辐照糖类食品的快速鉴别检测方法研究

采用超微弱发光分析技术,检测了辐照食品中3种主要糖分的化学发光过程,拟建立一种实用的辐照食品鉴别检测方法。研究结果表明:经与未经辐照处理的糖,在干燥状态下的超微弱发光特性变化不大,但在测量时自动加入检测液的瞬间,超微弱发光大幅度增加,且光子数与辐照剂量(低于0.7kGy)密切相关,从而提示可将此技术开发为鉴定辐照食品的分析方法。     

辐照食品的热释光分析鉴定方法研究

本文研究了用热释光分析仪鉴定食品辐照与否的具体方法和鉴定标准。在分离样品中的矿物质后,测量其热释光发光曲线的发光峰面积积分值G1,矿物质经1kGy的剂量照射后,再测量其热释光发光曲线的发光峰面积积分值G2;以G1/G2之值作为样品是否经过辐照的判断依据。通过对国家允许辐照的6大类食品中85个样品的检测分析得出:当G1/G2≥0.10时,可判定样品是辐照过的;当G1/G2<0.10时,判定样品是未辐照过的。     

LAL/GNB法筛选辐照鸡肉的应用研究

目的：探讨内毒素检测(LAL)与革兰氏阴性菌计数(GNB)相结合的方法可否应用于辐照鸡肉的筛选。方法：市售鸡肉丁以50g 每份分装后,以γ射线进行辐照处理,剂量分别为0、2、6kGy,每个剂量各12 份,通过革兰氏阴性菌的培养计数估计样品中存在的活的革兰氏阴性菌的量,通过内毒素浓度定量估计活的和死亡的革兰氏阴性菌总量,比较两者差异来判定是否经过辐照处理。结果：辐照剂量为6kGy 时,12 个样品被检测出经过辐照处理。辐照剂量为2kGy 时,8 个样品被检测出经过辐照处理,4 个样品检测出未经过辐照处理。辐照剂量为0kGy 时,12 个样品均被检测出未经过辐照处理。结论：LAL/GNB 法可以应用于辐照鸡肉的筛选。     

电子束辐照对即食凤爪品质的影响

以即食凤爪为试材,研究了电子加速器辐照处理对凤爪品质的影响,分析了不同剂量处理条件下凤爪的脂质氧化TBARS值、总挥发性盐基氮、弹性、汁液流失率、感官品质和菌落的变化情况。结果表明:当辐照剂量达到6.0 kGy时,产品贮藏180 d后其菌落总数为4 300 cfu/g,菌落总数电子束辐照的D10值在1.84～2.22 kGy;辐照剂量大于6.0 kGy时,TBARS值与空白相比有显著差异,而TVB-N则无显著差异;辐照剂量超过8.0 kGy时,则凤爪的弹性与汁液流失率有显著的影响。辐照剂量在一定范围内(8.0 kGy),对产品的感官品质不会产生明显的影响。常温下180 d的贮藏实验结果显示,采用电子束辐照可以显著降低并控制即食凤爪微生物含量,延长产品的货架期。     

辐照与真空包装联合作用对即食食品货架期的影响

为确定辐照与真空包装联合作用对室温条件下即食食品货架期的影响,并确定杀灭食品中腐败微生物和某些非芽孢致病微生物（乙型副伤寒沙门氏菌、痢疾志贺氏菌）的最低剂量进行本研究。采用的辐照剂量分别为２．５、５、１０、２０ｋＧｙ。实验结果表明,大多数经过辐照的即食食品在室温下均可保存２年,而且一些即食食品的试样在一年后变得非常干硬。杀灭即食食品腐败微生物的最低辐照剂量为２．５ｋＧｙ。用１．０×１０２～１．０×１０４／ｇ乙型副伤寒沙门氏菌人工污染真空包装条件下的即食食品,经过５ｋＧｙ的剂量照射后,可以有效地杀灭该致病菌,并在室温条件下存放２年仍未检出沙门氏菌。在相同条件下杀灭痢疾志贺氏菌的最低辐照剂量为２．５ｋＧｙ。辐照与真空包装联合作用可有效地延长室温条件下即食食品的货架期。     

