Dose rate effect of gamma irradiation on phenolic compounds, polyphenol oxidase, and browning of mushrooms (Agaricus bisporus).

To enhance the shelf life of edible mature mushrooms, Agaricus bisporus, 2 kGy ionizing treatments were applied at two different dose rates: 4.5 kGy/h (I(-)) and 32 kGy/h (I(+)). Both I(+) and I(-) showed a 2 and 4 day shelf-life enhancement compared to the control (C). Before day 9, no significant difference (p>0.05) in L value was detected in irradiated mushrooms. However, after day 9, the highest observed L value (whiteness) was obtained for the mushrooms irradiated in I(-). Analyses of phenolic compounds revealed that mushrooms in I(-) contained more phenols than I(+) and C, the latter containing the lower level of phenols. The fluctuation of the precursors of glutaminyl-4-hydroxyaniline (GHB) was less in I(-) than in I(+). The polyphenol oxidase (PPO) activities of irradiated mushrooms, analyzed via catechol oxidase, dopa oxidase, and tyrosine hydroxylase substrates, were found to be significantly lowered (p = 0.05) compared to C, with a further decrease in I(+). Analyses of the enzymes indicated that PPO activity was lower in I(+), contrasting with its lower phenols concentration. The observation of mushrooms' cellular membranes, by electronic microscopy, revealed a better preserved integrity in I(-) than in I(+). It is thus assumed that the browning effect observed in I(+) was caused by both the decompartmentation of vacuolar phenol and the entry of molecular oxygen into the cell cytoplasm. The synergetic effect of the residual active PPO and the molecular oxygen, in contact with the phenols, allowed an increased oxidation rate and, therefore, a more pronounced browning I(+) than in I(-).     

Effect of 60Co-irradiation on postharvest quality and selected enzyme activities of Hypsizygus marmoreus fruit bodies

Hypsizygus marmoreus fruit bodies were exposed to different doses of (60)Co gamma-irradiation, stored at 4 degrees C and 65-70% relative humidity, and various physiological changes associated with postharvest deterioration, as well as the activities of selected enzymes widely considered to play a role in the process of senescence, were monitored over a subsequent storage period of 25 days. Exposure to 0.8 kGy irradiation was clearly beneficial in maintaining the postharvest appearance of the mushroom sporophores compared to non-irradiated samples and fruit bodies exposed to higher doses (1.2-2.0 kGy) of irradiation. Samples treated with 0.8 kGy also exhibited smaller initial declines in soluble protein, smaller increases in reducing sugar content, and lower levels of malondialdehyde accumulation during the early storage period. Smallest increases in proteinase activity were recorded in samples dosed with 0.8 and 2.0 kGy, and levels of superoxide dismutase were significantly higher in samples exposed to 0.8 kGy compared with non-irradiated controls. Large initial increases in catalase activity were detected in samples irradiated with 0.8, 1.2, and 1.6 kGy and, although enzyme levels gradually decreased in all samples during further storage, residual levels after 25 days were still severalfold higher in irradiated samples compared with controls. The data increase the current understanding of the effects of gamma-irradiation on the biochemical changes associated with postharvest senescence and should lead to more targeted strategies for reducing postharvest quality loss in H. marmoreus and other mushrooms.     

Effect of gamma-irradiation on phenolic compounds and phenylalanine ammonia-lyase activity during storage in relation to peel injury from peel of Citrus clementina hort. Ex. tanaka

The influence of gamma-irradiation on the content of phenolic compounds was evaluated on Moroccan Citrus fruits (Citrus clementina Hort. ex. Tanaka) treated at a mean dose of 0.3 kGy and stored for 49 days at 3 degrees C. The results show that irradiation has enhanced the synthesis of total phenolic compounds and is correlated with phenylalanine ammonia-lyase activity (PAL) during storage. Accumulation of phenolic compounds in cells is demonstrated and may be explained by the enhancement of PAL activity. HPLC/UV (diode array detector) analysis demonstrated that hesperidin was the major flavanone and nobiletin and heptamethoxyflavone were the major polymethoxylated flavones. Hesperidin is also the major phenolic compound in clementines. Irradiation stimulates the biosynthesis of hesperidin after 14 days of storage, corresponding to the maximum of PAL activity. p-Coumaric acid was also identified, and its content was particularly high in irradiated fruits after 49 days of storage. Accumulation of flavonoids and p-coumaric acid could be related to a better resistance. The percentage of losses due to peel injury "pitting" during storage was between 1 and 5% after 49 days of storage. The connections between irradiation, enzyme activity, phenolic content, and peel injury are briefly discussed.     

