Use of egg yolk phospholipids to improve the thermal-oxidative stability of fatty acids, capsaicinoids and carotenoids in chili oil.

Phospholipids can act as antioxidants in food. In this study, egg yolk phospholipids (EPL) and sunflower oil were utilized in making chili oil, and proton nuclear magnetic resonance spectroscopy was employed to quantify the concentrations of fatty acyl groups, carotenoids, capsaicinoids in chili oil according to their specific signals in the spectra. The results showed that the changes in the concentrations of fatty acyl groups in the control samples were greater than those in the EPL-treated samples at the same frying temperature, while the contents of carotenoids and capsaicinoids were significantly lower than those of the EPL-treated samples when fried at 150 °C (p < 0.05). Two-way ANOVA indicated that frying temperature and EPL treatment, as well as their interaction had significant impacts on the thermal-oxidative stability of chili oil (p < 0.05). The results suggest that EPL may act as antioxidants during frying, and EPL can improve the thermal-oxidative stability of chili oil.

The effect of lutein on the oxidation of egg yolk phospholipids in a liposome model.

Egg yolk phospholipids (PLs) extracted by organic solvent are prone to oxidation, while they are quite stable in egg yolk. This study was to verify the decisive role of lutein (naturally present in egg yolk) on the oxidative stability of PLs by constructing liposome. The liposome samples were heated at 100 °C for 10 min, and then the oxidation products of the liposome samples were analyzed by 1H NMR and GC-MS. The results showed that the concentrations of most of the oxidation products in the PLs-liposomes sample were significantly higher than those in the PLs&lutein-liposomes sample. Therefore, lutein could protect egg yolk PLs from oxidation, thus inhibiting the formation of lipid-derived volatile compounds. As those lipid-derived volatile compounds are the key fatty note odorants, this study has confirmed that the removal of lutein is the determining factor in using egg yolk PLs as an ideal precursor of fatty note odorants.

Egg yolk phospholipids as an ideal precursor of fatty note odorants for chicken meat and fried foods: A review.

Egg yolk phospholipids (PLs) have been demonstrated to generate large quantities of lipid-derived odorants, especially the fatty note odorants. Recently, egg yolk PLs have been successfully used in chicken meat and fried foods to improve aroma. This review comprehensively summarizes the properties of egg yolk PLs as precursors of fatty note odorants, including their classes, extraction, identification, oxidation, decomposition and odorant formation, applications, considerations and future prospects in the food industry. Most likely, phosphatidylcholine (PC) is the most abundant class in egg yolk PLs, and PC is more efficient than phosphatidylethanolamine in generating fatty note odorants; moreover, the predominant polyunsaturated fatty acid is linoleic acid, and its corresponding predominant hydroperoxide is 9-hydroperoxy-10,12-octadecadienoic acid during autoxidation, which is the precursor of 2,4-decadienals and 2,4-nonadienals, the key fatty note odorants. Therefore, egg yolk PLs could be an ideal precursor of fatty note odorants for chicken meat and fried foods.

Investigation on the changes of carotenoids and capsaicinoids in chili oil at different frying temperature by using 1H NMR.

The color and pungency are important indicators for evaluating the quality of chili oil, which are mainly determined by the carotenoids and capsaicinoids, respectively. In this study, the effect of frying temperature on the changes of carotenoids and capsaicinoids in chili oil was qualitatively and quantitatively analyzed by 1H NMR. The increasing frying temperature caused the thermal degradation of carotenoids to be intensified, and the degradation of red carotenoids was greater than that of yellow carotenoids. After 10 min of frying at 130, 150, 170 and 190 °C, the contents of capsanthin in chili oil were 40.3, 15.4, 9.6 and 6.2 mg/kg, respectively. Meanwhile, the contents of total carotenoids were 63.0, 25.5, 17.7 and 13.3 mg/kg, respectively. The observed change of R/Y values correlated well with the degradation of carotenoids. The contents of capsaicinoids were 14.8, 20.9, 19.4 and 7.4 mg/kg, respectively. The best frying temperature for the extraction of carotenoids was 130 °C, and over 90% of the carotenoids were dissolved in the frying oil at this frying condition. However, capsaicinoids were more stable than carotenoids, and the best frying temperature for capsaicinoids was 150-170 °C with over 90% extraction rate. Therefore, the temperature fried at 130-150 °C was suitable for the quality of chili oil, considering the higher extraction rates of both total carotenoids and capsaicinoids. This study is of great significance for the quality control of chili oil.

