Valorization of dragon fruit peel into advanced functional carbon quantum dot/betalain composite films for smart and active beef packaging.

Food waste represents a critical challenge, and transforming food waste into functionalized products is paramount. This study utilized dragon fruit (DF) peel to synthesize carbon quantum dots (CQDs) and extract betalains for multifunctional films to monitor and preserve beef freshness. CQDs synthesis was confirmed through structural, FTIR, XRD, UV-vis, zeta-sizer, and fluorescence spectroscopy. Betalains from DF were incorporated into tricomponent packaging films. These films showed antioxidant and antibacterial properties with CQDs and DF extract, while exhibiting strong UV, water, and oxygen barrier properties. The films displayed color transition in response to pH changes from acidic to alkaline conditions, and were mechanically robust and thermally stable. The films monitored beef freshness, changing color from light pink to yellow to green upon spoilage. The addition of CQDs and DF extract extended beef shelf-life by up to three days. This multifunctional film will enhance active and intelligent packaging systems through real-time freshness indicators and food preservation.