Determination of 15 β-lactam antibiotics in pork muscle by matrix solid-phase dispersion extraction (MSPD) and ultra-high pressure liquid chromatography tandem mass spectrometry

An UPLC–MS/MS method based on matrix solid-phase dispersion (MSPD) was developed for simultaneous determination of 15 β-lactams in pork muscle. Muscle tissue was blended with Oasis HLB adsorbent. A column made from the sorbent/muscle tissue matrix was washed with hexane, after which β-lactams was eluted with acetonitrile/water (50:50, v/v) both containing 0.1% formic acid. The final extract was evaporated, and reconstituted into acetonitrile/water (10:90, v/v) for the analysis of UPLC-MS/MS. The correlation coefficient (r²) with each matrix-matched calibration curve is higher than 0.99. Limits of detection (LODs) and limits of quantification (LOQs) of β-lactams were ranged from 0.02 to 0.63 μg kg⁻¹ and 0.07–0.97 μg kg⁻¹, respectively. At the fortified levels, mean recoveries of all compounds were ranged from 92 to 111%, and the RSDs were lower than 12%. The method was accurate and reproducible, being successfully applied to the monitoring of 15 β-lactams in pork muscles obtained from the Chinese market.     

Mobility and distribution of eight fungicides in surface,skin and pulp in grapes. An application to pyraclostrobin and boscalid

The study discusses the mobility and distribution of vinclozolin, dichlofluanid, penconazol, captan, quinoxyfen, fluquinconazol, boscalid and pyraclostrobin residues in surface, skin and pulp in red grapes. A lab test was carried out by immersing grapes in solutions with different concentrations of fungicides and for different periods of time; followed by a determination of the fungicide residues by GC-ECD with an additional confirmation by GC-MS. The distribution between surface, skin and pulp of the grapes was also determined. The percentage sorption ranged from 6.4 to 116%. Results showed that sorption values depended on the time that grapes had been in contact with the fungicide solutions, but not on the initial concentration of solutions. Residues were mainly found in skin, with percentages ranging from 53.0 to 88.4% of total residues. In pulp, these values ranged from 9.6 to 41.7%. Pyraclostrobin showed higher penetration than the other compounds.A field test using three new commercial formulations containing pyraclostrobin, boscalid and a mixture of both, was carried out by applying these formulations to a vineyard. When fungicides were applied individually the ratios of the skin/pulp residues were similar to those obtained in lab; whereas when a mixture of both pesticides was sprayed results showed a lower penetration of the fungicides in the grape pulp.     

Occurrence of four mycotoxins in cereal and oil products in Yangtze Delta region of China and their food safety risks

A total of 76 cereal and oil products collected from Yangtze Delta region of China were analyzed for occurrences of aflatoxins (AFs), aflatoxin B₁ (AFB₁), ochratoxin A (OTA), deoxynivalenol (DON) and zearalenone (ZEN). The mycotoxins were determined by the standard detection procedures using immunoaffinity column clean-up coupled with fluorometer (or HPLC-UV). ZEN was the most prevalent toxin, with the incidence of 27.6% (range = 10.0–440.0 μg kg⁻¹), and 9.2% of the evaluated samples were contaminated with a concentration higher than that of the legislation limit of China (60 μg kg⁻¹). AFs and AFB₁ were detected in 14.5% of the samples analyzed, the concentrations ranging 1.1–35.0 μg kg⁻¹ for AFs, and 1.0–32.2 μg kg⁻¹ for AFB₁; 4.0% of the samples had the concentrations of AFs and AFB₁ higher than that of the corresponding legislation limits of China (5.0, 10.0 and 20.0 μg kg⁻¹ for different products). OTA was detected in 14.5% of the cereal and oil products collected; the concentrations ranged 0.51–16.2 μg kg⁻¹. Only 2 samples showed OTA levels higher than that of the legislation limit of China (5.0 μg kg⁻¹). DON was detected in 7.9% of the samples; the concentrations ranged 100–700 μg kg⁻¹, and none of the samples showed DON concentration higher than that of the legislation limit of China (1.0 mg kg⁻¹). A total of 15.8% cereal and oil products were contaminated with at least two mycotoxins (multiple contaminations with different combinations including AFs-ZEN, AFs-OTA-ZEN, OTA-ZEN, ZEN-DON, OTA-ZEN-DON). The dietary exposure assessment results indicated that AFs (AFB₁), OTA, DON and ZEN from cereal-based products represented a series health risk to both adults and children in Yangtze Delta region of China. This is the first report of safety evaluation associated with major mycotoxins for the area.     

