Bioaccumulation of cyanuric acid in edible tissues of shrimp following experimental feeding

Due to concerns that cyanuric acid (CYA)-contaminated feed had been used in aquaculture and could enter the human food chain, a method to quantify CYA residues in the edible tissues of fish and shrimp was previously developed and validated. This paper provides further data on the deliberate feeding of CYA to shrimp to determine the extent of residue accumulation in edible tissue. Liquid chromatography–tandem mass spectrometry (LC–MS/MS) was employed for the analysis of CYA in shrimp tissue. Edible tissue of shrimp fed 1666 or 3333?mg?kg^?1 CYA in their diet (approximately 55 and 124?mg?kg^?1 body weight) contained 0.767 and 0.406?mg?kg^?1 CYA, respectively. The residue levels are below the World Health Organization (WHO) tolerable daily intake level for CYA and are generally considered unlikely to pose a human health risk.     

虾的营养及其食用安全

虾是口味鲜美、营养丰富,可制多种佳肴的美味,有菜中之“甘草”的美称。我国海域宽广,江河湖泊众多,盛产海虾和淡水虾。海虾有对虾、明虾等,淡水虾有青虾(沼虾和草虾)等,还有半咸水虾如白虾等。不管何种虾,都含有丰富的蛋白质,营养价值高,其肉质和鱼一样松软,易消化,是对人类健康极有裨益的佳品。营养学家介绍,虾含有丰富的优质蛋白质及钙、磷、铁、锌、碘、硒、维生素A等,它低糖、低脂、低胆固醇。体内蛋白含量较高,占总体的16%～20%左右。脂肪含量不到0.2%,而且所含的脂肪主要是由不饱和脂肪酸组成,适宜人体吸收。尤其是所含的原肌球蛋白…     

Residues of melamine and cyanuric acid in milk and tissues of dairy cows fed different doses of melamine

Melamine (1,3,5-triazine-2,4,6-triamine) may be degraded into cyanuric acid and some other compounds by rumen microorganisms. This study was conducted to assess the transfer of melamine and cyanuric acid in to milk and tissues by dairy cows fed different doses of melamine. Forty mid-lactation dairy cows (157 ± 43 d in milk, 20.8 ± 1.4 kg of milk/d) were divided into 4 groups (n = 10/group) using a completely randomized design. The groups were fed the following amounts of melamine (purity ≥ 99.5%) at 0 (control), 300 [treatment (Trt) 1], 500 (Trt 2), and 1,000 (Trt 3) mg/d per cow, respectively. The trial lasted for 18 d (12-d feeding period, followed by a 6-d clearance period). Milk samples were collected from the 4 groups on d 1, 2, 3, 4, 8, 12, 13, 14, 15, and 18, and analyzed for melamine and cyanuric acid. On d 13, 3 cows from Trt 2 and Trt 3 were randomly selected and slaughtered; tissue samples including kidney, liver, mammary, bladder, gluteus medius, and longissimus dorsi were collected for melamine and cyanuric acid analyses. Milk and tissue samples were analyzed for melamine and cyanuric acid using a simultaneous liquid chromatography tandem mass spectrometry procedure. Neither melamine nor cyanuric acid was detected in concentrated feed that was being fed to the cows. In melamine-treated groups, milk melamine concentration increased quickly and reached a stable level by d 4 and was at similar levels on d 8 and 12 after the first administration of melamine. Milk melamine levels in treated groups were 0.18, 0.27, and 0.50 mg/L for Trt 1, Trt 2, and Trt 3, respectively, and were highly correlated (R² = 0.91) with melamine dosing levels. No cyanuric acid was detected in any of the milk collected from the various groups. Melamine residue levels in tissues of Trt 3 were about 2-fold higher than that in Trt 2, with the highest concentration being found in kidney. No differences in cyanuric acid levels in tissues were found between Trt 3 and Trt 2. Liver, kidney, and bladder tissues were found to contain the highest cyanuric acid levels. This study shows a relationship between dietary melamine levels and cyanuric acid levels found in tissues, which might be the result of melamine being converted to cyanuric acid by microorganisms in the rumen.     

可食性涂膜保鲜虾的品质控制研究

以海藻酸钠和壳聚糖为涂膜剂对鲜虾及虾仁进行涂膜处理,然后分别进行冷藏及冷冻保鲜.通过测定解冻汁液流失、煮汁损失、干耗率及质构变化,研究在不同贮藏条件下采用可食性涂膜保鲜虾在品质控制方面的作用.实验结果表明:可食性涂膜保鲜能显著减少解冻汁液流失、降低煮汁损失及干耗率,并且能保持较好的硬度和弹性.壳聚糖复合涂膜的保鲜效果优于海藻酸钠的保鲜效果.     