Carvedilol ameliorates persistent erythema of erythematotelangiectatic rosacea by regulating the status of anxiety/depression.

The treatment of persistent erythema and rosacea flushing is extremely challenging, especially for patients with anxiety. The aim of this study was to verify the efficacy of carvedilol in rosacea patients with persistent erythema and flushing. A total of 156 patients were randomized to use oral carvedilol 5 mg bid (twice per day) (n = 105) or topical brimonidine (n = 51) for a 10-week period with 6 weeks of follow-up. Both the efficacy of carvedilol and the status of anxiety/depression were analyzed by patient self-assessment (PSA), clinician erythema assessment (CEA), generalized anxiety disorder (GAD-7), and patient health questionnaire-9 (PHQ-9). Our study found that carvedilol exerted a dramatic reduction in CEA/PSA scores and sting/burning sensation scores in comparison to topical brimonidine. Additionally, carvedilol treatment dramatically improved telangiectasia, erythema, and pigmentation with no obvious side effects. Patients with carvedilol treatment showed an improvement of depression/anxiety, as reflected by lower GAD-7 and PHQ-9 scores than patients with topical brimonidine. Notably, we found carvedilol treatment had better outcomes among patients under 30 years of age with rosacea younger than 30 years old. Conclusively, our findings reveal that carvedilol could quickly and effectively improve facial erythema, which might stem from the improved the status of anxiety/depression.

Use of egg yolk to imitate meat aroma.

Egg yolk contains abundant meat precursors, but its odor is quite different from meat aroma. In this study, the lipids in egg yolk were partly removed by acetone or totally removed by chloroform/methanol, and lutein was removed simultaneously by the solvents. Then, the samples were heated, and the volatiles and aroma profiles were analyzed. The results showed that chicken meat aroma and meat aroma were imitated successfully through the removal of neutral lipids and lutein (acetone-treated) and total lipids and lutein (chloroform/methanol-treated) egg yolk samples, respectively. Finally, additional lutein and tert-butylhydroquinone were employed for validating the inhibiting effects of lutein on lipid oxidation and Maillard reaction, and the results demonstrated that it was lutein rather than lipids or their degradation products that determined the flavor formation. These findings push forward the mechanisms for the formation of meat flavor and provide insights for future manufacturing of meat aroma.

Key aroma-active compounds in brown sugar and their influence on sweetness.

Brown sugar (non-centrifugal cane sugar) is popular for its pleasant caramel-like aroma and sweetness. Vacuum simultaneous steam distillation and extraction (V-SDE) and gas chromatography-mass spectrometry (GC-MS) was used to study the volatile fraction of brown sugar. To further determine the aroma-active compounds in brown sugar, gas chromatography-mass spectrometry-olfactometry (GC-MS-O) were used in conjunction with aroma extraction dilution analysis (AEDA), odor activity values (OAVs), and sensory evaluation to analyze the effects of the key aroma-active compounds on sweetness. A total of 37 aroma-active compounds were obtained, mainly including ketones, pyrazines, alkanes, phenols and alcohols, which contributed caramel, sweet and fruity notes to brown sugar. Among them, furfural, benzeneacetaldehyde, 2,3-butanedione, ß-damascenone, 2-methoxyphenol, dihydro-2-methyl-3(2H)-furanone, 2-furanmethanol and butyrolactone could significantly enhance the sweetness of sugar solution because of the congruency of the aroma attributes and sweetness.

Characterisation of aroma-active compounds in Guilin Huaqiao white sufu and their influence on umami aftertaste and palatability of umami solution.

Sufu is a traditional fermented soybean curd, and Guilin Huaqiao white sufu is one of the most famous mould-fermented white sufu in China. The volatile compounds in sufu were extracted by vacuum simultaneous steam distillation and extraction (V-SDE) and analysed by gas chromatography-mass spectrometry-olfactometry (GC-MS-O). The aroma-active compounds were identified by aroma extract dilution analysis (AEDA) and odour activity values (OAVs), and their influence on umami aftertaste and palatability of umami solution was identified by sensory evaluation analysis in the follow-up research. A total of 88 volatile compounds, contained 20 aroma-active compounds were identified, of which (E,E)-2,4-decadienal, 1-octen-3-ol, (E,E)-2,4-nonadienal, eugenol, ethyl hexanoate and phenylacetaldehyde were not only the aroma-active compounds in Guilin Huaqiao white sufu, but also played an important role in enhancing the umami aftertaste and palatability of umami solution because of the congruency of the aroma and umami taste.

