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Young children's food preferences: a comparison of three modalities of food stimuli.

Food preferences are widely agreed to be important determinants of eating behaviour in young children. Existing studies of methods of assessing preferences have suggested tasting and ranking foods can generate reliable responses with young children, but there have been few attempts to assess other methods which might provide a more convenient alternative in situations where the use of real foods could be difficult (e.g. outside the laboratory), or tasting could be undesirable (e.g. if there are large numbers of foods, or foods which children would be unwilling to taste). The present study is a comparison of the reliability of preferences measured using: (i) real foods; (ii) food photographs; and (iii) food models, in 3 to 5-year-old children. The results showed that the tasting method produced good results, replicating existing data from U.S. samples. Food photographs came a close second in reliability but food models produced unreliable rankings, especially in the youngest group. Five-year-olds produced significantly more consistent results than the younger children. These results indicate that using real foods as the stimuli produces the most reliable taste preferences with children in this young age range, but photographs may provide a convenient alternative with adequate reliability.

Age Factors↗

Development of a PCR microplate-capture hybridization method for simple, fast and sensitive detection of Salmonella serovars in food.

The authors have developed an easy and rapid detection and identification system for Salmonella spp. in food. The gene inv A was selected as the target sequence. Oligonucleotides derived from conserved regions of this gene were able to exclusively prime the amplification of a 389 bp fragment when Salmonella spp. DNA was used as the template. An internal Salmonella spp. specific DNA probe was used for confirmation of the amplified polymerase chain reaction(PCR)product, by Southern blot or microplate-capture hybridization assay. In this fashion the sensitivity of the method was increased 100-fold (4.5 fg total DNA). To validate the method, a total of 75 food samples were tested. The PCR-microplate capture hybridization assay is easy to perform and much faster than traditional detection methods for Salmonella spp. in food. Hybridization in microtitre plates is more readily observed than in Southern blot and is more sensitive than conventional agarose gel electrophoresis.

Biotin↗

Sensitive determination of erythrosine and other red food colorants using capillary electrophoresis with laser-induced fluorescence detection.

Capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) was applied to separation and sensitive determination of red food colorants. Diode pumped frequency-doubled Nd:YAG laser (532 nm) was used as an excitation source in a laboratory-built CE-LIF system. For highly fluorescent erythrosine B (E127), an extrapolated limit of detection (LOD) of 0.4 ng mL(-1) (S/N=3) was achieved. Extrapolated LODs of other tested red additives, such as carmoisine, E122 (0.5 microg mL(-1)); amaranth, E123 (0.2 microg mL(-1)); ponceau 4R, E124 (0.3 microg mL(-1)) and red 2G, E128 (0.3 microg mL(-1)) were about one-order lower compared to results obtained with CE with absorbance detection in UV/vis (CE-UV/vis). The main advantages of using CE-LIF for analysis of food samples are high selectivity and minimization of matrix effect. To our knowledge, this is the first use of CE-LIF for determination of red food colorants.

Coloring Agents↗

Cadmium dietary intake in the Canary Islands, Spain.

Cadmium (Cd) in the human diet constitutes a potential chronic hazard to health. In the nonsmoking general population, diet is the major source of cadmium exposure; therefore, it is important to monitor the dietary intake of this heavy metal to quantify and improve the understanding of Cd accumulation in the human body. The purpose of this study was to determine the levels of Cd in a range of food and drink commonly consumed in the Canary Islands. Food samples (420) were analyzed for Cd by atomic absorption spectrometry. The most recent nutritional survey conducted for the Canarian population was used to define the food and drink groups analyzed. The measured Cd concentrations combined with the food consumption data resulted in a total Cd intake in the Canary Islands of 0.16 microg/kg of body weight/day, which is well below the respective provisional tolerable weekly intake of Cd of 1 microg/kg of body weight per day determined by the FAO/WHO. The results are also compared with values reported for other national and international communities.

Beverages↗

Detection of enterotoxigenic Clostridium perfringens type A isolates in American retail foods.

