In this work, the inner filter effect (IFE) of caffeine (CF) over the fluorescence signal of glibenclamide (GLB) was used for the determination of CF in beverage samples. The system worked in a turn-off mode since the absorption spectrum of CF overlaps the excitation band of GLB resulting in a decline in its fluorescence signal (λ_exc = 234 nm, λ_em = 350 nm). No changes in the fluorescence lifetime of GLB (0.29 ns) were observed in the presence of CF up to 127.6 mg L⁻¹ concentration. The parameters that affect the fluorescence intensity were investigated, such as fluorophore concentration (16 mg L⁻¹), pH (3.2) and temperature (25 °C). Under optimized conditions, the IFE-based approach can determine CF in a range between 1.00 and 100.0 mg L⁻¹, with a detection limit (LOD) of 0.10 mg L⁻¹. The relative standard deviation (% RSD) values for the intra-day and inter-day precision were 0.75 and 1.24, respectively. The new method was successfully tested in the determination of the target analyte in beverage samples without previous treatment. The results were compared with those obtained by a reference method, leading to the conclusion that there were no significant differences at the studied confidence level (α = 0.05).

Eco-friendly packaging for functional foods aims to reduce environmental impact while maintaining product integrity and ensuring consumer safety. Both the food industry and consumers must transition toward packaging solutions that are sustainable, biodegradable, and non-toxic. Among the key benefits of using environmentally friendly materials for functional food packaging are their sustainability, growing consumer preference, and regulatory compliance. Functional foods are products that offer health benefits beyond basic nutrition, such as enhancing immunity, improving digestion, or promoting overall well-being. This review emphasizes that the packaging of functional foods using an eco-friendly design approach is aligned with the Sustainable Development Goals and the consumers’ preferences. It included the definition and regulatory framework of functional foods, the bioactivity and health effects of bioactive compounds/microorganisms, packaging requirements and solutions for functional foods, as well as conventional and innovative analytical techniques for bioactive compound analysis. Eco-friendly packaging for functional foods is environmentally vital for waste reduction, socially crucial for meeting conscious demand, and economically sound for driving sustainable innovation and green markets.