Nonthermal sterilization of Listeria monocytogenes in infant foods by intense pulsed-light treatment

The purposes of this study were to determine the inactivation effects of intense pulsed light (IPL) on Listeria monocytogenes and the commercial feasibility of this sterilization method. The inactivation of L. monocytogenes at cultivated plates increased with increasing electric power and treatment time. Approximately 4–5 log reduction of the cell was achieved with IPL treatment for 5000, 600, 300, and 100 μs at 10, 15, 20, and 25 kV of voltage pulse, respectively. In the early stages of IPL treatments at 10, 15, and 20 kV, little inactivation was observed with a critical treatment time (t_c) of 360.6, 95.5, and 32.2 μs, respectively, while an abrupt inactivation without a critical treatment time was observed at 25 kV. The sterilization effects on commercial infant foods inoculated with L. monocytogenes were investigated at 15 kV, which showed higher energy efficiency for the inactivation of L. monocytogenes.     

Food processing increases casein resistance to simulated infant digestion

The objective of this study was to determine whether processing could modify the resistance of casein (CN) to digestion in infants. A range of different dairy matrices was manufactured from raw milk in a pilot plant and subjected to in vitro digestion using an infant gut model. Digestion products were identified using MS and immunochemical techniques. Results obtained showed that CNs were able to resist digestion, particularly κ‐ and αs₂‐CN. Resistant areas were identified and corresponded to fragments hydrophobic at pH 3.0 (gastric conditions) and/or carrying post‐translational modifications (phosphorylation and glycosylation). Milk processing led to differences in peptide patterns and heat treatment of milk tended to increase the number of peptides found in digested samples. This highlights the likely impact of milk processing on the allergenic potential of CNs.     

Occurrence of major and trace elements in powdered milk from Argentina

The concentrations of major and trace elements in Argentinean commercial powdered milk samples were determined with inductively coupled plasma mass spectrometry. Also the daily intake (DI) was calculated for adults and infants. The concentrations of B, Mg, Na, K and Ca were significantly higher in skimmed milk. Cu, Mo, Fe, Mn and Zn were significantly higher in infant formula. All the DIs were below the tolerable upper intake levels. The mean As concentration (26.0 ± 8.6 ng/g) in the powdered skimmed milk samples was slightly higher than in the others. Mean Pb concentrations ranged from 4.1 ± 2.1 to 13.5 ± 8.2 ng/g. The highest mean U concentration was 7.8 ± 2.6 ng/g for whole milk. This study contributes to the knowledge of major and trace elements in powdered milk and its contribution to the diet in Argentina.     

Prediction of dry mass glass transition temperature and the spray drying behaviour of a concentrate using a desorption method

A predictive tool (SD²P®) based on a drying by desorption method was recently developed in order to determine the key process parameters values prior to spray drying. However, the SD²P® software cannot currently take into account the risk of stickiness during the process. In the study reported here, new standardized desorption method was tested and with this new method an equation was proposed to evaluate the dry glass transition temperature (T_g) of a concentrate according to its total solid content, its viscosity and its average evaporation rate. The concentrate’s behaviour during spray drying could then be predicted on the basis of the T_g. Four validation experiments were performed using different infant formula samples; the concentrates prepared from the four infant formula powders were then spray dried using a one-stage pilot dryer. The drying parameters were predicted using the SD²P® software. The results showed that the T_g predicted using this method were 18-30 °C higher than T_g measured by DSC (Differential Scanning Calorimetry). The drying temperatures predicted by SD²P® corresponded well to the values measured and this new method can correctly predict the behaviour of a concentrate with regard to spray drying. The advantage of the method presented here is that it can easily and quickly evaluate a concentrate’s T_g range and spray drying behaviour by direct analysis of the fresh concentrate sample.     

