Amino acid-amidated pectin: Preparation and characterization.

There is interest in extending the functionality of natural polymers using simple chemical derivatization methods. In this study, the ability of pectin to react with various amino acids (40 °C) in aqueous solution without a catalyst was investigated, including glutamic acid, glycine, cysteine, lysine, and arginine. Only glycine, lysine, and arginine could form conjugates with pectin under these conditions. Amino acid-amidated pectin (AAAP) conjugates with a degree of amidation of 6.50% were prepared and characterized using elemental analysis, FT-IR, and 1H NMR. Size exclusion chromatography combined with multiangle light scattering and refractive index detection indicated pectin degradation occurred during the reaction. These results were supported by measurements of apparent viscosities. Scanning electron microscopy showed appreciable differences among the surface topographies of samples. Cell culture experiments showed the AAAP conjugates exhibited no cytotoxic effects. Our results suggested the AAAP conjugates may be suitable for use as new functional ingredients in food industry.

Characteristics of polycyclic aromatic hydrocarbons in food oils in Beijing catering services.

The concentrations and characteristics of 16 polycyclic aromatic hydrocarbons (PAHs) in 48 oil samples randomly collected from 30 catering services that employ six cooking methods were quantified via high-performance liquid chromatography (HPLC). These 16 PAHs were detected in almost all of the samples. The levels of Σ16PAHs, Σ4PAHs, benzo[a]pyrene (BaP), and total BaP equivalents (ΣBaPeq) for the six cooking methods exceeded the legal limit. The concentrations of Σ4PAHs were approximately 9.5 to 16.4 times the legal limit proposed by the European Commission (Off J Eur Union 215:4-8, 2011), and the level of BaP exceeded the national standard in China by 4.7- to 10.6-fold, particularly in oil from fried foods. Low molecular weight PAHs (LMW PAHs) were predominant in fried food oil from different catering services and accounted for 94.8 % of these oils, and the ΣBaPeq of the high molecular weight PAHs (HMW PAHs) was 11.5-fold higher than that of the LMW PAHs. The concentrations of Σ16PAHs (3751.9-7585.8 µg/kg), Σ4PAHs (144.6-195.7 µg/kg), BaP (79.7-135.8 µg/kg), and ΣBaPeq (231.0-265.4 µg/kg) were highest in the samples from fast food restaurants/buffets (FB), followed by those from fried food stalls (FS) and then cooking restaurants/cafeterias (RC). The results of this study suggest that the government should strengthen control and supervision of PAH contamination in food and edible oils.