Chemical changes in powdered infant formulas during storage

Hydroxymethylfurfural (HMF), furosine (FUR), lactulose (LU), lysine loss, ascorbic acid and colour (ΔE) were determined in powdered infant formulas stored under nitrogen and oxygen conditions at 20°C and 55°CC during 15, 30 and 90 days. The indicators of the assay at 20°C showed similar behaviour in nitrogen or oxygen atmospheres. Changes in furosine and lysine loss after 90 days occurred under oxygen. Storage at 55°C produced considerable browning. Browning was always greater in nitrogen than in oxygen. Most of the studied parameters increased with the storage time and are useful in controlling the extent of browning in powdered infant formulas under adverse storage conditions.     

Enterococcus faecalis and Enterococcus faecium isolates from milk,beef, and chicken and their antibiotic resistance

The occurrence and antibiotic resistance of enterococci, especially Enterococcus faecalis and Enterococcus faecium, in milk, beef, and chicken in Gaborone, Botswana, were studied. Enterococci were isolated from these sources with the use of bile esculin agar and identified with API 20 Strep kits. Antibiotic resistance was determined by the disk diffusion method. The antibiotics tested were vancomycin, teicoplanin, ampicillin, tetracycline, and cephalothin. Among the 1,467 enterococci isolated from the samples, E. faecalis (46.1%) and E. faecium (29.0%) were found to be the predominant species. Other enterococcal species made up 25% of the isolates. More than 96 and 97% of the E. faecalis and E. faecium isolates, respectively, were found to be resistant to ampicillin. Almost 34, 27.3, and 22.4% of the E. faecalis isolates from milk, beef, and chicken, respectively, were also resistant to cephalothin. The percentages of E. faecium isolates that were found to be resistant to cephalothin were 32.8, 16.9, and 17.3% for milk, beef, and chicken, respectively. Resistance to vancomycin was widespread. It was found that 18.8, 7.8. and 13.1% of the E. faecalis isolates from milk, beef, and chicken samples, respectively, were resistant to vancomycin. In contrast, 32.8, 24.7, and 30.7% of the E. faecium isolates from milk, beef, and chicken samples, respectively, were resistant to vancomycin. Isolates that were resistant to multiple drugs were found in relatively large numbers.     

Influence of two lipid extraction procedures on the peroxide value in powdered infant formulas

The influence of two extraction procedures on the peroxide value (PV) of lipid extracts of powdered infant formulas (IFs) was investigated. Thirteen commercial IFs contained in their original packages were assessed after storage at room temperature for 18 months. The extraction procedures mainly differed in the extraction solvent polarity. Extraction method 1 was one of the methods more widely applied in the industry of powdered IFs. It consisted of a single extraction with a polar solvent composed of dichloromethane : methanol (2:1, v/v). Extraction method 2 consisted of disruption of the solid matrix simply by rubbing with a mortar and pestle and subsequent extraction of the lipids released with hexane, used as a non-polar solvent. The PV was contrasted with the quantitative analysis of the non-volatile lipid oxidation compounds and tocopherols. The oxidation compounds were isolated by solid phase extraction (SPE) and analyzed by high-performance size-exclusion chromatography (HPSEC) with refraction index detection. Results showed high significant differences (P < 0.0001) in the PV between the extraction methods, with lower values for method 1. However, no significant differences were found either in the levels of oxidation compounds or in those of tocopherols (P > 0.05). It was found that the lower PVs in method 1 were due to reducing substances co-extracted with the lipids by the polar solvent. Therefore, the quantitative analysis of the lipid oxidation compounds by SPE–HPSEC was more reliable for evaluation of the oxidation level in powdered IFs.     