gamma-Radiation influences browning, antioxidant activity, and malondialdehyde level of apple juice

Apple juice was gamma-irradiated at 5 degrees C at doses ranging from 0 to 8.9 kGy and then stored at 5 degrees C for 15 days. Ionizing radiation reduced the browning of apple juice and increased antioxidant activity measured by the ferric-reducing antioxidant power (FRAP) assay. The magnitude of changes increased with radiation dose. The level of malondialdehyde (MDA) measured using the thiobarbituric acid reactive substrates assay increased at radiation doses above 2.67 kGy. The browning of irradiated juices increased during storage at 5 degrees C, but the irradiated juices were still lighter than controls at the end of storage. Differences in FRAP values disappeared during early periods of storage while higher MDA levels were observed in irradiated samples during most of the storage period. Elimination of suspended matter from apple juice did not alter irradiation-induced changes in browning, FRAP, or MDA formation. As compared to irradiation conducted at 5 and 20 degrees C, treatment at -15 degrees C was less effective in reducing browning and in increasing MDA formation but elevated FRAP values. The exclusion of oxygen from juices did not affect the reduction in browning due to irradiation but promoted the increase in FRAP values and decreased the irradiation-induced MDA formation.     

2-alkylcyclobutanones as irradiation dose indicators in irradiated ground beef patties

Alkylcyclobutanones have been recognized as chemical markers of irradiated lipid-containing foods since 1970. They are important because they are produced solely as a result of irradiation and not any other processing method. This study investigated the formation of 2-dodecylcyclobutanone (2-DCB) and 2-tetradec-5'-enylcyclobutanone (2-TDCB) in irradiated ground beef patties from commercial and noncommercial sources. Patties were irradiated using a (60)C source (gamma-irradiation) and electron beam irradiation, at five targeted absorbed doses of 0.5, 1.0, 2.5, 5.0, and 7.0 kGy. Commercially available irradiated patties were also studied. A supercritical fluid extraction (SFE) procedure was optimized and used for the extraction and isolation of the alkylcyclobutanones. Samples can be used for extraction without a prior cleanup step, which makes this procedure rapid and convenient to use. Identification and quantitation of the cyclobutanones were done by gas chromatography-mass spectroscopy. 2-DCB was detected in all of the irradiated samples (including commercial patties), and its concentration increased linearly with the irradiation dose. Electron beam irradiation produced a greater amount of 2-DCB compared to gamma-irradiation at dose levels >2.5 kGy. 2-TDCB was detected only at the two higher irradiation doses, whereas both marker compounds were not detected in the non-irradiated samples.     

Effect of gamma-irradiation combined with washing and waxing treatment on physicochemical properties,vitamin C,and organoleptic quality of Citrus clementina Hort. Ex. Tanaka

To enhance the shelf life of a late variety of Moroccan Citrus clementina (Nour), ionizing treatments were applied at 0.3 kGy, as well as washing (cold water) and waxing treatments. It has been found that, despite the irradiation treatment, the washing and waxing treatment do not improve the quality of C. clementina, but rather result in yellower peels, peel injury, and reductions of vitamin C content, acidity, and soluble solids. However, gamma-irradiation alone enhanced significantly (p 相似文献   

高能电子束辐照对鲜切哈密瓜生理生化品质的影响

通过0．5、1．0、1．5和2．0kGy剂量的电子柬辐照处理鲜切哈密瓜,采用聚丙烯（PP）材质托盘和聚乙烯（PE）保鲜膜包装,置于5℃,相对湿度85％-95％的冷库中贮藏,研究高能电子束辐照对鲜切哈密瓜生理生化品质的影响。结果表明,电子束辐照能显著降低呼吸速率,显著抑制Vc、可溶性固形物的含量的下降,减少丙二醛积累,降低多酚氧化酶和过氧化物酶活性,并提高苯丙氨酸解氨酶活性。1．5kGv辐照处理的鲜切哈密瓜在贮藏至第13天时,感官品质保持良好。综合电子束辐照对鲜切哈密瓜的保鲜效果,确定最佳处理剂量为1．5kGy。     

