Valorization of Citrus maxima Peel Waste Using Different Drying Methods: Phytochemical Profiling for Eco-Friendly Natural Fertilizer Development for Plant Growth

Phytochemical Characterization of Cucumis callosus towards Potential Valorization: Effect of Maturity Stage and Drying Temperature on Bioactivity of Polyphenols Extracted from Fruit Waste

Cucumis callosus is an underutilized desert fruit with significant nutritional and therapeutic promise. Despite its availability in arid and semi-arid regions, C. callosus remains largely untapped regarding its phytochemical and nutraceutical potential. In this study, three anatomical parts of the fruit- peel, seed, and pulp were investigated across different physiological maturity stages: tender, mature, and old, with particular emphasis on the peel and seeds, which are typically treated as agro-food waste or domestic kitchen waste. Each sample was subjected to various drying methods, including 35°C, 40°C, and 45°C, as well as shade- and sun-drying, to assess the influence of processing conditions on phytochemical retention. Antioxidant activity was evaluated using the DPPH radical scavenging assay, along with quantification of total phenolic content (TPC) and total flavonoid content (TFC), followed by the identification of key metabolites by LC-MS analysis of fruit peel extracts. Principal component analysis of fruit peels revealed a correlation between TPC, TFC, and antioxidant activity. The results revealed marked variations in antioxidant capacity across maturity stages and in response to drying temperatures, highlighting the impact of post-harvest treatment procedures on the bioactive profile of Cucumis callosus. Drying at 35 °C resulted in the highest phytochemical retention, with tender peels exhibiting the maximum TPC- 9.33 ± 0.07 mg GAE/g and TFC 130.78 ± 2.15 mg QE/g, followed by tender seeds TPC: 1.57 ± 0.07 mg GAE/g; TFC- 16.05 ± 0.25 mg QE/g and tender pulp TPC- 1.20 ± 0.04 mg GAE/g; TFC- 12.56 ± 0.29 mg QE/g of the extract. LC–MS analysis of samples dried at 35 °C revealed the presence of bioactive metabolites, including chlorogenic acid, rutin, and ellagic acid in tender peels; rutin, and kaempferol-3-O-neohesperidoside in mature peels; and caffeic acid, vitexin, and methyl ellagic acid in old peels. The findings reveal that fruit components, often treated as waste, possess considerable antioxidant potential, reinforcing sustainable use of the resources and alignment with responsible production and consumption practices (SDG 12). This study also provides foundational data for the potential valorization of this desert fruit as a source of natural antioxidants, supporting its integration into functional food systems or nutraceutical formulations.

Valorizing mango (Mangifera indica) peel and kernel extracts as sustainable edible coatings for preservation of fresh strawberries (Fragaria × ananassa)

Coatings play an imperative role in increasing the shelf life of strawberries and have the potential to minimize post-harvest losses. In this study, the impact of coating formulated from starch, isolated from mango kernel and bioactive compounds, extracted by using three different techniques (conventional solvent extraction, microwave-assisted extraction, and ultrasonic-assisted extraction) and solvents (distilled water, ethanol, and hydro-alcohol) was evaluated. Microwave-assisted extraction using hydro-alcohol resulted in the highest total phenolic content (36.77 mg gallic acid equivalents [GAE]/g), total flavonoid content (23.81 mg QE/g), antioxidant activity (84.78%), and total carotenoid content (9.58 mg/g). Starch-based coating was analyzed for various physico-chemical properties like yield (40.73 ± 0.97%), amylose content (36.68 ± 0.05%), swelling power (16.81 ± 0.03 g/g), solubility power (1.54 ± 0.12 g/g), and gelatinization power (72 ± 3.57 °C). Thus, the effects of edible coating concentrations (2, 4, and 6%) and bioactive compounds (0.5, 1.0, 1.5, and 2.0%) were effective for prolonging the shelf life of strawberries during the storage period. Lowest decrease (12.66, 0.47%, 1.59 mg GAE/g, and 1.96 × 10 4 colony-forming unit (CFU)/g) in physiological weight loss, titratable acidity, total antioxidant activity, and microbial count was recorded in 4% starch, and the highest (19.30, 0.40%, 1.52 mg GAE/g, and 3.40 × 10 4  CFU/g) decrease was recorded in 2% starch. Therefore, the combined effect of starch and bioactive compounds can be integrated into the supply chain management of strawberry fruit to extend storage life, retain maximum quality attributes, marketability, and maintain quality during transport and storage. Coatings are proven to be feasible due to their edible, non-reactive, and biodegradable nature.

