Prickly pear (Opuntia ficus-indica L. Miller) is a natural source of antioxidant compounds that have gained significant attention due to their potential health benefits. This study aims to investigate the effectiveness of pressurized liquid extraction (PLE) and Ultrasound-Assisted Extraction (UAE), combined with water–ethanol mixtures from 0 to 60%, at moderate temperatures between 50 °C to 70 °C to improve the recovery of antioxidant compounds from red peel prickly pear. The recovery of these compounds was affected by solvent composition and temperature for both extraction techniques. Interestingly, the use of pure water at 70 °C during the PLE process allowed the recovery of high concentrations of antioxidant compounds (12.96 mg GAE/g dw, IC_5O: 2.03 mg/mL, ORAC: 625 µmol TE/g dw). On the contrary, when the UAE process was combined with 30% ethanol at 50 °C, the extractability of these compounds (10.52 mg GAE/g dw, IC_5O: 3.09 mg/mL, ORAC: 561.26 µmol TE/g dw) was improved. In addition, different solvent compositions were identified to improve the recovery of specific polyphenols. For PLE, pure water at 70 °C was effective in recovering phenolic acids, flavanols, and flavonols, while the highest concentrations of stilbenes were obtained with 60% ethanol at 70 °C. For UAE, the use of 30% ethanol at 50 °C was more effective in extracting phenolic acids and stilbenes, whereas pure water at 50 °C provided high concentrations of flavanols and flavonols. These results contribute to the development of sustainable and efficient extraction strategies for obtaining antioxidant-rich extracts from prickly pear peel with important applications in functional foods, nutraceuticals, and pharmaceutical industries.

Edible mushrooms are well-known for their culinary and nutritional values. Additionally, they serve as a natural source of polyphenols, a group of bioactive compounds that significantly treat diseases associated with oxidative stress. The polyphenolic profile of mushrooms mainly consists of phenolic acids and flavonoids, whose chemical properties have attracted the attention of both the food and pharmaceutical industries. Consequently, methods for extracting polyphenols from mushrooms encompass conventional techniques (maceration and Soxhlet extraction) as well as innovative or green methods (ultrasound-assisted extraction, microwave-assisted extraction, pressurized liquid extraction, supercritical fluid extraction, enzyme-assisted extraction, and pulsed electric field extraction). Nonetheless, extraction with pressurized liquids and supercritical fluids is considered the most suitable method, as they function in a gentle and selective manner, preserving the integrity of the phenolic compounds. The use of mushroom-derived phenolic compounds in food and pharmaceutical formulations continues to face challenges concerning the safety of these extracts, as they might contain unwanted substances. Future applications should incorporate purification systems to yield highly pure extracts, thereby creating safe polyphenol carriers (for food and pharmaceutical products) for consumers.

The olive industry produces large quantities of olive leaves, an agro-industrial byproduct without commercial value and with significant environmental disposal challenges. However, olive leaves are a rich source of antioxidant compounds known for their diverse biological properties. This highlights the need for green processes that utilize environmentally friendly solvents. Thus, this research aimed to evaluate the effectiveness of two different solvents: ethanol (at concentrations of 0%, 15%, and 30%) and glycerol (also at 0%, 15%, and 30%), combined with moderate temperatures (50 °C and 70 °C) using ultrasound-assisted extraction (20 kHz and 60% amplitude for 30 min) to recover antioxidant compounds from olive leaves. Our results showed that 30% glycerol at 70 °C was more effective at recovering polyphenols (14.85 ± 0.09 mg GAE g⁻¹ dw) compared to ethanol (12.26 ± 0.13 mg GAE g⁻¹ dw) under the same conditions. Additionally, the antioxidant capacity, measured using DPPH and ORAC assays, yielded higher results with 30% glycerol, showing values of 2.65 ± 0.16 mg mL⁻¹ and 684.65 ± 20.79 µmol TE g⁻¹ dw, respectively. The polyphenol profile quantified different families of polyphenols like phenolic acids, flavanols, flavonols, stilbenes, and secoiridoids. However, oleuropein, a secoiridoid, was the most predominant polyphenol found in the extracts (1122.52 ± 33.72 μg g⁻¹ dw). Interestingly, the use of 30% ethanol at 70 °C reduced the glucose and fructose content by 48% and 84%, respectively. Therefore, glycerol emerges as an efficient green solvent for the extraction of antioxidant compounds. These findings support the valorization of this agricultural residue by recovering its valuable components, contributing to food sustainability and a circular economy.

The formation of toxic compounds such as acrylamide (AA) and hydroxymethylfurfural (HMF) during thermal food processing (>120 °C) represents a significant risk to human health, as they have been associated with neurotoxic, genotoxic, and carcinogenic effects. However, several studies have shown that polyphenols can reduce the levels of these toxic compounds. In this context, this review examines the potential of polyphenols to mitigate the formation of AA and HMF via distinct mechanisms during the Maillard reaction (MR). In general, these compounds interact with precursors and intermediates of the MR. Thus, polyphenols represent a natural and effective strategy for improving food safety, thereby promoting the development of healthier products. However, Future challenges remain, including the elucidation of the chemical mechanisms involved in the action of polyphenols, an in-depth study of factors such as pH, temperature, and food matrix, toxicological and metabolic evaluations, regulatory aspects, the use of clean and sustainable technologies for obtaining polyphenols, optimization of extraction methods, and application in food matrices while considering sensory effects. A multidisciplinary approach will be vital to achieving the effective and safe application of polyphenols in the food industry.

Oca (Oxalis tuberosa) skin is considered an agroindustrial waste byproduct, which currently holds no economic value. Nevertheless, this waste is a natural source of antioxidant compounds, which can be recovered through the use of sustainable technologies. Thus, this study aims to evaluate and compare the efficacy of 15% ethanol combined with two extraction techniques like solid–liquid extraction (SLE) and pressurized liquid extraction (PLE) for the recovery of antioxidant compounds from five oca skin cultivars. Regardless of the oca cultivar, the use of PLE was more efficient for obtaining extracts rich in polyphenol with high antioxidant capacity compared to the SLE process. Under PLE conditions, Pachatusan and Yawar cultivars presented the highest value of total polyphenols and antioxidant capacity. In comparison, the QuesWe and Pachatusan cultivars presented the lowest values. Polyphenol profile analysis showed that the PLE process effectively disrupted the cell wall matrix, resulting in a greater release of monomers (gallic acid, catechin, and epicatechin) and procyanidin B2 compared to the SLE process, while procyanidin A2 was more efficiently recovered under SLE, particularly in the Pachatusan cultivar. Principal component analysis (PCA) confirmed cultivar-dependent polyphenolic patterns, explaining 81.7% and 84.8% of total variance for SLE and PLE, respectively, with PLE generating more pronounced differentiation among cultivars driven by catechin, epicatechin, and gallic acid. The integration of PLE technology with the Oca skin framework facilitates the standardized production of extracts rich in antioxidants. Future research should concentrate on evaluating the stability of these specific dimers within food matrices, as well as their bioavailability in human clinical models.