Food additives, thermal analysis

Analytical procedures sensitive to 2 ppm for styrene and 0.05 ppm or less for other items were used for examining the extracts. Even under these exaggerated exposure conditions no detectable levels of the monomers, of the polymer, or of other potential residuals were observed. The materials are truly non-food-additive by the FDA definitions. Hydrogen cyanide was included in the list of substances for analysis since it can be present at low levels in commercial acrylonitrile monomer, and it has been reported as a thermal decomposition product of acrylonitrile polymers. As shown here, it is not detectable in extracts by tests sensitive to... 

In addition to the references discussed in the previous sections, there are a number of other references that provide examples of the use of thermal analysis and calorimetry in quality control and assurance situations. These are listed at the end of the list of other references. They cover polymers [46-71], organic chemicals [72-73], foods [74-76], inorganic chemicals [77] and metals [78-81]. Even this list of references is not nearly a complete bibliography of the use of these techniques in this area. 

Thermal Analysis Curves of Foods and Food Additives... 

Differential scanning calorimetry (DSC) is the main approach used today for studying thermal properties of foods (phase transitions, reactions, and specific heats). Older systems, such as containers fitted with sensors that follow the rising temperature of a heating bench, autoclaves with additional pressure sensors, or (high pressure) differential thermal analysis (DTA) instruments, are still useful. Modulated DSC is also applied today to food studies [4-9],... 

From an analytical perspective, the single most important physicochemical characteristic of riboflavin is its photosensitivity (80-82). Exposure of this vitamin to ultraviolet and visible light results in irreversible photoreduction to lumiflavin and lumichrome and loss of vitamin activity. In addition, the coenzymes are subject to hydrolysis by endogenous phosphatases that are present in a number of foods. Since these enzymes are generally inactivated by thermal processing, they are a concern only in the analysis of fresh products. 

This overview is focused on the on-line coupling of pressurized liquid extraction (PLE), microwave-assisted extraction (MAE), supercritical fluid extraction (SEE) and sonication-assisted extraction (SAE) with liquid and gas chromatography for the analysis of solid agricultural and food samples. In addition, head-space techniques and direct thermal extraction are discussed. 

Even though we consider it a good immunoenzymatic kit, some inconveniences can affect analytical determinations using this system. The assay does not always apply to matrices that have undergone thermal processing, hydrolysis, or fermentation, as the protein structure could be destroyed by these treatments. In few cases we obtained doubtful results, probably due to interferences from other food components. In addition to this, as the assay is temperature and time sensitive, it is necessary to perform the analysis complying strictly with the indication reported in the kit instructions. General kit characteristics ... 

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