Oxytetracycline, Sulfadimethoxine, and Ormetoprim Residues in Channel Catfish by HPLC

HPLC methods and modified extraction procedures were used to analyze residues of oxytetracycline (Terramycin, OTC) or sulfadimethoxine (SDM) and ormetoprim (OMP) in channel catfish fed OTC or Romet-30 under controlled conditions. Mean recovery rates in fish muscle were 92.5% for OTC over concentrations of 0.05–1.0 ppm and 86.3% for OMP and 87.9% for SDM over 0.05–5.0 ppm. SDM and OMP were rapidly depleted from large catfish (about 345g) after 5 days feeding with Romet-30 at 50–100 mg/kg body weight. By day 2 post-treatment, no residue was detected. Residues of OTC, SDM and OMP were also detected in fingerling channel catfish (about 20.3g) after 4 and 8 wk of feeding with Romet-30 or OTC at 12.5, 25, or 50 mg/kg body weight, but not after a 3-wk-withdrawal period.     

Oxytetracycline and oxolinic acid residues in kuruma prawn (Penaeus japonicus) and the effect of cooking procedures on the residues

Tissue distribution and residue depletion of oxytetracycline (OTC) and oxolinic acid (OA) were studied in the kuruma prawn (Penaeus japonicus). The prawn were kept in tanks with recirculated artificial seawater at a salinity of 22-23@1000. The water temperature was maintained at 25 degrees C. The average body weight was 22.9 +/- 4.9 g for OTC and 22.5 +/- 3.6 g for OA. The drug was mixed with the diet and orally administered through a catheter to the prawn. The doses of OTC and OA, respectively, were 50 mg/kg body weight. At each sample time, four prawns were sacrificed and tissues were sampled. OTC and OA levels were determined by high-performance liquid chromatography. At the highest levels, the concentrations of OTC were in the other: shell (13.57 micrograms/g) > hemolymph (12.20 micrograms/mL) > muscle (8.30 micrograms/g). For OA, the order was: shell (20.74 micrograms/g) > hemolymph (7.06 micrograms/mL) > muscle (2.05 micrograms/g). The elimination half-lives of hemolymph and muscle were 44.7 and 46.8 hours for OTC and 55.0 and 107.9 hours for OA, respectively. Residual OTC could not be detected in hemolymph and muscle at 20 days after dosing. Residual OA disappeared from hemolymph and muscle at 25 days after dosing. A 25-day period for OTC and 30-day period for OA could be regarded as the proper withdrawal time established for kuruma prawn by the Pharmaceutical Law in Japan. However, the elimination half-lives of shell for OTC and OA could not be calculated because both drug residues persisted in shell tissues, and the elimination phase was not completed during the experimental period. Residual OTC (14.10 +/- 2.26 micrograms/g, n = 6) and OA (0.32 +/- 0.06 microgram/g, n = 7) were detected in exuviae at 3 days and 4 days after dosing, respectively. Residual OTC was reduced to 50-70% in muscle by the usual methods of cooking (boiling, baking at 200 degrees C and frying at 180 degrees C), whereas reduction levels in shell were only 20-30%. Residual OA was reduced to 20-30% in muscle and shell by the cooking. These results confirm that the cooking procedures could only reduce but not completely eliminate these drug residues in prawn.     

Analysis of trace residues of tetracyclines in dark-colored honeys by high-performance liquid chromatography using polymeric cartridge and metal chelate affinity chromatography

An efficient clean-up procedure was developed for the trace residue determination of tetracyclines (TCs) in dark-colored honeys. TCs were extracted from samples with McIlvaine buffer (pH 4.0) containing 0.01 mol/L Na(2)EDTA. The extracts were treated with both a polymeric cartridge (GL-Pak PLS-2) and a metal chelate affinity column (MCAC) preloaded with copper(II). TCs were eluted and analyzed by high-performance liquid chromatography (HPLC) using fluorescence detection. The method was evaluated for the determination of oxytetracycline (OTC), tetracycline (TC), and chlortetracycline (CTC) in buckwheat honey, because its color is the darkest. The mean recoveries of OTC, TC and CTC from spiked samples, at three fortification levels, were >70%, and the relative standard deviations (RSDs) were <10%. Limits of quantitation (LOQs) of OTC, TC, and CTC were estimated to be 0.015 mg/kg, 0.019 mg/kg, and 0.024 mg/kg, respectively.     