Isolation of Enterobacter sakazakii and other Enterobacteriaceae from powdered infant formula milk and related products

The presence of Enterobacter sakazakii and other Enterobacteriaceae was surveyed in 82 powdered infant formula milk (IFM) and 404 other food products. The presence of Ent. sakazakii was detected using the conventional method (growth on violet red bile glucose agar plus yellow pigment production on TSA) and a new chromogenic medium (Druggan–Forsythe–Iversen agar, DFI) which enables results to be obtained 2 days earlier than the conventional method. Ent. sakazakii was isolated from 2/82 powdered IFM, 5/49 dried infant foods, 3/72 milk powder, 2/62 cheese products and various dry food ingredients, especially herbs and spices (40/122). Ent. sakazakii was isolated from 67 samples using the DFI medium, however only 19 of the samples were positive following the conventional method. The largest difference in isolation between the two methods was with dry food ingredients.Although Enterobacteriaceae were enumerated from one powdered IFM sample (Klebsiella ozaenae, 200 cfu/g), 7/82 had detectable Enterobacteriaceae after enrichment in EE broth. Using the ISO 6579 2002 method and immuno-magnetic separation technique no Salmonella serovars were isolated from powdered IFM, dried infant foods or milk samples. Therefore hygienic production of powdered IFM and milk production as monitored by control of Salmonella and enumeration of Enterobacteriaceae did not control Ent. sakazakii.     

Microdetermination of phosphorus from infant formulas, casein and casein phosphopeptides

A spectrophotometric method, which has been proposed for the determination of phosphorus in biological fluids based on the formation of a phosphomolybdate complex, is adapted and validated for the determination of phosphorus in milk-based infant formulas, casein, casein phosphopeptides (CPPs) and the soluble fractions resulting from their gastrointestinal digestion, as well as in the fractions resulting from the ion-exchange high-performance liquid chromatography (IE-HPLC) of CE90CPP and in the soluble fraction of infant formula. The detection and quantification limits (1.1 and 3.6 mg P/100 g sample, respectively) are low enough for the purpose described. The linearity (from 0.1 to 8 g of phosphorus in the assay) is adequate. The precision of the method, expressed as relative standard deviation, is lower than 1%, and the accuracy checked by the analysis of SRM 1846: milk-based powdered infant formula is good. The quality of the method, together with the low cost and ease of use, makes it suitable for routine analysis.     

Short communication: Investigation of aflatoxin M1 levels in infant follow-on milks and infant formulas sold in the markets of Ankara,Turkey

Aflatoxins are fungal toxins known to be carcinogenic and are classified as food contaminants. This study was performed to investigate aflatoxin (AF) M₁ levels in baby foods sold in Ankara (Turkey) and to evaluate the obtained results according to the Turkish Food Codex (TFC). For this purpose, a total of 84 baby food samples (50 follow-on milks and 34 infant formulas) were obtained from different markets in Ankara and the presence of AFM₁ in the samples was analyzed by ELISA. In 32 (38.1%) of 84 infant food samples, the presence of AFM₁ was detected in concentrations ranging between 0.0055 and 0.0201 µg/kg. The mean level (±standard error) of AFM₁ was found to be 0.0089 ± 0.0006 µg/kg in positive infant follow-on milks. Aflatoxin M₁ was detected in only 1 infant formula sample (2.94%) at a concentration of 0.0061 µg/kg. The extrapolated levels of AFB₁ contamination in feedstuffs were calculated based on levels of AFM₁ in baby food samples. The data estimating AFB₁ contamination in dairy cattle feedstuff indicate that contamination may range from 0.3410 to 1.2580 µg/kg, with the mean level (±standard error) being 0.5499 ± 0.0385 µg/kg, which is lower than the level set by the TFC and European Union regulations (5 µg/kg). According to the obtained results, the levels of AFM₁ in analyzed samples were within the allowed limit (0.025 µg/kg) set in the TFC. Low levels of AFM₁ in infant follow-on milks and infant formula samples obtained during the study do not pose a health risk to infants.     