Tylosin depletion in edible tissues of turkeys

The depletion of tylosin residues in edible turkey tissues was followed after 3 days of administration of tylosin tartrate at 500 mgl^-1 in drinking water, to 30 turkeys. Immediately after the end of the treatment (day 0) and at day 1, 3, 5 and 10 of withdrawal, six turkeys (three males and three females) per time were sacrificed and samples of edible tissues were collected. Tissue homogenates were extracted, purified and analysed by HPL C according to a method previously published for the analysis of tylosin residues in pig tissues. In all tissues, tylosin residues were already below the detection limits of 50 μg kg^-1 at time zero. However, in several samples of tissues (skin ₊ fat, liver, kidney, muscle), from the six turkeys sacrificed at that time, one peak corresponding to an unknown tylosin equivalent was detected at measurable concentrations. The identification of this unknown compound was performed by L C-MS/MS analysis of the extracts from incurred samples. The mass fragmentation of the compound was consistent with the structure of tylosin D (the alcoholic derivative of tylosin A), the major metabolite of tylosin previously recovered and identified in tissues and/or excreta from treated chickens, cattle and pigs.     

Residue depletion of sulfachlorpyrazine in edible tissues of broiler chickens

The residue depletion profile of sulfachlorpyrazine was studied in healthy broilers after oral administration of Sulfatyf®, given at a dose of 50?mg sulfachlorpyrazine (SCP) per kg body weight once daily for 3 consecutive days. Twenty-five medicated broilers were slaughtered on the 5th, 10th, 14th and 16th day of post-medication, and muscle, fat with skin, liver and kidney tissues were sampled and analysed using an high-performance liquid chromatography (HPLC) method with satisfactory recovery (74.5%?±?2.9%) and specificity. The estimated values of LOD and LOQ were 18.40 and 55.70?ng?ml^?1, respectively. On the 5th and 10th day of post-medication, the concentrations of SCP residue in all samples examined were higher than the corresponding MRLs established by the European Union and the highest SCP concentrations were measured in muscle. A maximum withdrawal time of 14 days was calculated to ensure consumer safety.     

Essential elements and contaminants in edible tissues of European and American lobsters

In several European countries clawed lobsters, such as the European (Homarus gammarus) and American (H. americanus) ones are widely consumed. Yet, information about essential elements and contaminants in both species is still scarce. Therefore, the aim of this work was to characterise the elemental content in the edible part (muscle, hepatopancreas, gonads and roe) of both homarids and to compare them with the daily intake recommendations and maximum allowed levels. Two techniques were employed: energy-dispersive X-ray fluorescence (EDXRF) to quantify Cl, S, K, Ca, Fe, Cu, Zn, As, Se, Br and Sr; and flame atomic-absorption spectrometry (FAAS) to analyse Na, Mg, Mn, Cd, Hg and Pb. Significant differences were found in the elemental composition of edible tissues of both species, likely reflecting the distinct physiological role of those tissues: muscle (higher: Na, Mg, Ca and Sr; lower: Fe, Se, Cd); hepatopancreas (higher: Fe, Cu, Br and Cd); gonads (lower: Cl, Ca, Zn and Hg); and roe (higher: Na and Br; lower: K and As). Statistical differences in the elemental composition of each tissue were found between both homarids: Muscle (Na, Se, As and Hg); Hepatopancreas (Na, Mg, Fe, Cu, Se, Br and Hg); and gonads (S and Zn). Since the geographical distribution of both species is different, the differences likely reflect distinct elemental composition in the aquatic environment and, consequently in the feed chain. Both lobster species were rich sources of Na, Cl, Cu, Zn and Se for human consumption. Regarding contaminants, only Cd was detected at high concentrations in the hepatopancreas of both homarids. Despite Cd values were well above the maximum allowed level set by the European Commission for crustaceans’ muscle, so far any limit value was set for crustaceans’ hepatopancreas. Nonetheless, the present study recommends avoiding or moderately consuming this tissue in homarids.     

