.5 hr.; and when gassed with 20% O₂+5% CO₂+75% N₂, about 2 hr. In Petri dishes gassed with 20% O₂+5% CO₂+75% N₂, the half-life of L-ascorbic acid was 0.9 hr. About 4% of the L-ascorbic acid was lost per day when medium was stored at 0°C and about 9% per day when stored at 5°C. When medium with an initial content of 300 μg per ml was stored at room temperature, the half-life was found to be 15.5 hr. The L-ascorbic acid in five commercially available media, which contain the vitamin in their formulations, was assayed immediately after their delivery to the laboratory. The values of L-ascorbic acid measured in these media were in all cases far lower than prescribed. A continuous-flow organ culture system has been designed which allows the provision of a relatively constant level of L-ascorbic acid to an explant by taking advantage of the slow oxidation of L-ascorbic acid at 0°C.     

Supercritical Carbon Dioxide Extraction of Allium ursinum: Impact of Temperature and Pressure on the Extracts Chemical Profile

The aim of this study was to extract Allium ursinum L. for the first time by supercritical carbon dioxide (SC−CO₂) as green sustainable method. The impact of temperature in the range from 40 to 60 °C and pressure between 150 and 400 bar on the quality of the obtained extracts and efficiency of the extraction was investigated. The highest extraction yield (3.43 %) was achieved by applying the extraction conditions of 400 bar and 60 °C. The analysis of the extracts was performed by gas chromatography and mass spectrometry (GC/MS). The most dominant sulfur-containing constituent of the extracts was allyl methyl trisulfide with the highest abundance at 350 bar and 50 °C. In addition, the presence of other pharmacologically potent sulfur compounds was recorded including S-methyl methanethiosulfinate, diallyl trisulfide, S-methyl methylthiosulfonate, and dimethyl trisulfide. Multivariate data analysis tool was utilized to investigate distributions of the identified compounds among the extracts obtained under various extraction conditions and yields. It was determined that the SC−CO₂ extraction can by efficiently used for A. ursinum.     

Post-harvest treatments for the control of Phytophthora syringae storage rot of apples

Oospores of Phytophthora syringae germinating at 10 and 15°C under artificial light formed one or more sporangia, which yielded zoospores. Furalaxyl and metalaxyl demonstrated eradicant action against infections occurring on zoospore-inoculated apples. Control was obtained at 10°C when treatment was delayed 5–11 days after inoculation. Storage in 5% CO₂+ 3% O₂ and 0% CO₂+ 2% O₂ reduced rotting compared with storage in air.     

Feasibility of supercritical CO2 treatment for controlling biofouling in the reverse osmosis process

Physical cleaning and/or chemical cleaning have been generally used to control biofouling in the reverse osmosis (RO) process. However, conventional membrane cleaning methods to control biofouling are limited due to the generation of by-products and the potential for damage to the RO membranes. In this study, supercritical carbon dioxide (SC CO₂) treatment, an environmentally friendly technique, was introduced to control biofouling in the RO process. SC CO₂ (100 bar at 35°C) treatment was performed after biofouling was induced on a commercial RO membrane using Pseudomonas aeruginosa PA01 GFP as a model bacterial strain. P. aeruginosa PA01 GFP biofilm cells were reduced on the RO membrane by >8 log within 30 min, and the permeate flux was sufficiently recovered in a laboratory-scale RO membrane system without any significant damage to the RO membrane. These results suggest that SC CO₂ treatment is a promising alternative membrane cleaning technique for biofouling in the RO process.     

Brewing of saké from rice and rice-koji defatted by supercritical carbon dioxide treatment

Saké was brewed using rice and rice-koji defatted by extraction with supercritical carbon dioxide (SCCO₂). Extraction with SC:CO₂ at 300 atm and 40°C decreased the total contents of lipids of 90%- and 80%-polished rice to levels comparable to those of 80%- and 70%-polished rice. Addition of 5 wt% ethanol to SCCO₂ further decreased the total lipids. SCCO₂ extraction also removed lipids from rice-koji without decreasing its enzymatic activities. SCCO₂ treatment of rice improved the quality of saké, but SCCO₂ treatment of rice-koji did not.     

High Temperatures and Net CO2 Uptake, Growth, and Stem Damage for the Hemiepiphytic Cactus Hylocereus undatus1

Hylocereus undatus, which is native to tropical forests experiencing moderate temperatures, would not be expected to tolerate the extremely high temperatures that can be tolerated by cacti native to deserts. Nevertheless, total daily net CO₂ uptake by this hemiepiphytic cactus, which is widely cultivated for its fruits, was optimal at day/night air temperatures of 30/20°C, temperatures that are higher than those optimal for daily net CO₂ uptake by cacti native to arid and semiarid areas. Exposure to 35/25°C for 30 weeks led to lower net CO₂ uptake than at 10 weeks; exposure to 40/30°C led to considerable necrosis visible on the stems at 6 weeks and nearly complete browning of the stems by 19 weeks. Dry mass gain over 31 weeks was greatest for plants at 30/20°C, with root growth being especially noteworthy and root dry mass gain representing an increasing percentage of plant dry mass gain as day/night air temperatures were increased. Viability of chlorenchyma cells, assayed by the uptake of the vital stain neutral red into the central vacuoles, was decreased 50 percent by a one‐hour treatment at 55°C compared with an average of 64°C for 18 species of cacti native to deserts. The lower high‐temperature tolerance for H. undatus reflected its low high‐temperature acclimation of only 1.4°C as growth temperatures were raised by 10°C compared with an average acclimation of 5.3°C for the other 18 species of cacti. Thus, this tropical hemiepiphytic cactus is not adapted to day/night air temperatures above ca 40/30°C, although its net CO₂ uptake is optimal at the relatively high day/night air temperatures of 30/20°C.