电子束辐照后即食小龙虾贮藏品质的变化

该研究探讨了4 kGy电子束辐照（EBI4）与8 kGy电子束辐照（EBI8）处理对于即食小龙虾尾在冷藏条件下贮藏期内品质的影响。测定了贮藏期内菌落总数、TVB-N、TBA、pH、感官品质的变化,以及贮藏前后电子鼻的变化。结果表明,4 kGy与8 kGy电子束辐照处理后,都有效抑制了微生物的生长繁殖,在贮藏期结束时,微生物仍未超过限定值,分别为4.64 lg CFU/g和4.26 lg CFU/g。且在贮藏期内TVB-N值得到有效抑制,能较好的保持虾肉不致腐败。与8 kGy相比,4 kGy辐照处理能更好保持即食小龙虾的品质,脂肪氧化程度更低,pH值变化与未经辐照的小龙虾更为相近,且在贮藏期内感官评价可接受度更高。经过4 kGy电子束辐照后与新鲜即食小龙虾气味更为相近,对于风味的保留更好。因此,在实际生产中,选取4 kGy电子束辐照处理结合冷藏更有利保持即食小龙虾尾的品质。     

不同剂量辐照酱驴肉贮藏效果快速检测

采用37℃贮藏条件快速检测了辐照酱驴肉的贮藏效果及品质指标变化情况。结果表明:不同剂量的γ-射线辐照处理能够有效地杀灭酱驴肉产品表面污染菌、不同程度地减缓了贮藏过程中产品挥发性盐基氮含量的增加,辐照剂量越高作用效果越好。2.0～10.0kGy的辐照处理对酱驴肉色泽指标(L*值、a*值和b*值)和质构指标的影响规律性不明显。6.0kGyγ-射线辐照后酱驴肉产生微弱的辐照味,随着辐照剂量升高辐照味越浓。     

鲈鱼半成品辐照灭菌剂量研究

为探讨鲈鱼半成品辐照杀菌的最适剂量,以鲈鱼半成品为研究对象,采用0.00~8.74kGy剂量的(60)~Co-γ射线进行辐照灭菌,考察辐照剂量对菌落总数、色度值、pH值、持水力、剪切力和挥发性成分等指标的影响。结果表明,辐照3.25kGy后鲈鱼半成品菌落总数降至10CFU/g;菌落总数在D10值为1.54kGy时降至250CFU/g,D值为3.64kGy时降至10CFU/g,满足灭菌要求,且与实际辐照灭菌剂量(3.25kGy)相当。1.55~4.78kGy可控制pH值的上升;1.55~7.57kGy辐照剂量对持水力、色泽及剪切力影响较小。挥发性成分随辐照剂量的增加而增加,较小的辐照剂量(3.25kGy)有利于减少苯类、烷类等挥发性成分的产生。故使用辐照剂量范围3.25~4.78kGy的(60)~Co-γ射线对鲈鱼进行处理,可达到灭菌目的。     

辐照对真空包装鲫鱼的保藏作用及对鲫鱼中沙门氏菌属和志贺氏菌属的杀灭作用

为研究辐照对真空包装鲫鱼的保藏作用进行本试验.发现30℃条件下不适于辐照鲫鱼的保藏.在4℃条件下,2.5 kGy的辐照可明显延长鲫鱼的保存期,随着辐照剂量的增加,保存期不断延长.对辐照后鲫鱼进行微生物分析发现,辐照可明显地降低鲫鱼试样中菌落总数和大肠菌群数,1.0 kGy的辐照剂量可使鲫鱼中大肠菌群的MPN值小于30/100 g.1.0 kGy的辐照剂量可有效地杀灭鲫鱼中人工污染的志贺氏菌,1.5 kGy的辐照剂量可有效地杀灭鲫鱼中人工污染的沙门氏菌.     