广西省八角二氧化硫残留量检测结果分析与卫生标准的探讨

了解广西省八角二氧化硫残留情况以及烹饪对八角二氧化硫残留量的影响。方法 按照随机抽样原则在广西省大型超市、批发市场(包括个体零售点)、八角生产地,随机抽取八角生果和干果样品共计185份,按照NY/T 1435—2007《水果、蔬菜及其制品中二氧化硫总量的测定》测定其二氧化硫残留量,按照GB/T 7652—2006《食品添加剂使用标准》规定八角二氧化硫残留量<30 mg/kg进行评价,并测定其二氧化硫残留量随存放时间的变化,测定高残留量的二氧化硫八角经过烹饪后其二氧化硫残留量的变化。结果 监测的134份干八角二氧化硫残留量检出率为42.5%,超标率为36.6%,干八角二氧化硫残留量范围在1.5～660.6 mg/kg之间,中位值为106.6 mg/kg。其中来源于大型超市、批发市场(包括个体零售点)的八角二氧化硫超标率分别是27.1%和41.9%;八角(二氧化硫残留量为660 mg/kg)经水煮后,其二氧化硫残留量降为19.2 mg/kg。结论 广西省流通领域八角存在硫熏现象,但烹饪过后,其汤样(水样)与八角中的二氧化硫残留量都大大降低,有关部门应加强监管监测。     

Oxytetracycline Residues in Cultured White Shrimp Tissue by HPLC and a Microbial Receptor Assay

The residue depletion of oxytetracycline (OTC) from muscle tissue of cultured shrimp (Penaeus vannamei) was evaluated. OTC was measured using high performance liquid chromatography (HPLC) and a microbial receptor assay. Samples were taken on days 7, 14 and 21 during the treatment and 23, 25 and 28 after the treatment. OTC was detectable in all groups after 7 days depletion time at concentrations of 0.28, 0.19 and 0.05 μg/g for diets containing 500, 250 and 100 mg/kg OTC, respectively. Results by the microbial receptor assay were in good agreement with those by HPLC.     

Mercury residues in duck breast tissue after moist and dry heat cooking

Fifty McGraw Mallard ducks were given methyl-mercury chloride (MeHg) at dosage levels of 0.0, 2.0, 6.0, 10.0 and 19.0 mg/kg body weight. Breasts were either roasted or braised and mercury concentration in cooked tissue and in drip was compared with that in the raw breast. The amount of mercury recovered after cooking averaged 87.6% after braising and 96.6% after roasting. Mercury losses were not significantly reduced by either cooking method.     

鲶鱼火腿加工过程中各个因素对其凝胶特性的影响

以鲶鱼为研究对象,研究鱼糜加工过程中各种因素对其凝胶特性的影响,以期获得凝胶性能较强的各工艺参数。采用单因素设计,对鲶鱼火腿加工过程中漂洗、腌制、擂溃、煮制等工艺环节的不同变化进行研究,以鲶鱼火腿产品的凝胶质构特性(弹性、黏聚性、硬度和咀嚼性)为考察指标,确定鲶鱼火腿加工的最佳工艺参数。结果表明：用5 倍肉质量的5mg/mL NaCl 溶液(温度为5～7℃)漂洗鱼肉两次,加入21mg/mL 食盐4℃腌制10h,擂溃时用碎冰使温度保持6℃斩拌6min,然后将鱼糜装入不锈钢火腿模具中,85℃煮制2.5h,所制成的鲶鱼火腿制品凝胶特性最好,弹性可达到0.86,黏聚性为0.66。     

Formaldehyde and hexamethylenetetramine as food additives: chemical interactions and toxicology.

Formaldehyde (FA) and hexamethylenetetramine (HMT) are used in cheese production to control gas-forming clostridia; FA also occurs naturally in some foods at levels of 1-20 mg/kg. The toxicology of FA and HMT are briefly discussed together with their reaction in foods. The most abundant end-product of FA in cheese is spinacine derived from the N-terminal histidine residue in gamma 2-casein. Acute and short term toxicological studies on spinacine enable a No Observed Effect Level of 300 mg/kg body weight/day to be determined, leading to an Acceptable Daily Intake (ADI) for man of 3 mg/kg body weight/day. From these data a Tolerance Level (TL) of 1800 mg spinacine/kg cheese can be derived, leading to a Safety Margin (SM) of 12.9. It is concluded that there is no appreciable health risk from consumption of cheese made using formaldehyde (Grana Padano) or hexamethylenetetramine (Provolone).     