Concentrations of antibiotic residues vary between different edible muscle tissues in poultry

Antibiotics are used by veterinarians and producers to treat disease and improve animal production. The federal government, to ensure the safety of the food supply, establishes antibiotic residue tolerances in edible animal tissues and determines the target tissues (e.g., muscle) for residue monitoring. However, when muscle is selected as the target tissue, the federal government does not specify which type of muscle tissue is used for monitoring (e.g., breast versus thigh). If specific muscle tissues incorporate residues at higher concentrations, these tissues should be selected for residue monitoring. To evaluate this possibility in poultry, chickens were divided into four groups and at 33 days of age were dosed with enrofloxacin (Baytril), as per label directions, at either 25 ppm for 3 days, 25 ppm for 7 days, 50 ppm for 3 days, or 50 ppm for 7 days. Breast and thigh muscle tissues were collected from each bird (n = 5 birds per day per group) during the dosing and withdrawal period, and fluoroquinolone concentrations were determined. The results indicate higher overall enrofloxacin concentrations in breast versus thigh muscle for each treatment group (P < 0.05). These data indicate, at least for enrofloxacin, that not all muscle tissues incorporate antibiotics at the same concentrations. These results may be helpful to regulatory agencies as they determine what tissues are to be monitored to ensure that the established residue safety tolerance levels are not exceeded.     

振动流化床中氰尿酸合成反应的试验研究

在特制的多层立式振动流化床上,对加热反应时间、加热温度、进风量、进风形式以及设备的振动强度等因素对由尿素缩合反应生成氰尿酸的影响进行了实验研究和讨论。结果表明:影响转化率的主要因素是加热反应时间和加热温度;该设备中的缩合反应具有时间短、转化率高和粘壁现象少等特点;在加热进风温度为220℃时,反应进行80~90min后产物中氰尿酸的含量即可超过80%。     

同时检测畜禽肉中呋喃唑酮、地塞米松残留高效液相色谱法的建立

为建立畜禽肉中呋喃唑酮、地塞米松HPLC检测方法。经试验,得到的色谱条件为流动相:乙腈-水(40+60);检测波长:240nm;流速:1.0mL/min。采用该方法检测了市售畜禽肉中呋喃唑酮、地塞米松的残留量,结果表明:该方法分离效果良好,平均回收率范围85.41%～95.2%,相对标准偏差为2.0%～4.5%,最低检出限达1.0～2.0μg/mL,说明该方法灵敏、准确、精密、无杂质干扰,可以用于肉品中呋喃唑酮、地塞米松残留的检测。     

Development and validation of an indirect competitive enzyme-linked immunosorbent assay for monitoring quinoxaline-2-carboxylic acid in the edible tissues of animals

The feed drug additive carbadox is a suspected carcinogen and mutagen. To monitor effectively residues of carbadox in the edible tissues of food-producing animals, an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) to detect quinoxaline-2-carboxylic acid, the marker residue of carbadox, was developed. Several haptens were synthesised and conjugated to the carrier protein. Nine female New Zealand white rabbits were immunised with the immunising conjugates to produce polyclonal antibodies according to the designed schemes of immunisation. The highly specific antibody that was very sensitive to N-butylquinoxaline-2-carboxamide with an IC₅₀ value of 7.75?µg?l^?1 was selected for the development of an ic-ELISA. The standard curves based on the N-butylquinoxaline-2-carboxamide matrix calibration ranged from 0.2 to 51.2?µg?l^?1. The decision limit and detection capability of the ic-ELISA were 0.60 and 0.83?µg?kg^?1 for liver and 0.68 and 0.79?µg?kg^?1 for muscle of swine, respectively. The recoveries were 57–108% with coefficients of variation of less than 20% when the quinoxaline-2-carboxylic acid was spiked into liver and muscle with the concentrations of 1.0–20.0?µg?kg^?1. Excellent correlations between the results of the ic-ELISA and an HPLC method (r?=?0.9956???0.9969) were observed for incurred tissues. These results suggest that the ic-ELISA is a sensitive, accurate and low-cost method that would be a useful tool for screening residues of carbadox in the edible tissues of food-producing animals.     

