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.     

Changes in thermoluminescence properties of minerals separated from irradiated potatoes and garlic during long-term storage under different light conditions

The effect of different light conditions on the specificity and reliability of thermoluminescence (TL) analysis to detect irradiated samples (potatoes and garlic) during 2?years of storage was investigated. The silicate minerals separated from the nonirradiated samples provided a low-intensity TL glow curve with a maximum peak after 300?°C demonstrating the absence of an irradiation history. The TL glow curve from the irradiated samples provided easy discrimination with TL glow curves of high intensity and maximum peak in temperatures range of 160?C185?°C. The results were also confirmed by calculating the TL ratio (TL₁/TL₂) through normalization (re-irradiation) step. The key parameters of the TL analysis including the TL intensity, TL glow curve shape, and the TL ratio exhibited a time-dependent change. The bleaching effect of different light conditions was also significant, which was most prominent in the case of natural light with a prominent decrease in the TL intensity and ratio. The maximum TL glow peak also showed a shift towards the higher temperature. However, all irradiated samples, irrespective of the storage conditions and time, were easily discernable from the nonirradiated ones considering the shape and intensity of the TL glow curve.     

Effect of Drying Treatment on Physical Identification Characteristics of Irradiated Seasonings

The effect of different drying treatments such as spray drying and vacuum drying on the sensitivity of physical detection methods (photostimulated luminescence (PSL), electron spin resonance (ESR), and thermoluminescence (TL)) was investigated for four types of irradiated seasonings. The slurry feed of each seasoning was exposed to γ-ray irradiation at doses of 0, 5, 10 kGy before being subjected to drying process. Spray drying was applied to beef and soybean seasoning while garlic and broth seasoning were exposed to vacuum drying according to routine protocols adopted in the industry. The samples were analyzed by PSL as a rapid screening method followed by validated methods including ESR spectroscopy and TL analysis. The PSL photon counts drastically dropped in all irradiated samples after both drying processes. No ESR signal was obtained from any of the irradiated seasonings before or after the drying applications. All the irradiated seasoning samples produced typical TL glow curves between the specific temperature range of 150–250 °C. However, the shape, peak, and intensity of TL glow curves were greatly affected particularly after the spray drying treatment. In conclusion, the dry treatment can significantly affect the irradiation detection characteristics in seasoning samples.     

茶叶辐照的热释光分析研究

不采用二次辐照,将TL 分析法应用于辐照茶叶的定性鉴定。分离并收集茶叶中黏附的硅酸盐,采用热释光剂量仪测量获得硅酸盐的热释光发光曲线,比较未辐照与辐照不同剂量茶叶的热释光发光曲线的积分强度、峰值和峰值温度等特征参数。未辐照茶叶的热释光发光曲线的积分强度小于50、峰值小于0.4、峰值温度大于260℃;反之,辐照茶叶的热释光发光曲线的积分强度大于50000、峰值大于600、峰值温度位于160～190℃。TL 分析法能判别出茶叶的辐照与否,尤其对不能满足参比剂量辐照条件的样品很有帮助。     

Identification of Irradiated Shellfish Using Well-Characterized Thermoluminescence Properties of Biogenic Minerals Present in the Exoskeletons

The shellfish exoskeleton is mainly composed of carbonate minerals with very minute traces of silicate minerals. Feldspar (silicate mineral) has outstanding thermoluminescence (TL) characteristics, whereas carbonate minerals could lead to the false detection of irradiation history. The silicate minerals present in the biogenic exoskeleton matrix of shellfish (Corbicula and Melanian snail) were targeted for their TL properties after separating through different acid treatments of shell samples. Excellent TL results for the TL glow curve shape, intensity, and TL ratio (TL₁/TL₂) were obtained where the clear discrimination of irradiation treatment (0, 2, and 4 kGy) was possible. The results were compared to the whole shell powder samples, feldspar, and calcite standard minerals to present a better understanding of their luminescence characteristics. The developed TL method showed the potential to successfully identify irradiated shellfish for the regulatory requirements.     

Applicability of thermoluminescence techniques to identify irradiated seafoods using different methods of mineral separation: An interlaboratory blind trial

Thermoluminescence (TL) technique for identifying γ-irradiated (0–10 kGy) anchovies (dried), kelp (dried), and mackerel (fresh) was validated in an interlaboratory blind trial. Different irradiation detection laboratories were involved by using 2 methods of mineral separation (density separation and acid hydrolysis) for the analysis. Key TL parameters, including the TL glow-curve shape, intensity, and the TL ratio (TL₁/TL₂) were used to characterize the irradiation status. All irradiated samples exhibited an intense TL peak at approximately 200°C, which was absent in non-irradiated samples. TL glow curve interpretations were also confirmed by determining the TL ratio. Different participating laboratories reported 89–100% correct results. Both methods of mineral separation were equally effective; however, some variation was observed in the results from different laboratories for irradiated mackerel, which might be due to a lack of isolated minerals, differences in personnel expertise, and different TL instruments.     