Currently there is only limited understanding of the reservoirs for Clostridium perfringens type A food poisoning. A recent survey (Y.-T. Lin and R. Labbe, Appl. Environ. Microbiol. 69:1642-1646, 2003) of non-outbreak American retail foods did not identify the presence of a single C. perfringens isolate carrying the enterotoxin gene (cpe) necessary for causing food poisoning. The present study revisited this issue, using revised methodology and food sampling strategies. In our survey, cpe-positive C. perfringens isolates were detected in approximately 1.4% of approximately 900 surveyed non-outbreak American retail foods. Interestingly, those enterotoxigenic isolates in non-outbreak foods appear indistinguishable from C. perfringens isolates known to cause food poisoning outbreaks: i.e., the enterotoxigenic retail food isolates all carry a chromosomal cpe gene, are classified as type A, and exhibit exceptional heat resistance. Collectively, these findings indicate that some American foods are contaminated, at the time of retail purchase, with C. perfringens isolates having full potential to cause food poisoning. Furthermore, demonstrating that type A isolates carrying a chromosomal cpe gene are the enterotoxigenic isolates most commonly present in foods helps to explain why these isolates (rather than type A isolates carrying a plasmid cpe gene or cpe-positive type C or D isolates) are strongly associated with food poisoning outbreaks. Finally, since type A chromosomal cpe isolates present in the surveyed raw foods exhibited strong heat resistance, it appears that exceptional heat resistance is not a survivor trait selected for by cooking but is instead an intrinsic trait possessed by many type A chromosomal cpe isolates.

Animals↗

Estimation of bacterial concentrations in commercial foods by measuring ATP changes during incubation.

Recently we have developed new kinetic methods of bacterial cell estimation in food products by measurement of the increase in bacterial adenosine-triphosphate (ATP) content during incubation using a conventional firefly luminometer [Fujikawa and Morozumi: Jpn. J. Food Hyg. (2002)]. The methods were the end point method and the delay method. We, in this study, evaluated these methods for bacterial concentration estimation in commercial foods. The methods were successfully applied to food products inoculated with Escherichia coli or Staphylococcus aureus. The methods were then used to estimate bacterial concentrations in commercial foods. For estimation, the kinetic parameter values were determined first from the data of bacterial strains studied previously. The bacterial concentrations estimated with these parameter values were slightly smaller than the measured concentrations for most of the food samples. The parameter values obtained with the least-squares method gave better estimations in both methods. The delay method predicted the bacterial concentrations in food products better than the end point method. This study showed that with appropriate parameter values, these methods could be useful tools for bacterial concentration estimation of commercial foods.

Adenosine Triphosphate↗

PCDD/F levels in plasma of a belgian population before and after the 1999 belgian PCB/DIOXIN incident.

We evaluated the impact of the 1999 Belgian dioxin incident on the blood plasma polychlorinated dibenzo-p-dioxin (PCDD) and polychlorinated dibenzofuran (PCDF) levels among 232 Belgian blood donors (74% men, mean age 47 years). The Red Cross made plasma samples from before the incident of these donors available. A second plasma sample was collected during the second half of 2000. The sum of the 17 PCDD/F congeners was significantly lower in 2000 compared to 1998 (417 pg/g fat versus 445 pg/g fat, respectively). This could be completely attributed to the significant decrease of OctaCDD (301 pg/g fat in 2000 versus 277 pg/g fat in 1998). Moreover a slight but significant decrease was observed for 2,3,7,8-TetraCDF and for 1,2,3,4,6,7,8-HeptaCDF. 1,2,3,7,8-PentaCDF and 2,3,4,7,8-PentaCDF however showed a slight but significant increase (respective levels in 1998 were 0.004 and 14.5 pg/g fat compared to 0.006 and 17.9 pg/g fat in 2000). Given their significantly higher presence in incident related food samples this increase can be attributed to the food contamination episode. However, the total toxicity remained unchanged (22.9 in 1998 versus 23.1 pg WHO-TEQ/g fat, p>0.05). Moreover the observed congener profiles and the total PCDD/F levels were similar to those of other European non-occupationally exposed populations. In conclusion, the 1999 PCB/dioxin incident was traceable in the plasma profiles (rise of the two specific PCDF congeners), but comparison of the results for both years indicates that the changes were too small to cause an adverse public health effect.

