吸收剂量、贮藏时间及贮藏温度对辐照牛肉中2-十二烷基环丁酮的影响

分析了辐照牛肉中辐解产物2-十二烷基环丁酮在不同的吸收剂量(0.5~10.0kGy)、贮藏时间(0-40d)及贮藏温度(-20℃~4℃)下的变化规律。采用硅胶层析柱-气相色谱/质谱联用技术萃取分离并检测。结果表明,2-十二烷基环丁酮的浓度与吸收剂量呈线性正相关,随着贮藏时间延长其含量减少,贮藏温度对其没有显著影响。利用2-十二烷基环丁酮可鉴定牛肉是否经过辐照,在已知贮藏温度和时间的条件下,可评估辐照牛肉的大约吸收剂量范围。     

辐照对肉味香精蛋白质及氨基酸组分的影响

研究了辐照处理对常见肉味香精中蛋白质和氨基酸的影响。结果表明,在不同剂量(0、2、4、6、8和10kGy)辐照处理下,除牛肉香精外,猪肉香精和鸡肉香精的蛋白质含量均有所变化,但4~10kGy剂量处理间差异不明显;辐照处理对游离氨基酸总量及其种类没有明显作用。     

氮离子束与γ射线辐照日本晴和“9311”水稻突变体库的筛选

利用氮离子束和γ射线辐照处理粳稻日本晴和籼稻"9311",经过M1代损伤鉴定、M2代筛选和M3代重复鉴定,分别得到了740份和666份日本晴突变体,571份和781份"9311"突变体。获得的突变体发生了叶片、茎秆、穗部和籽粒、生理等性状的突变。在氮离子束辐照处理中,日本晴和"9311"分别在5.0×1016N+/cm2和2.5×1016N+/cm2剂量辐照时获得高突变率,为6.44%和6.38%;γ射线辐照处理中,2种材料均在150Gy剂量辐照时获得高突变率,分别为5.68%和9.44%。在本试验中,各高突变率群体均为辐照当代损伤最低的群体。新构建的突变体库将为水稻功能基因组学研究提供较好的基础材料。     

~(60)Co-γ射线和电子束辐照对冷鲜鸡保鲜效果的异同性研究

为研究~(60)Co-γ射线和电子束辐照对冷鲜鸡微生物含量的影响及肉品品质的异同性,采用2.5k Gy剂量的~(60)Co-γ射线和电子束辐照处理真空包装冷鲜鸡,对其贮藏期内菌落总数、大肠菌群、丙二醛含量、pH值、嫩度、系水力值、挥发性盐基氮(TVB-N)值、色度进行测定。结果表明,γ射线和电子束辐照处理均能显著降低冷鲜鸡菌落总数,大肠菌群均未检出;2种辐照处理组冷鲜鸡的丙二醛含量、pH值、TVB-N值在整个贮藏期内均呈上升趋势;与对照组相比,2种辐照处理组均显著提高了冷鲜鸡的L*值和a*值,且电子束处理组显著高于γ射线组,对照组b*值在同一贮藏期显著高于2种辐照处理组。由此可知,~(60)Co-γ射线和电子束辐照均对冷鲜鸡的微生物含量和肉品品质产生了显著影响,这为辐照技术应用于冷鲜鸡保藏提供了理论依据。     

电子束辐照对美国红鱼肉挥发性风味成分的影响

为了分析电子束辐照剂量对美国红鱼肉挥发性风味物质的影响。本文采用固相微萃取-气质联用技术,分离鉴定不同剂量电子束辐照后红鱼肉的挥发性风味成分。结果表明:(1)辐照后红鱼肉风味有一定变化,感官评分随辐照剂量的增加而有所降低;(2)红鱼肉经1、3、5、7、9kGy剂量处理,检出的挥发性风味成分由36种分别增加到52、46、65、55、55种;挥发性成分中羰基化合物及醇类物质的相对含量最高;辐照后挥发性醇类、酯类、芳香类物质相对含量降低,高剂量辐照后醛酮类、含硫含氮类化合物相对含量普遍增加,是导致气味改变的主要因素。总之,美国红鱼肉经低于5kGy剂量辐照后能较好的保持其原有风味,高剂量电子束辐照会导致异味的产生。     