Warm water treatment in combination with modified atmosphere packaging reduces undesirable effects of irradiation on the quality of fresh-cut iceberg lettuce

Fresh-cut iceberg lettuce dipped in either 5 or 47 degrees C water for 2 min was packaged in modified atmosphere film bags and then exposed to 0, 0.5, 1, or 2 kGy gamma-radiation. Dipping cut lettuce in 47 degrees C water for 2 min prior to irradiation reduced antioxidant and phenolic accumulations induced by irradiation. Irradiation at 2 kGy increased cellular leakage and sogginess of cut lettuce dipped in both temperatures. Samples irradiated at 0.5 and 1 kGy had similar firmness and vitamin C and antioxidant contents as the controls after 14 and 21 days of storage except 1 kGy samples dipped at 47 degrees C had lower antioxidant contents than controls at 14 days of storage. Lettuce dipped at 47 degrees C and irradiated at 0.5 and 1 kGy had better overall visual quality and less tissue browning than corresponding irradiated samples dipped at 5 degrees C. These results suggest lettuce treated with warm water and irradiated at 0.5 or 1 kGy had the best sensory quality without significant loss in texture, vitamin C, or total antioxidants.     

Identification of irradiated prawn (Penaeus monodon ) using thermoluminescence and 2-alkylcyclobutanone analyses

Thermoluminescence (TL) and 2-alkylcyclobutanone (2-ACB) analyses were performed to identify irradiated prawns ( Penaeus monodon ). With the TL method, minerals were extracted from prawns using acid hydrolysis. The experimental results satisfied the evaluation criteria of European Norm (EN) 1788, even after low-dose irradiation (0.5 kGy) and a 60 day storage at -20 °C. With the 2-ACB method, 2-dodecylcyclobutanone (2-DCB) and 2-tetradecylcyclobutanone (2-TCB) were successfully extracted from prawns by direct solvent extraction with purification using a conventional silica column and a sulfoxide column, which was used for 2-ACB for the first time. Both 2-ACB derivatives were absent from the non-irradiated samples but were identified in all irradiated samples by gas chromatography-mass spectrometry. Moreover, 2-DCB and 2-TCB production correlated with the applied dose (2.5-10 kGy), and the correlation did not diminish after 60 days of storage at -20 °C for any dose. Therefore, these two techniques provide rapid, simple, and promising methods for routine investigation of frozen prawns.     

Changes in volatile compounds of gamma-irradiated fresh cilantro leaves during cold storage

Consumption of salsas and dishes containing cilantro has been linked to several recent outbreaks of food-borne illness due to contamination with human pathogens. Ionizing irradiation can effectively eliminate food-borne pathogens from various vegetables including cilantro. However, the effect of irradiation on aroma of fresh cilantro is unknown. This study was conducted to investigate the effect of irradiation on volatile compounds of fresh cilantro leaves. Fresh cilantro leaves (Coriandrum sativum L) were irradiated with 0, 1, 2, or 3 kGy gamma radiation and then stored at 3 degrees C up to 14 days. Volatile compounds were extracted using solid-phase microextraction (SPME), followed by gas chromatographic separation and mass spectra detection at 0, 3, 7, and 14 days after irradiation. Most of the volatile compounds identified were aldehydes. Decanal and (E)-2-decenal were the most abundant compounds, accounting for more than 80% of the total amount of identified compounds. The amounts of linalool, dodecanal, and (E)-2-dodecenal in irradiated samples were significantly lower than those in nonirradiated samples at day 14. However, the most abundant compounds [decanal and (E)-2-decenal] were not consistently affected by irradiation. During storage at 3 degrees C, the amount of most aldehydes peaked at 3 days and then decreased afterward. Our results suggest irradiation of fresh cilantro for safety enhancement at doses up to 3 kGy had minimal effect on volatile compounds compared with the losses that occurred during storage.     

