This study aimed to evaluate the effect of pretreatments and extraction conditions on the antioxidant and antifungal characteristics of garlic peel extracts. The effect of pretreatments (fermentation and steam cooking) on the yield, antifungal (Colletotrichum gloeosporioides and Botrytis cinerea), and antioxidant (total phenolic compounds, total flavonoids, and antioxidant capacity) properties of garlic peel extracts were evaluated. A selected pretreatment was applied to evaluate the extraction conditions (solvent, solvent concentration, temperature, and time) on the antifungal activity of garlic peel extracts. At last, garlic peel extracts obtained under specific conditions was applied to papaya and strawberry fruits as preventive and curative treatments against Colletotrichum gloeosporioides and Botrytis cinerea, respectively. Steam cooking pretreatment significantly increased the antifungal and antioxidant capacities of garlic peel extracts compared to the fermentation process. Garlic peel extracts obtained with methanol (60%) for 18 h (25 °C) showed the highest antifungal activity against both microorganisms assessed (57.57% and 75.76% for B. cinerea and C. gloeosporioides, respectively,) on in vitro assays. Moreover, in vivo results indicated that preventive treatment significantly reduced rot disease in papaya (88.95%) and strawberry (54.13%) fruits. Although more studies about the antifungal mechanisms of garlic peel extracts are needed, these results indicated that garlic peel extracts could be used as an antifungal agent.

This study investigates agro-industrial by-products as sources of bioactive compounds, particularly focusing on phenolic compounds known for their antioxidant properties. With growing interest in natural alternatives to synthetic antioxidants due to safety concerns, this study highlights the health benefits of plant-derived phenolic compounds in food preservation and healthcare products. Traditional and advanced analytical techniques were used to obtain phytochemical profiles of various residue extracts, including espresso (SCG) and cold-brew spent coffee grounds (CBCG), pineapple peel (PP), beetroot pomace (BP), apple pomace (AP), black carrot pomace (BCP), and garlic peel (GP). Assessments of total phenolic content (TPC), total flavonoid content (TFC), and antioxidant capacity (AC) supported their revalorization. CBCG showed the highest TPC, TFC, and AC. TPC content in by-products decreased in the order CBCG > SCG > GP > BCP > PP > AP > BP, with a similar trend for TFC and AC. Phytochemical profiling via FI-ESI-FTICR-MS enabled the preliminary putative identification of a range of compounds, with polyphenols and terpenes being the most abundant. Univariate and multivariate analyses revealed key patterns among samples. Strong positive correlations (Pearson’s R > 0.8) indicated significant contribution of polyphenols to antioxidant capacities. These findings highlight the potential of agro-industrial residues as natural antioxidants, advocating for their sustainable utilization.

Apple, pear and grape pomaces are underexploited sources of phenolic compounds, potential natural alternatives to synthetic antioxidants. This study evaluated their cold-macerated (4 °C) extracts in ghee and in butter packaged in active chitosan films. Extracts were obtained under a 2² factorial design (water or absolute ethanol; 24 or 48 h). Ethanol yielded higher total phenolic content (TPC) and antioxidant capacity than water, particularly in grape pomace. The 48 h ethanolic extracts of apple (AP-E), pear (PP-E) and grape (GP-E) pomaces were selected for their higher TPC and antioxidant capacity; GP-E showed an IC₅₀ at least 94% lower than AP-E and PP-E in 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays. In ghee under accelerated storage (30, 45 and 60 °C, 35 days), extracts were compared to a synthetic Butylated Hydroxyanisole/Butylated hydroxytoluene (BHA/BHT) blend using oxidation kinetics and Arrhenius modeling. GP-E exhibited the lowest oxidation rate constants at all temperatures, significantly below BHA/BHT. PP-E did not differ significantly from the synthetic blend at 45 and 60 °C, and AP-E presented no significant effect at 60 °C. In butter wrapped in functionalized chitosan films (15 days storage at 21 and 30 °C), GP-E films produced the lowest oxidation values. PP-E films did not differ significantly from polyethylene control. These results suggest GP-E, and to a lesser extent PP-E, as a potential natural antioxidant for high-fat dairy matrices.