Evaluation of Tannin-Delivery Approaches for Gut Microbiota Modulation: Comparison of Pectin-Based Microcapsules and Unencapsulated Extracts.

The aim of this study was to investigate the impact of tannins on gut microbiota composition and activity, and to evaluate the use of pectin-microencapsulation of tannins as a potential mode of tannin delivery. Thus, pectin-tannin microcapsules and unencapsulated tannin extracts were in vitro digested and fermented, and polyphenol content, antioxidant capacity, microbiota modulation, and short-chain fatty acid (SCFA) production were analyzed. Pectin microcapsules were not able to release their tannin content, keeping it trapped after the digestive process, and are therefore not recommended for tannin delivery. Unencapsulated tannin extracts were found to exert a positive effect on the human gut microbiota. The digestion step resulted to be a fundamental requirement in order to maximize tannin bioactive effects, especially with regard to condensed tannins, as the antioxidant capacity exerted and the SCFAs produced were greater when tannins were submitted to digestion prior to fermentation. Moreover, tannins interacted differently with the intestinal microbiota depending on whether they underwent prior digestion or not. Polyphenol content and antioxidant capacity correlated with SCFA production and with the abundance of several bacterial taxa.

X-ray computerized microtomography and confocal Raman microscopy as complementary techniques to conventional imaging tools for the microstructural characterization of Cheddar cheese.

This study explored the use of X-ray computerized microtomography (micro-CT) and confocal Raman microscopy to provide complementary information to well-established techniques, such as confocal laser scanning microscopy (CLSM), for the microstructural characterization of cheese. To evaluate the potential of these techniques, 5 commercial Cheddar cheese samples, 3 with different ripening times and 2 with different fat contents, were analyzed. Confocal laser scanning microscopy was particularly useful to describe differences in fat and protein distribution, especially between the 2 samples with different fat contents. The quantitative data obtained through image analysis correlated well with the nutritional information provided in the product labels. Conversely, micro-CT was more advantageous for studying the size and spatial distribution of microcrystals present within the cheese matrix. Two types of microcrystals were identified that differed in size, shape, and X-ray attenuation. The smallest, with a diameter of approximately 10 to 20 µm, were more abundant in the samples and presented a more uniform roundish shape and higher X-ray attenuation. Larger and more heterogeneous crystals with diameters reaching 50 µm were also observed in scarcer numbers and showed lower X-ray attenuation. Confocal Raman microscopy was useful not only for identifying the distribution of all these components but also allowed comparing the presence of micronutrients such as carotenoids in the cheeses and provided compositional information on the crystals detected. Small and large crystals were identified as calcium phosphate and calcium lactate, respectively. Overall, using micro-CT, confocal Raman microscopy, and CLSM in combination generated novel and complementary information for the microstructural and nutritional characterization of Cheddar cheese. These techniques can be used to provide valuable knowledge when studying the effect of milk composition, processing, and maturation on the cheese quality attributes.

Encapsulation of Plant-derived Bioactive Ingredients through Electrospraying for Nutraceuticals and Functional Foods Applications.

The electrospraying technique, which consists of electrohydrodynamic atomization of polymeric fluids, can be used to generate dry nano- and microparticles by subjecting a polymer solution, suspension or melt to a high voltage (typically in the range of 7-20 kV) electric field. This potential can be exploited for developing nano- and microencapsulation structures under mild temperature conditions. Thus, it constitutes a promising alternative to conventional microencapsulation techniques for sensitive ingredients, like most plant-derived bioactive compounds, especially for their application in the food sector. Given the importance of plants as one of the major sources of dietary bioactive compounds, significant attention has been recently paid to research the encapsulation of phytochemicals through novel techniques such as electrospraying, aiming to provide new tools for the development of innovative functional food products and nutraceuticals. In this review, the latest advances in the application of electrospraying for nano- and microencapsulation of phytochemicals are discussed, with a focus on their potential use in the food sector.