Enzymes are outstanding (bio)catalysts, not solely on account of their ability to increase reaction rates by up to several orders of magnitude but also for the high degree of substrate specificity, regiospecificity and stereospecificity. The use and development of enzymes as robust biocatalysts is one of the main challenges in biotechnology. However, despite the high specificities and turnover of enzymes, there are also drawbacks. At the industrial level, these drawbacks are typically overcome by resorting to immobilized enzymes to enhance stability. Immobilization of biocatalysts allows their reuse, increases stability, facilitates process control, eases product recovery, and enhances product yield and quality. This is especially important for expensive enzymes, for those obtained in low fermentation yield and with relatively low activity. This review provides an integrated perspective on (multi)enzyme immobilization that abridges a critical evaluation of immobilization methods and carriers, biocatalyst metrics, impact of key carrier features on biocatalyst performance, trends towards miniaturization and detailed illustrative examples that are representative of biocatalytic applications promoting sustainability.

Polyphenolic compounds (PC) are among the most abundant secondary metabolites in nature. They are widely distributed in the world and can be found in fruits, cereals, tea, coffee, and beverages. Due to their structural diversity, polyphenols have many different properties and biological effects. They are resistant to the acid of the gastric tract, and very few are hydrolysed or absorbed in the stomach. Significant portions of ingested polyphenols reach the large intestine and interact with the local bacteria, the so-called gut microbiota. Epidemiological studies confirm that moderate and prolonged intake of foods rich in polyphenols could prevent the development of cancer and chronic diseases, such as cardiovascular, neurodegenerative, type 2 diabetes, and obesity. The current work aims to provide an updated overview on the nature and occurrence of polyphenols, quantification methods, bioaccessibility and bioavailability, and impact on human health, namely through interactions with the gut microbiota.