Identification of the Non-Volatile Taste-Active Components in Crab Sauce.

Crab sauce is a traditional umami seasoning in the coastal cities in South East China. The putative non-volatile taste-active components in crab sauce were measured, and their impacts on the taste were evaluated on the basis of the taste activity value (TAV), omission test, addition test and equivalent umami concentration (EUC). The EUC used to evaluate the synergistic effect of the flavor nucleotides and umami amino acids was 19.3 g monosodium glutamate (MSG)/100 mL, which illuminated that crab sauce had a very intense umami taste. The key non-volatile taste-active components in crab sauce demonstrated by the omission test and addition test were glutamic acid (Glu), aspartic acid (Asp), glycine (Gly), alanine (Ala), lysine (Lys), histidine (His), 5'-inosine monophosphate (IMP), 5'-guanosine monophosphate (GMP), NaCl, KCl, serine (Ser) and valine (Val), and most of these components also had a higher TAV. So, the TAV could be a high-efficiency tool to predict the taste-active components, and the TAV combined with the omission test and addition test could be a very useful method to determine the taste-active components in crab sauce.

Egg yolk phospholipids: a functional food material to generate deep-fat frying odorants.

BACKGROUND: Phospholipids are an important precursor for the generation of carbonyl compounds that play a significant role in the characteristic aroma of deep-fat fried foods. RESULTS: Phospholipids extracted from hen egg yolks were added into sunflower oil (2.0 g kg-1 ) and heated with or without chicken meat at 160 °C for 10 min, and then dynamic headspace extraction and gas chromatography-mass spectrometry were used to extract and analyse the volatiles. The results showed that the characteristic deep-fat frying odorants, such as (E,E)-2,4-decadienal and (E,Z)-2,4-decadienal, as well as 1-octen-3-one, (E)-2-nonenal, octanal, methional, dimethyl disulfide and alkylpyrazines, had increased by 3-65 times in the sunflower oil with added phospholipids, and increased up to six times in chicken meat that had been treated with phospholipids prior to heating. CONCLUSION: There is potential for the food industry to use low levels of phospholipids, particularly egg yolk phospholipids, to increase deep-fat frying odorants in a wide range of deep-fried products. © 2019 Society of Chemical Industry.

Targeting mitochondria-associated membranes as a potential therapy against endothelial injury induced by hypoxia.

Mitochondrial dysfunction plays a principal role in hypoxia-induced endothelial injury, which is involved in hypoxic pulmonary hypertension and ischemic cardiovascular diseases. Recent studies have identified mitochondria-associated membranes (MAMs) that modulate mitochondrial function under a variety of pathophysiological conditions such as high-fat diet-mediated insulin resistance, hypoxia reoxygenation-induced myocardial death, and hypoxia-evoked vascular smooth muscle cell proliferation. However, the role of MAMs in hypoxia-induced endothelial injury remains unclear. To explore this further, human umbilical vein endothelial cells and human pulmonary artery endothelial cells were exposed to hypoxia (1% O2 ) for 24 hours. An increase in MAM formation was uncovered by immunoblotting and immunofluorescence. Then, we performed small interfering RNA transfection targeted to MAM constitutive proteins and explored the biological effects. Knockdown of MAM constitutive proteins attenuated hypoxia-induced elevation of mitochondrial Ca2+ and repressed mitochondrial impairment, leading to an increase in mitochondrial membrane potential and ATP production and a decline in reactive oxygen species. Then, we found that MAM disruption mitigated cell apoptosis and promoted cell survival. Next, other protective effects, such as those pertaining to the repression of inflammatory response and the promotion of NO synthesis, were investigated. With the disruption of MAMs under hypoxia, inflammatory molecule expression was repressed, and the eNOS-NO pathway was enhanced. This study demonstrates that the disruption of MAMs might be of therapeutic value for treating endothelial injury under hypoxia, suggesting a novel strategy for preventing hypoxic pulmonary hypertension and ischemic injuries.

