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With the increase in the world population, the overexploitation of the planet's natural resources is becoming a worldwide concern. Changes in the way humankind thinks about production and consumption must be undertaken to protect our planet and our way of living. For this change to occur, sustainable development together with a circular economic approach and responsible consumption are key points. Agriculture activities are responsible for more than 10% of the greenhouse gas emissions; moreover, by 2050, it is expected that food production will increase by 60%. The valorization of food waste is therefore of high importance to decrease the environmental footprint of agricultural activities. Fruits and vegetables are wildly consumed worldwide, and grapes are one of the main producers of greenhouse gases. Grape biomass is rich in bioactive compounds that can be used for the food, pharmaceutical and cosmetic industries, and their extraction from this food residue has been the target of several studies. Among the extraction techniques used for the recovery of bioactive compounds from food waste, subcritical water extraction (SWE) has been the least explored. SWE has several advantages over other extraction techniques such as microwave and ultrasound extraction, allowing high yields with the use of only water as the solvent. Therefore, it can be considered a green extraction method following two of the principles of green chemistry: the use of less hazardous synthesis (principle number 3) and the use of safer solvents and auxiliaries (principle number 5). In addition, two of the green extraction principles for natural products are also followed: the use of alternative solvents or water (principle number 2) and the use of a reduced, robust, controlled and safe unit operation (principle number 5). This review is an overview of the extraction process using the SWE of grape biomass in a perspective of the circular economy through valorization of the bioactive compounds extracted. Future perspectives applied to the SWE are also discussed, as well as its ability to be a green extraction technique. [ABSTRACT FROM AUTHOR]

Different extraction techniques, namely ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), subcritical water extraction (SWE), and conventional extraction (CE), were tested to evaluate their efficiency in recovering bioactive compounds from grapevine by-products. SWE was the extraction technique that allowed for the highest recovery of polyphenolic compounds, while grape stalk from the Cerceal Branco variety obtained using SWE at 150 °C had the highest TPC (17.0 ± 0.2 mgGAE/g fw) as well as the highest antioxidant activity from ABTS and FRAP assays (19.9 ± 0.3 and 13.0 ± 0.3 mgAAE/g fw). The phenolic composition revealed high amounts of catechin, epicatechin, chlorogenic, and neochlorogenic acids. SWE was demonstrated to be a powerful extraction technique for the recovery of polyphenols from grapevine by-products. [ABSTRACT FROM AUTHOR]

In recent years, shrimp consumption has increased, resulting in massive amounts of waste. In this study, different extraction techniques, namely, ultrasound-assisted extraction (UAE), subcritical-water extraction (SWE) and conventional extraction (CE), were tested to evaluate their efficiency in recovering bioactive compounds from shrimp shells. SWE performed at 200 °C was the extraction technique that allowed for the highest recovery of polyphenolic and carotenoid compounds (5.43 ± 0.17 mgGAE/g dw and 59.9 ± 1.0 μg carotenoids/g dw) as well as the highest antioxidant activity in ABTS and FRAP assays (7.93 ± 0.01 and 4.35 ± 0.31 mgAAE/g dw). These results demonstrate the potential of shrimp shells, which can be further incorporated into other products. [ABSTRACT FROM AUTHOR]

The acorn, a fruit of the Quercus genus, is abundant in Portugal and offers a high nutritional content, including essential minerals and vitamins, unsaturated fatty acids, and bioactive compounds like tannins, phenolic acids, and flavonoids. Despite their antioxidant properties, excessive consumption of tannins can cause health problems due to their effect on protein bioavailability. This study evaluated two extraction techniques, water immersion at room temperature for seven days and thermal hydrolysis via boiling for 30 min, and their effects on acorns' tannin and mineral content. The results reveal that both extraction methods are viable options for extracting tannins, although they also reduce some important minerals. [ABSTRACT FROM AUTHOR]

Chayote leaves are known for culinary and traditional medicine applications. This work intended to recover carotenoids and phenolic compounds from chayote leaves using the ultrasound-assisted extraction (UAE). A Box–Behnken design was employed to investigate the impact of extraction time, temperature, and ultrasonic power on the recovery of total carotenoids, total phenolic compounds, and antioxidant activities. For comparative purposes, chayote leaf extracts were prepared by maceration (ME) and microwave-assisted extraction (MAE), using the same time and temperature conditions optimized by UAE. Extraction at 50 °C and 170 Watts for 30 min provided the optimal UAE conditions. UAE showed better extraction efficacy than ME and MAE. The HPLC analysis of the extracts showed that the xanthophyll class was the main class of carotenoids, which constituted 42–85% of the total carotenoid content, followed by β-carotene and tocopherol. Moreover, 26 compounds, classified as phenolic acids, flavonols, flavonoids and other polar compounds, were identified in the chayote leaf extracts. Flavonols accounted for 55% of the total compounds quantified (the major compound was myricetin) and phenolic acids represented around 35%, mostly represented by ferulic acid, chlorogenic acid and (+)-catechin. This study revealed the potential of UAE as an effective green extraction technique to recover bioactive compounds from chayote leaves, for food, and for pharmaceutical and cosmetic applications. [ABSTRACT FROM AUTHOR]