In this study, we investigate the valorization of asparagus processing by-products—cut-off waste (CAW) and whole asparagus waste (WAW)—as sources of bioactive compounds, primarily polyphenolics, and their conjugation with chitosan (CS) to enhance their antioxidant and antibacterial properties, with potential applications as a food-preservation additive. Aqueous (CAWaq, WAWaq) and ethanolic (CAWet, WAWet) extracts were prepared and characterized to determine total phenol and flavonoid content, antioxidant capacity, and polyphenolic compound profile. Among the extracts, WAWaq exhibited the highest antioxidant activity, with a total phenolic content of 9.93 mg gallic acid equivalents/g DW, and quercetin, rutin, and phenolic acids were identified as major constituents. A novel conjugate (WAWaq–CS) was synthesized via free-radical-mediated chemical modification of chitosan with WAWaq and characterized by means of ultraviolet-visible (UV–vis) and Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and determination of bioactive properties. WAWaq-CS improved the antioxidant activity of chitosan and exhibited selective inhibition of Staphylococcus aureus across all tested concentrations, inducing cell death, as confirmed by resazurin viability and optical density measurements. Conversely, Pediococcus acidilactici maintained viability at low concentrations, preserving probiotic functionality in antibacterial systems. These findings indicate the potential of asparagus waste extract–chitosan conjugates as sustainable materials with dual functionality, highlighting the transformation of agro-industrial residues into functional materials for active food packaging and food preservation.
Moreno-Robles et al. (Sun,) studied this question.