Nogo-B Receptor Directs Mitochondria-Associated Membranes to Regulate Vascular Smooth Muscle Cell Proliferation.

Mitochondria-associated membranes (MAM) are a well-recognized contact link between the mitochondria and endoplasmic reticulum that affects mitochondrial biology and vascular smooth muscle cells (VSMCs) proliferation via the regulation of mitochondrial Ca2+(Ca2+m) influx. Nogo-B receptor (NgBR) plays a vital role in proliferation, epithelial-mesenchymal transition, and chemoresistance of some tumors. Recent studies have revealed that downregulation of NgBR, which stimulates the proliferation of VSMCs, but the underlying mechanism remains unclear. Here, we investigated the role of NgBR in MAM and VSMC proliferation. We analyzed the expression of NgBR in pulmonary arteries using a rat model of hypoxic pulmonary hypertension (HPH), in which rats were subjected to normoxic recovery after hypoxia. VSMCs exposed to hypoxia and renormoxia were used to assess the alterations in NgBR expression in vitro. The effect of NgBR downregulation and overexpression on VSMC proliferation was explored. The results revealed that NgBR expression was negatively related with VSMCs proliferation. Then, MAM formation and the phosphorylation of inositol 1,4,5-trisphosphate receptor type 3 (IP3R3) was detected. We found that knockdown of NgBR resulted in MAM disruption and augmented the phosphorylation of IP3R3 through pAkt, accompanied by mitochondrial dysfunction including decreased Ca2+m, respiration and mitochondrial superoxide, increased mitochondrial membrane potential and HIF-1α nuclear localization, which were determined by confocal microscopy and Seahorse XF-96 analyzer. By contrast, NgBR overexpression attenuated IP3R3 phosphorylation and HIF-1α nuclear localization under hypoxia. These results reveal that dysregulation of NgBR promotes VSMC proliferation via MAM disruption and increased IP3R3 phosphorylation, which contribute to the decrease of Ca2+m and mitochondrial impairment.

Use of egg yolk phospholipids to generate chicken meat odorants.

Lipids, particularly phospholipids, are known to play a significant role in the characteristic aroma of the different meat species. Both neutral lipids and phospholipids were extracted from egg yolk and added to minced chicken (1% w/w) prior to cooking in water at 100 °C for 20 min. Sensory analysis of the broths showed that the addition of phospholipids significantly increased the chicken meat aroma whereas the addition of neutral lipids did not. GC-MS analysis showed a significant increase in most of the lipid-derived volatile components when the phospholipids were added, especially 2,4-decadienal, which is a characteristic odour impact compound in chicken. There were very few significant changes in the volatile profile when the neutral lipids were added. These data provide direct evidence that the addition of phospholipids can enhance chicken meat aroma, and addition of egg yolk phospholipids could be applied to improve chicken meat aroma.

Hypoxia Exacerbates Inflammatory Acute Lung Injury via the Toll-Like Receptor 4 Signaling Pathway.

Acute lung injury (ALI) is characterized by non-cardiogenic diffuse alveolar damage and often leads to a lethal consequence, particularly when hypoxia coexists. The treatment of ALI remains a challenge: pulmonary inflammation and hypoxia both contribute to its onset and progression and no effective prevention approach is available. Here, we aimed to investigate the underlying mechanism of hypoxia interaction with inflammation in ALI and to evaluate hypoxia-inducible factor 1 alpha (HIF-1α)-the crucial modulator in hypoxia-as a potential therapeutic target against ALI. First, we developed a novel ALI rat model induced by a combined low-dose of lipopolysaccharides (LPS) with acute hypoxia. Second, we used gene microarray analysis to evaluate the inflammatory profiles of bronchi alveolar lavage fluid cells of ALI rats. Third, we employed an alveolar macrophage cell line, NR8383 as an in vitro system together with a toll-like receptor 4 (TLR4) antagonist TAK-242, to verify our in vivo findings from ALI animals. Finally, we tested the therapeutic effects of HIF-1α augmentation against inflammation and hypoxia in ALI. We demonstrated that (i) LPS upregulated inflammatory genes, tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1ß), and interleukin-6 (IL-6), in the alveolar macrophages of ALI rats, which were further enhanced when ALI combined with hypoxia; (ii) hypoxia exposure could further enhance the upregulation of alveolar macrophageal TLR4 that was noticed in LPS-induced inflammatory ALI, conversely, TLR4 antagonist TAK-242 could suppress the macrophageal expression of TLR4 and inflammatory cytokines, including TNF-α, IL-1ß, and IL-6, suggesting that the TLR4 signaling pathway as a central link between inflammation and hypoxia in ALI; (iii) manipulation of HIF-1α in vitro could suppress TLR4 expression induced by combined LPS and hypoxia, via suppressing promoter activity of the TLR4 gene; (iv) preconditioning augmentation of HIF-1α in vivo by HIF hydroxylase inhibitor, DMOG excreted protection against inflammatory, and hypoxic processes in ALI. Together, we see that hypoxia can exacerbate inflammation in ALI via the activation of the TLR4 signaling pathway in alveolar macrophages and predispose impairment of the alveolar-capillary barrier in the development of ALI. Targeting HIF-1α can suppress TLR4 expression and macrophageal inflammation, suggesting the potential therapeutic and preventative value of HIF-1α/TLR4 crosstalk pathway in ALI.