60Co-γ辐照结合1-MCP处理对蓝莓贮藏品质的影响

为研究⁶⁰Co-γ辐照结合1-甲基环丙烯(1-MCP)处理对蓝莓贮藏品质的影响,以粉蓝蓝莓为试验材料,对采后蓝莓生理指标、营养指标及相关酶活性进行测定,研究0±0.5℃条件下6种处理(1.5 kGy辐照处理记为A、2.5 kGy辐照处理记为B、1.5 kGy辐照+1 μL·L^-1 1-MCP 处理记为C、2.5 kGy辐照+1 μL·L^-1 1-MCP处理记为D、1 μL·L^-1 1-MCP处理记为E,不进行任何处理记为F)对蓝莓贮藏品质的影响。结果表明,与对照(F)比较,4种处理(A、C、D、E)均能够抑制果实腐烂率的上升和风味指数的下降,延缓果实的生理代谢,更好地保持果实的营养品质和酶活性,而2.5 kGy辐照处理(B)降低了果实的硬度、L^*值、可溶性固形物含量和花色苷含量,加快了果实多聚半乳糖醛酸酶活性的上升。其中,在贮藏80 d时,A、B、C、D、E、F组蓝莓的腐烂率分别为24.94%、38.36%、13.87%、30.78%、22.96%和48.38%。因此,1.5 kGy ⁶⁰Co-γ辐照结合1 μL·L^-1 1-MCP处理蓝莓对果实的贮藏效果最好。本研究结果为蓝莓的贮藏保鲜提供了新思路。     

Characteristic hydrocarbons and 2-alkylcyclobutanones for detecting gamma-irradiated sesame seeds after steaming, roasting, and oil extraction

Hydrocarbons and 2-alkylcyclobutanones in sesame seeds ( Sesamum indicum L.) irradiated at 0.5-4 kGy were used to determine the effect of subsequent steaming, roasting, and oil extraction from the roasted samples on the changes in their concentrations. The concentrations of radiation-induced hydrocarbons increased almost linearly (R(2) = 0.8671-0.9953) with the applied dose. The hydrocarbons, 1,7-hexadecadiene and 8-heptadecene, were detected only in the irradiated samples before and after three types of treatments at doses > or =0.5 kGy, but they were not detected in non-irradiated samples before and after treatment. These two hydrocarbons could be used as markers to identify irradiated sesame seeds. The concentrations of the three detected 2-alkylcyclobutanones, 2-dodecylcyclobutanone (2-DCB), 2-tetradecylcyclobutanone (2-TCB), and 2-(5'-tetradecenyl)cyclobutanone (2-TeCB), linearly increased with the irradiation dose. These compounds could be detected at doses > or =0.5 kGy but not in non-irradiated samples. The three types of treatments had no significant effect on the levels of 2-alkylcyclobutanones.     

Influences of gamma-irradiation and storage on the carotenoids of sun-dried and dehydrated paprika

The effects of drying methods, gamma-irradiation, and storage on the carotenoids (capsanthin, capsorubin, zeaxanthin, capsolutein, violaxanthin, beta-carotene, and beta-cryptoxanthin) of paprika were investigated. Sun-dried and dehydrated paprika samples were irradiated in a (60)Co gamma-irradiator at five doses (0, 2.5, 5.0, 7.5, and 10 kGy) in polyethylene bags and stored for 10 months at ambient temperature. Individual carotenoid analyses were carried out on the paprika and fresh red pepper during a 2 month period using the reverse phase HPLC technique. The concentrations of capsanthin and capsorubin, which are responsible for the attractive red color of sun-dried paprika, were higher than those of dehydrated paprika. Higher irradiation doses and a longer storage period resulted in a significant (P < 0.01) reduction of all the carotenoids, except capsorubin. There was no significant (P < 0.05) effect of irradiation dose on capsorubin destruction. The decrease of red carotenoids, for all irradiation treatments, was less than that of the storage period. Even the highest irradiation dose, 10 kGy, caused a 11.1% capsanthin reduction; however, 10 months of storage at the ambient temperature caused a 42.1% reduction of capsanthin. Yellow pigments of paprika (zeaxanthin, capsolutein, violaxanthin, beta-carotene, and beta-cryptoxanthin) were significantly (P < 0.01) decreased by all treatments. These yellow pigments were also found to be at high levels in those sun-dried samples with red pigments. This difference could be caused by the contribution of pigment biosynthesis during the sun-drying period. The most significant pigment reduction was realized in the processing and storage conditions of paprika, rather than in the irradiation process.     