Residue levels of captan and trichlorfon in field-treated kaki fruits, individual versus composite samples, and after household processing.

The dissipation of residue levels of captan and trichlorfon in field-treated kaki crops was studied according to good laboratory practices to propose maximum residue limits (MRLs). Residue levels of captan and trichlorfon were analysed by GC/MS and LC-MS/MS, respectively. Residue levels of captan and trichlorfon permitted one to propose MRLs in kaki of 3 and 5 mg kg(-1), respectively. The behaviour of these residues was also studied after peeling and cooking, and in individual fruits versus composite samples. Residue levels of these compounds for individual fruits suggested that a variability factor up to three could be set for the acute risk assessment. Levels of captan decreased by more than 90% after peeling and completely after cooking. Trichlorfon penetrates into the flesh in a proportion of 70% of the residue at the pre-harvest interval. Cooking resulted in a decrease of 27% of residue levels of trichlorfon.     

Analysis of environmental chemical residues in products of emerging aquaculture industry in Uganda as case study for Sub-Saharan Africa

A study was conducted to analyse market-regulated heavy metals (lead, mercury and cadmium), organochlorine pesticides and total polychlorinated biphenyls (PCBs) in samples of 38 farmed fish comprising Nile tilapia (Oreochromis niloticus) (20 samples) and African catfish (Clarias gariepinus) (18 samples) from ten selected fish farms in Uganda. The goal of this case study was to understand the safety of aquaculture products from Sub-Saharan Africa. Lead was detected in all the 38 samples (maximum = 1.08 mg kg^?1 (dry weight)), mercury in 31 out of 38 samples (maximum = 0.35 mg kg^?1 (dry weight)), and cadmium in two samples (maximum = 0.03 mg kg^?1 (dry weight)). Total levels of PCBs were below the limit of detection of 0.02 mg kg^?1 (wet weight) in all the samples. Traces of 4,4′-dichloro-diphenyldichloroethylene (DDE) were detected in ten out of 38 samples (maximum = 0.01 mg kg^?1 (wet weight)) making it the most prevalent organochlorine pesticide. Other pesticides detected were: 4,4′-dichloro-diphenyl-trichloroethane (DDT) and endosulfan sulphate, which were found in one fish sample (both 0.002 mg kg^?1 (wet weight)). There was no statistically significant difference between the levels of lead and mercury in catfish and tilapia (t-test at p = 0.05). More catfish samples (eight) contained DDE as compared with tilapia (two). Cadmium, DDT and endosufan sulphate were only detected in catfish implying that catfish is more prone to contamination than tilapia. The levels of contaminants were below the US Food and Drug Administration (USFDA) action levels and European Union maximum residue limits (MRLs), indicating that such fish have the potential for export to these markets.     

叶黄素对黄腊丁体色影响的研究

在黄腊丁养殖过程中,通过喂养添加不同含量的叶黄素饲料,对野生与养殖黄腊丁体色及肤色、肌肉叶黄素含量进行了比较,发现从万寿菊中提取的叶黄素能有效地使黄腊丁着色,叶黄素添加量以100 mg/kg为最佳。     

Di(2-ethylhexyl) phthalate contamination of retail packed lunches caused by PVC gloves used in the preparation of foods