Dose dependence and fading effect of the thermoluminescence signals in γ-irradiated paprika

The thermoluminescence (TL) method can be used to discriminate irradiated and non-irradiated paprika. This study reports the polymineral composition of the dust adhered to paprika; radiation-specific luminescence is emitted by the inorganic material (mainly quartz, feldspars and calcite). On the basis of the shape of the TL curves (or glow curves) some physical parameters are evaluated. Natural TL curves, from non-irradiated samples, show three very low intensity peaks while induced TL curves, from irradiated paprika, seem to consist of five overlapping peaks. TL spectra reveal a very important difference in intensity and in the position of the peaks between irradiated and non-irradiated paprika. Fading observations of TL after irradiation at 5, 10 and 21 kGy, show the same behaviour in all the cases: an initial rapid decay to maintain a certain stability from 300–400 h onwards. © 1998 SCI.     

Applicability of different analytical methods for the identification of γ-irradiated fresh mushrooms during storage

Photostimulated luminescence (PSL), thermoluminescence (TL), and electron spin resonance (ESR) analyses were performed to identify γ-irradiated (0, 1,2, and 3 kGy) fresh mushrooms (oyster, king oyster, and shiitake mushrooms) during storage at 5°C. PSL analysis gave negative results [<700 photon counts (PCs)] for the nonirradiated and intermediate (700–5,000 PCs) or positive results (>5,000 PCs) for the irradiated samples. The shape, intensity, and occurrence of TL glow curve in a typical temperature range (150–250°C) along with TL ratio (TL₁/TL₂) provided sufficient information to confirm the irradiation history of samples. Storage resulted in a negligible fading effect on PSL and TL characteristics. X-ray diffraction analysis showed the abundance of feldspar and quartz minerals in the separated dust from mushrooms. In detailed ESR analysis employing different sample pre-treatments, all samples were silent for radiation-specific ESR signals giving only a central signal (g=2.005) that showed an increase in intensity upon irradiation.     

Inter-Laboratory study to define the temperature interval for a thermoluminescence heating unit used to identify irradiated food

EN 1788:2001 suggests defining the temperature range for the thermoluminescence (TL) heating unit to calculate the TL ratio (TL₁/TL₂). In the present study, practical temperature ranges were established by using well-characterized lithium fluoride (LiF, TLD-100®) at 4 different research institutes in Korea. Temperature ranges differed according to models of TLD heating unit, which were wide in the case of RISØ (160–249°C) as compared with Harshaw (155–232°C) TLD readers. The silicate minerals separated from irradiated turmeric samples were measured to check these intervals on a practical basis. The X-ray diffraction (XRD) analysis of separated minerals showed that quartz and feldspar minerals were the main source of well-characterized TL glow curve following irradiation. The TL glow peaks from the separated minerals were narrower in Harshaw than RISØ TLD readers. The TL ratios determined after re-irradiation (1 kGy) for the tested minerals, using the pre-defined temperature intervals, provided the satisfactory results.     

热释光法在辐照食品检测中出现假阳性问题的探讨

目的探讨热释光法在辐照食品检测中出现假阳性的问题。方法按照标准EN1788-2001《食品与硅酸盐矿物隔绝的食品的辐射检验热致发光法》,采用热释光法对深海鱼加工产品进行辐照食品检测。结果与花椒粉等典型辐照样品不同,深海鱼加工产品虽然检测结果为阳性,但其谱图与典型辐照样品谱图存在一定差异。主要表现为一次发光曲线中,典型辐照样品谱图的发光峰下降舒缓,峰型符合正态分布;而深海鱼加工产品的发光峰下降陡峭,并不符合正态分布。据此,怀疑热释光法对深海鱼加工产品的检测分析结果实为假阳性。结论建议在对深海鱼产品进行辐照检测时,谨慎选用热释光法或采用其他检测方法如气相色谱分析碳氢化合物法进行复验。     

Pulsed photostimulated- and thermo-luminescence investigations of γ ray-irradiated herbs