Volatile sulfur compounds in irradiated precooked turkey breast analyzed with pulsed flame photometric detection

Ionizing radiation is an effective processing technology for pathogen inactivation on various foods. However, the generation of off-odor is a concern for some irradiated meats. This study was conducted to investigate volatile sulfur compounds of precooked ready-to-eat turkey breast as functions of radiation dose and subsequent storage. Precooked turkey breast was exposed to 0, 1, 2, 3, 4, and 5 kGy of gamma radiation and stored for 14 days at 5 degrees C. Volatile sulfur compounds were extracted using solid phase microextraction (SPME), followed by gas chromatographic separation and pulsed flame photometric detection. Irradiation dramatically increased concentrations of hydrogen sulfide, sulfur dioxide, methanethiol, and dimethyl disulfide. The rate of increase was higher at low doses (0-2 kGy) than at higher doses of 3-5 kGy. Carbon disulfide was the only volatile sulfur compound that was reduced by irradiation. Concentrations of all volatile sulfur compounds decreased in both irradiated and nonirradiated samples stored at 5 degrees C.     

1- MCP和60Co-γ辐照处理对自发气调包装大五星枇杷贮藏品质的影响

为研究1-甲基环丙烯(1-MCP)熏蒸和⁶⁰Co-γ辐照处理对枇杷贮藏品质的影响,本研究以大五星枇杷为试验材料,对采后自发气调包装枇杷的腐烂指数、木质素、硬度、呼吸强度、乙烯生成速率、相对电导率、可滴定酸(TA)、可溶性固形物(TSS)以及苯丙氨酸解氨酶(PAL)、脂氧合酶(LOX)、多酚氧化酶(PPO)、过氧化物酶(POD)活性进行测定,研究6±0.5℃条件下1 μL·L^-1 1-MCP、1.5 kGy⁶⁰Co-γ、1 μL·L^-1 1-MCP+1.5 kGy ⁶⁰Co-γ不同处理对枇杷贮藏品质的影响。结果表明, 1-MCP和⁶⁰Co-γ复合处理效果最好,可延缓腐烂指数和木质素含量上升,维持果实硬度,降低果实呼吸强度、乙烯生成速率和相对电导率,保持果实TA和TSS含量,抑制PAL、LOX、PPO和POD活性的上升。在贮藏40 d时,1-MCP和⁶⁰Co-γ复合处理枇杷的腐烂指数仅为17.95%,而1-MCP组、⁶⁰Co-γ组、CK组分别为22.86%、25.72%和36.24%。因此,1-MCP和⁶⁰Co-γ复合处理对枇杷果实的贮藏效果最好。本研究结果为枇杷的贮藏保鲜提供了理论依据。     

Effect of different washing procedures on phenolic metabolism of shredded, packaged iceberg lettuce during storage

Different washing treatments applying chlorinated, ozonated, and tap water were examined for their effect on the phenolic metabolism of minimally processed iceberg lettuce (Lactuca sativa L.) during storage in consumer-sized bags at 4 degrees C for up to 9 days. To eliminate problems associated with raw material inhomogeneity, processing was conducted on a pilot-plant scale under operating conditions of industrial practice. Inherent product heterogeneity caused by diverse lettuce leaf tissues was compensated for by pooling large-sized samples, and frequent sampling ensured significant data about the activities of phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO), and peroxidase (POD), as well as the contents of caffeic acid derivatives over storage time. In the homogeneous lettuce samples, specific responses caused by different washing procedures were detectable. PAL activity in the samples increased for up to 5-8 days of storage. Compared to tap and ozonated water, the use of chlorinated water (100-200 mg/L free chlorine) for washing trimmed heads or shredded lettuce significantly reduced PAL activity and the concomitant rise of 3,5-di-O-caffeoylquinic acid (isochlorogenic acid isomer) concentrations. The phenolic acids O-caffeoyltartaric (caftaric acid), di-O-caffeoyltartaric (chicoric acid), 5-O-caffeoylquinic (chlorogenic acid isomer), and O-caffeoylmalic were less influenced by different washing treatments. Individual contents either were constant or decreased during storage. Additionally, the novel finding of a further caffeic acid isomer, tentatively identified as meso-di-O-caffeoyltartaric acid, is reported. PPO and POD activities were less affected by different washing treatments and thus were less suitable physiological indicators of stress reactions triggered by alternative processing.     