Treatments of tilapia (Oreochromis niloticus) using nitric oxide for quality improvement: Establishing a potential method for large-scale processing of farmed fish.

BACKGROUND: To find a succedaneum of present methods for slaughtering tilapia, we have demonstrated the influence of nitric oxide (NO) (saturated NO solution) through euthanasia before slaughter on the animal welfare and muscle color of tilapia. The results suggested that NO euthanasia significantly improved the animal welfare and muscle color. Besides, the investigation of NO postmortem treatment on the muscle color and color stability of tilapia fillets suggested that NO postmortem treatment not only improved the muscle color and color stability but also prolonged the shelf-life of tilapia fillets during the refrigerated storage. OBJECTIVE: To further investigate the effect of NO euthanasia on the quality of tilapia fillets and to estimate the safety of NO treatments (NO euthanasia and NO postmortem treatment) for the application of NO treatments in industrial manufacturing of tilapia and possibly of other fish species. METHODS: NO euthanasia was adopted in this study following a simulated fish processing line. HbNO and MbNO values were measured to clarify the mechanism and process of NO euthanasia. The blood parameters, muscle pH, rigor index, drip loss and total volatile basic nitrogen (TVB-N) values were measured to evaluate the quality of the fillets obtained from NO euthanized tilapia. Besides, the nitrate (NO3-) levels in the muscles after the refrigerated storage were detected to estimate the food safety of both NO euthanasia and NO postmortem treatment. RESULTS: Fillets obtained from the tilapia euthanized by NO showed a later reduction of muscle pH, a later onset of rigor mortis postmortem and less drip loss during the refrigerated storage than control. NO euthanasia caused less TVB-N than control and prolonged the shelf life of tilapia fillets. Moreover, the NO3- levels in the muscles of both NO euthanasia and NO postmortem treatment after the refrigerated storage were below the maximum permitted limit. CONCLUSION: Both the NO euthanasia and NO postmortem treatment are suitable for improving the quality of tilapia fillets and reducing the food safety threats, which may be valuable for industrial manufacturing of tilapia and may be applicable for other fish species.

Adenosine A2A receptor involves in neuroinflammation-mediated cognitive decline through activating microglia under acute hypobaric hypoxia.

Hypobaric hypoxia (HH) at high altitudes leads to a wide range of cognitive impairments which can handicap human normal activities and performances. However, the underlying mechanism is still unclear. Adenosine A2A receptors (A2ARs) of the brain are pivotal to synaptic plasticity and cognition. Besides, insult-induced up-regulation of A2AR regulates neuroinflammation and therefore induces brain damages in various neuropathological processes. The present study was designed to determine whether A2AR-mediate neuroinflammation involves in cognitive impairments under acute HH. A2AR knock-out and wild-type male mice were exposed to a simulated altitude of 8000 m for 7 consecutive days in a hypobaric chamber and simultaneously received behavioral tests including Morris water maze test and open filed test. A2AR expression, the activation of microglia and the production of TNF-α were evaluated in the hippocampus by immunohistochemistry and ELISA, respectively. Behavioral tests showed that acute HH exposure caused the dysfunction of spatial memory and mood, while genetic inactivation of A2AR attenuated the impairment of spatial memory but not that of mood. Double-labeled immunofluorescence showed that A2ARs were mainly expressed on microglia and up-regulated in the hippocampus of acute HH model mice. Acute HH also induced the accumulation of microglia and increased production of TNF-α in the hippocampus, which could be markedly inhibited by A2AR inactivation. These findings indicate that microglia-mediated neuroinflammation triggered by A2AR activation involves in acute HH-induced spatial memory impairment and that A2AR could be a new target for the pharmacotherapy of cognitive dysfunction at high altitudes.

