Effect of Acidic Challenge Preceded by Food Consumption on Enamel Erosion

Objectives: This in vitro study aimed to evaluate the effect of food consumption followed by acidic challenge on enamel erosion.Methods: Seventy-five enamel blocks obtained from bovine teeth were divided randomly into five groups (n=15 per group): GI – erosion with previous immersion in milk; GII – erosion with previous immersion in cheese extract; GIII – erosion with previous immersion in liver extract; GIV – erosion with previous immersion in broccoli extract; and GV – erosive effect of cola drink (control). Over 24 h, the slabs were submitted to 3 pH-cycles, each consisting of immersion in the studied food (GI to GIV) for 5 min followed by immersion in a cola drink for 5 min, and subsequently, the slabs were stored in artificial saliva (110 min). At the end of the pH-cycles, the slabs were stored in artificial saliva for 18 h. Enamel alterations were assessed by profilometry (μm). Data were tested using ANOVA and Scott-Knott’s tests (P<.05).Results: Mean erosion depths for enamel (μm) were 0.46 in GI, 0.55 in GII, 0.64 in GIII, 0.54 in GIV, and 1.18 in GVI. Enamel loss by acidic challenge alone (GV) was significantly higher than when the acidic challenges were preceded by food extract immersion.Conclusions: The data suggest that all studied foods could minimize the erosive effect on enamel. (Eur J Dent 2010;4:412-417)

Modeling the Combined Effect of pH and Temperature on the Heat Resistance of Bacillus stearothermophilus Spores Heated in a Multicomponent Food Extract

The combined effect of pH and temperature on the heat resistance of Bacillus stearothermophilus spores heated in an extract of complex food was studied. The results showed that, in general, reducing the pH reduced the heat resistance of the spores. Similarly, the value for the D parameter in the nonacidified extract was between 30 and 70% lower than the one obtained with double-distilled water. This result once again shows the importance of the substrate in inactivation studies of microorganisms. The experimental data were used to carry out a comparison of two predictive mathematical models of inactivation, one based on a multiparametric regression obtained in this study and the other obtained from the bibliography and based on a linear-Bigelow equation. Both models predict reasonably well, although the multiparametric model presented a slightly better accuracy factor (1.11) than the one obtained with the linear-Bigelow equation (1.13).

Concentration of Staphylococcal Enterotoxin from Food Extract Using Copper Chelate Sepharose

A simple and rapid method is described for detecting as little as 1 ng each of staphylococcal enterotoxins A, B, and C2 in 100 mL samples of food extracts. Samples were fractionated on copper chelate Sepharose 6B and the recovery of added staphylococcal enterotoxin was measured by the reversed passive latex agglutination test. An approximate 100 fold concentration of toxin was obtained. The method should prove useful as a partial purification and concentration step in the analysis of foods incriminated in food poisoning outbreaks.

Behavioral Alterations in Arctic Char (Salvelinus alpinus) Briefly Exposed to Sublethal Chlorine Levels

Changes in the locomotor behavior of Arctic char (Salvelinus alpinus) exposed inadvertently to sublethal chlorine concentrations (> 19μg total residual chlorine/L) for 6 d are described. Compared with their preexposure behavior, the char became hypoactive, much more strongly thigmotactic, and less responsive to a food extract during the exposure. After the high chlorine levels subsided, the char continued to be hypoactive for at least 1 wk and failed to respond positively to the food extract for 20 d. There is evidence that some individuals displayed chlorine stress behavior for at least 46 d after the return of nonstressful conditions.

Behavioral and Biochemical Studies of Onset and Recovery from Acid Stress in Arctic Char (Salvelinus alpinus)

The time course of acid stress was followed in Arctic char (Salvelinus alpinus) exposed to pH 4.5 (HCl) for 2 wk and then returned to control conditions (pH 7.8). Behavioral parameters (activity, thigmotaxis, appetite, and attraction to a food extract) and blood parameters (hematocrit and plasma Cl−, Na+, osmolality, protein, cortisol, and glucose) were monitored. Reaction to the acid was evident in all parameters. Fish were initially hyperactive but became hypoactive with continued exposure. Thigmotaxis was generally greater in the acid-stressed fish than the controls. Feeding intensity and attraction to food extract were depressed throughout the exposure, but periods of partial recovery occurred. Hematocrit, protein, cortisol, and glucose increased, while osmolality, Cl−, and Na+ decreased in acid-exposed fish. Partial recovery occurred in some blood parameters during the latter part of the exposure. After return to control conditions, behavioral and blood parameters except cortisol recovered within 2 wk but might have recovered earlier if fish had not contracted a Saprolegnia infection. Extract attraction was negatively correlated with hematocrit, protein, cortisol, and glucose and positively correlated with plasma Cl. Activity was negatively correlated with plasma protein and glucose. Thigmotaxis was not correlated with any blood parameter.