The potential of citrus by-products in the development of functional food and active packaging

Unlocking the Potential of Citrus medica L.: Antioxidant Capacity and Phenolic Profile across Peel, Pulp, and Seeds

Citrus medica L. is a traditional citrus fruit that is rich in bioactive compounds and has the potential to be used as a natural source of food additives. This study aims to evaluate the antioxidant capacity and characterize the phenolic compounds present in the peels (including flavedo and albedo), pulp, and seeds of citron. The results showed that, compared to the other parts, the pulp had a substantially higher Antioxidant Activity Coefficient (AAC) of 168.2. The albedo and the seeds had significantly lower AAC values, while the green and yellow flavedo showed noteworthy results. O-coumaric acid was the predominant phenolic acid in all of the citron fractions; it was found in the highest concentration in albedo (37.54 µg/g FW). Flavanones and flavanols were the primary flavonoids in the pulp, peel, and seeds, with total flavonoid concentration ranging from ~9 µg/g FW in seeds to 508 µg/g FW in the pulp. This research offers significant insights into the antioxidant properties of this ancient fruit, emphasizing its potential applications as a natural source of antioxidants to be used in different applications.

Formulation of Antioxidant Gummies Based on Gelatin Enriched with Citrus Fruit Peels Extract

In this work, the peels of red and blonde oranges as well as lemons were efficiently (5.75-9.65% yield) extracted by hydroalcoholic solution with ultrasound assistance and employed as active molecule sources in the preparation of functional gummies. Antioxidant performances of the hydroalcoholic extracts were characterized by colorimetric assays, whereas LC-HRMS analyses identified the main bioactive compounds (phenolic acids and flavonoids). The highest scavenging activity was recorded for lemon extract in an aqueous environment (IC50 = 0.081 mg mL-1). An ecofriendly grafting procedure was performed to anchor polyphenols to gelatin chains, providing macromolecular systems characterized by thermal analysis and antioxidant properties. Scavenger abilities (IC50 = 0.201-0.454 mg mL-1) allowed the employment of the conjugates as functional ingredients in the preparation of gummies with remarkable antioxidant and rheological properties over time (14 days). These findings confirmed the possible employment of highly polluting wastes as valuable sources of bioactive compounds for functional gummies preparation.