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.

The physicochemical and biochemical changes during the fermentation of four clones and two native varieties of Theobroma cacao L. were studied. Fermentation was performed in traditional wood cubes. During fermentation, the cotyledon pH decreased, and the temperature increased to more than 10 °C above the ambient temperature (47 °C). The fermentation index (FI) increased in the clones C1, C4, C8, C9, and Guayaquil (G) to close to one at 120 h of fermentation. For the FI of the cocoa Criollo (Cr), a value of 2.5 was proposed according to the spectrophotometric scan performance. The total polyphenol content increased in all the samples from 21 (C8) to 70 (Cr) % in a comparison of the TPC at T0 and T120, respectively. The total flavonoid content increased from 16 (C8) to 51% in Guayaquil (G) during the fermentation period. In the case of the methylxanthines, such as theobromine and caffeine, both quantities decreased. The theobromine content decreased in all the samples from 6 (G) to 31% (C8). The caffeine content decreased in all the samples from 3% in Cr to 25% in C1 and G after fermentation. The antioxidant capability did not change after 120 h of fermentation, and the amount of methylxanthines did not affect the antioxidant potential of the fermented cocoa. The FTIR scan of the fat-free cocoa showed significant differences between the unfermented and fermented beans, and several peaks assigned to carbohydrates and proteins decreased.

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.