电子束辐照对美国红鱼杀菌保鲜效果的研究

以美国红鱼为对象,利用不同剂量电子束处理,对冷藏期内鱼肉菌落总数、总挥发性盐基氮（TVB-N）、过氧化值（POV）及鲜度指标K值进行测定,分析不同剂量电子束辐照对美国红鱼肉的杀菌效果及品质影响。结果表明：电子束辐照能有效降低美国红鱼肉的菌落总数,其中D10=161kGy,D=540kGy,冷藏期间辐照组样品菌落生长缓慢,且辐照剂量越大,杀菌效果越强;电子束处理后美国红鱼肉TVB-N值、POV均有不同程度增加,但在冷藏期内对照组TVB-N值、POV、K值的上升速度大于辐照组样品;辐照对美国红鱼肉感官影响不明显,但6kGy辐照组鱼肉色泽略微变红。综合考虑,美国红鱼肉经4kGy 电子束辐照,能有效杀灭其中的微生物,冷藏条件下保质期可达到14d,比对照延长5d左右。     

Effect of gamma-irradiation on the lipid profile of nutmeg (Myristica fragrans Houtt.)

The effect of gamma-irradiation on the lipid constituents of nutmeg (Myristica fragrans) was examined at radiation doses between 2.5 and 10 kGy. The fatty acid composition of the triacylglycerol, the major lipid component, was found to be made up of myristic (90%), palmitic (6%), lauric (3%), petroselinic (0.13%), and stearic acids (0.5%) as determined by gas chromatography-mass spectrometry. A dose-dependent decrease in the triacylglycerol content and a concomitant increase in free fatty acids characterized the lipid profile of the irradiated spice. This suggested a breakdown of acylglycerols during radiation processing, resulting in the release of free fatty acids. These changes were found to be significant at doses above 5 kGy. The impact of the above changes on the flavor of the spice is discussed. These studies suggest that radiation processing of nutmeg should be limited to a dose of 5 kGy.     

Effects of irradiated phytic acid on antioxidation and color stability in meat models

Lipid oxidation and color stability of meats treated with irradiated phytic acid were investigated during storage for 2 weeks at 4 degrees C. The phytic acid in deionized distilled water (DDW) was degraded by irradiation at 10 and 20 kGy, and the irradiated phytic acid showed a strong antiradical activity. For measuring the antioxidant effects of irradiated phytic acid in food models, beef and pork were prepared with DDW (control), irradiated (10 and 20 kGy) or non-irradiated phytic acid, and ascorbic acid as a model system. Irradiated phytic acid significantly inhibited the lipid oxidation in meats compared to the control and ascorbic acid treated samples during storage (P < 0.05). The redness of the meats treated with phytic acid had a higher value than did the control and ascorbic acid treated samples, but a significant difference was not observed in the samples treated with phytic acid regardless of irradiation treatment. Irradiated phytic acid was also effective in inhibiting the loss of heme iron and metmyoglobin formation during storage. Results indicated that irradiation might be helpful for improving the antioxidant activity of phytic acid in meats.     

Influence of washing treatment and storage atmosphere on phenylalanine ammonia-lyase activity and phenolic acid content of minimally processed carrot sticks

The influence of washing uncut and shredded carrots (Daucus carota L. ssp. sativa var. Bangor) with chlorinated and ozonated water, respectively, as well as the storage of the produce under aerobic and anaerobic conditions, respectively, on PAL activity and synthesis of phenolic compounds have been evaluated on pilot plant scale. Inherent raw material inhomogeneity was compensated by pooling large sized samples, and frequent sampling ensured significant data. PAL activity was induced by processing and linearly increased throughout storage under aerobic conditions, whereas an anaerobic atmosphere resulted in a maximum activity peak at storage day 2-4. The accumulation of phenolic compounds showed good correlation with the kinetics of PAL activity. Although the influence of the washing treatments was weak, the use of chlorinated water for washing shredded carrots slightly delayed the onset of PAL activity. The phenolic content of the minimally processed carrots was dominated by trans and cis isomers of chlorogenic acid ( approximately 95%). Additionally, the occurrence of p-coumaroylquinic acid ( approximately 5%) and the novel finding of three dicaffeoylquinic acid isomers were reported. The synthesis of phenolic compounds was controlled, depending on storage atmosphere.