Comparison of dietary fiber contents of selected baby foods from two major brands in Canada using three methods.

Of the two major brands of baby foods in Canada, one reports lower dietary fiber values than the other, although the products appear to be similar. To investigate the reasons for this discrepancy, seven selected samples of baby foods from both brands were analyzed for total dietary fiber (TDF) according to the Mongeau (rapid Health Protection Branch; HPB) method. Two cereals were also analyzed by using the Prosky and the Englyst (nonstarch polysaccharide; NSP) methods as an internal check on the methodology as well as a means of investigating the reasons for the discrepancies. The sampling included at least four different lots of each product (cereals, fruits, vegetables, and legumes). Each lot was analyzed individually. The TDF values determined using the rapid HPB method were in agreement with those obtained by other dietary fiber methods. Comparison between manufacturer-reported and measured values showed that the low values reported in brand A products were due, in part, to under-reporting of TDF content: measured TDF values were significantly higher than manufacturer-reported values. For brand B products, the manufacturer-reported and measured TDF values were in general agreement. This shows that a large part of the discrepancy between the two brands was due to methodological problems associated with measuring TDF in brand A. Differences in TDF content were also apparent as shown by the fact that brand A TDF values were consistently lower than those of brand B when both were measured by the same method. The differences in TDF content were not explained by differences in the polysaccharide composition of the fiber residues or by differences in water content. Although the limited number of samples does not allow any general conclusion about the TDF content of specific brands, the results show that formulation and/or manufacturing differences may influence TDF values in processed baby foods.

A collaborative study on the detection of staphylococcal enterotoxins in foods by an enzyme immunoassay kit (RIDASCREEN).

The RIDASCREEN SET kit (R-Biopharm GmbH, Darmstadt, Germany), a commercial staphylococcal enterotoxin (SE) immunoassay kit, utilizes monovalent capture antibodies against SE types A to E (SEA to SEE); therefore, it simultaneously detects and identifies the enterotoxin types. A collaborative study was conducted to ascertain whether the specificity, sensitivity, repeatability and reproducibility of the kits would meet food safety criteria. Twelve Canadian laboratories participated in this study to analyze various foods to which 1.0 to 2.0 ng of SE/g had been added and negative control samples. The results indicate that the sensitivity and specificity of the kit were excellent; all collaborators were able to detect the minimum toxin levels of 1.0 ng SEA/g in ham and cheese, 1.0 ng SEB/g in salami and turkey, and 2.0 ng SED/g in other samples without any false-negative results. With regard to negative control samples, all analysts obtained correct results except for one analyst who recorded weak false-positive results with several foods detecting SEC or SEA. The overall rate of false-positive results was 0.7% for 600 triplicate assays. In addition, it was confirmed that the RIDASCREEN kit did not yield false-positive results with mussels in contrast to some other EIA kits. Overall repeatability and reproducibility of the kit were in the range of 11.69-42.57% and 17.25-68.05%, respectively.

A Collaborative Study on the Detection of Staphylococcal Enterotoxins in Foods with an Enzyme Immunoassay Kit (TECRA).

One of the commercially available enzyme immunoassay kits for the detection of staphylococcal enterotoxins (SEs) in foods, the TECRA screening kit (Bioenterprises Pty. Ltd., Roseville, New South Wales, Australia), has microtiter plates coated with a mixture of antibodies to all of the SEs. A collaborative study was conducted to ascertain whether specificity, sensitivity, repeatability, and reproducibility of the results obtained using this kit would meet food-safety criteria. Thirteen Canadian collaborators participated in this study to analyze both various foods to which 1.0 to 3.0 ng of SE/g of food had been added and negative control samples. In addition, the effect of animal serum in these analyses was examined. The results indicate that all collaborators (100%) were able to detect the minimum toxin levels of 1.0 ng of SEA/g of ham and 1.0 ng of SEB/g of salami and SE or SEs in other samples (chicken, turkey, and cheese) containing 2.0 to 3.0 ng/g, without any false-negative results. With regard to negative control samples, all collaborators obtained correct results except when analyzing two types of food: two collaborators (15%) showed weak false-positive results with salami and all analysts found strong false-positive results with mussels. The problem regarding specificity could be largely corrected by treating the sample with rabbit serum (0.1 volume in 1.0 volume food extract). The repeatability and reproducibility of results from the kit were acceptable.

Glutathione peroxidase activity in a healthy Canadian population. Effects of age, smoking and drinking habits, exercise and oral contraceptive use.

The activity of the enzyme glutathione peroxidase (SeGSHPx) has been suggested as an indicator of selenium status. The purpose of this study was to measure the activity of this enzyme in a large sample of healthy, free-living Canadians to determine normal distributions and the effects of age, smoking, and drinking habits, exercise, and the use of oral contraceptives (OCs) or estrogen replacement therapy. The population consisted of 386 self-selected subjects between the ages of 24 and 75. Erythrocyte SeGSHPx activity was 21.5 +or- 7 (Mean +or- SD) and 33.6 +or- 8U/g Hb and plasma activity was 226 +or- 31 and 214 +or- 38 U/L for males (n=239) and females (n=147), respectively. Erythrocyte activity was significantly higher in females and males (p0.01). The Se form of GSHPx accounted for 76% and 54% of total activity in plasma and erythrocytes, respectively. No differences due to age were seen in males, although plasma SeGSHPx, non-SeGSHPx, and total GSHPx activities were elevated in females 65 years of age and older. Cigarette smoking significantly elevated erythrocyte SeGSHPx and total activity in male subjects. This elevation did not vary with the amount smoked and was not seen in ex-smokers. Drinking elevated erythrocyte non-SeGSHPx and total activity in male subjects with the highest activity seen in drinkers who also smoked. No significant differences were seen with level of exercise except for a slight elevation with vigorous exercise. Estrogen use significantly elevated erythrocyte SeGSHPx, non-SeGSHPx, and total activities in both pre- and postmenopausal women. These data suggest that some lifestyle factors can have small but significant effects of GSHPx activity and must be controlled for when population-based surveys are being conducted.