Exposure of cadmium from infant formulas and weaning foods

Cadmium levels were determined in 59 baby food samples, including milk-based, cereal and milk-based and soy-based formulas, recommended from 0 to 18 months of age. Determinations were performed by Zeeman graphite furnace atomic absorption spectrophotometry, after dry ashing, with parallel determinations of certified reference samples. Mean cadmium levels were found to range from 1.10 to 23.5 mu g / kg fresh weight concentrated formulas. L evels were related to the composition of the diets. Formulas based on cow's milk had the lowest concentrations. Soy formulas contained approximately six times more cadmium than cow's milk formulas, and diets with a cereal content had 4-21 times higher mean levels. The mean weekly intakes of dietary cadmium were estimated to vary between 0.10 and 3 : 05 mu g / kg body weight of the child, if the recommended amount of formula were to be consumed at the recommended age, and if the child were of average weight. This estimation however does not include the contribution of cadmium from drinking water. The highest intake on a body weight basis was found in 6-month-old children, consuming the recommended amount of wheat-, oat- and milk-based formulas. This intake is below the provisional tolerable weekly intake (PTW I) of 7 mu g / kg body weight, established by a W HO/FAO expert group. However, the risk assessment is based on renal effects in adults. Furthermore, preparations of a formula by adding water with cadmium concentrations at the W HO guideline level could lead to intakes at the PTW I level. Compared to breast-fed children, the exposure of dietary cadmium from weaning diets can be up to 12 times higher in children fed infant formula.     

A headspace solid-phase microextraction method of use in monitoring hexanal and pentane during storage: Application to liquid infant foods and powdered infant formulas

The determination of two secondary lipid oxidation compounds (hexanal and pentane) in liquid infant foods using a headspace solid-phase microextraction gas chromatographic (HS-SPME-GC) method has been developed and validated.     

Isolation and molecular identification of Cronobacter spp. from powdered infant formula (PIF) in Bangladesh

Cronobacter spp. formerly known as Enterobacter sakazakii is an occasional contaminant of powdered infant formula (PIF). This pathogen has been associated with out-breaks of a rare form of infant meningitis, necrotizing enterocolitis (NEC), bacteremia and neonate deaths. The organism is ranked by the International Commission for Microbiological Specifications for Foods (ICMSF) as a ‘Severe hazard for restricted populations, life threatening or substantial chronic sequelae or long duration’. Present study aimed to isolate Cronobacter spp. from PIF and clinical samples, such as blood, stool and CSF collected from 93 neonates and child patients, age ranged from 0 to 24 months. We did not detect Cronobacter spp. in any of these samples. Later 32 PIF samples collected from retail markets in Bangladesh were tested for the presence of Cronobacter spp. Of these only one was found to be contaminated with Cronobacter sp. This is the first case of Cronobacter contaminated PIF found in Bangladesh to be reported. The organism was successfully identified based on its typical culture characteristics, producing blue-green colonies on chromogenic DFI agar and also by a standardized conventional PCR assay targeting the alpha glucosidase and 16 S rRNA gene sequence of Cronobacter sp. The 16 S rRNA gene was partially sequenced to provide for the phylogenetic analysis of this isolate (DA01) and found to cluster with some other Cronobacter isolates in the phylogram.     

Simultaneous detection and identification of pathogenic Cronobacter species by high‐resolution melting analysis in powdered infant formulas

A combination method of real‐time PCR and high‐resolution melting (HRM) analysis for the rapid detection and specific classification of six pathogenic Cronobacter species based on gene cgcA was developed. HRM profiles with distinct T_m (melting temperature) peaks were consistently obtained with each species, represented by a single peak ranging from 86.02 to 86.80 °C. The detection limit ranged from 0.1 to 1 pg per reaction. Desiccated Cronobacter sakazakii and Cronobacter muytjensii of 2 cfu/25 g were successfully detected after 4‐week storage at room temperature. The newly developed method provided a molecular tool for direct detection and simultaneous identification of pathogenic Cronobacter species in powdered infant formulae.     

Optimization of spray drying parameters and food additives to reduce glycation using response surface methodology in powdered infant formulas

Food Science and Biotechnology - The heat-based spray drying process generating the highest level of advanced glycation end-products (AGEs) in the infant formula processing was set as a control...     

