Development of enzymic time-temperature integrators with rapid detection for evaluation of continuous HTST pasteurization processes

The assessment of the thermal process impact in terms of food safety and quality is of great importance for process evaluation and design. This can be accomplished from the analysis of the residence time and temperature distributions coupled with the kinetics of thermal change, or from the use of a proper time-temperature integrator (TTI) as indicator of safety and quality. The objective of this work was to develop and test enzymic TTIs with rapid detection for the evaluation of continuous HTST pasteurization processes (70-85 degrees C, 10-60 s) of low-viscosity liquid foods, such as milk and juices. Enzymes peroxidase, lactoperoxidase and alkaline phosphatase in phosphate buffer were tested and activity was determined with commercial reflectometric strips. Discontinuous thermal treatments at various time-temperature combinations were performed in order to adjust a first order kinetic model of a two-component system. The measured time-temperature history was considered instead of assuming isothermal conditions. Experiments with slow heating and cooling were used to validate the adjusted model. Only the alkaline phosphatase TTI showed potential to be used for the evaluation of pasteurization processes. The choice was based on the obtained z-values of the thermostable and thermolabile fractions, on the cost and on the validation tests. (C) 2012 Elsevier Ltd. All rights reserved.

Responsiveness to change for the Brazilian Scale of Oral Health Outcomes for 5-year-old children (SOHO-5)

Abstract Background The responsiveness of oral health-related quality of life (OHRQoL) instruments has become relevant, given the increasing tendency to use OHRQoL measures as outcomes in clinical trials and evaluations studies. The purpose of this study was to assess the responsiveness of the Brazilian Scale of Oral Health Outcomes for 5-year-old children (SOHO-5) to dental treatment. Methods One hundred and fifty-four children and their parents completed the child self- and parental’ reports of the SOHO-5 prior to treatment and 7 to 14 days after the completion of treatment. The post-treatment questionnaire also included a global transition judgment that assessed subject’s perceptions of change in their oral health following treatment. Change scores were calculated by subtracting post-treatment SOHO-5 scores from pre-treatment scores. Longitudinal construct validity was assessed by using one-way analysis of variance to examine the association between change scores and the global transition judgments. Measures of responsiveness included standardized effect sizes (ES) and standardized response mean (SRM). Results The improvement of children’s oral health after treatment are reflected in mean pre- and post-treatment SOHO-5 scores that declined from 2.67 to 0.61 (p < 0.001) for the child-self reports, and 4.04 to 0.71 (p < 0.001) for the parental reports. Mean change scores showed a gradient in the expected direction across categories of the global transition judgment, and there were significant differences in the pre- and post-treatment scores of those who reported improving a little (p < 0.05) and those who reported improving a lot (p < 0.001). For both versions, the ES and SRM based on change scores mean for total scores and for categories of global transitions judgments were moderate to large. Conclusions The Brazilian SOHO-5 is responsive to change and can be used as an outcome indicator in future clinical trials. Both the parental and the child versions presented satisfactory results.

An analysis of Taguchi's on-line quality monitoring procedure for variables based on the results of a sequence of inspections

In this paper, a procedure for the on-line process control of variables is proposed. This procedure consists of inspecting the m-th item from every m produced items and deciding, at each inspection, whether the process is out-of-control. Two sets of limits, warning (µ0 ± W) and control (µ0 ± C), are used. If the value of the monitored statistic falls beyond the control limits or if a sequence of h observations falls between the warning limits and the control limits, the production is stopped for adjustment; otherwise, production goes on. The properties of an ergodic Markov chain are used to obtain an expression for the average cost per item. The parameters (the sampling interval m, the widths of the warning, the control limits W and C(W < C), and the sequence length (h) are optimized by minimizing the cost function. A numerical example illustrates the proposed procedure.