食用植物油中酸价测定的不确定度评定

根据食用植物油中酸价测定的原理,全面考虑了整个分析过程的不确定度来源,建立其结果的数学模型,并计算其测定全过程的不确定度分量、结果标准不确定度及扩展不确定度。提出的方法适用于食用植物油中酸价测定的不确定度评定。     

Development and validation of an indirect competitive enzyme-linked immunosorbent assay for monitoring quinoxaline-2-carboxylic acid in the edible tissues of animals

The feed drug additive carbadox is a suspected carcinogen and mutagen. To monitor effectively residues of carbadox in the edible tissues of food-producing animals, an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) to detect quinoxaline-2-carboxylic acid, the marker residue of carbadox, was developed. Several haptens were synthesised and conjugated to the carrier protein. Nine female New Zealand white rabbits were immunised with the immunising conjugates to produce polyclonal antibodies according to the designed schemes of immunisation. The highly specific antibody that was very sensitive to N-butylquinoxaline-2-carboxamide with an IC(50) value of 7.75 μg l(-1) was selected for the development of an ic-ELISA. The standard curves based on the N-butylquinoxaline-2-carboxamide matrix calibration ranged from 0.2 to 51.2 μg l(-1). The decision limit and detection capability of the ic-ELISA were 0.60 and 0.83 μg kg(-1) for liver and 0.68 and 0.79 μg kg(-1) for muscle of swine, respectively. The recoveries were 57-108% with coefficients of variation of less than 20% when the quinoxaline-2-carboxylic acid was spiked into liver and muscle with the concentrations of 1.0-20.0 μg kg(-1). Excellent correlations between the results of the ic-ELISA and an HPLC method (r = 0.9956 - 0.9969) were observed for incurred tissues. These results suggest that the ic-ELISA is a sensitive, accurate and low-cost method that would be a useful tool for screening residues of carbadox in the edible tissues of food-producing animals.     

RP-HPLC法测定食用动物油脂中苯甲酸与山梨酸的含量

建立测定食用动物油脂中苯甲酸与山梨酸含量的反相高效液相色谱法。采用反相高效液相色谱法,色谱柱为Wondasil C18(4.6mm×250mm,5μm),以甲醇-0.02mol/L乙酸铵溶液(5∶95)为流动相,检测波长为230nm,测定食用动物油脂中苯甲酸与山梨酸的含量。柱温为30℃,流速1.0mL/min,进样量10μL。结果表明,苯甲酸与山梨酸在0~320μg/mL范围内,峰面积与其浓度线性关系良好,相关系数均为0.999 76,平均回收率分别为99.0%、99.1%,重复性试验相对标准偏差分别为0.88%和0.71%(n=9)。本法准确、简便、快速,适用于食用动物油脂中苯甲酸与山梨酸含量的测定,建议用于食用动物油脂的质量控制。     

食用油中邻苯二甲酸酯的GC-MS测定方法研究

为了检测食用油中邻苯二甲酸酯污染程度,建立了气相色谱-质谱法检测食用油中邻苯二甲酸酯含量的方法.样品经环己烷-乙酸乙酯溶解,凝胶渗透色谱分离系统净化,减压浓缩至于,正己烷定容,气相色谱-质谱联用仪测定,外标法定量.在50μg/L～5000μg/L范围内具有良好的线性关系(R2＞0.997),方法检测限小于40μg/kg;在100μg/kg～5000μg/kg的添加水平下,邻苯二甲酸酯的加标回收率在77.52%～103.10%之间,相对标准偏差在0.29%～4.68%之间;方法精密度实验的相对标准偏差在5%之内;基质加标校正曲线的定量优于标准品校正曲线.结果表明,该方法适用于食用油中邻苯二甲酸酯定性和定量测定.     

三种食用植物油中不饱和脂肪酸含量调查

对市售大豆油、花生油、菜籽油等常见食用植物油中不饱和脂肪酸含量进行调查,调查结果表明:80个大豆油、花生油和菜籽油三种食用植物油样品中,不饱和脂肪酸的含量不符合相应国家标准规定的样品分别占相应品种调查数量的6.38%、7.14%和47.37%,部分食用植物油中存在掺杂现象。在符合国家标准规定的67个食用植物油样品中,含量较高的不饱和脂肪酸组成为大豆油中的亚油酸,花生油中的油酸和菜籽油中的油酸,平均含量分别为51.54%、42.20%、38.87%。     

反式脂肪酸的产生及降低措施

反式脂肪酸能增加患心脏病、冠心病、乳腺癌的几率,同时还有抑制幼儿生长发育的负面作用.对反式脂肪酸的来源、各国的限制性规定,以及油脂加工过程中采用何种措施降低反式脂肪酸含量进行了论述.通过降低油脂脱臭温度和时间,选用填料脱臭塔可有效降低油脂脱臭过程中产生的反式脂肪酸;通过控制油脂氢化反应条件,选择Pt作催化剂或选择超临界流体反应器可降低油脂部分氢化产生的反式脂肪酸.另外,通过基因改良生产多不饱和脂肪含量低的油料,或采用交酯化反应也可生产低或零反式脂肪酸含量的产品.     