Plasticizer contamination of foods sold in retail packed lunches and set lunches in restaurants was determined by GC/MS. The phthalate esters were as follows: diethyl, dipropyl, dibutyl, dipentyl, dihexyl, butylbenzyl, dicyclohexyl, di(2-ethylhexyl), dioctyl, diisooctyl (mixture of isomers) and diisononyl (mixture). Di(2- ethylhexyl) adipate was also determined. Sixteen packed lunches and ten set lunches were analysed, and in all samples the concentration of di(2-ethylhexyl) phthalate (DEHP) was the highest, at 0.80-11.8 mg/ kg in packed lunches and 0.012-0.30 mg/kg in set lunches. The DEHP content of five packed lunches exceeded 1.85 mg, which is the EU tolerable daily intake (TDI) for a person of 50 kg body weight. Foodstuffs that were components of the packed lunches were taken from the factory at each step of preparation and phthalates were determined. For example, chicken contained 0.08 mg/kg DEHP when uncooked, 13.1 mg/ kg after frying and 16.9 mg/kg after packing. Disposable PVC gloves used in the preparation of foods were apparently the source of high DEHP concentrations. The gloves used during cooking or packaging were sprayed with 68% (w/w) ethanol to sterilize them. PVC gloves from the factory contained 22 or 41% by weight of DEHP. To confirm the link with the contamination problem, samples of boiled rice, croquette and boiled dry radish were handled in the laboratory with PVC gloves containing 30% (w/w) DEHP. DEHP migration levels of 0.05 mg/kg in rice or 0.33 mg/kg in croquette, and 11.1 mg/kg in radish were found. The alcohol sprayed onto the gloves increased the migration of DEHP to 2.03 mg/kg in rice, 2.45 mg/ kg in croquette, and 18.4 mg/kg in radish.     

Weight maintenance through behaviour modification with a cooking course or neurolinguistic programming

We compared the effect on weight regain of behaviour modification consisting of either a gourmet cooking course or neurolinguistic programming (NLP) therapy. Fifty-six overweight and obese subjects participated. The first step was a 12-week weight loss program. Participants achieving at least 8% weight loss were randomized to five months of either NLP therapy or a course in gourmet cooking. Follow-up occurred after two and three years. Forty-nine participants lost at least 8% of their initial body weight and were randomized to the next step. The NLP group lost an additional 1.8 kg and the cooking group lost 0.2 kg during the five months of weight maintenance (NS). The dropout rate in the cooking group was 4%, compared with 26% in the NLP group (p=0.04). There was no difference in weight maintenance after two and three years of follow-up. In conclusion, weight loss in overweight and obese participants was maintained equally efficiently with a healthy cooking course or NLP therapy, but the dropout rate was lower during the active cooking treatment.     

Effects of European foulbrood treatment regime on oxytetracycline levels in honey extracted from treated honeybee (Apis mellifera) colonies and toxicity to brood

This study aimed to assess oxytetracycline (OTC) residue levels in honey up to 12 weeks after treatment of honeybee colonies with two methods of application (in liquid sucrose and in powdered icing sugar). Significantly greater mortality was seen in the all stages of brood development for the treated colonies when compared with the controls. Samples of honey were extracted up to 12 weeks after treatment and analysed by HPLC following metal chelation with a limit of quantitation of 0.05 mg/kg. These data showed that the current method of application of Terramycin in liquid form results in very high residue levels in honey with residues of 3.7 mg/kg eight weeks after application. Further work is required to determine whether the levels can be further reduced by changes in the method of application whilst ensuring efficacy and minimizing the effects on brood.     

COMPARISON OF METHODS TO VERIFY END POINT COOKING TEMPERATURE OF CHANNEL CATFISH (ICTALURUS PUNCTATUS) FILLETS

Cooking to 63C for 15 s remains an important step to ensure safe fish for human consumption. Methods for heat process verification have not been validated for channel catfish ( Ictalurus punctatus ). The present research compared extractable protein quantification, lactate dehydrogenase, acid phosphatase and catalase activity assays for verification of internal cooking temperature of channel catfish fillets. Ground raw catfish fillet samples (fresh and frozen) were cooked to 55, 60, 62, 63, 64 and 66C. Extractable protein, acid phosphatase and catalase activities decreased as internal cooking temperature increased, but lactate dehydrogenase activity remained unchanged. Samples cooked to 63C had extractable protein concentrations between 9.11 and 10.02 mg/g (95% confidence). Catalase was rapidly inactivated between 55 and 60C and may be suitable for identification of severely undercooked product. Acid phosphatase activity was influenced by method of storage (fresh versus frozen). A method based on total extractable protein appeared to be the most promising for determining the end point cooking temperature of catfish.

PRACTICAL APPLICATIONS

The most precise and reliable method to verify maximum cooking temperature attained during heat treatment of catfish fillets was total extractable protein. This finding may be useful for critical control point verification and may be valuable where claims of foodborne illness associated with catfish consumption are being litigated or investigated. To confirm gross undercooking, an easier test would be to measure catalase activity.     

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.     

