Interactions between dietary cholesterol and intestinal flora and their effects on host health.

The interactions between dietary cholesterol and intestinal microbiota strongly affect host health. In recent years, relevant studies have greatly advanced this field and need to be summarized to deepen the understanding of dietary cholesterol-intestinal microbiota interactions and their effects on host health. This review covers the most recent frontiers on the effects of dietary cholesterol on the intestinal microbiota and its metabolites, the metabolism of cholesterol by the intestinal microbiota, and the effects of the interactions on host health. Several animal-feeding studies reported that dietary cholesterol altered different intestinal microbiota in the body, while mainly causing alterations in intestinal microbial metabolites such as bile acids, short-chain fatty acids, and tryptophan derivatives. Alterations in these metabolites may be a novel mechanism mediating cholesterol-related diseases. The cholesterol microbial metabolite, coprostanol, has a low absorption rate and is excreted in the feces. Thus, microbial conversion of cholesterol-to-coprostanol may be an important way of cholesterol-lowering by the organism. Cholesterol-3-sulfate is a recently discovered microbial metabolite of cholesterol, mainly metabolized by Bacteroides containing the Bt_0416 gene. Its effects on host health have been preliminarily characterized and are mainly related to immune modulation and repair of the intestinal epithelium.

Direct identification and quantitation of fluorescent whitening agent in wheat flour based on multi-molecular infrared (MM-IR) spectroscopy and stereomicroscopy.

Fluorescent brighteners, illegally used to whitening wheat flour, are detrimental to people health. The aim was to establish a rapid and direct method to identify and quantify fluorescent whitening agent OB-1 (FWA OB-1) in wheat flour by using multi-molecular infrared (MM-IR) spectroscopy combined with stereomicroscopy. Characteristic peak profile of FWA OB-1 used as a judgment basis was spatially revealed by stereomicroscopy with group-peak matching of MM-IR at 1614 cm-1, 1501 cm-1 and 893 cm-1 and were further unveiled by the second derivative infrared spectroscopy (SD-IR) and its two-dimensional correlation infrared (SD-2DCOS IR) spectroscopy for higher resolution, and were validated by high-performance liquid chromatography (HPLC). Moreover, a quantitative prediction model based on IR spectra was established by partial least squares 1 (PLS1) (R2, 98.361; SEE, 5.032; SEP, 5.581). The developed method was applicable for rapid and direct analysis of FWA OB-1 (low to 10 ppm) in flour with relative standard deviation (RSD) of 5%. The capabilities of MM-IR with spectral qualitative and quantitative analysis would be applicable to direct identification and quantitation of fluorescent whitening agents or other IR-active compounds in powder objects.

Simultaneous detection of trace adulterants in food based on multi-molecular infrared (MM-IR) spectroscopy.

Simultaneously rapid detection of trace adulterants in the complex systems of food without extraction is considered highly challenging. Herein, a high-throughput and rapid methodology, multi-molecular infrared (MM-IR) spectroscopy was developed for simultaneous detection of multiple trace adulterants in food. Flour was applied to demonstrate the capabilities of MM-IR with spatial resolution, spectral qualitative and quantitative analysis. Signals of 5 trace adulterants (rongalit, potassium bromate, borax, aluminum potassium sulfate and fluorescent brighter) were spatially revealed by IR hyperspectral imaging with group-peak matching, and further unveiled spectrally with second derivative two dimensional correlation infrared (SD-2DCOS IR) spectroscopy for higher resolution. Moreover, quantitative analysis of trace adulterants was conducted with partial least squares (PLS) modeling in ppm level. Composed of the above techniques and a series of resolution enhancement techniques (MW-2DCOS IR, 2T-2DCOS IR, etc.), MM-IR presented significant advantages on simultaneous detection of trace adulterants in food and therefore possessed the potential for food comprehensive analysis.