Belgium↗

Rapid detection of glycyrrhizin by immunochromatographic assay.

An immunochromatographic assay was developed for detecting glycyrrhizin (1). The qualitative assay is based on a competitive immunoassay using anti-1 monoclonal antibody (MAb) and a detector reagent that contains colloidal gold particles coated with anti-1 MAb. The immunochromatographic strip test, which has a detection limit of 250 ng/mL, is useful as a rapid screening method for detecting glycyrrhizin in plants, biological fluids and food samples.

Antibodies, Monoclonal↗

Selective identification by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of different types of gluten in foods made with cereal mixtures.

The gluten toxic fractions responsible for the mucosal damage in coeliac disease (CD), so-called gliadins, hordeins, secalins and avenins from a large number (30-40) of wheat, barley, rye and oats cultivars respectively, have been mass analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Gliadin, secalin and avenin characteristic mass profiles are nearly identical amongst distinct cultivars from the corresponding cereal, while hordeins profiles show more variability depending on the particular barley cultivar. On the basis of these four distinguishable characteristic mass patterns spreading within the 20,000-40,000 Da range, MALDI-TOF-MS has permitted the direct and simultaneous visualization of gliadins, hordeins, secalins and avenins in foods elaborated with cereal mixtures of wheat, barley, rye and oats. This capacity has been demonstrated by mass analyzing foods made with these four cereals in varying ratios. Thus MALDI-TOF-MS can be preliminarily established as a unique system with the ability to discriminate the specific type of gluten toxic fractions present in food samples.

Avena↗

Use of pyrrolidonyl peptidase to distinguish Citrobacter from Salmonella.

In the routine testing of foods for Salmonella, Citrobacter and other members of the Enterobacteriaceae often produce colonies which are almost indistinguishable from Salmonella on commonly used selective agars. Biochemical confirmation of such colonies can be expensive and time-consuming. It has been suggested that the enzyme pyrrolidonyl peptidase (PYRase) could be used as a rapid test to distinguish Citrobacter colonies (PYRase-positive) from Salmonella (PYRase-negative). Pure cultures of Salmonella, Citrobacter and other Enterobacteriaceae were tested for PYRase activity; all strains of Salmonella tested were PYRase-negative, and all Citrobacter tested were PYRase-positive. Inoculated and naturally contaminated food samples were tested for the presence of Salmonella by a standard cultural method. A PYR test was used to test Salmonella-like colonies isolated on selective agar and potentially, eliminate PYR-positive isolates from further biochemical testing. The test was able to screen out 6% of colonies selected from samples inoculated with Salmonella, and 43% of colonies selected from uninoculated samples.

Bacterial Typing Techniques↗

Rapid quantification of Yersinia enterocolitica in pork samples by a novel sample preparation method, flotation, prior to real-time PCR.

The development of real-time PCR thermal cycles in the late 1990s has opened up the possibility of accurate quantification of microorganisms in clinical, environmental, and food samples. However, a lack of suitable sample preparation methods that allow rapid quantification of the nucleic acids, remove PCR inhibitors, and prevent false-positive results due to DNA originating from dead cells has limited the use of quantitative PCR. We have used for the first time a new variant of density gradient centrifugation, called flotation, as a user-friendly sample preparation method prior to PCR. This paper describes the use of this sample preparation method, without DNA purification, for direct detection and quantification of Yersinia enterocolitica in PCR-inhibitory meat juice from pork. Flotation combined with qPCR could overcome PCR interference in juice from pork, as was shown by amplification efficiencies of 1.006 +/- 0.021 and 1.007 +/- 0.025, which are comparable to the amplification efficiency obtained for purified DNA samples (1.005 +/- 0.059). Applying flotation to meat juice samples containing natural background flora and spiked with different levels of Y. enterocolitica showed that direct quantification of Y. enterocolitica was possible down to a level of at least 4.2 x 10(3) CFU per ml of meat juice, even in the presence of 10(6) CFU of background flora per ml. Finally, the results showed that samples containing large amounts of Y. enterocolitica DNA did not result in a positive PCR signal. This indicates that the risk of false-positive results due to detection of DNA originating from dead cells can be greatly reduced by using flotation prior to PCR.