电子束辐照进口冷冻牛腩的剂量分布及感官特性研究

目的 确认电子束辐照冷冻牛腩的剂量分布特性,研究不同剂量电子束辐照对冷冻牛腩的杀菌效果及辐照后产品色泽、风味、质构等感官指标的变化,为冷冻牛腩辐照杀菌的工艺设定和质量控制提供技术参考依据。方法 对不同厚度的冷冻牛腩块分别用8 kGy进行单面及双面电子束辐照,检测其内部剂量分布,确定辐照适宜的产品厚度,在此基础上用0 kGy、2 kGy、4 kGy不同剂量对商品包装（1 kg/袋,最大厚度不超过8 cm）的冷冻牛腩进行电子束双面辐照,检测菌落总数、霉菌和酵母、大肠菌群,同时利用色差仪、电子鼻、质构仪检测冷冻牛腩及其熟制品的色泽、风味、质构等感官指标。结果 单面电子束辐照冷冻牛腩的内部剂量呈先上升后下降趋势,快速下降发生在3.5~5 cm深度区域,产品厚度3.5 cm时剂量不均匀度为1.57。双面辐照可增加电子束穿透深度,8.1cm厚度双面辐照的剂量不均匀度为1.62。冷冻牛腩中菌落总数、霉菌和酵母、大肠菌群均有检出,电子束辐照可显著降低冷冻牛腩微生物水平,商品包装的冷冻牛腩经2 kGy电子束双面辐照后无大肠菌群检出,菌落总数、霉菌和酵母分别较未辐照处理降低98.8%和89.2%。电子束辐照对冷冻牛腩及其熟制品风味、质构无不良影响,4 kGy处理显著还提高了冷冻牛腩回复性,但电子束辐照导致冷冻牛腩色泽参数a值和b值显著下降,且剂量越高下降幅度越大。电子束辐照对色泽的影响程度在冷冻牛腩熟制后降低,2 kGy处理的b值显著高于未辐照处理,其它各处理的a值、b值与未辐照处理均无显著差异。结论 8.1cm厚度冷冻牛腩电子束双面辐照的剂量不均匀度为1.62,冷冻牛腩2 kGy双面辐照后无大肠菌群检出,菌落总数显著降低,风味、质构无不良变化,但色泽参数a、b值显著下降,产品红色消退,熟制可以降低辐照对色泽的不良影响。     

Effect of the gamma radiation dose rate on psychrotrophic bacteria, thiobarbituric acid reactive substances, and sensory characteristics of mechanically deboned chicken meat

Frozen samples of mechanically deboned chicken meat (MDCM) with skin were irradiated with gamma radiation doses of 0.0 kGy (control) and 3 kGy at 2 different radiation dose rates: 0.32 kGy/h (3 kGy) and 4.04 kGy/h (3 kGy). Batches of irradiated and control samples were evaluated during 11 d of refrigerated (2 ± 1 °C) storage for the following parameters: total psychrotrophic bacteria count, thiobarbituric acid reactive substances (TBARS), evaluation of objective color (L*, a*, and b*) and a sensory evaluation (irradiated odor, oxidized odor, pink and brown colors). No statistical difference (P > 0.05) was found amongst the TBARS values obtained for the MDCM samples irradiated with dose rates of 0.32 and 4.04 kGy/h. There was a significant increase (P < 0.05) in the psychrotrophic bacterial count as from the 7th day of refrigerated storage, for the MDCM samples irradiated at the dose rate of 4.04 kGy/h. With respect to the attribute of oxidized odor, the samples irradiated with a dose rate of 0.32 kGy/h showed a stronger intensity and were significantly different (P < 0.05) from the sample irradiated with a dose rate of 4.04 kGy/h on days 0 and 2 of refrigerated storage. Irradiation with a dose rate of 4.04 kGy/h (3 kGy) was shown to be the best condition for the processing of MDCM according to the evaluation of all the variables, under the conditions of this study. Practical Application: The results obtained for the application of different dose rates of ionizing radiation to mechanically deboned chicken meat will provide the food industry with information concerning the definition of the best processing conditions to maximize the sensory and food quality.     

Identification of gamma-irradiated ingredients in liquid seasonings by thermoluminescence analysis: an interlaboratory blind trial

An interlaboratory blind trial was conducted to validate the thermoluminescence (TL)-based identification of gamma-irradiated (0, 1, and 10 kGy) ingredients (garlic powder) in liquid seasonings. Two kinds of forty (20 each) coded samples containing irradiated ingredients at blending ratio of 0–3 % were processed in a food industry and sent to two different irradiation detection laboratories. The garlic powders were also analyzed by both laboratories as reference materials. Irradiated garlic powder provided a strong TL peak at about 200 °C, which was absent in the non-irradiated ones, and the results were also confirmed by determining the TL ratio (TL₁/TL₂). In the blind trial of sauces containing an irradiated ingredient, 75–80 % validated results were reported. The problematic results were observed for the samples containing low quantities of 1 kGy-irradiated ingredients. The TL ratios of all sauce samples were <0.1 irrespective of their irradiation history, where the evaluation was made using the glow curve shapes and intensities. Low amounts of irradiated ingredients could be effectively detected; however, the lower detection limits need to be established after getting a better understanding of the complex TL glow curve results.     