Effects of processing and cooking on the levels of pesticide residues in soybean samples

The effects of processing and cooking on the levels of pesticide residues in soybean samples were investigated for 14 pesticides in pre-harvest samples. On soaking, the transfer ratios (%, total pesticide residue amount in product/that in soybean) of soaked soybean were greater than 60% for most of the pesticides investigated. The transfer ratio of soymilk ranged from 37% to 92%, and that of tofu ranged from 7% to 63%. The processing factor (Pf, the concentration (mg/kg) of pesticide in product/that in soybean) of tofu ranged from 0.026 to 0.28. These values varied among pesticides. There was a high correlation between the log P(ow) and the transfer ratio of tofu. The test described here should be useful to obtain the transfer ratios of pesticide residues in processing and/or cooking steps.     

Analysis of trace residues of tetracyclines in animal tissues and fluids using metal chelate affinity chromatography/HPLC

A novel method of analysis for the trace residue determination of tetracyclines in animal tissues and fluids has been developed. Clean-up of sample extracts is based upon the specific ability of tetracyclines to chelate with divalent metal ions (metal chelate affinity chromatography, MCAC) and determination made by high-performance liquid chromatography. The method has been tested for the determination of oxytetracycline (OTC), tetracycline (TC) and chlortetracycline (CTC) in porcine kidney and muscle, ovine kidney, bovine kidney and milk, and trout muscle. Recoveries at the 0.05 mg/kg level for OTC, TC and CTC respectively were 75%, 63%, 73% in porcine kidney, 77%, 79%, 76% in porcine muscle, 85%, 54%, 53% in bovine kidney, 78%, 63%, 57% in ovine kidney, 75%, 58%, 56% in fish (trout) muscle, and 80%, 59%, 59% in bovine milk. At this level both within- and between-batch precision, as measured by the coefficient of variation (CV), was less than 10%. Determination to the 0.01 mg/kg level was carried out in all cases, although the method becomes less precise. The method has been used for several months and found to be both reliable and sufficiently rapid for use as a routine quantitative screening procedure. When coupled with liquid chromatography-mass spectrometry (LC-MS) it is suitable for use as a confirmatory method. Analysis of animals treated with tetracyclines has been carried out.     

Toxicity of moniliformin from Fusarium fujikuroi culture material to growing barrows.

In two studies, the effects of moniliformin (M)-contaminated diets from Fusarium fujikuroi culture material on growing barrows were evaluated. In the first study, six barrows (three replicates of two each, mean body weight = 17.8 kg) per group (four groups; 24 barrows total) were fed diets calculated to contain 0 mg M/kg feed (control); 25 mg M/kg feed; 50 mg M/kg feed; or 100 mg M/kg feed for 28 days. In the second study, the same experimental design and numbers of barrows (mean body weight = 15.3 kg) were used, and diets were formulated to contain 0 mg M/kg feed (control); 50 mg M/kg feed; 100 mg M/kg feed; or 200 mg M/kg feed. Diets of 100 mg or 200 mg M/kg feed reduced body weight, body weight gain, and feed consumption. Serum biochemical analytes were affected by 100 to 200 mg M/kg feed. Hematologic values were affected by 50, 100, and 200 mg M/kg feed. In the first study, one barrow in the 100 mg M-treated group died, and in the second study. one barrow died in the 100 mg M-treated group, and five barrows died in the 200 mg M-treated group. Relative heart weight was increased in the 200 mg M-treated barrows, yet tissues from organs collected from treatment groups were generally histologically unimpressive. The most consistent sign of M toxicity in barrows appeared to be death induced within 2 to 5 days by 100 to 200 mg M/kg feed.     

TOXICITY OF PURE HEXACHLOROBENZENE AND HCB-CONTAMINATED PORK TO CATS

Swine were fed a diet containing hexachlorobenzene (HCB) in order to generate contaminated pork which was subsequently cooked and fed to female cats. Feeding the fresh weight equivalent of 50 g cooked pork/day/cat (1 < mg HCB/kg/day) caused marginal weight loss. Oral dosing with 10 mg/kg/day purified HCB resulted in significant weight loss, mild anemia, neutropenia and hepatomegaly. Using the residue of HCB accumulating in the cat adipose tissue as the criterion, the low doses in the pork were absorbed and retained about five times more effectively than the larger oral bolus.