重离子辐照对绵羊精子的蛋白质组学影响研究北大核心CSCD

本研究为了分析由重离子辐照引起的绵羊精子蛋白质组学变化,用二维凝胶电泳分离精子蛋白,凝胶用考马斯亮蓝染色。PDQuest8.0软件检测分析差异表达蛋白斑点并经高效液相色谱串联离子阱质谱鉴定。结果显示:辐照后的精子凝胶图谱上有4个蛋白质斑点表达上调,1个蛋白质斑点缺失,这5个蛋白质斑点经鉴定后,在国际生物信息学中心数据库搜索到相对应的2种蛋白质:烯醇酶和烯醇酶1,在辐照后的精子中这2种蛋白质表达上调。研究表明:重离子辐照会引起绵羊精子蛋白质组学变化,通过对差异蛋白质的研究探索重离子辐照对绵羊精子生理功能的影响,为重离子辐照绵羊育种提供理论依据。     

辐照对宠物干粮食品酸价的影响

为研究辐照对宠物干粮食品在储藏过程中脂肪氧化的影响,以新鲜牛肉为材料,添加抗氧化剂后制成宠物干粮食品,通过检测储藏过程中样品酸价的变化研究辐照对抗氧化效果的影响,未添加抗氧化剂的样品作为对照。所用抗氧化剂包括叔丁基对苯二酚、没食子酸丙酯、茶多酚、生育酚和抗坏血酸钠。结果表明:储藏100d时,复合抗氧化剂smc对酸价的抑制率最高为51.0%,辐照处理结合复合抗氧化剂smc的方式对酸价的抑制率次之为48.7%;辐照后,样品的酸价在储藏过程中的升高速度缓于未辐照样品的速度。辐照处理可以抑制酸价的升高,辐照处理结合复合抗氧化剂smc的方式更适用于抑制货架期超过4个月的宠物干粮食品在储藏过程中酸价升高的脂肪氧化。     

辐照后食品超微弱发光性质的变化

干燥物质经过辐照处理后 ,其超微弱发光性质会发生一些变化。经过对多种样品辐照前后的超微弱发光性质的研究 ,依据加入测量液前后的发光变化 ,发现其超微弱发光可以分为四种情况 :( 1 )辐照后在加入测量液的情况下产生辐照特征峰 ;( 2 )超微弱发光性质始终无变化 ;( 3)辐照本身对超微弱发光性质无影响 ,测量液的加入使样品在辐照前后均能产生一明显超微弱发光峰 ;( 4 )辐照激发超微弱发光 ,测量液对此超微弱发光有猝灭作用。上述超微弱发光性质可以应用于辐照食品的检测。     

电子束和γ射线辐照对冷鲜猪肉保鲜效果的研究

为探究电子束和γ射线辐照效应的差异性,分别采用2种辐照方式处理冷鲜猪肉,研究其对冷鲜猪肉氧化效应、营养品质、理化性质及感官风味的影响。结果表明,2种处理冷鲜猪肉的TBARS、羰基值和双烯值均显著高于对照组,且γ射线辐照处理高于电子束辐照;处理组的a*、a*/b*、蒸煮损失、剪切力均显著高于对照组,气味等感官品质显著优于对照组;处理组和对照组的脂肪、蛋白质和灰分含量无显著差异。综上所述,辐照处理提高了冷鲜猪肉的氧化,但电子束辐照引起的脂肪氧化效应小于等剂量γ射线辐照引起的氧化效应;电子束辐照冷鲜肉后,其理化性质、营养品质和感官风味均优于等剂量γ射线辐照,因此电子束辐照对冷鲜猪肉的保鲜效果更好。研究结果为电子束辐照技术在冷鲜猪肉保鲜中的应用提供了理论指导。     

不同能量重离子注入农作物的诱变效应

用不同能量、不同注量的MEV级12C离子束辐照玉米和冬小麦干种子,用MEV级16O离子束辐照冬小麦干种子,研究其对M1代幼苗生长的影响和M2代的诱变效应。结果表明,在一定离子通量(注量)下,所用注入能量范围内的离子束对幼苗造成的辐射损伤随辐射能量的增加而增大。用12~16MEV/U的12C离子束辐照玉米和8MEV/U16O离子束辐照小麦,对M1代幼苗造成的辐射损伤比贯穿能量(45MEV/U)下的辐射损伤明显加重。12C离子束可以诱发玉米产生植株矮化、雄性不育、白化苗、多穗型等多种类型变异,多数白化苗能够转绿并正常结实。12C和16O离子束诱发冬小麦产生的早熟和矮杆突变最多,12C辐照冬小麦原冬6产生的早熟突变在辐照能量为8MEV/U、离子通量为80×107/CM2时高达10.7%;矮秆突变在辐照能量为8MEV/U、离子通量为120×107/CM2时高达7.59%。品种间的变异频率也存在差异。     

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.     