Influence of postmortem treatment with nitric oxide on the muscle color and color stability of tilapia (Oreochromis niloticus) fillets.

BACKGROUND: Nitric oxide (NO) has been recognized as pivotal for color and color stability of meat products and has an evident effect on inhibiting microbial growth in processed meat. The use of indirect NO (nitrate/nitrite) in industrial meat curing has potential deleterious effects and great concerns have been expressed over residual nitrite in meat after curing. To find a succedaneum, we have demonstrated the influence of direct NO (saturated NO solution) through euthanasia before slaughter on the fillets color of tilapia and the results suggested that direct NO treatment prior to slaughter is a good procedure to improve the color of tilapia fillets. OBJECTIVE: To further investigate the effect of direct NO on the muscle color and shelf-life of fillets from tilapia, this study was conducted to investigate the muscle color and color stability of tilapia fillets postmortem treated with saturated NO solution and their shelf-life during refrigerated storage. METHODS: Tilapia fillets were immersed in a saturated NO solution for 13 min, vacuum-packed and stored at refrigerated temperature for 15 days. Visual observations, color values and absorption maxima were used to evaluate the muscle color and color stability of tilapia fillets. Total volatile basic nitrogen (TVB-N) values were used to evaluate the shelf-life of tilapia fillets during refrigerated storage. RESULTS: By visual observation, NO treated tilapia fillets showed a brighter red color as compered to control samples after NO-treatment and during the whole storage. The redness (a*) values of NO treated tilapia fillets were significantly increased (P < 0.05) after NO-treatment, continuously increased (P < 0.05) during the earlier 9 days of the storage and remained roughly unchanged during the rest days of the storage. While the a* values of control samples decreased progressively during the storage. NO-treatment effectively improved the muscle color and color stability of tilapia fillets. The peak wavelengths of extract from the muscles of NO treated tilapia fillets increased from 418 nm to 421 nm at 15 d of the storage, while that of control decreased from 418 nm to 410 nm, indicated that color improvement in NO-treated tilapia fillets is mainly due to the formation of MbNO. Moreover, NO-treatment resulted in less TVB-N values than control (16.06 and 21.93 mg of N/100 g at the end of the storage, respectively), prolonging the shelf-life of tilapia fillets. CONCLUSION: The results suggested that postmortem treatment with NO is a good procedure not only for improving the muscle color and color stability but also for prolonging the shelf-life of tilapia fillets during the storage, which is valuable for industrial manufacturing of tilapia and possibly for other fish species.

Cooling combined with hyperoxic CO2 anesthesia is effective in improving the air exposure duration of tilapia.

Tilapia were subjected to cooling (CO, a stepwise reduction in temperature from 30 °C to 15 °C), anesthesia (AN, anesthetized by hyperoxic carbon dioxide), air exposure (AE, exposed to air) and cold tolerance (CT, in 15 °C water) treatments, and the physiological responses were determined after the treatments. CO followed by AN treatment for tilapia could meet the criteria of an ideal anesthetic. Fish were deeply sedated within 69 s, completely anesthetized within 276 s and recovered within 308 s without any mortality. The stress responses induced by the CO&AN treatment were mild, whereas they were consistently increased in the AE treatment. Furthermore, the AE treatment caused tissue damage. The AE duration was significantly improved by CO&AN treatment, and the survival time of the CO&AE, AN&AE and CO&AN&AE treatments were 313 min, 351 min and 561 min, respectively, in the laboratory experiments, whereas the survival rate of the CO&AN&AE treatment group after 240-min air exposure was 95.2% in the pilot test. It appeared that cooling followed by hyperoxic CO2 anesthesia would be suitable for handling tilapia in a short-time air exposure procedure.