GAMMA IRRADIATION ON FROZEN AND PACKAGED HEADED SHRIMP

The objective of this work was to evaluate the effects of γ irradiation (0, 2, 4 and 6 kGy doses), applied on frozen and packaged headed shrimps, on pathogenic Vibrio cholerae O1 and Salmonella enteritidis bacteria, as well as on some of the physical and sensory characteristics of this kind of food. The 6 kGy dose was highly efficient in inhibiting V. cholerae O1 and S. enteritidis and in decreasing lipid oxidation in shrimps compared with the nonirradiated product. Shrimp texture was not affected by any of the irradiation doses studied, but the lightness of the surface color increased in shrimps irradiated with 6 kGy compared with those irradiated with 2 kGy. Shrimps irradiated with 6 kGy showed lower overall acceptability than those irradiated with 2 kGy or were nonirradiated. The application of γ irradiation in doses up to 6 kGy on frozen and packaged headed shrimps could improve the microbiological quality of this commodity.

PRACTICAL APPLICATIONS

The use of γ irradiation has the potential to ensure safety effectively by inactivating bacteria, increasing shelf life and maintaining food quality without significant chemical changes in the food matrix. Besides, this process can be applied to frozen and packaged products. Thus, irradiation of frozen and packaged shrimps could benefit the local processing industry, which could offer the international market a high-quality product, with an additional safety treatment.     

Determination of radiation-induced hydrocarbons in processed food and complex lipid matrices A new solid phase extraction (SPE) method for detection of irradiated components in food

 Detection of irradiated components in processed food with complex lipid matrices can be affected by two problems. First, the processed food may contain only a small amount of the irradiated component, and the radiation-induced hydrocarbons may be diluted throughout the lipid matrix of the whole food. Second, in complex lipid matrices, the detection of prior irradiation is often disturbed by fat-associated compounds. In these cases, common solid phase extraction (SPE) Florisil clean-up alone is inadequate in the detection of prior irradiation. Subsequent SPE argentation chromatography of the Florisil eluate allows the measurement of small amounts of irradiated lipid-containing ingredients in processed food as well as the detection of prior irradiation in complex lipid matrices such as paprika and chilli. SPE argentation chromatography is the first method available for the selective enrichment of radiation-specific hydrocarbons from even complex lipid matrices, thus enabling the detection of irradiation doses as low as 0.025 kGy. Furthermore, by using radiation-induced hydrocarbons in the detection of prior irradiation of paprika and chilli powder, a second independent method, the first being measurement of thermoluminescence, is available for the analysis of these matrices. Such analysis could be achieved by using this highly sensitive, cheap and easy to perform combined SPE Florisil/argentation chromatography method, without the need for sophisticated techniques like SFE-GC/MS or LC-GC/MS, so that highly sensitive detection of prior irradiation could be performed in almost every laboratory. Received: 19 February 1996/Revised version: 24 May 1996     

Detection of irradiated food using 2-alkylcyclobutanones as markers: verification of the european committee standardization method EN1785 for the detection of irradiated food containing lipids

2-Alkylcyclobutanones (ACBs) are specific radiolytic products in irradiated lipid-containing food and can be used to detect irradiation of foodstuffs. EN1785, a European Committee Standardization Method, can detect 2-dodecylcyclobutanone (DCB) and 2-tetradecylcyclobutanone (TCB), which are ACBs, using GC/MS, thereby allowing judgement as to whether foodstuffs have been irradiated. In this study, the performance of EN1785 as a qualitative test in a single laboratory was evaluated and its applicability to beef, pork, chicken and salmon was verified. In the performance evaluation test, lipids extracted from unirradiated food using the Soxhlet extraction method were used as negative samples. Further, negative samples, to which DCB and TCB were added at 0.05 μg/g lipid (equivalent to the amount generated in food when irradiated at 0.5 kGy or more), were used as positive samples. For each food type examined, 4 negative and 16 positive samples were analyzed by EN1785 to verify the method's ability to detect irradiation. All of the negative samples were judged negative and all of the positive samples were judged positive. Thus, the method should be able to detect irradiation in beef, pork chicken and salmon irradiated at 0.5 kGy or higher. Next, to confirm that this is the case, the same types of food examined above, both unirradiated and irradiated at doses of 0.5-4 kGy, were analyzed by the method. All of the unirradiated samples were judged negative and all of the irradiated samples were judged positive. In a laboratory different from the one where the aforementioned evaluation was conducted, a performance evaluation test was carried out. Blind coded samples, including unirradiated and irradiated samples, were then analyzed in the laboratory according to EN178S. Ten samples (2 unirradiated and 8 irradiated samples) were analyzed for each type of food and the verified method was found to be 100% accurate. Even after the irradiated foodstuffs had been frozen for 6-9 months, it was still possible to judge whether the foodstuffs had been irradiated or not using the EN1785 method.     