不同地域来源牛肉中脂肪酸组成及含量特征分析

建立食品追溯体系是食品安全风险管理的重要措施之一。本研究采用气相色谱仪对来自吉林、宁夏、贵州和河北地区的牛肉脂肪样品进行检测,分析不同地域来源样品中脂肪酸组成及含量差异特征,探讨脂肪酸分析对牛肉产地来源区分的可行性。结果表明,不同地域来源牛肉样品中脂肪酸组成及含量有显著差异,吉林和河北地区牛肉中的SFA(含量均高于62%)显著高于贵州和宁夏地区;宁夏地区牛肉中C16:1和C18:1均显著高于其他地区,含量分别为3.362%和27.041%;贵州与河北地区牛肉中a-C18:3、C20:5和PUFA-n3极显著高于吉林和宁夏地区,吉林地区牛肉中的PUFA-n3含量仅为贵州地区的46%。脂肪酸组成及含量特征分析是鉴别牛肉产地来源一种很有潜力的方法。     

橘小实蝇雄性不育技术应用过程中混入雌虫活力的研究

取羽化前1、2和3d(即-1d、-2d和-3d)来自橘小实蝇遗传性别品系的雌蛹,分别经过90、100和105Gy的60Co辐照后,检测成虫的羽化率、飞行能力和耐压存活率;辐照处理的雌蛹羽化后再分别与普通雄虫和来自遗传性别品系的不育雄虫杂交,在羽化后的第10天、第17天分别采卵,记录产卵量和卵孵化率。结果表明,雌虫羽化率、飞行能力和耐压存活率等变化与雄虫接受辐照后的质量监测结果相同;经过辐照的雌、雄虫相互交配不产卵;辐照处理过的雌虫与普通雄虫交配,成虫的产卵量明显减少,而且剂量越大,蛹龄越小,产卵量越少。     

Analysis of acrylamide in a complex matrix of polyacrylamide solutions treated by heat and ultraviolet light

A recently developed headspace/solid-phase microextraction/gas chromatograph (GC) equipped with a nitrogen-phosphorus detector (NPD) (HS/SPME/GC/NPD) method was used to analyze acrylamide formed in an aqueous polyacrylamide solution (25%) treated by heat or photo-irradiation. Original polyacrylamide contained 0.43 +/- 0.11 microg/mL of acrylamide. When polyacrylamide solution was heated at 70 degrees C for 16 h with 0.5% potassium persulfate, the amount of acrylamide increased to 1.02 +/- 0.11 microg/mL. When polyacrylamide solution was irradiated by UV (lambda = 300 nm) for 16 h with 0.05% 2-anthraquinone sulfate sodium salt, the amount of acrylamide increased to 1.14 +/- 0.54 microg/mL. Polyacrylamide has been used in cosmetic formulations. The present study, therefore, suggests that there is another route of acrylamide exposure to humans in addition to foods and beverages.     

Effect of gas environment and sorbate addition on flavor characteristics of irradiated apple cider during storage

Apple cider, with (0.1%) and without potassium sorbate, was packaged in polystyrene containers and exposed to three different gas environments: oxygen flush, nitrogen flush, and atmospheric air. To evaluate the effects of irradiation (2 kGy) and storage on flavor and microbial quality, these irradiated apple cider samples were compared to a control, unirradiated sample exposed to atmospheric air. Volatile compounds, soluble solids, titratable acidity, and microbiological counts were determined weekly throughout 7 weeks of refrigerated (4 degrees C) storage. Cider irradiated and stored in atmospheric air or nitrogen-flush environments had lower rates of loss for characteristic flavor volatiles compared to unirradiated apple cider and cider irradiated and stored in an oxygen-flush environment. The addition of potassium sorbate to the apple cider resulted in lower counts of yeasts and aerobic microorganisms, reduced fermentation of sugars to organic acids, and improved retention of volatile compounds characteristic of apple cider.     