Efficacy of natural antimicrobials to prolong the shelf-life of minimally processed apples packaged in modified atmosphere

Minimally processed fruit are susceptible to microbial proliferation and to a fast loss of sensory quality. In this experimental work, in order to increase shelf-life and quality parameters (texture and colour) maintenance of sliced apples (Malus communis, var. Golden delicious), the use of natural antimicrobials was proposed as alternative to the traditional sanitization methods. Citron EO, hexanal, 2-(E)-hexenal, citral and carvacrol, alone or in combination, were employed. As control, apples washed only with 0.5% of ascorbic and 1% of citric acid were used. The apples were dipped with traditional or natural antimicrobial solutions according to a defined protocol. After the treatment, apples were packaged in active modified atmosphere (7% O₂ and 0% CO₂₎, into medium permeability bags. The products were stored at 6 °C and, immediately after washing and during storage, the yeast cell loads were monitored until the spoilage threshold (6 log CFU/g). In addition, the volatile profiles, electronic nose analyses, colour and texture analyses were monitored during the storage. In all the samples the spoilage yeast threshold was not attained within the 35 days of storage independently on the substance or mixture of substances supplemented. Samples treated with the combinations citral/2-(E)-hexenal and hexanal/2-(E)-hexenal showed a good retention of colour parameter during storage. Among investigated samples, hexanal/2-(E)-hexenal treatment promoted the best retention of firmness throughout 35 days of storage. These results evidence the potentiality of dipping treatment based on these natural antimicrobials to strongly prolong the shelf-life of fresh-cut apples.     

恩诺沙星、氟苯尼考和泰万菌素在鸡蛋中残留消除规律研究

目的 评估恩诺沙星、氟苯尼考和泰万菌素在鸡蛋中的残留消除规律。方法 将80羽高产海兰褐蛋鸡随机等分成4组, 对照组饲喂基础日粮, 恩诺沙星组、氟苯尼考组和泰万菌素组分别经混饲给予相应药物, 每日1次, 连续给药5 d, 停药19 d, 检测各枚鸡蛋中相应药物及其主要代谢产物的残留量。结果 恩诺沙星及其主要代谢产物环丙沙星与氟苯尼考及其主要代谢产物氟苯尼考胺可迅速残留于鸡蛋中, 残留物分别以恩诺沙星原型和氟苯尼考原型为主, 且其残留蓄积期都超过19 d。泰万菌素及其主要代谢产物3-乙酰胺基泰万菌素在鸡蛋中的残留总量低于最大允许残留限量, 且平均残留蓄积期为7 d, 3-乙酰胺基泰万菌素占总残留量的50%以上。结论 恩诺沙星和氟苯尼考在海兰褐品系鸡蛋中残留消除周期超过19 d, 在对后备蛋鸡、肉蛋兼用鸡给药时需严格控制用法用量。在适用情况下, 可优先选择平均残留消除周期相对较短的泰万菌素。     