Animals↗

A comparative study of food retail premises by means of visual inspection and microbiological quality of food.

The relationship between visual inspection ratings given to ten food retail premises and the microbiological quality of food samples was examined. Viable counts of bacteria and of Staphylococcus aureus were determined for cooked meat samples from each of the premises. There was no correlation between potential risk of foodborne infection, as assessed by total inspection rating, and bacteriological counts in food (P < 0.05). Neither was there a consistent relationship between scores given to any component of the total rating and the bacteriological quality of food. The effectiveness of the current UK inspection scheme in assessing risk of foodborne infection is questioned. Inclusion of appropriately weighted criteria such as food temperature abuse is suggested to improve the scheme.

Animals↗

The direct application of the polymerase chain reaction to DNA extracted from foods.

Two methods for the successful extraction of DNA from foods are described. The rapid lysis method uses a proteinase K buffer system to lyse cells and solubilize food samples. DNA is then precipitated using isopropanol. The second method achieves cell lysis using toluene and mutanolysin, and solubilization using guanidium thiocyanate. Following protein removal with organic solvents DNA is precipitated with isopropanol. Both methods enabled the polymerase chain reaction to be applied directly to DNA extracted from samples of cheese, coleslaw and raw chicken and allowed the direct rapid, sensitive and specific detection of Yersinia enterocolitica, Aerococcus viridans and Listeria monocytogenes in these foods.

Base Sequence↗

An unusual outbreak of food poisoning.

On August 25 1990, over 400 people who attended a Thailand handicappeds' sport day at a provincial physical education college developed gastrointestinal symptoms after having dinner. An epidemiological team want to determine causes(s) and recommend how to prevent and control a food poisoning outbreak. The investigation included interviewing all 1,210 persons who attended the sport's day. In addition, an environmental survey, laboratory analysis of food samples, and rectal, ear, throat and nasal swabs from foodhandlers were also performed. A case was defined as a person who ate any items of dinner food and experienced vomiting, nausea, abdominal pain, and diarrhea. There were 485 cases out of 1,094 persons, an attack rate of 43%. Interviews were completed for 470 out of 485 cases. The three most common symptoms were nausea (93%), vomiting (88%), and abdominal pain (81.5). The mean incubation period was 3.20 hours. Three out of four items of food had a significant association with illness. Among these 3 items, eclairs had to the highest crude relative risk, 7.0 (95% CI = 4.8, 10.2). For statistical analysis, logistic regression by unconditional method was used, and found that only eclairs which were prepared during the night before the dinner and kept at room temperature for at least 12 hours before serving, remained statistically significant in the model (RR = 11.96; 95% CI = 9-22). Laboratory examination of foods and foodhandlers indicated heavy growth of Staphylococcus aureus producing toxins A and C and Bacillus cereus in eclairs. Culture of nasal swabs from healthy foodhandlers identified B. cereus and S. aureus of different phage types from those in eclairs.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

Validated sandwich enzyme-linked immunosorbent assay for casein and its application to retail and milk-allergic complaint foods.