Analysis of 2-alkylcyclobutanones with accelerated solvent extraction to detect irradiated meat and fish

A new analytical procedure has been developed to analyze 2-alkylcyclobutanones to detect gamma-ray-irradiated fat-containing foodstuffs. Samples were extracted with an accelerated solvent extraction system via hot and pressurized ethyl acetate in cells. A large amount of fat in the extract was precipitated and removed with filtration by standing at -20 degrees C after the addition of acetonitrile. The extract was further cleaned with a 1 g silica gel mini column, and the radiolytic compounds of 2-docecylcyclobutanone (2-DCB) and 2-tetradecylcyclobutanone (2-TCB) were determined with gas chromatography with mass spectrometry (GC/MS). Sample preparation time before GC/MS was 7-8 h. At first, the procedure was evaluated with a recovery test in eight samples spiked with 2-DCB and 2-TCB at 20 ng/g, resulting in 70-105% recoveries with mostly less than 10% relative standard deviations. The procedure was further evaluated with beef, pork, chicken, and salmon samples irradiated with gamma-rays from 0.7 to 7.0 kGy at -19 degrees C. Both 2-DCB and 2-TCB in most samples were detected with good dose-response relations at all doses, while salmon was detected more than 2 kGy irradiation. The amounts of 2-alkylcyclobutanones produced reflected precursor fatty acids levels in samples, especially for the combination of 2-TCB and stearic acid. The results indicated that the production rate of 2-TCB to stearic acid was more obvious than that of 2-DCB to palmitic acid in frozen samples with gamma-ray irradiation.     

辐照对棉铃虫精子传导及产卵反应的影响

本文报道辐照棉铃虫与正常棉铃虫精子传导。棉铃虫的精子传导是一个复杂的过程 ,正常棉铃虫精子传导的失败率为 1 9% ,经 2 50Gy和 40 0Gy辐照后 ,精子传导的失败率分别为 2 1 %和 50 %。精包“帽”定位的异常是精子传导失败的一个重要原因。当棉铃虫雌虫与高剂量辐照雄虫交配后 ,产卵反应表现异常。     

Evaluation of 2-dodecylcyclobutanone as an irradiation dose indicator in fresh irradiated ground beef

Alkylcyclobutanones (2-ACBs) are radiolytic products formed when fatty acids are irradiated. These cyclobutanones are unique irradiation byproducts and therefore may serve as indicators of irradiation exposure. As only limited information exists about 2-ACB formation in retail meat products, reliable methods that can quantify 2-ACBs and thus estimate irradiation dose in commercial meat products are desired. The cyclobutanone studied in this experiment was 2-dodecylcyclobutanone (2-DCB), which is formed from palmitic acid. The formation of 2-DCB was evaluated in fresh irradiated ground beef patties at two fat levels. Patties containing 15% and 25% fat were irradiated by electron beam at 1.0, 2.0, 3.0, and 4.5 kGy. Commercially available 1-lb irradiated ground beef chubs with different fat levels were analyzed in order to estimate dose absorbed by these samples. The 2-DCB was extracted using supercritical fluid extraction (SFE) and analyzed by gas chromatography-mass spectroscopy (GC-MS) and was detected in all the irradiated samples. The concentration of 2-DCB increased linearly with dose with R2 = 0.9646 for 25% fat samples and R2 = 0.9444 for 15% fat samples. Further, there was no significant difference in 2-DCB concentrations between the two fat levels. The estimated doses applied to the commercial samples ranged between 1.38 and 1.55 kGy, values consistent with doses normally used in the industry (1.0-2.0 kGy). Our results show that 2-DCB can be used to monitor fresh irradiated beef and approximate the absorbed dose.     

土壤中痕量指示性多氯联苯三种质谱检测技术的分析比较

为分析土壤复杂基质中7种痕量多氯联苯(PCBs)指示剂,分别采用常规气相–四级杆质谱(GC Q-MS)、气相–飞行时间质谱(GC TOF-MS)和全二维气相–飞行时间质谱(GC×GC TOF-MS)对土壤样品进行检测。结果显示:GC Q-MS检测方法未能检测出复杂体系中的痕量目标物;GC TOF-MS定性出其中2种PCBs,并检测出另外4种目标物的主要特征离子;GC×GC TOF-MS则能够一次性清晰分离出样品中7种PCBs指示剂,并同时检测到样品中其他20种PCBs、杀虫剂和多环芳烃类物质,且均获得较高匹配度。因此,相比于常规GC Q-MS,GC TOF-MS具有更高的定性检测能力,GC×GC TOF-MS分离能力最强,且具有较高的灵敏度和分辨率。