Potential of SERS for rapid detection of melamine and cyanuric acid extracted from milk

Melamine, a nitrogen-rich chemical, was implicated in the pet and human food recalls in 2007 and in the global food safety scares in 2008 involving milk and other milk-derived products. In this study, we investigated the feasibility of using surface-enhanced Raman spectroscopy (SERS) coupled with SERS-active gold substrates for rapid detection of trace amounts of melamine and its analogue (that is, cyanuric acid) in liquid milk. Raman signals of tested samples were significantly enhanced by SERS. The identification limit for SERS using gold substrate can reach 2 ppm of melamine in liquid milk. Partial least squares (PLS) models were established for the quantification of melamine in liquid milk by SERS: R = 0.90, RMSEP = 1.48 × 10⁻⁵. Our results demonstrate that rapid detection of melamine in milk can be achieved by SERS; while detection of cyanuric acid in milk remains a challenging task due to rapid enol-keto tautomerism of cyanuric acid. The SERS method is faster and simpler than other traditional methods, and requires minimum sample preparation. These results demonstrate that SERS could be used to detect food contaminants such as melamine in foods and food ingredients quickly and accurately.     

选择食用油调味品时应注意脂肪酸比例

通过分析构成脂肪的3种脂肪酸的性质及对人体的影响,提出了有利于人体健康的选择食用油的方法。     

Changes in ruminal bacterial community composition following feeding of alfalfa ensiled with a lactic acid bacterial inoculant

Some silage inoculants help to improve silage quality and promote an increase in milk production, possibly through altering the rumen microflora. We hypothesized that rumen bacterial community composition (BCC) would be different in cows fed alfalfa ensiled with the inoculant Lactobacillus plantarum MTD/1 (LP) compared with those fed alfalfa ensiled without the inoculant (Ctrl). Eight ruminally cannulated Holstein cows were allotted to 2 diets (Ctrl or LP) in a double crossover design with four 28-d periods. Diets were formulated to contain (% dry matter basis) 28.0% neutral detergent fiber and 16.2% crude protein, and contained alfalfa silage, 50.9; corn silage, 20.6; high-moisture shelled corn, 21.4; soy hulls, 4.7; plus minerals and vitamins, 2.4. Ruminal digesta were collected just before feeding on 3 consecutive days near the end of each period, and were separated into solid and liquid phases. Microbial DNA was extracted from each phase, amplified by PCR using domain-level bacterial primers, and subjected to automated ribosomal intergenic spacer analysis. The pH was 4.56 and 4.86 and the lactate-to-acetate ratio 9.8 and 4.4, respectively, for the treated and untreated alfalfa silages. Dry matter intakes and milk production data were not influenced by diets but showed a cow effect. Total volatile fatty acids (mM) tended to be greater for LP compared with Ctrl. Individual volatile fatty acids were not influenced by diets but showed a significant cow effect. Ruminal acetate (mol/100 mol) and acetate-to-propionate ratio were lower and propionate (mol/100 mol) greater for the 2 milk fat-depressed (MFD; <3.2% fat content) cows compared with the other 6 cows. Correspondence analysis of the 265 peaks in the automated ribosomal intergenic spacer analysis profile across the 188 samples revealed that the first 2 components contributed 7.1 and 3.8% to the total variation in the profile. The ordination points representing the liquid and solid phases clustered separately, indicating that these phases differed in BCC. The analysis of similarity data showed differences between Ctrl and LP. The lactic acid bacterial counts (log(10) cfu/g of wet silage) were 3.94 and 4.53 for the untreated and treated silage, respectively, at ensiling. The relative population size (RPS) of L. plantarum, determined by real-time PCR of 16S rRNA gene copies, was greater in LP compared with Ctrl. The ordination points corresponding to certain individual cows clustered separately, and the most distinctive bacterial communities were those associated with MFD cows. The RPS of Megasphaera elsdenii was greater in 1 of the 2 MFD cows, although mean RPS of M. elsdenii did not differ between the treatments. In addition to the differences in rumen BCC between LP and Ctrl, MFD cows also displayed differences in BCC compared with cows with normal milk fat yield.