Cows' milk is a commonly allergenic food. Cross-contamination of milk proteins into nondairy, kosher-pareve foods prepared on shared processing equipment can cause severe, life-threatening reactions in milk-allergic individuals. A sandwich-type enzyme-linked immunosorbent assay (ELISA; 96-well plate format) was developed for the detection of undeclared casein in foods. Rabbit anti-casein antibodies were used as the capture reagent. Food samples and standards were ground, extracted in 0.01 M phosphate-buffered saline, clarified by centrifugation, and added to the wells. Goat anti-casein antibodies were employed as the detector antibody, and the amount of antibody bound was determined with a commercial rabbit anti-goat immunoglobulin conjugated to alkaline phosphatase, with subsequent substrate reaction. Antibodies developed were specific to casein, with no cross-reaction observed with 30 foods and food ingredients. Non-milk-containing products such as fruit juices, fruit juice bars, sorbets, and dark and pareve-labeled chocolate were purchased from June 2002 through June 2003. In addition, samples allegedly causing eight milk-allergic consumer complaints were analyzed. The ELISA had a detection limit of less than 0.5 ppm of casein. The casein content in the analyzed foods ranged from less than 0.5 ppm to more than 40,000 ppm casein; undeclared casein residues were found in all of the samples implicated in allergic reactions. The levels of milk contamination in some of the other surveyed products could also be hazardous for milk-allergic consumers. This ELISA method provides a useful quality control tool for the food industry and could also be used as a validation of kosher-pareve status.

Animals↗

A gas chromatography/electron ionization-mass spectrometry-selected ion monitoring method for determining the fatty acid pattern in food after formation of fatty acid methyl esters.

A method using gas chromatography/electron ionization-mass spectrometry (GC/EI-MS) in the selected ion monitoring (SIM) mode was developed for the analysis of fatty acids as methyl esters (FAMEs) in order to determine their percentage contribution to the fatty acid profile in food. In the GC/EI-MS-SIM mode, saturated fatty acids were determined with m/z 87, monoenoic fatty acids were determined with m/z 74, and polyenoic fatty acids were determined via the sum of m/z 79 and m/z 81. The ratios of these fragment ions and the GC retention data provided additional information for tentative structural assignments. The 28 FAME standards tested provided similar results for the novel GC/EI-MS-SIM method and GC/EI-MS in the full scan mode, both of which were slightly worse than GC/flame ionization detection (FID). Analysis of sunflower oil, suet, and cod liver oil verified that both major and minor fatty acids (20-60% and down to 0.001% contribution to the fatty acid pattern) were determined with sufficient quality that justifies application of the GC/EI-MS-SIM method for the analysis of food samples. Furthermore, the method was approximately 20- or approximately 10-fold more sensitive than GC/EI-MS in the full scan mode or GC/FID, respectively. The method is suited for both quantitative purposes and fatty acid identification in samples where only low amounts of lipids are available.

Chromatography, Gas↗

An electronic DNA microarray technique for detection and differentiation of viable Campylobacter species.

An electronic oligonucleotide microarray technique was developed for detection and differentiation of the viable Campylobacter species, C. jejuni, C. coli, and C. lari. This development consisted of four major components: identification of single nucleotide polymorphisms (SNPs) within the hsp60 gene as species markers, design of fluorescently labelled SNP-based reporters, development of an electronic microarray detection, and application of the integrated technique to analysis of Campylobacter species in food samples. A unique capability of this technique is the specific detection of viable cells and not dead ones. This is achieved by using mRNA of the 60 kDa heat-shock protein as the viability marker. The identification of two unique SNPs closely located at positions 291 and 294 of the hsp60 gene enabled the differentiation of the three Campylobacter species. This technique was able to detect as few as two viable Campylobacter cells. The analysis of 19 blind Campylobacter samples showed 100% agreement with their identities obtained using pulsed-field gel electrophoresis. The analysis of six chicken samples revealed the presence of C. coli in one of the samples.

Animals↗

Cadmium content in foodstuffs from the Greek market.

Determinations of the cadmium content of a wide variety of foodstuffs from the Greek market were carried out. The values detected ranged from <0.1 ng x g(-1) in alcoholic beverages to 1595.8 ng x g(-1) in large snails. The highest values were observed in molluscs and crustaceans (117.4 ng x g(-1)), followed by leafy vegetables (28.3 ng x g(-1)), potatoes (22.3 ng x g(-1)) and organs and offal (20.7 ng x g(-1)), whereas the other food categories had a lower cadmium content. The results are comparable with those from the rest of Europe. Preliminary analytical data on the cadmium content of food samples of organic cultivation showed significantly lower values compared with those of samples of conventional produce.

Animals↗