The pineapple (Ananas comosus) is one of the most commercialized tropical fruits worldwide. Its high processing and consumption generate huge quantities of organic waste and severe economic and environmental issues. Embracing the circular bioeconomy concept, this fruit waste can be applied as a bioresource (raw material) for the obtention of a wide range of high-valued biocompounds by applying innovative and ecofriendly technologies. In this paper, we critically describe pineapple-derived waste, from their chemical composition to their functional and biological properties, as well as the latest advances on valorization technologies, particular solid and submerged fermentations. Notably, this article highlights the possibility of using pineapple waste to obtain bioactive compounds such as bromelain, phenolic compounds, and dietary fiber, which have important biological properties such as antioxidant, anticancer, antimicrobial, and prebiotic capacities. Indeed, pineapple wastes can become valued materials by using green and biotechnological technologies that allow us to maximize their potential and might avoid wastage and environmental issues. Nevertheless, it is necessary to further investigate the biomolecules present in the waste derived from different pineapple varieties and their health beneficial effects as well as emerging technologies in order to obtain a full spectrum of natural value-added compounds that industries and society demand today.

The exploration of natural antimicrobial compounds is necessary due to the current bacterial resistance to synthetic antibiotics. For this reason, pineapple residues were evaluated as a natural source of phenolic compounds with antimicrobial capacity. Pineapple residues were fermented with A. niger GH1 and subjected to ultrasound for the extraction of phenolic compounds. In the solid-state fermentation (SSF), the peel and the core (70:30) were fermented for 32 h. Ultrasonic-assisted extraction (UAE) was optimized. The factors solid–liquid ratio (X1), ethanol concentration (X2), and extraction cycle (X3) were optimized through a Box–Behnken statistical design, using the total phenol content (TPC) as a response variable. The optimized and pre-purified extract with amberlite was characterized using HPLC-MS and we measured the antimicrobial activity against Listeria monocytogenes, Staphylococcus aureus, and Escherichia coli. The optimal values for X1, X2, and X3 were 82 mg/mL, 26%, and two cycles, respectively. The extract was effective as an antimicrobial agent against S. aureus and L. monocytogenes, with MICs of 50 mg/mL and 12.5 mg/mL, respectively; the bacterial growth curve and transmission electron microscopy (TEM) confirmed the antimicrobial activity. The main compounds identified in the antimicrobial extract were 3,4-DHPEA-EA, Phloretin 2′-O-xylosyl-glucoside, and Feruloyl tartaric acid. Overall, the combination SSF-UAE showed to be a promising strategy to recover phenolic compounds from pineapple residues, exhibiting great potential as a natural antimicrobial agent.