Pyrolysis-based valorization of Pinus sylvestris bark waste into bioactive fractions: LC–MS/MS analysis and antioxidant, anti-inflammatory, antidiabetic, and antibacterial activities

In this study, bark waste from the forest industry derived from Pinus sylvestris was processed by pyrolysis extraction, and the chemical compositions and biological activities of the resulting light (PLF) and heavy (PHF) fractions were comparatively investigated. When the extraction yields of the pyrolysis fractions were compared, PHF (20.80%) showed a significantly higher recovery than PLF (10.35%). Total phenolic content (TPC) was higher in the PHF (365.80 GAE/g), whereas total flavonoid content (TFC) was concentrated in the PLF (200.80 mg QE/g). LC–MS/MS analyses of the PHF fraction, which exhibited more pronounced biological activity, revealed caffeic acid (7190.65 µg/g) and protocatechuic acid (2694.30 µg/g) as the predominant phenolic compounds. Antioxidant capacity analyses indicated that the PLF exhibited stronger radical scavenging activity, lower IC50 values in DPPH and ABTS⁺• assays (50.01 and 101.60 µg/mL, respectively) and higher TAC values (901.00 mg TE/L). Fe3+ and Cu2+ reducing assays demonstrated strong redox activity in both fractions, with Cu2+ reducing capacity particularly higher in PLF. In enzyme inhibition studies, the PHF showed stronger inhibition against 5-lipoxygenase (IC50 = 29.28 µg/mL) and α-glucosidase (IC50 = 82.50 µg/mL) compared to PLF. The antibacterial potential of the fractions was assessed using Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis, Staphylococcus aureus, Salmonella typhimurium, and Klebsiella pneumoniae. The PHF exhibited significant inhibition zones, particularly against P. aeruginosa (17.40 mm) and S. aureus (13.40 mm). Consequently, these findings suggest that pyrolysis-based fractionation may be an effective and sustainable method for converting P. sylvestris bark waste into functional fractions with high antioxidant, anti-inflammatory, antidiabetic, and antibacterial potential.

Green extraction of anthocyanins from Solanum betaceum peel by natural deep eutectic solvents: optimization, recycling, and evaluation of antioxidant, anti-inflammatory and skin-whitening activities

This study developed a green and sustainable extraction method for anthocyanins from Solanum betaceum peel using choline chloride–based natural deep eutectic solvents (NADES). Among seven tested systems, the choline chloride−1,4-butanediol (ChCl–BD) NADES exhibited the highest extraction yield (26.8 mg/g), significantly outperforming conventional 60% ethanol (12.3 mg/g). Optimization yielded ideal conditions of 60 °C, 1 h, a solid–liquid ratio of 1:20 g/mL, and 30% water content. The ChCl–BD DES showed good recyclability, retaining over 79% efficiency after four reuse cycles. Characterization by SEM, FTIR, and XRD confirmed effective disruption of the lignocellulosic matrix, facilitating anthocyanin release. Molecular docking revealed stronger interactions between anthocyanins and DES components than ethanol. The DES extract displayed superior thermal and storage stability, low cytotoxicity, and markedly better antioxidant, antibacterial, anti-inflammatory, and tyrosinase-inhibitory activities compared with the ethanol extract. Moreover, the DES extract exhibited enhanced skin permeation in a Franz diffusion cell assay, achieving 33.61% dermal absorption after 4 h. These results demonstrated that ChCl–BD NADES could serve as an efficient, recyclable, and multifunctional extraction platform, producing anthocyanin-rich extracts with promising applications in the fields of functional foods, cosmetics and pharmaceuticals.

Optimizing Bacterial Cellulose from Coffee Husk Waste for Enhanced Vegan Leather Production

Coffee production in Indonesia continues to increase each year, necessitating sustainable waste management to reduce the accumulation of coffee husk waste in the environment. This waste still contains natural carbon sources that can potentially be utilized as a fermentation medium for bacterial cellulose (BC) production, which is promising for vegan leather applications. This study aims to determine the most effective combination of molasses and ammonium sulfate (ZA) to enhance BC production and optimize the BC pretreatment process for vegan leather application. In this study, chemical composition analysis was also carried out using Fourier transform infrared (FTIR) spectroscopy analysis on samples of coffee fruit peel following the thermal delignification process to determine the optimal conditions for the process. BC production was carried out over 14 days with treatment variations of 5%, 10%, and 15% molasses and 0.3%, 0.5%, and 1% ZA. The pretreatment involved pressing and coating with a coconut oil–beeswax mixture, followed by characterization of BC through physicochemical properties, weight, and thickness. The effect of varying concentrations of molasses and ZA in the coffee husk extract medium had an effect on the weight and thickness of the cellulose membrane produced, with optimal results in treatment P3 (10% molasses and 0.3% ZA) (weight 509 g; thickness 9.69 mm). The pH value was measured before and after fermentation and showed a decrease caused by the activity of acetic acid bacteria.

Green Extraction of Phenolic Compounds from Cucumis metuliferus Cultivated in Tunisia Using Microwave-Assisted Extraction: Process Optimization and Biological Activities