婴幼儿用纸尿裤(片)及隔尿垫巾中荧光增白剂的研究

总结了婴儿纸尿裤(片/垫)和隔尿垫巾的相关标准,通过不同方法方式对婴儿纸尿裤(片/垫)和隔尿垫巾中荧光增白剂进行研究,结果发现有部分婴儿纸尿裤(片/垫)和隔尿垫巾有荧光现象;隔尿垫巾通过擦拭和尿液浸泡时发现荧光迁移的现象;并且检出FWA393(4,4’-双(苯并噁唑-2-基)二苯乙烯)和FWA1842,2’-(2,5-二苯基硫代)双[5-(1,1-二甲基乙基)苯并噁唑])两种荧光增白剂,且大部分的检出值较高。婴幼儿纸尿裤/片、隔尿垫巾等产品其使用对象为免疫系统未发育完善、皮肤较为薄弱且社会关注度极高的婴幼儿,且使用部位非常敏感,该类产品中荧光增白剂含量如此之高应引起有关部门的关注。     

阪崎肠杆菌-食品安全控制的新目标

自 196 1年英国首次报道阪崎肠杆菌引起婴儿脑膜炎病例以来 ,世界上相继有多个国家报道了新生儿阪崎肠杆菌感染事件 ,婴儿配方奶粉与疾病的暴发密切相关。在 2 0 0 3年第 35次食品卫生法典大会上 ,美国和加拿大提出了有关控制婴幼儿配方奶粉中阪崎肠杆菌的危险性框架 ,指出 1岁以下的易感婴幼儿感染阪崎肠杆菌后有生命危险。 2 0 0 4年第 36次食品卫生法典大会一致通过并设立了以加拿大为首的起草工作组 ,加速修订婴幼儿食品国际卫生操作规范 ,制定阪崎肠杆菌和其它可能导致婴幼儿健康危害的相关病原菌的微生物标准。     

Fe, Cu and Zn distribution in different components of commercial infant formulas

Fe, Cu and Zn determination by AAS was performed in 35 infant formula samples from different manufacturers. The trace element content was studied in whole, fat and whey milk, and different chemometric tools have been used in order to observe differences or correlations between infant formulas fortified with inorganic salts (iron, copper and zinc sulphates) or with organic and inorganic salts (iron and copper gluconates, or zinc and iron lactates and zinc oxides). Principal-components analysis (PCA) achieved a reduction from nine variables to three (accounting for 80.8% of the total variability), and some differences between infant formula from the two groups were observed.Cluster analysis gave similar results as PCA. Linear discriminant analysis (LDA) allowed the classification of infant formulas in two categories or classes: the first class formed by samples fortified with inorganic salts (category A) and the second one by samples fortified with organic and inorganic salts (category B). The percentages of samples correctly classified were 96.1 and 100.0 for the categories A and B, respectively. After the application of the soft independent modelling of class analogy (SIMCA) approach, percentages of cases correctly assigned of 87.5 and 12.5 were achieved for the categories A and B, respectively. However, it must be said that the application of SIMCA led to bad results because of the small number of sample used, mainly in category B.     

Epoxidized soy bean oil (ESBO) migrating from the gaskets of lids into food packed in glass jars

Epoxidized soy bean oil (ESBO) was determined in foods packed in glass jars closed by lids with a poly(vinyl chloride) (PVC) gasket. The methyl ester of a diepoxy linoleic acid isomer was measured, using transesterification directly in the homogenized food and on-line HPLC-GC-FID analysis. Infant foods from the Swiss market consisting of vegetables, potato and rice or muesli with fruits and berries contained less than 7 mg/kg ESBO, but meat (its fat?) strongly increased ESBO migration up to 86 mg/kg. Some 12% of the products exceeded 15 mg/kg. Austrian and Norwegian samples gave similar results. Edible oil strongly extracts the ESBO from the gasket in food contact within a few weeks. Since this part of the gasket on average contained 91 mg ESBO, the legal limit is likely to be far exceeded whenever the food contains free oil contacting the gasket, such as oily sauces or vegetables and fish in oil. In fact, the mean ESBO concentration in 86 samples was 166 mg/kg, with a maximum of 580 mg/kg.     

气相色谱质谱联用测定婴幼儿奶粉中香兰素和乙基香兰素

本研究采用了气相色谱质谱测定方法,检测婴幼儿配方奶粉中香兰素和乙基香兰素.通过调节pH值沉淀样品中蛋白和脂肪,采用三氯甲烷溶剂直接提取,简化样品处理过程,并且减少有害物质的使用.同时,本研究优化了气相色谱质谱仪的仪器参考条件,使用PE-5MS色谱柱,本方法回收率达到95％以上.本方法同时具有样品处理简单,检出限低,干扰少等特点,能够较好地满足婴幼儿奶粉中香兰素和乙基香兰素的检测要求.