肉牛唾液作为氯丙那林残留易获表征样本的可行性研究

目的 评估牛唾液作为氯丙那林残留易获表征样本的可行性。 方法 选取4只雌性健康育肥期肉牛(500±25 kg),其中1只作为对照,另3只作为试验组,每日将氯丙那林按1 mg/kg?bw 经基础日粮混饲试验组肉牛1次,连续给药30 d。基于高效液相色谱串联质谱技术,建立肉牛唾液中的氯丙那林残留量检测方法,并对给药期内肉牛唾液中的氯丙那林残留量进行跟踪测定。 结果供试品溶液中氯丙那林浓度在0.1～100 ng/mL范围内时,浓度-峰面积线性关系良好;方法检测限为1.0 ng/mL;方法回收率在73.7%～87.2%之间,重现性良好。混饲给药24 h后,3头受试牛唾液中氯丙那林残留量在33.5～119 ng/mL;连续给药25 d的期间内,尽管残留量表现出较大的个体差异,但受试牛唾液中氯丙那林残留量均呈逐步上升趋势,最高值达到273.6 ng/mL。结论 肉牛唾液较血液和尿液易于获取,基于高效液相色谱串联质谱法,能准确地反映养殖过程非法使用氯丙那林的情况,可作为行政监管的易获表征组织。     

Occurrence of patulin in various fruit products and dietary exposure assessment for consumers in China

A quantitative method with broad applicability was developed and validated for patulin determination in fruit products by high-performance liquid chromatography (HPLC) with UV detection. Sample pretreatment was optimized for patulin extraction. 4.0 g of fruit products was extracted for patulin determination with acetonitrile and purified with a mixture of 1.0 g PSA and 3 g MgSO₄ plus a multifunctional cartridge to remove interferences. Under optimized conditions, the recoveries ranging from 75.6% to 118.5% were obtained at different spiking concentrations in various fruit products. The correlation coefficient of patulin from 5 to 1000 μg/L was approximately 1.00. The limits of detection (LODs) were from 2.6 to 7.5 μg/kg, and the limits of quantification (LOQs) were from 8.0 to 15.0 μg/kg for patulin in various fruit products. A total of 137 fruit products (97 dried fruits, 20 fruit juice and 20 jams) marketed and consumed in China were investigated. The incidence of patulin in fruit products was 30.7% (42/137) with a concentration ranging from 10.0 to 276.9 μg/kg. This study revealed that the dried figs, dried longans (seedless) and dried hawthorn products showed an average of patulin contamination of 87.6 μg/kg, 68.4 μg/kg and 5.1 μg/kg, respectively; the fruit juice of 5.4 μg/kg; the fruit jams of 5.0 μg/kg. The highest levels of patulin were found mostly in dried longans (seedless) and dried figs. Overall, 17.5% of total samples exceeded the maximum limit of 50 μg/kg set by the EU regulation. Chronic intake assessment indicated that only 0.29% (Hazard Quotient) acceptable daily intake (PMTDI, 0.4 μg/kg bw/day) was consumed through dried fruits, fruit juice and jams. Individual dietary risk assessment indicated patulin contamination in fruit products doesn't pose public health risks, but combined additive or synergistic toxic effects caused by multiple mycotoxin contaminations should not be ignored.     

贮藏条件对杭白菊功能成分的影响

为探究存储包装材料及温度条件对中药杭白菊中各功能组分的影响,本研究采用产业上最常用的铝箔袋、牛皮纸、透明聚乙烯袋对杭白菊进行包装并在冷冻（?20 ℃）、冷藏（2 ℃）及常温（20 ℃）条件下贮藏。测定杭白菊的水分、多糖、黄酮、绿原酸、木犀草苷及奎宁酸等功能性成分含量及揭示其变化规律。相关性分析结果表明,不同贮藏条件的杭白菊水分含量与贮藏时间呈正相关,但其它四种成分与贮藏时间呈负相关。通过建立功能成分与贮藏温度和贮藏时间的二元非线性回归模型,表明冷冻和冷藏贮藏时不同包装里的杭白菊功能成分均维持较好,包装材料之间差异不显著（P>0.05）。常温贮藏时,杭白菊品质劣变较快,且包装材料之间具有显著差异（P<0.05）。其中,铝箔袋包装的杭白菊各项功能成分相对牛皮纸包装和透明聚乙烯袋变化更小。因此,综合杭白菊的功能成分变化及贮藏经济成本,建议杭白菊使用铝箔袋包装,并在冷藏条件下贮藏。