Recently, growing demand for products enriched with natural compounds that support human health has been observed. Black rice, its by-products, and residues are known to have in their composition a large amount of these compounds with biological potential, mainly anthocyanins. These compounds have reported effects on anti-obesity, antidiabetic, antimicrobial, anticancer, neuroprotective, and cardiovascular disease. Therefore, the extract from black rice or its by-products have great potential for application as ingredients in functional foods, supplements, or pharmacological formulations. This overview summarizes the methods employed for the extraction of anthocyanins from both black rice and its by-products. In addition, trends in applications of these extracts are also evaluated regarding their biological potential. Commonly, the extraction methods used to recover anthocyanins are conventional (maceration) and some emerging technologies (Ultrasound-Assisted Extraction - UAE, and Microwave-Assisted Extraction - MAE). Anthocyanin-rich extracts from black rice have presented a biological potential for human health. In vitro and in vivo assays (in mice) showed these compounds mainly with anti-cancer properties. However, more clinical trials are still needed to prove these potential biological effects. Extracts from black rice and its by-products have great potential in applying functional products with beneficial characteristics to humans and reducing agro-industrial residues.

The production of kombucha generates as fermentation products a beverage and also bacterial cellulose (BC). Despite several studies on the production and characteristics of the beverage, BC from kombucha is still little explored and there are not many reports on the reuse of this material. The main objective of the present study was to demonstrate typical kombucha fermentation results in a satisfactory amount of BC with morphological and physicochemical characteristics similar to those produced in synthetic medium. For this, the fermentation kinetics for obtaining kombucha beverage and bacterial cellulose (BC) were evaluated in a medium containing green tea and sugar. The microbial composition of the culture was identified and Komagataeibacter rhaeticus proved to be the main strain responsible for BC production. The fermentation showed typical behavior with the production of acetic acid, citric acid, ethanol, and a slight increase in total phenolic content and antioxidant activity. The final concentration of 4.56 g/L of BC was obtained and identified as type I, showing a structure of fine tangled fibers and crystallinity of 74.3%. Knowing that there is a high demand for cellulose in many areas, BC produced by the kombucha industry can be an alternative source to the conventional production method.