In this study, physical detection methods like pulsed photo-stimulated luminescence (PPSL) and thermoluminescence (TL) were investigated to indentify γ-ray irradiation treatment of some medicinal herbs. Dried herbal samples consisting of root, rhizome, cortex, fruit, seed, flower, spike, ramulus, folium and whole plant of nineteen different herbs were irradiated using a 60Co irradiator at 0–50 kGy. Fifteen non-irradiated control samples had photon counts (PCs) less than the lower threshold value (700 counts/60 s). The photon counts of four non-irradiated samples (roots of osterici, angelica gigas, liriope, and whole plant of taraxaci herba) were between the lower and upper threshold values (700–5000 counts/60 s). However, PCs of all the irradiated samples were found to be higher than the upper threshold value (5000 counts/60 s), clearly screening them out from the non-irradiated ones. Even after 12 weeks of storage PPSL signals of all irradiated samples were observed to be higher than the upper threshold value, making it possible to distinguish them from the non-irradiated control samples. The first TL glow curves (TL₁) for the non-irradiated samples were of very low intensity at about 250–300 °C. Irradiated samples (5–50 kGy) showed a higher peak at around 150–250 °C. TL ratios [ratio of the integrated areas of the first (TL₁) and second (TL₂) glow], measured after re-irradiation for the TL₁-tested samples at 1 kGy, were found to be less than 0.1 for the non-irradiated samples and higher than 0.1 for the irradiated ones. TL ratios for all irradiated samples measured after 12 weeks of storage under dark condition at (23 ± 2 °C) were apparent for distinguishing them from the non-irradiated controls.     

国际蔬菜调味料的开发动向

介绍了8种此类调味料的简单生产工艺及配方，分别为透明番茄调料；洋葱调味料；玉葱精调料；辣白菜粉末调味料；菇类调味粉；蔬菜汁粉；蔬菜汤料；无臭大蒜浸膏。     

Comparison of three methods for detection of herbal food supplement irradiation

A survey for irradiation of 106 herbal food supplements was carried out in Denmark in 2003. The results from three methods, two screening methods and a specific method, were compared: Direct epifluorescent filter technique/aerobic plate count (DEFT/APC), photostimulated luminescence (PSL) and thermoluminescence (TL) standardised by Comité Européen de Normalisation (CEN). Forty samples screened positive with the DEFT/APC method. However, the TL method could only confirm irradiation of 15 samples, 11 samples wholly irradiated and 4 samples with a minor irradiated ingredient. Thus, the DEFT/APC method gave a large number of false positive results, although the number of false negative results probably was very low. Only 7 of the 15 confirmed irradiated samples screened positive with the PSL screening method, the samples with low photon counts escaping detection. For 10% of the samples also the TL method was lacking in sensitivity, as not enough minerals could be isolated to get a signal over the minimum detection level. For such clean herbal food supplements no suitable method exists at all among the CEN standardised methods for irradiation detection.     

Effect of γ-irradiation on physical quality attributes and identification properties of different sauces

Gamma-irradiated (0, 1, and 10 kGy) ketchup (KTP), barbeque sauce (BBQ), and sweet chili sauce (SWC) were identified using photostimulated-luminescence (PSL) and thermoluminescence (TL) analysis and characterized for physical properties like Brix, consistency, and color. PSL-based screening showed negative results for all nonirradiated samples, while intermediated results were found for irradiated samples. Routine density separation method for mineral extraction provided better TL results; however, alkaline and acid hydrolysis could ease the process with acceptable results. A slight decrease in consistency of all the samples was observed. Brix of KTP remained unchanged, while increase of same was obvious in BBQ and SWC following irradiation. The Hunter L* value of the γ-irradiated sauces decreased except SWC samples, and the a* and b* values showed a general increase compared to the non-irradiated samples. The studied methods have potential to successfully identify and characterize the irradiated sauces for technical and regulatory requirements.     

Frequency and behavior of Salmonella and Escherichia coli on whole and sliced jalapeño and serrano peppers

The frequencies of coliform bacteria (CB), thermotolerant coliforms (TC), Escherichia coli, and Salmonella were determined for jalape?o and serrano peppers. In addition, the behavior of four serotypes of Salmonella and three E. coli strains on whole and sliced jalape?o and serrano peppers as well as in blended sauce at 25 ± 2°C and 3 to 5°C was investigated. Chili peppers were collected from markets in the city of Pachuca, Hidalgo, Mexico. CB, TC, E. coli, and Salmonella were detected on serrano peppers in 100, 90, 50, and 10 % of the samples, and on jalape?o peppers in 100, 86, 32, and 12 % of the samples. Concentrations of CB ranged from 3.8 to 7.9 log CFU per serrano sample and from 5.3 to 8.2 log CFU per jalape?o sample, whereas concentrations of TC and E. coli were between < 3 and 1,100 most probable number per serrano and jalape?o samples. On whole serrano and jalape?o peppers stored at 25 ± 2°C or 3 to 5°C, no growth was observed for rifampin-resistant strains of Salmonella and E. coli. After 6 days at 25 ± 2°C, the tested Salmonella serotypes and E. coli strains had decreased from an initial inoculum level of 5 log CFU to 1 and 2.5 log on serrano and jalape?o peppers, respectively, and at 3 to 5°C they decreased to approximately 1.8 and 1.2 log, respectively, on serrano and jalape?o. Both the Salmonella serotypes and E. coli grew on sliced chili peppers and in blended sauce; after 24 h at 25 ± 2°C, both bacteria types had grown to approximately 4 and 5 log CFU on pepper slices and in sauce, respectively. At 3 to 5°C the bacterial growth was inhibited.     