Characterization of Staphylococcus aureus isolated from powdered infant formula milk and infant rice cereal in China

Dry infant foods are not sterile and could be contaminated with various bacteria including certain pathogens. The aim of this study was to investigate the prevalence of Staphylococcus aureus in infant foods and to characterize these strains. A total of 367 infant food samples, including 143 samples of powdered infant formula milk (PIF) and 224 samples of infant rice cereal (IRC), were collected in the Shaanxi Province of China during the period of July to August 2010 and screened for S. aureus. All S. aureus isolates were characterized by antimicrobial susceptibility testing, pulsed-field gel electrophoresis (PFGE), and detection of genes encoding enterotoxins, exfoliative toxins, Panton-Valentine leukocidin (PVL), and toxic shock syndrome toxin 1. Among all the samples examined, sixteen of 143 PIF samples (11.2%) and 14 of 224 IRC samples (6.3%) were positive for S. aureus. From these positive samples, 29 S. aureus strains were isolated from PIF and 25 from IRC. Of these S. aureus isolates, 83.3% were resistant to at least one antimicrobial, 35.2% to three or more antimicrobials. Resistance was most frequently observed to erythromycin (75.9%), followed by ciprofloxacin (51.9%) and trimethoprim/sulfamethoxazole (27.8%), while significantly fewer isolates were resistant to gentamicin (22.2%), tetracycline (18.5%), or cefoxitin (3.7%). In addition, 63.0% of isolates were positive for one or more toxin genes tested. The three most predominant toxin genes were pvl (40.7%), seg (38.9%), and sec (18.5%), followed by sea (7.4%), seb (7.4%), sed (5.6%), and see (5.6%). The ets, tsst-1, seh, sei, and sej genes were not detected. A total of 39 PFGE patterns were generated among 51 selected food isolates. Our findings indicate that PIF and IRC in the Shaanxi province were contaminated with S. aureus, and many S. aureus isolates harbored multiple toxin genes and exhibited multiple antimicrobial resistance. In addition, these S. aureus isolates were genetically diverse. The presence of S. aureus strains in these infant foods poses a potential threat to infant health.     

真菌Simplicillium lanosoniveum抗生素的分离纯化和初步表征

以蓝藻的共生真菌Simplicillium lanosoniveum为研究对象,对其代谢产生的抑制革兰氏阳性菌的抗生素进行发酵条件的筛选、分离纯化和初步表征。通过单因素实验确定真菌Simplicillium lanosoniveum产生抗生素的最佳培养基为改良的沙氏培养基:蔗糖30.0 g/L和蛋白胨12.0 g/L;发酵曲线表明该抗生素的合成与菌体的生长关系为生长非偶联型;通过样品液的分离纯化以及初步表征确定该抗生素在254 nm处有最大吸收峰,以乙腈:0.02 mol/L的碳酸盐缓冲溶液(体积比为5∶95)为流动相时,其保留时间为4.1031 min,分子量为163.0182;双缩脲和茚三酮反应均呈阴性。该抗生素的发现为Simplicillium属的分类提供了理论依据。      

Occurrence,sources, and pathways of chemical contaminants in infant formulas

Infant formulas are manufactured products to meet specific nutritional requirements for infants. However, infant formulas can contain harmful substances, such as chemical contaminants and residues, normally due to possible contamination of the raw material or from the production chain. Some studies have demonstrated that veterinary drugs, pesticides, mycotoxins, heavy metals, packaging materials, within other chemicals are found in infant formulas from different sources of contamination. It is known that some of these substances can be hepatotoxic, carcinogenic, teratogenic, mutagenic, immunotoxic, contributing to antibiotic resistance, among other detrimental consequences for consumers’ health. The purpose of this review is to assess the scientific evidence concerning the occurrence, sources, and pathways of contamination, as well as the detrimental impacts on infant health due to the possible presence of chemical contaminants and residues in infant formulas. Moreover, strategies to reduce the risk of contamination of infant formulas are presented to ensure the highest standards of quality of infant formulas. The entire infant formula manufacturing process should be monitored and controlled to minimize the risk of contamination during processing, storage, and distribution, besides ensuring the use of raw materials with as low as acceptable levels of harmful substances in order to assure that the final product shall comply with the maximum levels and maximum residue limits, when established, for residues and contaminants in the final product.     

Dietary factors affecting trace element bioavailability from human milk, cow's milk and infant formulas

Bioavailability of trace elements is affected by the type of diet in which they are presented. In general, absorption of the elements iron, zinc, copper, manganese and selenium appears to be higher from human milk than from cow's milk or cow's milk formula while absorption from soy formula appears to be lower than from milk-based products. The effects of individual components such as protein source, carbohydrate, phytate, organic acids and other cations on absorption need to be assessed and the integrated effects of individual dietary components need to be assessed in the intact diet. While ideally absorptive studies should be performed in human infants, there is a need for developing useful and valid models for assessing trace element bioavailability. Increased knowledge about trace element absorption from different infant diets and the factors involved will lead to a better understanding of trace element requirements of infants. This will help in the suggestion of ways to improve means of supplementation.     