高能电子束辐照对金丝绞瓜的保鲜效果

为探究高能电子束辐照对金丝绞瓜保鲜效果及贮藏品质的影响.本研究采用0 kGy(CK)、0.4 kGy、0.6 kGy和0.8 kGy不同剂量高能电子束分别辐照金丝绞瓜的四个面,置于温度9±1℃、相对湿度65％～70％冷库中贮藏,研究不同剂量高能电子束对金丝绞瓜不同部位贮藏品质的影响.结果表明,与对照瓜相比,该辐照促进了...     

嘉兴市即食食品中致病微生物的污染现状调查

目的了解市售食品中食源性致病微生物的污染现状,发现高危食品,为预防和控制食源性疾病提供科学依据。方法在农贸市场、超市和餐饮环节采集与嘉兴市消费者生活密切相关的8类即食食品,开展常见致病微生物监测。结果采集的640份食品样品中,检出致病菌56株,检出率为8.75%(56/640),检出菌株以副溶血性弧菌为主,占总检出数的69.64%(39/56);金黄色葡萄球菌居次位,占14.29%;单核细胞增生李斯特菌、蜡样芽胞杆菌和创伤弧菌占比依次为8.93%、5.36%和1.79%。三季度致病微生物检出率(16.92%)最高,农贸市场、散装食品、水产品检出率相对较高,分别为17.60%、13.30%和25.00%。结论嘉兴市即食食品存在食源性致病微生物污染风险,需加强监督管理、规范食品操作和提高人群健康教育水平。     

基于间酪氨酸和邻酪氨酸鉴定辐照海产品

利用超高效液相色谱-三重四极杆/线性离子阱质谱（ultra performance liquid chromatography-quadrupole linear ion trap tadem mass spectrometry,QTRAP-UPLC-MS/MS）技术测定海产品中与辐照相关的多种氨基酸及同分异构体,研究辐照剂量（0.5～20?kGy）与不同海产品中辐照标识性产物间酪氨酸和邻酪氨酸的产生和含量的关系。不同贮藏条件和加工方式对间酪氨酸和邻酪氨酸特异性和稳定性,以及对辐照海产品测定的影响。结果表明：辐照可诱导苯丙氨酸产生对酪氨酸、间酪氨酸和邻酪氨酸,无需其他酶和微生物的作用,且含量与辐照剂量呈线性关系;辐照剂量和样品含水量与辐照标识物的产生量密切相关;在－20?℃,间酪氨酸和邻酪氨酸具有良好的稳定性;不同贮藏条件和加工方式对辐照海产品中间酪氨酸和邻酪氨酸含量具有一定影响,但是仍能提取到足够量的间酪氨酸和邻酪氨酸用于辐照海产品的鉴定;利用QTRAP-UPLC-MS/MS对海产品中邻酪氨酸和间酪氨酸作为辐照标识物的测定,最低可检测到经0.5?kGy辐照的样品,可准确地对辐照海产品是否经过辐照进行判定,为辐照海产品的检测提供依据。     

Solid phase extraction (SPE) method for detection of irradiated meats

Solid phase extraction (SPE) has been proposed as an alternative to the currently used florisil column chromatography. The hydrocarbons formed from beef, pork and chicken irradiated with 0-10 kGy were determined by the SPE and quantified by GC/MS. The limit of detection for the hydrocarbons in irradiated meats was 0.5 kGy. The correlation between the irradiation dose and the concentrations of hydrocarbons in beef, pork and chicken was high that linear regression coefficients (r²) were 0.87-0.99. SPE method would be used as the rapid detection of irradiated meats.