Innovative Quality Improvement by Continuous Microwave Processing of a Faba Beans Pesto Sauce

Nowadays, consumers demand healthy, safe, and ready-to-eat horticultural products because of their lifestyle. In this regard, new legume-based food product development with eco-innovative technologies seems to be an interesting market. The effect on quality of an innovative pesto sauce, made of fresh faba bean seeds, of an alternative continuous microwave treatment pasteurization (MW, 11 kW; 30 s) regarding a conventional pasteurization (85 °C; 5 min) throughout 20 days at 5 °C was studied. Non-heated blended samples were used as control. The microbial quality was satisfactory in all treatments. MW treatment improved the sensorial quality of pesto sauce and decreased condensed tannins. Additionally, MW-treated samples showed the best texture, consistency, and color, preserving its chlorophyll and carotenoid content. On the other hand, thermal treatments showed a decrease in total phenolic compounds (TPC) and antioxidant capacity (TEAC) after heating, regarding control samples; however, TPC and TEAC remained quite constant throughout the storage.     

Development and single laboratory validation for thermoluminescence detection of irradiated foods using X-ray irradiation

The thermoluminescence (TL) method using X-rays was investigated for the purpose of detection of irradiated food, and the method was validated at a single laboratory level. A small X-ray irradiator was developed as an alternative radiation source for normalization, and X-ray irradiation conditions equivalent to gamma-ray irradiation from (60)Co were established. Gamma-ray irradiated spices were used for the method validation. The detection limits (MDL) and lower limit of integrated TL intensities (MDL×10) for the spices were checked and the separation of silicate minerals from the spices was confirmed to be sufficient for TL analysis. There was no significant difference in TL glow ratio obtained using two sets of X-ray irradiation equipment including the newly developed equipment. Repeatability and intermediate precision showed no influence of analysts, X-ray irradiation equipments, or measurement days on the TL ratios. From these results, this detection method was validated in a single laboratory.     

Addition of garlic or onion before irradiation on lipid oxidation, volatiles and sensory characteristics of cooked ground beef

Addition of 0.5% onion was effective in reducing lipid oxidation in irradiated cooked ground beef after 7 day storage. Addition of garlic or onion greatly increased the amounts of sulfur volatiles from cooked ground beef. Irradiation and storage both changed the amounts and compositions of sulfur compounds in both garlic- and onion-added cooked ground beef significantly. Although, addition of garlic and onion produced large amounts of sulfur compounds, the intensity of irradiation odor and irradiation flavor in irradiated cooked ground beef was similar to that of the nonirradiated control. Addition of garlic (0.1%) or onion (0.5%) to ground beef produced a garlic/onion aroma and flavor after cooking, and the intensity was stronger with 0.1% garlic than 0.5% onion treatment. Considering the sensory results and the amounts of sulfur compounds produced in cooked ground beef with added garlic or onion, 0.5% of onion or less than 0.1% of garlic is recommended to mask or change irradiation off-odor and off-flavor.     

Thermoluminescence Spectra of Inorganic Dust from Irradiated Herbs and Spices

Thermoluminescence (TL) is used to determine whether certain foodstuffs have been irradiated. A high sensitivity TL spectrometer was used to analyze irradiated and unirradiated inorganic dusts from herbs and spices. Unlike earlier TL work using emissions in the UV-green spectral range, the spectrometer monitored transient TL emissions across the spectral range from UV to infra-red as samples were heated to 400°C. A strong high temperature red emission peak was detected in all irradiated samples. This signal was much higher than the background level, insensitive to post-irradiation light exposure, and has potential for irradiation exposure determination.     

五香牛肉鸡枞菌风味酱的研制

以鸡枞菌、牛肉和豆豉为主要原料,植物油、食用盐、五香粉、白糖、葱姜蒜等为辅料制作牛肉酱,以感官评分为评价指标,首先通过单因素、正交试验对影响酱品质的主料和辅料配方进行优化,然后以主料、辅料和淀粉为3个因素,采用响应面法对五香鸡枞菌牛肉风味酱配方进行优化研究。结果表明,最佳风味酱配方为鸡枞菌30.0%,牛肉26.7%、豆豉23.4%、植物油7.1%、葱姜蒜4.4%、白糖2.2%、食用盐2.8%、五香粉1.5%、淀粉1.9%。此优化条件下,感官得分为92.97分。鸡枞菌和牛肉香味浓郁,色泽较为鲜亮,酱体浓稠适中,营养丰富,方便即食。该产品的亚硝酸盐含量为2.3 mg/kg,所有指标均符合国家标准。