Available lysine,protein digestibility and lactulose in commercial infant formulas

Available lysine, in vitro protein digestibility and lactulose values were determined in 23 commercial infant formulas. The mean available lysine content of the formulas based on dairy proteins was 66.7±9.5 mg g⁻¹ protein, similar to that of human milk, while that of soy based formulas was considerably lower (45.0±8.3 mg g⁻¹ protein). In vitro protein digestibility values ranged 85.5–88.9% for soy-based formulas and 90.5–98.3% for formulas based on dairy proteins. Formulas based on milk enriched with whey had higher lactulose content than those based on cow's milk. However, all values were below the limit of 600 mg L⁻¹ recommended for UHT milk.     

Development of an immobilization and detection method of Enterobacter sakazakii from powdered infant formula

Enterobacter sakazakii is an emerging opportunistic pathogen that is associated with rare but life-threatening cases of meningitis, necrotizing enterocolitis, and sepsis in premature and full-term infants. In the present study, a procedure was developed for immobilization of E. sakazakii with zirconium hydroxide coupled with detection by a species-specific duplex PCR, based on 16s-23s rDNA internal transcribed spacer (ITS) and ompA gene. Specificity of duplex PCR was tested against two-type strains, six isolates of E. sakazakii and other eight non-E. sakazakii species. When pure culture of E. sakazakii was used for immobilization, total recovery rate ranged from 79.4% to 99.6% of input bacteria, and the detection limit of duplex PCR was 3x10(5)CFU/ml. Different levels of E. sakazakii were inoculated into 90ml reconstituted powdered infant formula (PIF), and detection limit of duplex PCR was 3x10(0)CFU/ml with 24-30h enrichment after immobilization. When the experiment was performed in the presence of 10(2)CFU/ml Salmonella typhimurium, the detection limit of duplex PCR was not affected after enrichment. Seven out of 13 commercial PIF were detected positive by duplex PCR after immobilization, while only three were positive by biological methods. This study demonstrates that the combination of immobilization method with duplex PCR is easy, rapid, and efficient, and may have applications for the detection of E. sakazakii in more PIF samples.     

Isolation and characterization of tyramine-producing Enterococcus faecium strains from red wine

Enterococcus faecium strains were isolated from red wines undergoing malolactic fermentation and identified by comparison of their 16S rDNA gene sequences with those included in the GenEMBL Databases. The tyrosine decarboxylase gene was identified in all the strains analysed by PCR using gene-specific primers and the ability to produce tyramine in a synthetic media was analysed by RP-HPLC. Survival of an E. faecium strain was also evaluated in microvinification assays using two different musts with different ethanol concentrations (10% and 12% (v/v)). Tyramine production was monitored during the vinification trials. Our results suggest that E. faecium strains isolated from wine are able to produce tyramine and tolerate wine conditions following a pre-acidic stress.     

Dielectric loss mechanism of powdered infant formula milk

Dipole loss of main compositions of powdered infant formula milk (PIFM), including whey protein (WP), fat and lactose and the ionic loss of PIFM were analyzed over frequency range of 10 to 3000 MHz at temperature range of 20–80 °C. Dielectric loss factor of PIFM decreased with increasing fat content, while increased with increasing WP content and lactose content at investigated frequencies in our study. The dipole loss of WP, fat and lactose followed Debye equation which increased with increasing frequency till around 1.2,1 and 1 GHz, respectively, and then decreased. Ionic loss of PIFM was constant with increasing frequency at investigated frequencies and increased with increasing temperature. A general formula to calculate ionic loss for both solid and liquid materials was obtained. Validation experiments based on the dielectric loss factor of different compositions indicated that increasing WP proportion in PIFM can increase heating rate in radio frequency field and also result in lower lipid oxidation of treated PIFM. This provides a solution to adjust RF heating performance and product quality based on loss mechanisms of different ingredients.